A Concise Binary Object Representation (CBOR)-based Serialization Format for the Software Updates for Internet of Things (SUIT) Manifest
draft-ietf-suit-manifest-12
SUIT B. Moran
Internet-Draft H. Tschofenig
Intended status: Standards Track Arm Limited
Expires: August 26, 2021 H. Birkholz
Fraunhofer SIT
K. Zandberg
Inria
February 22, 2021
A Concise Binary Object Representation (CBOR)-based Serialization Format
for the Software Updates for Internet of Things (SUIT) Manifest
draft-ietf-suit-manifest-12
Abstract
This specification describes the format of a manifest. A manifest is
a bundle of metadata about code/data obtained by a recipient (chiefly
the firmware for an IoT device), where to find the that code/data,
the devices to which it applies, and cryptographic information
protecting the manifest. Software updates and Trusted Invocation
both tend to use sequences of common operations, so the manifest
encodes those sequences of operations, rather than declaring the
metadata.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 26, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 6
3. How to use this Document . . . . . . . . . . . . . . . . . . 8
4. Background . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1. IoT Firmware Update Constraints . . . . . . . . . . . . . 9
4.2. SUIT Workflow Model . . . . . . . . . . . . . . . . . . . 10
5. Metadata Structure Overview . . . . . . . . . . . . . . . . . 11
5.1. Envelope . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2. Delegation Chains . . . . . . . . . . . . . . . . . . . . 13
5.3. Authentication Block . . . . . . . . . . . . . . . . . . 13
5.4. Manifest . . . . . . . . . . . . . . . . . . . . . . . . 14
5.4.1. Critical Metadata . . . . . . . . . . . . . . . . . . 14
5.4.2. Common . . . . . . . . . . . . . . . . . . . . . . . 14
5.4.3. Command Sequences . . . . . . . . . . . . . . . . . . 14
5.4.4. Integrity Check Values . . . . . . . . . . . . . . . 15
5.4.5. Human-Readable Text . . . . . . . . . . . . . . . . . 15
5.5. Severable Elements . . . . . . . . . . . . . . . . . . . 15
5.6. Integrated Dependencies and Payloads . . . . . . . . . . 16
6. Manifest Processor Behavior . . . . . . . . . . . . . . . . . 16
6.1. Manifest Processor Setup . . . . . . . . . . . . . . . . 16
6.2. Required Checks . . . . . . . . . . . . . . . . . . . . . 17
6.2.1. Minimizing Signature Verifications . . . . . . . . . 19
6.3. Interpreter Fundamental Properties . . . . . . . . . . . 20
6.4. Abstract Machine Description . . . . . . . . . . . . . . 20
6.5. Special Cases of Component Index and Dependency Index . . 23
6.6. Serialized Processing Interpreter . . . . . . . . . . . . 24
6.7. Parallel Processing Interpreter . . . . . . . . . . . . . 25
6.8. Processing Dependencies . . . . . . . . . . . . . . . . . 25
6.9. Multiple Manifest Processors . . . . . . . . . . . . . . 26
7. Creating Manifests . . . . . . . . . . . . . . . . . . . . . 27
7.1. Compatibility Check Template . . . . . . . . . . . . . . 28
7.2. Trusted Invocation Template . . . . . . . . . . . . . . . 28
7.3. Component Download Template . . . . . . . . . . . . . . . 28
7.4. Install Template . . . . . . . . . . . . . . . . . . . . 29
7.5. Install and Transform Template . . . . . . . . . . . . . 30
7.6. Integrated Payload Template . . . . . . . . . . . . . . . 31
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7.7. Load from Nonvolatile Storage Template . . . . . . . . . 31
7.8. Load & Decompress from Nonvolatile Storage Template . . . 31
7.9. Dependency Template . . . . . . . . . . . . . . . . . . . 32
7.9.1. Composite Manifests . . . . . . . . . . . . . . . . . 33
7.10. Encrypted Manifest Template . . . . . . . . . . . . . . . 33
7.11. A/B Image Template . . . . . . . . . . . . . . . . . . . 34
8. Metadata Structure . . . . . . . . . . . . . . . . . . . . . 35
8.1. Encoding Considerations . . . . . . . . . . . . . . . . . 35
8.2. Envelope . . . . . . . . . . . . . . . . . . . . . . . . 36
8.3. Delegation Chains . . . . . . . . . . . . . . . . . . . . 36
8.4. Authenticated Manifests . . . . . . . . . . . . . . . . . 36
8.5. Encrypted Manifests . . . . . . . . . . . . . . . . . . . 37
8.6. Manifest . . . . . . . . . . . . . . . . . . . . . . . . 37
8.6.1. suit-manifest-version . . . . . . . . . . . . . . . . 38
8.6.2. suit-manifest-sequence-number . . . . . . . . . . . . 38
8.6.3. suit-reference-uri . . . . . . . . . . . . . . . . . 38
8.6.4. suit-text . . . . . . . . . . . . . . . . . . . . . . 38
8.7. text-version-required . . . . . . . . . . . . . . . . . . 40
8.7.1. suit-coswid . . . . . . . . . . . . . . . . . . . . . 40
8.7.2. suit-common . . . . . . . . . . . . . . . . . . . . . 40
8.7.3. SUIT_Command_Sequence . . . . . . . . . . . . . . . . 42
8.7.4. Reporting Policy . . . . . . . . . . . . . . . . . . 44
8.7.5. SUIT_Parameters . . . . . . . . . . . . . . . . . . . 46
8.7.6. SUIT_Condition . . . . . . . . . . . . . . . . . . . 56
8.7.7. SUIT_Directive . . . . . . . . . . . . . . . . . . . 60
8.7.8. suit-directive-garbage-collect . . . . . . . . . . . 67
8.7.9. Integrity Check Values . . . . . . . . . . . . . . . 68
8.8. Severable Elements . . . . . . . . . . . . . . . . . . . 68
9. Access Control Lists . . . . . . . . . . . . . . . . . . . . 69
10. SUIT Digest Container . . . . . . . . . . . . . . . . . . . . 69
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 69
11.1. SUIT Commands . . . . . . . . . . . . . . . . . . . . . 70
11.2. SUIT Parameters . . . . . . . . . . . . . . . . . . . . 72
11.3. SUIT Text Values . . . . . . . . . . . . . . . . . . . . 73
11.4. SUIT Component Text Values . . . . . . . . . . . . . . . 73
11.5. SUIT Algorithm Identifiers . . . . . . . . . . . . . . . 73
11.5.1. SUIT Digest Algorithm Identifiers . . . . . . . . . 73
11.5.2. SUIT Compression Algorithm Identifiers . . . . . . . 74
11.5.3. Unpack Algorithms . . . . . . . . . . . . . . . . . 74
12. Security Considerations . . . . . . . . . . . . . . . . . . . 75
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 75
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 75
14.1. Normative References . . . . . . . . . . . . . . . . . . 75
14.2. Informative References . . . . . . . . . . . . . . . . . 76
Appendix A. A. Full CDDL . . . . . . . . . . . . . . . . . . . . 78
Appendix B. B. Examples . . . . . . . . . . . . . . . . . . . . 87
B.1. Example 0: Secure Boot . . . . . . . . . . . . . . . . . 88
B.2. Example 1: Simultaneous Download and Installation of
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Payload . . . . . . . . . . . . . . . . . . . . . . . . . 90
B.3. Example 2: Simultaneous Download, Installation, Secure
Boot, Severed Fields . . . . . . . . . . . . . . . . . . 92
B.4. Example 3: A/B images . . . . . . . . . . . . . . . . . . 96
B.5. Example 4: Load and Decompress from External Storage . . 99
B.6. Example 5: Two Images . . . . . . . . . . . . . . . . . . 102
Appendix C. C. Design Rational . . . . . . . . . . . . . . . . . 105
C.1. C.1 Design Rationale: Envelope . . . . . . . . . . . . . 106
C.2. C.2 Byte String Wrappers . . . . . . . . . . . . . . . . 107
Appendix D. D. Implementation Conformance Matrix . . . . . . . . 107
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 111
1. Introduction
A firmware update mechanism is an essential security feature for IoT
devices to deal with vulnerabilities. While the transport of
firmware images to the devices themselves is important there are
already various techniques available. Equally important is the
inclusion of metadata about the conveyed firmware image (in the form
of a manifest) and the use of a security wrapper to provide end-to-
end security protection to detect modifications and (optionally) to
make reverse engineering more difficult. End-to-end security allows
the author, who builds the firmware image, to be sure that no other
party (including potential adversaries) can install firmware updates
on IoT devices without adequate privileges. For confidentiality
protected firmware images it is additionally required to encrypt the
firmware image. Starting security protection at the author is a risk
mitigation technique so firmware images and manifests can be stored
on untrusted repositories; it also reduces the scope of a compromise
of any repository or intermediate system to be no worse than a denial
of service.
A manifest is a bundle of metadata describing one or more code or
data payloads and how to:
- Obtain any dependencies
- Obtain the payload(s)
- Install them
- Verify them
- Load them into memory
- Invoke them
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This specification defines the SUIT manifest format and it is
intended to meet several goals:
- Meet the requirements defined in
[I-D.ietf-suit-information-model].
- Simple to parse on a constrained node
- Simple to process on a constrained node
- Compact encoding
- Comprehensible by an intermediate system
- Expressive enough to enable advanced use cases on advanced nodes
- Extensible
The SUIT manifest can be used for a variety of purposes throughout
its lifecycle, such as:
- a Firmware Author to reason about releasing a firmware.
- a Network Operator to reason about compatibility of a firmware.
- a Device Operator to reason about the impact of a firmware.
- the Device Operator to manage distribution of firmware to devices.
- a Plant Manager to reason about timing and acceptance of firmware
updates.
- a device to reason about the authority & authenticity of a
firmware prior to installation.
- a device to reason about the applicability of a firmware.
- a device to reason about the installation of a firmware.
- a device to reason about the authenticity & encoding of a firmware
at boot.
Each of these uses happens at a different stage of the manifest
lifecycle, so each has different requirements.
It is assumed that the reader is familiar with the high-level
firmware update architecture [I-D.ietf-suit-architecture] and the
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threats, requirements, and user stories in
[I-D.ietf-suit-information-model].
The design of this specification is based on an observation that the
vast majority of operations that a device can perform during an
update or Trusted Invocation are composed of a small group of
operations:
- Copy some data from one place to another
- Transform some data
- Digest some data and compare to an expected value
- Compare some system parameters to an expected value
- Run some code
In this document, these operations are called commands. Commands are
classed as either conditions or directives. Conditions have no side-
effects, while directives do have side-effects. Conceptually, a
sequence of commands is like a script but the used language is
tailored to software updates and Trusted Invocation.
The available commands support simple steps, such as copying a
firmware image from one place to another, checking that a firmware
image is correct, verifying that the specified firmware is the
correct firmware for the device, or unpacking a firmware. By using
these steps in different orders and changing the parameters they use,
a broad range of use cases can be supported. The SUIT manifest uses
this observation to optimize metadata for consumption by constrained
devices.
While the SUIT manifest is informed by and optimized for firmware
update and Trusted Invocation use cases, there is nothing in the
[I-D.ietf-suit-information-model] that restricts its use to only
those use cases. Other use cases include the management of trusted
applications (TAs) in a Trusted Execution Environment (TEE), as
discussed in [I-D.ietf-teep-architecture].
2. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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Additionally, the following terminology is used throughout this
document:
- SUIT: Software Update for the Internet of Things, also the IETF
working group for this standard.
- Payload: A piece of information to be delivered. Typically
Firmware for the purposes of SUIT.
- Resource: A piece of information that is used to construct a
payload.
- Manifest: A manifest is a bundle of metadata about the firmware
for an IoT device, where to find the firmware, and the devices to
which it applies.
- Envelope: A container with the manifest, an authentication wrapper
with cryptographic information protecting the manifest,
authorization information, and severable elements (see: TBD).
- Update: One or more manifests that describe one or more payloads.
- Update Authority: The owner of a cryptographic key used to sign
updates, trusted by Recipients.
- Recipient: The system, typically an IoT device, that receives and
processes a manifest.
- Manifest Processor: A component of the Recipient that consumes
Manifests and executes the commands in the Manifest.
- Component: An updatable logical block of the Firmware, Software,
configuration, or data of the Recipient.
- Component Set: A group of interdependent Components that must be
updated simultaneously.
- Command: A Condition or a Directive.
- Condition: A test for a property of the Recipient or its
Components.
- Directive: An action for the Recipient to perform.
- Trusted Invocation: A process by which a system ensures that only
trusted code is executed, for example secure boot or launching a
Trusted Application.
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- A/B images: Dividing a Recipient's storage into two or more
bootable images, at different offsets, such that the active image
can write to the inactive image(s).
- Record: The result of a Command and any metadata about it.
- Report: A list of Records.
- Procedure: The process of invoking one or more sequences of
commands.
- Update Procedure: A procedure that updates a Recipient by fetching
dependencies and images, and installing them.
- Invocation Procedure: A procedure in which a Recipient verifies
dependencies and images, loading images, and invokes one or more
image.
- Software: Instructions and data that allow a Recipient to perform
a useful function.
- Firmware: Software that is typically changed infrequently, stored
in nonvolatile memory, and small enough to apply to [RFC7228]
Class 0-2 devices.
- Image: Information that a Recipient uses to perform its function,
typically firmware/software, configuration, or resource data such
as text or images. Also, a Payload, once installed is an Image.
- Slot: One of several possible storage locations for a given
Component, typically used in A/B image systems
- Abort: An event in which the Manifest Processor immediately halts
execution of the current Procedure. It creates a Record of an
error condition.
3. How to use this Document
This specification covers five aspects of firmware update:
- Section 4 describes the device constraints, use cases, and design
principles that informed the structure of the manifest.
- Section 5 gives a general overview of the metadata structure to
inform the following sections
- Section 6 describes what actions a Manifest processor should take.
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- Section 7 describes the process of creating a Manifest.
- Section 8 specifies the content of the Envelope and the Manifest.
To implement an updatable device, see Section 6 and Section 8. To
implement a tool that generates updates, see Section 7 and Section 8.
The IANA consideration section, see Section 11, provides instructions
to IANA to create several registries. This section also provides the
CBOR labels for the structures defined in this document.
The complete CDDL description is provided in Appendix A, examples are
given in Appendix B and a design rational is offered in Appendix C.
Finally, Appendix D gives a summarize of the mandatory-to-implement
features of this specification.
4. Background
Distributing software updates to diverse devices with diverse trust
anchors in a coordinated system presents unique challenges. Devices
have a broad set of constraints, requiring different metadata to make
appropriate decisions. There may be many actors in production IoT
systems, each of whom has some authority. Distributing firmware in
such a multi-party environment presents additional challenges. Each
party requires a different subset of data. Some data may not be
accessible to all parties. Multiple signatures may be required from
parties with different authorities. This topic is covered in more
depth in [I-D.ietf-suit-architecture]. The security aspects are
described in [I-D.ietf-suit-information-model].
4.1. IoT Firmware Update Constraints
The various constraints of IoT devices and the range of use cases
that need to be supported create a broad set of requirements. For
example, devices with:
- limited processing power and storage may require a simple
representation of metadata.
- bandwidth constraints may require firmware compression or partial
update support.
- bootloader complexity constraints may require simple selection
between two bootable images.
- small internal storage may require external storage support.
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- multiple microcontrollers may require coordinated update of all
applications.
- large storage and complex functionality may require parallel
update of many software components.
- extra information may need to be conveyed in the manifest in the
earlier stages of the device lifecycle before those data items are
stripped when the manifest is delivered to a constrained device.
Supporting the requirements introduced by the constraints on IoT
devices requires the flexibility to represent a diverse set of
possible metadata, but also requires that the encoding is kept
simple.
4.2. SUIT Workflow Model
There are several fundamental assumptions that inform the model of
Update Procedure workflow:
- Compatibility must be checked before any other operation is
performed.
- All dependency manifests should be present before any payload is
fetched.
- In some applications, payloads must be fetched and validated prior
to installation.
There are several fundamental assumptions that inform the model of
the Invocation Procedure workflow:
- Compatibility must be checked before any other operation is
performed.
- All dependencies and payloads must be validated prior to loading.
- All loaded images must be validated prior to execution.
Based on these assumptions, the manifest is structured to work with a
pull parser, where each section of the manifest is used in sequence.
The expected workflow for a Recipient installing an update can be
broken down into five steps:
1. Verify the signature of the manifest.
2. Verify the applicability of the manifest.
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3. Resolve dependencies.
4. Fetch payload(s).
5. Install payload(s).
When installation is complete, similar information can be used for
validating and running images in a further three steps:
1. Verify image(s).
2. Load image(s).
3. Run image(s).
If verification and running is implemented in a bootloader, then the
bootloader MUST also verify the signature of the manifest and the
applicability of the manifest in order to implement secure boot
workflows. The bootloader may add its own authentication, e.g. a
Message Authentication Code (MAC), to the manifest in order to
prevent further verifications.
When multiple manifests are used for an update, each manifest's steps
occur in a lockstep fashion; all manifests have dependency resolution
performed before any manifest performs a payload fetch, etc.
5. Metadata Structure Overview
This section provides a high level overview of the manifest
structure. The full description of the manifest structure is in
Section 8.6
The manifest is structured from several key components:
1. The Envelope (see Section 5.1) contains Delegation Chains, the
Authentication Block, the Manifest, any Severable Elements, and
any Integrated Payloads or Dependencies.
2. Delegation Chains (see Section 5.2) allow a Recipient to work
from one of its Trust Anchors to an authority of the
Authentication Block.
3. The Authentication Block (see Section 5.3) contains a list of
signatures or MACs of the manifest..
4. The Manifest (see Section 5.4) contains all critical, non-
severable metadata that the Recipient requires. It is further
broken down into:
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1. Critical metadata, such as sequence number.
2. Common metadata, including lists of dependencies and affected
components.
3. Command sequences, directing the Recipient how to install and
use the payload(s).
4. Integrity check values for severable elements.
5. Severable elements (see Section 5.5).
6. Integrated dependencies (see Section 5.6).
7. Integrated payloads (see Section 5.6).
The diagram below illustrates the hierarchy of the Envelope.
+-------------------------+
| Envelope |
+-------------------------+
| Delegation Chains |
| Authentication Block |
| Manifest --------------> +------------------------------+
| Severable Elements | | Manifest |
| Human-Readable Text | +------------------------------+
| COSWID | | Structure Version |
| Integrated Dependencies | | Sequence Number |
| Integrated Payloads | | Reference to Full Manifest |
+-------------------------+ +------ Common Structure |
| +---- Command Sequences |
+-------------------------+ | | | Digests of Envelope Elements |
| Common Structure | <--+ | +------------------------------+
+-------------------------+ |
| Dependencies | +-> +-----------------------+
| Components IDs | | Command Sequence |
| Common Command Sequence ---------> +-----------------------+
+-------------------------+ | List of ( pairs of ( |
| * command code |
| * argument / |
| reporting policy |
| )) |
+-----------------------+
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5.1. Envelope
The SUIT Envelope is a container that encloses Delegation Chains, the
Authentication Block, the Manifest, any Severable Elements, and any
integrated payloads or dependencies. The Envelope is used instead of
conventional cryptographic envelopes, such as COSE_Envelope because
it allows modular processing, severing of elements, and integrated
payloads in a way that would add substantial complexity with existing
solutions. See Appendix C.1 for a description of the reasoning for
this.
See Section 8.2 for more detail.
5.2. Delegation Chains
Delegation Chains allow a Recipient to establish a chain of trust
from a Trust Anchor to the signer of a manifest by validating
delegation claims. Each delegation claim is a [RFC8392] CBOR Web
Tokens (CWTs). The first claim in each list is signed by a Trust
Anchor. Each subsequent claim in a list is signed by the public key
claimed in the preceding list element. The last element in each list
claims a public key that can be used to verify a signature in the
Authentication Block (Section 5.3).
See Section 8.3 for more detail.
5.3. Authentication Block
The Authentication Block contains a bstr-wrapped Section 10 and one
or more [RFC8152] CBOR Object Signing and Encryption (COSE)
authentication blocks. These blocks are one of:
- COSE_Sign_Tagged
- COSE_Sign1_Tagged
- COSE_Mac_Tagged
- COSE_Mac0_Tagged
Each of these objects is used in detached payload mode. The payload
is the bstr-wrapped SUIT_Digest.
See Section 8.4 for more detail.
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5.4. Manifest
The Manifest contains most metadata about one or more images. The
Manifest is divided into Critical Metadata, Common Metadata, Command
Sequences, and Integrity Check Values.
See Section 8.6 for more detail.
5.4.1. Critical Metadata
Some metadata needs to be accessed before the manifest is processed.
This metadata can be used to determine which manifest is newest and
whether the structure version is supported. It also MAY provide a
URI for obtaining a canonical copy of the manifest and Envelope.
See Section 8.6.1, Section 8.6.2, and Section 8.6.3 for more detail.
5.4.2. Common
Some metadata is used repeatedly and in more than one command
sequence. In order to reduce the size of the manifest, this metadata
is collected into the Common section. Common is composed of three
parts: a list of dependencies, a list of components referenced by the
manifest, and a command sequence to execute prior to each other
command sequence. The common command sequence is typically used to
set commonly used values and perform compatibility checks. The
common command sequence MUST NOT have any side-effects outside of
setting parameter values.
See Section 8.7.2, and Section 8.7.2.1 for more detail.
5.4.3. Command Sequences
Command sequences provide the instructions that a Recipient requires
in order to install or use an image. These sequences tell a device
to set parameter values, test system parameters, copy data from one
place to another, transform data, digest data, and run code.
Command sequences are broken up into three groups: Common Command
Sequence (see Section 5.4.2), update commands, and secure boot
commands.
Update Command Sequences are: Dependency Resolution, Payload Fetch,
and Payload Installation. An Update Procedure is the complete set of
each Update Command Sequence, each preceded by the Common Command
Sequence.
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Invocation Command Sequences are: System Validation, Image Loading,
and Image Invocation. A Invocation Procedure is the complete set of
each Invocation Command Sequence, each preceded by the Common Command
Sequence.
Command Sequences are grouped into these sets to ensure that there is
common coordination between dependencies and dependents on when to
execute each command.
See Section 8.7.3 for more detail.
5.4.4. Integrity Check Values
To enable Section 5.5, there needs to be a mechanism to verify
integrity of any metadata outside the manifest. Integrity Check
Values are used to verify the integrity of metadata that is not
contained in the manifest. This MAY include Severable Command
Sequences, Concise Software Identifiers (CoSWID
[I-D.ietf-sacm-coswid]), or Text data. Integrated Dependencies and
Integrated Payloads are integrity-checked using Command Sequences, so
they do not have Integrity Check Values present in the Manifest.
See Section 8.7.9 for more detail.
5.4.5. Human-Readable Text
Text is typically a Severable Element (Section 5.5). It contains all
the text that describes the update. Because text is explicitly for
human consumption, it is all grouped together so that it can be
Severed easily. The text section has space both for describing the
manifest as a whole and for describing each individual component.
See Section 8.6.4 for more detail.
5.5. Severable Elements
Severable Elements are elements of the Envelope (Section 5.1) that
have Integrity Check Values (Section 5.4.4) in the Manifest
(Section 5.4).
Because of this organisation, these elements can be discarded or
"Severed" from the Envelope without changing the signature of the
Manifest. This allows savings based on the size of the Envelope in
several scenarios, for example:
- A management system severs the Text and CoSWID sections before
sending an Envelope to a constrained Recipient, which saves
Recipient bandwidth.
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- A Recipient severs the Installation section after installing the
Update, which saves storage space.
See Section 8.8 for more detail.
5.6. Integrated Dependencies and Payloads
In some cases, it is beneficial to include a dependency or a payload
in the Envelope of a manifest. For example:
- When an update is delivered via a comparatively unconstrained
medium, such as a removable mass storage device, it may be
beneficial to bundle updates into single files.
- When a manifest requires encryption, it must be referenced as a
dependency, so a trivial manifest may be used to enclose the
encrypted manifest. The encrypted manifest may be contained in
the dependent manifest's envelope.
- When a manifest transports a small payload, such as an encrypted
key, that payload may be placed in the manifest's envelope.
See Section 7.9.1, Section 8.5 for more detail.
6. Manifest Processor Behavior
This section describes the behavior of the manifest processor and
focuses primarily on interpreting commands in the manifest. However,
there are several other important behaviors of the manifest
processor: encoding version detection, rollback protection, and
authenticity verification are chief among these.
6.1. Manifest Processor Setup
Prior to executing any command sequence, the manifest processor or
its host application MUST inspect the manifest version field and fail
when it encounters an unsupported encoding version. Next, the
manifest processor or its host application MUST extract the manifest
sequence number and perform a rollback check using this sequence
number. The exact logic of rollback protection may vary by
application, but it has the following properties:
- Whenever the manifest processor can choose between several
manifests, it MUST select the latest valid, authentic manifest.
- If the latest valid, authentic manifest fails, it MAY select the
next latest valid, authentic manifest, according to application-
specific policy.
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Here, valid means that a manifest has a supported encoding version
and it has not been excluded for other reasons. Reasons for
excluding typically involve first executing the manifest and may
include:
- Test failed (e.g. Vendor ID/Class ID).
- Unsupported command encountered.
- Unsupported parameter encountered.
- Unsupported Component Identifier encountered.
- Payload not available.
- Dependency not available.
- Application crashed when executed.
- Watchdog timeout occurred.
- Dependency or Payload verification failed.
- Missing component from a set.
- Required parameter not supplied.
These failure reasons MAY be combined with retry mechanisms prior to
marking a manifest as invalid.
Selecting an older manifest in the event of failure of the latest
valid manifest is a robustness mechanism that is necessary for
supporting the requirements in [I-D.ietf-suit-architecture], section
3.5. It may not be appropriate for all applications. In particular
Trusted Execution Environments MAY require a failure to invoke a new
installation, rather than a rollback approach. See
[I-D.ietf-suit-information-model], Section 4.2.1 for more discussion
on the security considerations that apply to rollback.
Following these initial tests, the manifest processor clears all
parameter storage. This ensures that the manifest processor begins
without any leaked data.
6.2. Required Checks
The RECOMMENDED process is to verify the signature of the manifest
prior to parsing/executing any section of the manifest. This guards
the parser against arbitrary input by unauthenticated third parties,
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but it costs extra energy when a Recipient receives an incompatible
manifest.
When validating authenticity of manifests, the manifest processor MAY
use an ACL (see Section 9) to determine the extent of the rights
conferred by that authenticity. Where a device supports only one
level of access, it MAY choose to skip signature verification of
dependencies, since they are referenced by digest. Where a device
supports more than one trusted party, it MAY choose to defer the
verification of signatures of dependencies until the list of affected
components is known so that it can skip redundant signature
verifications. For example, a dependency signed by the same author
as the dependent does not require a signature verification.
Similarly, if the signer of the dependent has full rights to the
device, according to the ACL, then no signature verification is
necessary on the dependency.
Once a valid, authentic manifest has been selected, the manifest
processor MUST examine the component list and verify that its maximum
number of components is not exceeded and that each listed component
is supported.
For each listed component, the manifest processor MUST provide
storage for the supported parameters. If the manifest processor does
not have sufficient temporary storage to process the parameters for
all components, it MAY process components serially for each command
sequence. See Section 6.6 for more details.
The manifest processor SHOULD check that the common sequence contains
at least Check Vendor Identifier command and at least one Check Class
Identifier command.
Because the common sequence contains Check Vendor Identifier and
Check Class Identifier command(s), no custom commands are permitted
in the common sequence. This ensures that any custom commands are
only executed by devices that understand them.
If the manifest contains more than one component and/or dependency,
each command sequence MUST begin with a Set Component Index or Set
Dependency Index command.
If a dependency is specified, then the manifest processor MUST
perform the following checks:
1. At the beginning of each section in the dependent: all previous
sections of each dependency have been executed.
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2. At the end of each section in the dependent: The corresponding
section in each dependency has been executed.
If the interpreter does not support dependencies and a manifest
specifies a dependency, then the interpreter MUST reject the
manifest.
If a Recipient supports groups of interdependent components (a
Component Set), then it SHOULD verify that all Components in the
Component Set are specified by one update, that is: a single manifest
and all its dependencies that together:
1. have sufficient permissions imparted by their signatures
2. specify a digest and a payload for every Component in the
Component Set.
The single dependent manifest is sometimes called a Root Manifest.
6.2.1. Minimizing Signature Verifications
Signature verification can be energy and time expensive on a
constrained device. MAC verification is typically unaffected by
these concerns. A Recipient MAY choose to parse and execute only the
SUIT_Common section of the manifest prior to signature verification,
if all of the below apply:
- The Authentication Block contains a COSE_Sign_Tagged or
COSE_Sign1_Tagged
- The Recipient receives manifests over an unauthenticated channel,
exposing it to more inauthentic or incompatible manifests, and
- The Recipient has a power budget that makes signature verification
undesirable
The guidelines in Creating Manifests (Section 7) require that the
common section contains the applicability checks, so this section is
sufficient for applicability verification. The parser MUST restrict
acceptable commands to conditions and the following directives:
Override Parameters, Set Parameters, Try Each, and Run Sequence ONLY.
The manifest parser MUST NOT execute any command with side-effects
outside the parser (for example, Run, Copy, Swap, or Fetch commands)
prior to authentication and any such command MUST Abort. The Common
Sequence MUST be executed again in its entirety after authenticity
validation.
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When executing Common prior to authenticity validation, the Manifest
Processor MUST evaluate the integrity of the manifest using the
SUIT_Digest present in the authentication block.
Alternatively, a Recipient MAY rely on network infrastructure to
filter inapplicable manifests.
6.3. Interpreter Fundamental Properties
The interpreter has a small set of design goals:
1. Executing an update MUST either result in an error, or a
verifiably correct system state.
2. Executing a Trusted Invocation MUST either result in an error, or
an invoked image.
3. Executing the same manifest on multiple Recipients MUST result in
the same system state.
NOTE: when using A/B images, the manifest functions as two (or more)
logical manifests, each of which applies to a system in a particular
starting state. With that provision, design goal 3 holds.
6.4. Abstract Machine Description
The heart of the manifest is the list of commands, which are
processed by a Manifest Processor-a form of interpreter. This
Manifest Processor can be modeled as a simple abstract machine. This
machine consists of several data storage locations that are modified
by commands.
There are two types of commands, namely those that modify state
(directives) and those that perform tests (conditions). Parameters
are used as the inputs to commands. Some directives offer control
flow operations. Directives target a specific component or
dependency. A dependency is another SUIT_Envelope that describes
additional components. Dependencies are identified by digest, but
referenced in commands by Dependency Index, the index into the array
of Dependencies. A component is a unit of code or data that can be
targeted by an update. Components are identified by Component
Identifiers, but referenced in commands by Component Index; Component
Identifiers are arrays of binary strings and a Component Index is an
index into the array of Component Identifiers.
Conditions MUST NOT have any side-effects other than informing the
interpreter of success or failure. The Interpreter does not Abort if
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the Soft Failure flag (Section 8.7.5.23) is set when a Condition
reports failure.
Directives MAY have side-effects in the parameter table, the
interpreter state, or the current component. The Interpreter MUST
Abort if a Directive reports failure regardless of the Soft Failure
flag.
To simplify the logic describing the command semantics, the object
"current" is used. It represents the component identified by the
Component Index or the dependency identified by the Dependency Index:
current := components\[component-index\]
if component-index is not false
else dependencies\[dependency-index\]
As a result, Set Component Index is described as current :=
components[arg]. The actual operation performed for Set Component
Index is described by the following pseudocode, however, because of
the definition of current (above), these are semantically equivalent.
component-index := arg
dependency-index := false
Similarly, Set Dependency Index is semantically equivalent to current
:= dependencies[arg]
The following table describes the behavior of each command. "params"
represents the parameters for the current component or dependency.
Most commands operate on either a component or a dependency. Setting
the Component Index clears the Dependency Index. Setting the
Dependency Index clears the Component Index.
+-------------------+-----------------------------------------------+
| Command Name | Semantic of the Operation |
+-------------------+-----------------------------------------------+
| Check Vendor | assert(binary-match(current, |
| Identifier | current.params[vendor-id])) |
| | |
| Check Class | assert(binary-match(current, |
| Identifier | current.params[class-id])) |
| | |
| Verify Image | assert(binary-match(digest(current), |
| | current.params[digest])) |
| | |
| Set Component | current := components[arg] |
| Index | |
| | |
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| Override | current.params[k] := v for-each k,v in arg |
| Parameters | |
| | |
| Set Dependency | current := dependencies[arg] |
| Index | |
| | |
| Set Parameters | current.params[k] := v if not k in params |
| | for-each k,v in arg |
| | |
| Process | exec(current[common]); exec(current[current- |
| Dependency | segment]) |
| | |
| Run | run(current) |
| | |
| Fetch | store(current, fetch(current.params[uri])) |
| | |
| Use Before | assert(now() < arg) |
| | |
| Check Component | assert(offsetof(current) == arg) |
| Offset | |
| | |
| Check Device | assert(binary-match(current, |
| Identifier | current.params[device-id])) |
| | |
| Check Image Not | assert(not binary-match(digest(current), |
| Match | current.params[digest])) |
| | |
| Check Minimum | assert(battery >= arg) |
| Battery | |
| | |
| Check Update | assert(isAuthorized()) |
| Authorized | |
| | |
| Check Version | assert(version_check(current, arg)) |
| | |
| Abort | assert(0) |
| | |
| Try Each | try-each-done if exec(seq) is not error for- |
| | each seq in arg |
| | |
| Copy | store(current, current.params[src-component]) |
| | |
| Swap | swap(current, current.params[src-component]) |
| | |
| Wait For Event | until event(arg), wait |
| | |
| Run Sequence | exec(arg) |
| | |
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| Run with | run(current, arg) |
| Arguments | |
| | |
| Garbage Collect | garbage-collect(current) |
+-------------------+-----------------------------------------------+
6.5. Special Cases of Component Index and Dependency Index
Component Index and Dependency Index can each take on one of three
types:
1. Integer
2. Array of integers
3. True
Integers MUST always be supported by Set Component Index and Set
Dependency Index. Arrays of integers MUST be supported by Set
Component Index and Set Dependency Index if the Recipient supports 3
or more components or 3 or more dependencies, respectively. True
MUST be supported by Set Component Index and Set Dependency Index if
the Recipient supports 2 or more components or 2 or more
dependencies, respectively. Each of these operates on the list of
components or list of dependencies declared in the manifest.
Integer indices are the default case as described in the previous
section. An array of integers represents a list of the components
(Set Component Index) or a list of dependencies (Set Dependency
Index) to which each subsequent command applies. The value True
replaces the list of component indices or dependency indices with the
full list of components or the full list of dependencies,
respectively, as defined in the manifest.
When a command is executed, it either 1. operates on the component or
dependency identified by the component index or dependency index if
that index is an integer, or 2. it operates on each component or
dependency identified by an array of indicies, or 3. it operates on
every component or every dependency if the index is the boolean True.
This is described by the following pseudocode:
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if component-index is true:
current-list = components
else if component-index is array:
current-list = [ components[idx] for idx in component-index ]
else if component-index is integer:
current-list = [ components[component-index] ]
else if dependency-index is true:
current-list = dependencies
else if dependency-index is array:
current-list = [ dependencies[idx] for idx in dependency-index ]
else:
current-list = [ dependencies[dependency-index] ]
for current in current-list:
cmd(current)
Try Each and Run Sequence are affected in the same way as other
commands: they are invoked once for each possible Component or
Dependency. This means that the sequences that are arguments to Try
Each and Run Sequence are NOT invoked with Component Index = True or
Dependency Index = True, nor are they invoked with array indices.
They are only invoked with integer indices. The interpreter loops
over the whole sequence, setting the Component Index or Dependency
Index to each index in turn.
6.6. Serialized Processing Interpreter
In highly constrained devices, where storage for parameters is
limited, the manifest processor MAY handle one component at a time,
traversing the manifest tree once for each listed component. In this
mode, the interpreter ignores any commands executed while the
component index is not the current component. This reduces the
overall volatile storage required to process the update so that the
only limit on number of components is the size of the manifest.
However, this approach requires additional processing power.
In order to operate in this mode, the manifest processor loops on
each section for every supported component, simply ignoring commands
when the current component is not selected.
When a serialized Manifest Processor encounters a component or
dependency index of True, it does not ignore any commands. It
applies them to the current component or dependency on each
iteration.
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6.7. Parallel Processing Interpreter
Advanced Recipients MAY make use of the Strict Order parameter and
enable parallel processing of some Command Sequences, or it may
reorder some Command Sequences. To perform parallel processing, once
the Strict Order parameter is set to False, the Recipient may issue
each or every command concurrently until the Strict Order parameter
is returned to True or the Command Sequence ends. Then, it waits for
all issued commands to complete before continuing processing of
commands. To perform out-of-order processing, a similar approach is
used, except the Recipient consumes all commands after the Strict
Order parameter is set to False, then it sorts these commands into
its preferred order, invokes them all, then continues processing.
Under each of these scenarios the parallel processing MUST halt until
all issued commands have completed:
- Set Parameters.
- Override Parameters.
- Set Strict Order = True.
- Set Dependency Index.
- Set Component Index.
To perform more useful parallel operations, a manifest author may
collect sequences of commands in a Run Sequence command. Then, each
of these sequences MAY be run in parallel. Each sequence defaults to
Strict Order = True. To isolate each sequence from each other
sequence, each sequence MUST begin with a Set Component Index or Set
Dependency Index directive with the following exception: when the
index is either True or an array of indices, the Set Component Index
or Set Dependency Index is implied. Any further Set Component Index
directives MUST cause an Abort. This allows the interpreter that
issues Run Sequence commands to check that the first element is
correct, then issue the sequence to a parallel execution context to
handle the remainder of the sequence.
6.8. Processing Dependencies
As described in Section 6.2, each manifest must invoke each of its
dependencies sections from the corresponding section of the
dependent. Any changes made to parameters by the dependency persist
in the dependent.
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When a Process Dependency command is encountered, the interpreter
loads the dependency identified by the Current Dependency Index. The
interpreter first executes the common-sequence section of the
identified dependency, then it executes the section of the dependency
that corresponds to the currently executing section of the dependent.
If the specified dependency does not contain the current section,
Process Dependency succeeds immediately.
The Manifest Processor MUST also support a Dependency Index of True,
which applies to every dependency, as described in Section 6.5
The interpreter also performs the checks described in Section 6.2 to
ensure that the dependent is processing the dependency correctly.
6.9. Multiple Manifest Processors
When a system has multiple security domains, each domain might
require independent verification of authenticity or security
policies. Security domains might be divided by separation technology
such as Arm TrustZone, Intel SGX, or another TEE technology.
Security domains might also be divided into separate processors and
memory spaces, with a communication interface between them.
For example, an application processor may have an attached
communications module that contains a processor. The communications
module might require metadata signed by a specific Trust Authority
for regulatory approval. This may be a different Trust Authority
than the application processor.
When there are two or more security domains (see
[I-D.ietf-teep-architecture]), a manifest processor might be required
in each. The first manifest processor is the normal manifest
processor as described for the Recipient in Section 6.4. The second
manifest processor only executes sections when the first manifest
processor requests it. An API interface is provided from the second
manifest processor to the first. This allows the first manifest
processor to request a limited set of operations from the second.
These operations are limited to: setting parameters, inserting an
Envelope, invoking a Manifest Command Sequence. The second manifest
processor declares a prefix to the first, which tells the first
manifest processor when it should delegate to the second. These
rules are enforced by underlying separation of privilege
infrastructure, such as TEEs, or physical separation.
When the first manifest processor encounters a dependency prefix,
that informs the first manifest processor that it should provide the
second manifest processor with the corresponding dependency Envelope.
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This is done when the dependency is fetched. The second manifest
processor immediately verifies any authentication information in the
dependency Envelope. When a parameter is set for any component that
matches the prefix, this parameter setting is passed to the second
manifest processor via an API. As the first manifest processor works
through the Procedure (set of command sequences) it is executing,
each time it sees a Process Dependency command that is associated
with the prefix declared by the second manifest processor, it uses
the API to ask the second manifest processor to invoke that
dependency section instead.
This mechanism ensures that the two or more manifest processors do
not need to trust each other, except in a very limited case. When
parameter setting across security domains is used, it must be very
carefully considered. Only parameters that do not have an effect on
security properties should be allowed. The dependency manifest MAY
control which parameters are allowed to be set by using the Override
Parameters directive. The second manifest processor MAY also control
which parameters may be set by the first manifest processor by means
of an ACL that lists the allowed parameters. For example, a URI may
be set by a dependent without a substantial impact on the security
properties of the manifest.
7. Creating Manifests
Manifests are created using tools for constructing COSE structures,
calculating cryptographic values and compiling desired system state
into a sequence of operations required to achieve that state. The
process of constructing COSE structures and the calculation of
cryptographic values is covered in [RFC8152].
Compiling desired system state into a sequence of operations can be
accomplished in many ways. Several templates are provided below to
cover common use-cases. These templates can be combined to produce
more complex behavior.
The author MUST ensure that all parameters consumed by a command are
set prior to invoking that command. Where Component Index = True or
Dependency Index = True, this means that the parameters consumed by
each command MUST have been set for each Component or Dependency,
respectively.
This section details a set of templates for creating manifests.
These templates explain which parameters, commands, and orders of
commands are necessary to achieve a stated goal.
NOTE: On systems that support only a single component and no
dependencies, Set Component Index has no effect and can be omitted.
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NOTE: *A digest MUST always be set using Override Parameters, since
this prevents a less-privileged dependent from replacing the digest.*
7.1. Compatibility Check Template
The goal of the compatibility check template ensure that Recipients
only install compatible images.
In this template all information is contained in the common sequence
and the following sequence of commands is used:
- Set Component Index directive (see Section 8.7.7.1)
- Set Parameters directive (see Section 8.7.7.5) for Vendor ID and
Class ID (see Section 8.7.5)
- Check Vendor Identifier condition (see Section 8.7.5.2)
- Check Class Identifier condition (see Section 8.7.5.2)
7.2. Trusted Invocation Template
The goal of the Trusted Invocation template is to ensure that only
authorized code is invoked; such as in Secure Boot or when a Trusted
Application is loaded into a TEE.
The following commands are placed into the common sequence:
- Set Component Index directive (see Section 8.7.7.1)
- Override Parameters directive (see Section 8.7.7.6) for Image
Digest and Image Size (see Section 8.7.5)
Then, the run sequence contains the following commands:
- Set Component Index directive (see Section 8.7.7.1)
- Check Image Match condition (see Section 8.7.6.2)
- Run directive (see Section 8.7.7.12)
7.3. Component Download Template
The goal of the Component Download template is to acquire and store
an image.
The following commands are placed into the common sequence:
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- Set Component Index directive (see Section 8.7.7.1)
- Override Parameters directive (see Section 8.7.7.6) for Image
Digest and Image Size (see Section 8.7.5)
Then, the install sequence contains the following commands:
- Set Component Index directive (see Section 8.7.7.1)
- Set Parameters directive (see Section 8.7.7.5) for URI (see
Section 8.7.5.13)
- Fetch directive (see Section 8.7.7.7)
- Check Image Match condition (see Section 8.7.6.2)
The Fetch directive needs the URI parameter to be set to determine
where the image is retrieved from. Additionally, the destination of
where the component shall be stored has to be configured. The URI is
configured via the Set Parameters directive while the destination is
configured via the Set Component Index directive.
Optionally, the Set Parameters directive in the install sequence MAY
also contain Encryption Info (see Section 8.7.5.10), Compression Info
(see Section 8.7.5.11), or Unpack Info (see Section 8.7.5.12) to
perform simultaneous download and decryption, decompression, or
unpacking, respectively.
7.4. Install Template
The goal of the Install template is to use an image already stored in
an identified component to copy into a second component.
This template is typically used with the Component Download template,
however a modification to that template is required: the Component
Download operations are moved from the Payload Install sequence to
the Payload Fetch sequence.
Then, the install sequence contains the following commands:
- Set Component Index directive (see Section 8.7.7.1)
- Set Parameters directive (see Section 8.7.7.5) for Source
Component (see Section 8.7.5.14)
- Copy directive (see Section 8.7.7.9)
- Check Image Match condition (see Section 8.7.6.2)
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7.5. Install and Transform Template
The goal of the Install and Transform template is to use an image
already stored in an identified component to decompress, decrypt, or
unpack at time of installation.
This template is typically used with the Component Download template,
however a modification to that template is required: all Component
Download operations are moved from the common sequence and the
install sequence to the fetch sequence. The Component Download
template targets a download component identifier, while the Install
and Transform template uses an install component identifier. In-
place unpacking, decompression, and decryption is complex and
vulnerable to power failure. Therefore, these identifiers SHOULD be
different; in-place installation SHOULD NOT be used without
establishing guarantees of robustness to power failure.
The following commands are placed into the common sequence:
- Set Component Index directive for install component identifier
(see Section 8.7.7.1)
- Override Parameters directive (see Section 8.7.7.6) for Image
Digest and Image Size (see Section 8.7.5)
Then, the install sequence contains the following commands:
- Set Component Index directive for install component identifier
(see Section 8.7.7.1)
- Set Parameters directive (see Section 8.7.7.5) for:
o Source Component for download component identifier (see
Section 8.7.5.14)
o Encryption Info (see Section 8.7.5.10)
o Compression Info (see Section 8.7.5.11)
o Unpack Info (see Section 8.7.5.12)
- Copy directive (see Section 8.7.7.9)
- Check Image Match condition (see Section 8.7.6.2)
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7.6. Integrated Payload Template
The goal of the Integrated Payload template is to install a payload
that is included in the manifest envelope. It is identical to the
Component Download template (Section 7.3) except that it places an
added restriction on the URI passed to the Set Parameters directive.
An implementer MAY choose to place a payload in the envelope of a
manifest. The payload envelope key MAY be a positive or negative
integer. The payload envelope key MUST NOT be a value between 0 and
24 and it MUST NOT be used by any other envelope element in the
manifest. The payload MUST be serialized in a bstr element.
The URI for a payload enclosed in this way MUST be expressed as a
fragment-only reference, as defined in [RFC3986], Section 4.4. The
fragment identifier is the stringified envelope key of the payload.
For example, an envelope that contains a payload a key 42 would use a
URI "#42", key -73 would use a URI "#-73".
7.7. Load from Nonvolatile Storage Template
The goal of the Load from Nonvolatile Storage template is to load an
image from a non-volatile component into a volatile component, for
example loading a firmware image from external Flash into RAM.
The following commands are placed into the load sequence:
- Set Component Index directive (see Section 8.7.7.1)
- Set Parameters directive (see Section 8.7.7.5) for Component Index
(see Section 8.7.5)
- Copy directive (see Section 8.7.7.9)
As outlined in Section 6.4, the Copy directive needs a source and a
destination to be configured. The source is configured via Component
Index (with the Set Parameters directive) and the destination is
configured via the Set Component Index directive.
7.8. Load & Decompress from Nonvolatile Storage Template
The goal of the Load & Decompress from Nonvolatile Storage template
is to load an image from a non-volatile component into a volatile
component, decompressing on-the-fly, for example loading a firmware
image from external Flash into RAM.
The following commands are placed into the load sequence:
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- Set Component Index directive (see Section 8.7.7.1)
- Set Parameters directive (see Section 8.7.7.5) for Source
Component Index and Compression Info (see Section 8.7.5)
- Copy directive (see Section 8.7.7.9)
This template is similar to Section 7.7 but additionally performs
decompression. Hence, the only difference is in setting the
Compression Info parameter.
This template can be modified for decryption or unpacking by adding
Decryption Info or Unpack Info to the Set Parameters directive.
7.9. Dependency Template
The goal of the Dependency template is to obtain, verify, and process
a dependency manifest as appropriate.
The following commands are placed into the dependency resolution
sequence:
- Set Dependency Index directive (see Section 8.7.7.2)
- Set Parameters directive (see Section 8.7.7.5) for URI (see
Section 8.7.5)
- Fetch directive (see Section 8.7.7.7)
- Check Image Match condition (see Section 8.7.6.2)
- Process Dependency directive (see Section 8.7.7.4)
Then, the validate sequence contains the following operations:
- Set Dependency Index directive (see Section 8.7.7.2)
- Check Image Match condition (see Section 8.7.6.2)
- Process Dependency directive (see Section 8.7.7.4)
NOTE: Any changes made to parameters in a dependency persist in the
dependent.
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7.9.1. Composite Manifests
An implementer MAY choose to place a dependency's envelope in the
envelope of its dependent. The dependent envelope key for the
dependency envelope MUST NOT be a value between 0 and 24 and it MUST
NOT be used by any other envelope element in the dependent manifest.
The URI for a dependency enclosed in this way MUST be expressed as a
fragment-only reference, as defined in [RFC3986], Section 4.4. The
fragment identifier is the stringified envelope key of the
dependency. For example, an envelope that contains a dependency at
key 42 would use a URI "#42", key -73 would use a URI "#-73".
7.10. Encrypted Manifest Template
The goal of the Encrypted Manifest template is to fetch and decrypt a
manifest so that it can be used as a dependency. To use an encrypted
manifest, create a plaintext dependent, and add the encrypted
manifest as a dependency. The dependent can include very little
information.
The following operations are placed into the dependency resolution
block:
- Set Dependency Index directive (see Section 8.7.7.2)
- Set Parameters directive (see Section 8.7.7.5) for
o URI (see Section 8.7.5)
o Encryption Info (see Section 8.7.5)
- Fetch directive (see Section 8.7.7.7)
- Check Image Match condition (see Section 8.7.6.2)
- Process Dependency directive (see Section 8.7.7.4)
Then, the validate block contains the following operations:
- Set Dependency Index directive (see Section 8.7.7.2)
- Check Image Match condition (see Section 8.7.6.2)
- Process Dependency directive (see Section 8.7.7.4)
A plaintext manifest and its encrypted dependency may also form a
composite manifest (Section 7.9.1).
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7.11. A/B Image Template
The goal of the A/B Image Template is to acquire, validate, and
invoke one of two images, based on a test.
The following commands are placed in the common block:
- Set Component Index directive (see Section 8.7.7.1)
- Try Each
o First Sequence:
* Override Parameters directive (see Section 8.7.7.6,
Section 8.7.5) for Offset A
* Check Offset Condition (see Section 8.7.6.5)
* Override Parameters directive (see Section 8.7.7.6) for
Image Digest A and Image Size A (see Section 8.7.5)
o Second Sequence:
* Override Parameters directive (see Section 8.7.7.6,
Section 8.7.5) for Offset B
* Check Offset Condition (see Section 8.7.6.5)
* Override Parameters directive (see Section 8.7.7.6) for
Image Digest B and Image Size B (see Section 8.7.5)
The following commands are placed in the fetch block or install block
- Set Component Index directive (see Section 8.7.7.1)
- Try Each
o First Sequence:
* Override Parameters directive (see Section 8.7.7.6,
Section 8.7.5) for Offset A
* Check Offset Condition (see Section 8.7.6.5)
* Set Parameters directive (see Section 8.7.7.6) for URI A
(see Section 8.7.5)
o Second Sequence:
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* Override Parameters directive (see Section 8.7.7.6,
Section 8.7.5) for Offset B
* Check Offset Condition (see Section 8.7.6.5)
* Set Parameters directive (see Section 8.7.7.6) for URI B
(see Section 8.7.5)
- Fetch
If Trusted Invocation (Section 7.2) is used, only the run sequence is
added to this template, since the common sequence is populated by
this template.
NOTE: Any test can be used to select between images, Check Offset
Condition is used in this template because it is a typical test for
execute-in-place devices.
8. Metadata Structure
The metadata for SUIT updates is composed of several primary
constituent parts: the Envelope, Delegation Chains, Authentication
Information, Manifest, and Severable Elements.
For a diagram of the metadata structure, see Section 5.
8.1. Encoding Considerations
The map indices in the envelope encoding are reset to 1 for each map
within the structure. This is to keep the indices as small as
possible. The goal is to keep the index objects to single bytes
(CBOR positive integers 1-23).
Wherever enumerations are used, they are started at 1. This allows
detection of several common software errors that are caused by
uninitialized variables. Positive numbers in enumerations are
reserved for IANA registration. Negative numbers are used to
identify application-specific values, as described in Section 11.
All elements of the envelope must be wrapped in a bstr to minimize
the complexity of the code that evaluates the cryptographic integrity
of the element and to ensure correct serialization for integrity and
authenticity checks.
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8.2. Envelope
The Envelope contains each of the other primary constituent parts of
the SUIT metadata. It allows for modular processing of the manifest
by ordering components in the expected order of processing.
The Envelope is encoded as a CBOR Map. Each element of the Envelope
is enclosed in a bstr, which allows computation of a message digest
against known bounds.
8.3. Delegation Chains
The suit-delegation element MAY carry one or more CBOR Web Tokens
(CWTs) [RFC8392], with [RFC8747] cnf claims. They can be used to
perform enhanced authorization decisions. The CWTs are arranged into
a list of lists. Each list starts with a CWT authorized by a Trust
Anchor, and finishes with a key used to authenticate the Manifest
(see Section 8.4). This allows an Update Authority to delegate from
a long term Trust Anchor, down through intermediaries, to a delegate
without any out-of-band provisioning of Trust Anchors or intermediary
keys.
A Recipient MAY choose to cache intermediaries and/or delegates. If
an Update Distributor knows that a targeted Recipient has cached some
intermediaries or delegates, it MAY choose to strip any cached
intermediaries or delegates from the Delegation Chains in order to
reduce bandwidth and energy.
8.4. Authenticated Manifests
The suit-authentication-wrapper contains a list containing a
Section 10 and one or more cryptographic authentication wrappers for
the Manifest. These are implemented as COSE_Mac_Tagged or
COSE_Sign_Tagged blocks. Each of these blocks contains a SUIT_Digest
of the Manifest. This enables modular processing of the manifest.
The COSE_Mac_Tagged and COSE_Sign_Tagged blocks are described in RFC
8152 [RFC8152]. The suit-authentication-wrapper MUST come before any
element in the SUIT_Envelope, except for the OPTIONAL suit-
delegation, regardless of canonical encoding of CBOR. All validators
MUST reject any SUIT_Envelope that begins with any element other than
a suit-authentication-wrapper or suit-delegation.
A SUIT_Envelope that has not had authentication information added
MUST still contain the suit-authentication-wrapper element, but the
content MUST be a list containing only the SUIT_Digest.
A signing application MUST verify the suit-manifest element against
the SUIT_Digest prior to signing.
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8.5. Encrypted Manifests
To use an encrypted manifest, it must be a dependency of a plaintext
manifest. This allows fine-grained control of what information is
accessible to intermediate systems for the purposes of management,
while still preserving the confidentiality of the manifest contents.
This also means that a Recipient can process an encrypted manifest in
the same way as an encrypted payload, allowing code reuse.
A template for using an encrypted manifest is covered in Encrypted
Manifest Template (Section 7.10).
8.6. Manifest
The manifest contains:
- a version number (see Section 8.6.1)
- a sequence number (see Section 8.6.2)
- a reference URI (see Section 8.6.3)
- a common structure with information that is shared between command
sequences (see Section 8.7.2)
- one or more lists of commands that the Recipient should perform
(see Section 8.7.3)
- a reference to the full manifest (see Section 8.6.3)
- human-readable text describing the manifest found in the
SUIT_Envelope (see Section 8.6.4)
- a Concise Software Identifier (CoSWID) found in the SUIT_Envelope
(see Section 8.7.1)
The CoSWID, Text section, or any Command Sequence of the Update
Procedure (Dependency Resolution, Image Fetch, Image Installation)
can be either a CBOR structure or a SUIT_Digest. In each of these
cases, the SUIT_Digest provides for a severable element. Severable
elements are RECOMMENDED to implement. In particular, the human-
readable text SHOULD be severable, since most useful text elements
occupy more space than a SUIT_Digest, but are not needed by the
Recipient. Because SUIT_Digest is a CBOR Array and each severable
element is a CBOR bstr, it is straight-forward for a Recipient to
determine whether an element has been severed. The key used for a
severable element is the same in the SUIT_Manifest and in the
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SUIT_Envelope so that a Recipient can easily identify the correct
data in the envelope. See Section 8.7.9 for more detail.
8.6.1. suit-manifest-version
The suit-manifest-version indicates the version of serialization used
to encode the manifest. Version 1 is the version described in this
document. suit-manifest-version is REQUIRED to implement.
8.6.2. suit-manifest-sequence-number
The suit-manifest-sequence-number is a monotonically increasing anti-
rollback counter. It also helps Recipients to determine which in a
set of manifests is the "root" manifest in a given update. Each
manifest MUST have a sequence number higher than each of its
dependencies. Each Recipient MUST reject any manifest that has a
sequence number lower than its current sequence number. For
convenience, an implementer MAY use a UTC timestamp in seconds as the
sequence number. suit-manifest-sequence-number is REQUIRED to
implement.
8.6.3. suit-reference-uri
suit-reference-uri is a text string that encodes a URI where a full
version of this manifest can be found. This is convenient for
allowing management systems to show the severed elements of a
manifest when this URI is reported by a Recipient after installation.
8.6.4. suit-text
suit-text SHOULD be a severable element. suit-text is a map
containing two different types of pair:
- integer => text
- SUIT_Component_Identifier => map
Each SUIT_Component_Identifier => map entry contains a map of integer
=> text values. All SUIT_Component_Identifiers present in suit-text
MUST also be present in suit-common (Section 8.7.2) or the suit-
common of a dependency.
suit-text contains all the human-readable information that describes
any and all parts of the manifest, its payload(s) and its
resource(s). The text section is typically severable, allowing
manifests to be distributed without the text, since end-nodes do not
require text. The meaning of each field is described below.
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Each section MAY be present. If present, each section MUST be as
described. Negative integer IDs are reserved for application-
specific text values.
The following table describes the text fields available in suit-text:
+--------------------------------+----------------------------------+
| CDDL Structure | Description |
+--------------------------------+----------------------------------+
| suit-text-manifest-description | Free text description of the |
| | manifest |
| | |
| suit-text-update-description | Free text description of the |
| | update |
| | |
| suit-text-manifest-json-source | The JSON-formatted document that |
| | was used to create the manifest |
| | |
| suit-text-manifest-yaml-source | The YAML ([YAML])-formatted |
| | document that was used to create |
| | the manifest |
+--------------------------------+----------------------------------+
The following table describes the text fields available in each map
identified by a SUIT_Component_Identifier.
+---------------------------------+---------------------------------+
| CDDL Structure | Description |
+---------------------------------+---------------------------------+
| suit-text-vendor-name | Free text vendor name |
| | |
| suit-text-model-name | Free text model name |
| | |
| suit-text-vendor-domain | The domain used to create the |
| | vendor-id condition |
| | |
| suit-text-model-info | The information used to create |
| | the class-id condition |
| | |
| suit-text-component-description | Free text description of each |
| | component in the manifest |
| | |
| suit-text-component-version | A free text representation of |
| | the component version |
| | |
| suit-text-version-required | A free text expression of the |
| | required version number |
+---------------------------------+---------------------------------+
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suit-text is OPTIONAL to implement.
8.7. text-version-required
suit-text-version-required is used to represent a version-based
dependency on suit-parameter-version as described in Section 8.7.5.18
and Section 8.7.6.8. To describe a version dependency, a Manifest
Author SHOULD populate the suit-text map with a
SUIT_Component_Identifier key for the dependency component, and place
in the corresponding map a suit-text-version-required key with a free
text expression that is representative of the version constraints
placed on the dependency. This text SHOULD be expressive enough that
a device operator can be expected to understand the dependency. This
is a free text field and there are no specific formatting rules.
By way of example only, to express a dependency on a component "['x',
'y']", where the version should be any v1.x later than v1.2.5, but
not v2.0 or above, the author would add the following structure to
the suit-text element. Note that this text is in cbor-diag notation.
[h'78',h'79'] : {
7 : ">=1.2.5,<2"
}
8.7.1. suit-coswid
suit-coswid contains a Concise Software Identifier (CoSWID) as
defined in [I-D.ietf-sacm-coswid]. This element SHOULD be made
severable so that it can be discarded by the Recipient or an
intermediary if it is not required by the Recipient.
suit-coswid typically requires no processing by the Recipient.
However all Recipients MUST NOT fail if a suit-coswid is present.
8.7.2. suit-common
suit-common encodes all the information that is shared between each
of the command sequences, including: suit-dependencies, suit-
components, and suit-common-sequence. suit-common is REQUIRED to
implement.
suit-dependencies is a list of Section 8.7.2.1 blocks that specify
manifests that must be present before the current manifest can be
processed. suit-dependencies is OPTIONAL to implement.
suit-components is a list of SUIT_Component_Identifier
(Section 8.7.2.2) blocks that specify the component identifiers that
will be affected by the content of the current manifest. suit-
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components is REQUIRED to implement; at least one manifest in a
dependency tree MUST contain a suit-components block.
suit-common-sequence is a SUIT_Command_Sequence to execute prior to
executing any other command sequence. Typical actions in suit-
common-sequence include setting expected Recipient identity and image
digests when they are conditional (see Section 8.7.7.3 and
Section 7.11 for more information on conditional sequences). suit-
common-sequence is RECOMMENDED to implement. It is REQUIRED if the
optimizations described in Section 6.2.1 will be used. Whenever a
parameter or Try Each command is required by more than one Command
Sequence, placing that parameter or commamd in suit-common-sequence
results in a smaller encoding.
8.7.2.1. Dependencies
SUIT_Dependency specifies a manifest that describes a dependency of
the current manifest. The Manifest is identified, but the Recipient
should expect an Envelope when it acquires the dependency. This is
because the Manifest is the one invariant element of the Envelope,
where other elements may change by countersigning, adding
authentication blocks, or severing elements.
The suit-dependency-digest specifies the dependency manifest uniquely
by identifying a particular Manifest structure. This is identical to
the digest that would be present as the payload of any suit-
authentication-block in the dependency's Envelope. The digest is
calculated over the Manifest structure instead of the COSE
Sig_structure or Mac_structure. This is necessary to ensure that
removing a signature from a manifest does not break dependencies due
to missing signature elements. This is also necessary to support the
trusted intermediary use case, where an intermediary re-signs the
Manifest, removing the original signature, potentially with a
different algorithm, or trading COSE_Sign for COSE_Mac.
The suit-dependency-prefix element contains a
SUIT_Component_Identifier (see Section 8.7.2.2). This specifies the
scope at which the dependency operates. This allows the dependency
to be forwarded on to a component that is capable of parsing its own
manifests. It also allows one manifest to be deployed to multiple
dependent Recipients without those Recipients needing consistent
component hierarchy. This element is OPTIONAL for Recipients to
implement.
A dependency prefix can be used with a component identifier. This
allows complex systems to understand where dependencies need to be
applied. The dependency prefix can be used in one of two ways. The
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first simply prepends the prefix to all Component Identifiers in the
dependency.
A dependency prefix can also be used to indicate when a dependency
manifest needs to be processed by a secondary manifest processor, as
described in Section 6.9.
8.7.2.2. SUIT_Component_Identifier
A component is a unit of code or data that can be targeted by an
update. To facilitate composite devices, components are identified
by a list of CBOR byte strings, which allows construction of
hierarchical component structures. A dependency MAY declare a prefix
to the components defined in the dependency manifest. Components are
identified by Component Identifiers, but referenced in commands by
Component Index; Component Identifiers are arrays of binary strings
and a Component Index is an index into the array of Component
Identifiers.
A Component Identifier can be trivial, such as the simple array
[h'00']. It can also represent a filesystem path by encoding each
segment of the path as an element in the list. For example, the path
"/usr/bin/env" would encode to ['usr','bin','env'].
This hierarchical construction allows a component identifier to
identify any part of a complex, multi-component system.
8.7.3. SUIT_Command_Sequence
A SUIT_Command_Sequence defines a series of actions that the
Recipient MUST take to accomplish a particular goal. These goals are
defined in the manifest and include:
1. Dependency Resolution: suit-dependency-resolution is a
SUIT_Command_Sequence to execute in order to perform dependency
resolution. Typical actions include configuring URIs of
dependency manifests, fetching dependency manifests, and
validating dependency manifests' contents. suit-dependency-
resolution is REQUIRED to implement and to use when suit-
dependencies is present.
2. Payload Fetch: suit-payload-fetch is a SUIT_Command_Sequence to
execute in order to obtain a payload. Some manifests may include
these actions in the suit-install section instead if they operate
in a streaming installation mode. This is particularly relevant
for constrained devices without any temporary storage for staging
the update. suit-payload-fetch is OPTIONAL to implement.
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3. Payload Installation: suit-install is a SUIT_Command_Sequence to
execute in order to install a payload. Typical actions include
verifying a payload stored in temporary storage, copying a staged
payload from temporary storage, and unpacking a payload. suit-
install is OPTIONAL to implement.
4. Image Validation: suit-validate is a SUIT_Command_Sequence to
execute in order to validate that the result of applying the
update is correct. Typical actions involve image validation and
manifest validation. suit-validate is REQUIRED to implement. If
the manifest contains dependencies, one process-dependency
invocation per dependency or one process-dependency invocation
targeting all dependencies SHOULD be present in validate.
5. Image Loading: suit-load is a SUIT_Command_Sequence to execute in
order to prepare a payload for execution. Typical actions
include copying an image from permanent storage into RAM,
optionally including actions such as decryption or decompression.
suit-load is OPTIONAL to implement.
6. Run or Boot: suit-run is a SUIT_Command_Sequence to execute in
order to run an image. suit-run typically contains a single
instruction: either the "run" directive for the invocable
manifest or the "process dependencies" directive for any
dependents of the invocable manifest. suit-run is OPTIONAL to
implement.
Goals 1,2,3 form the Update Procedure. Goals 4,5,6 form the
Invocation Procedure.
Each Command Sequence follows exactly the same structure to ensure
that the parser is as simple as possible.
Lists of commands are constructed from two kinds of element:
1. Conditions that MUST be true and any failure is treated as a
failure of the update/load/invocation
2. Directives that MUST be executed.
Each condition is composed of:
1. A command code identifier
2. A SUIT_Reporting_Policy (Section 8.7.4)
Each directive is composed of:
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1. A command code identifier
2. An argument block or a SUIT_Reporting_Policy (Section 8.7.4)
Argument blocks are consumed only by flow-control directives:
- Set Component/Dependency Index
- Set/Override Parameters
- Try Each
- Run Sequence
Reporting policies provide a hint to the manifest processor of
whether to add the success or failure of a command to any report that
it generates.
Many conditions and directives apply to a given component, and these
generally grouped together. Therefore, a special command to set the
current component index is provided with a matching command to set
the current dependency index. This index is a numeric index into the
Component Identifier tables defined at the beginning of the manifest.
For the purpose of setting the index, the two Component Identifier
tables are considered to be concatenated together.
To facilitate optional conditions, a special directive, suit-
directive-try-each (Section 8.7.7.3), is provided. It runs several
new lists of conditions/directives, one after another, that are
contained as an argument to the directive. By default, it assumes
that a failure of a condition should not indicate a failure of the
update/invocation, but a parameter is provided to override this
behavior. See suit-parameter-soft-failure (Section 8.7.5.23).
8.7.4. Reporting Policy
To facilitate construction of Reports that describe the success, or
failure of a given Procedure, each command is given a Reporting
Policy. This is an integer bitfield that follows the command and
indicates what the Recipient should do with the Record of executing
the command. The options are summarized in the table below.
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+-----------------------------+-------------------------------------+
| Policy | Description |
+-----------------------------+-------------------------------------+
| suit-send-record-on-success | Record when the command succeeds |
| | |
| suit-send-record-on-failure | Record when the command fails |
| | |
| suit-send-sysinfo-success | Add system information when the |
| | command succeeds |
| | |
| suit-send-sysinfo-failure | Add system information when the |
| | command fails |
+-----------------------------+-------------------------------------+
Any or all of these policies may be enabled at once.
At the completion of each command, a Manifest Processor MAY forward
information about the command to a Reporting Engine, which is
responsible for reporting boot or update status to a third party.
The Reporting Engine is entirely implementation-defined, the
reporting policy simply facilitates the Reporting Engine's interface
to the SUIT Manifest Processor.
The information elements provided to the Reporting Engine are:
- The reporting policy
- The result of the command
- The values of parameters consumed by the command
- The system information consumed by the command
Together, these elements are called a Record. A group of Records is
a Report.
If the component index is set to True or an array when a command is
executed with a non-zero reporting policy, then the Reporting Engine
MUST receive one Record for each Component, in the order expressed in
the Components list or the component index array. If the dependency
index is set to True or an array when a command is executed with a
non-zero reporting policy, then the Reporting Engine MUST receive one
Record for each Dependency, in the order expressed in the
Dependencies list or the component index array, respectively.
This specification does not define a particular format of Records or
Reports. This specification only defines hints to the Reporting
Engine for which Records it should aggregate into the Report. The
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Reporting Engine MAY choose to ignore these hints and apply its own
policy instead.
When used in a Invocation Procedure, the report MAY form the basis of
an attestation report. When used in an Update Process, the report
MAY form the basis for one or more log entries.
8.7.5. SUIT_Parameters
Many conditions and directives require additional information. That
information is contained within parameters that can be set in a
consistent way. This allows reduction of manifest size and
replacement of parameters from one manifest to the next.
Most parameters are scoped to a specific component. This means that
setting a parameter for one component has no effect on the parameters
of any other component. The only exceptions to this are two Manifest
Processor parameters: Strict Order and Soft Failure.
The defined manifest parameters are described below.
+----------------+----------------------------------+---------------+
| Name | CDDL Structure | Reference |
+----------------+----------------------------------+---------------+
| Vendor ID | suit-parameter-vendor-identifier | Section 8.7.5 |
| | | .3 |
| | | |
| Class ID | suit-parameter-class-identifier | Section 8.7.5 |
| | | .4 |
| | | |
| Device ID | suit-parameter-device-identifier | Section 8.7.5 |
| | | .5 |
| | | |
| Image Digest | suit-parameter-image-digest | Section 8.7.5 |
| | | .6 |
| | | |
| Image Size | suit-parameter-image-size | Section 8.7.5 |
| | | .7 |
| | | |
| Use Before | suit-parameter-use-before | Section 8.7.5 |
| | | .8 |
| | | |
| Component | suit-parameter-component-offset | Section 8.7.5 |
| Offset | | .9 |
| | | |
| Encryption | suit-parameter-encryption-info | Section 8.7.5 |
| Info | | .10 |
| | | |
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| Compression | suit-parameter-compression-info | Section 8.7.5 |
| Info | | .11 |
| | | |
| Unpack Info | suit-parameter-unpack-info | Section 8.7.5 |
| | | .12 |
| | | |
| URI | suit-parameter-uri | Section 8.7.5 |
| | | .13 |
| | | |
| Source | suit-parameter-source-component | Section 8.7.5 |
| Component | | .14 |
| | | |
| Run Args | suit-parameter-run-args | Section 8.7.5 |
| | | .15 |
| | | |
| Minimum | suit-parameter-minimum-battery | Section 8.7.5 |
| Battery | | .16 |
| | | |
| Update | suit-parameter-update-priority | Section 8.7.5 |
| Priority | | .17 |
| | | |
| Version | suit-parameter-version | Section 8.7.5 |
| | | .18 |
| | | |
| Wait Info | suit-parameter-wait-info | Section 8.7.5 |
| | | .19 |
| | | |
| URI List | suit-parameter-uri-list | Section 8.7.5 |
| | | .20 |
| | | |
| Fetch | suit-parameter-fetch-arguments | Section 8.7.5 |
| Arguments | | .21 |
| | | |
| Strict Order | suit-parameter-strict-order | Section 8.7.5 |
| | | .22 |
| | | |
| Soft Failure | suit-parameter-soft-failure | Section 8.7.5 |
| | | .23 |
| | | |
| Custom | suit-parameter-custom | Section 8.7.5 |
| | | .24 |
+----------------+----------------------------------+---------------+
CBOR-encoded object parameters are still wrapped in a bstr. This is
because it allows a parser that is aggregating parameters to
reference the object with a single pointer and traverse it without
understanding the contents. This is important for modularization and
division of responsibility within a pull parser. The same
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consideration does not apply to Directives because those elements are
invoked with their arguments immediately
8.7.5.1. CBOR PEN UUID Namespace Identifier
The CBOR PEN UUID Namespace Identifier is constructed as follows:
It uses the OID Namespace as a starting point, then uses the CBOR OID
encoding for the IANA PEN OID (1.3.6.1.4.1):
D8 DE # tag(111)
45 # bytes(5)
2B 06 01 04 01 # X.690 Clause 8.19
# 1.3 6 1 4 1 show component encoding
Computing a type 5 UUID from these produces:
NAMESPACE_CBOR_PEN = UUID5(NAMESPACE_OID, h'D86F452B06010401')
NAMESPACE_CBOR_PEN = 08cfcc43-47d9-5696-85b1-9c738465760e
8.7.5.2. Constructing UUIDs
Several conditions use identifiers to determine whether a manifest
matches a given Recipient or not. These identifiers are defined to
be RFC 4122 [RFC4122] UUIDs. These UUIDs are not human-readable and
are therefore used for machine-based processing only.
A Recipient MAY match any number of UUIDs for vendor or class
identifier. This may be relevant to physical or software modules.
For example, a Recipient that has an OS and one or more applications
might list one Vendor ID for the OS and one or more additional Vendor
IDs for the applications. This Recipient might also have a Class ID
that must be matched for the OS and one or more Class IDs for the
applications.
Identifiers are used for compatibility checks. They MUST NOT be used
as assertions of identity. They are evaluated by identifier
conditions (Section 8.7.6.1).
A more complete example: Imagine a device has the following physical
components: 1. A host MCU 2. A WiFi module
This same device has three software modules: 1. An operating system
2. A WiFi module interface driver 3. An application
Suppose that the WiFi module's firmware has a proprietary update
mechanism and doesn't support manifest processing. This device can
report four class IDs:
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1. Hardware model/revision
2. OS
3. WiFi module model/revision
4. Application
This allows the OS, WiFi module, and application to be updated
independently. To combat possible incompatibilities, the OS class ID
can be changed each time the OS has a change to its API.
This approach allows a vendor to target, for example, all devices
with a particular WiFi module with an update, which is a very
powerful mechanism, particularly when used for security updates.
UUIDs MUST be created according to RFC 4122 [RFC4122]. UUIDs SHOULD
use versions 3, 4, or 5, as described in RFC4122. Versions 1 and 2
do not provide a tangible benefit over version 4 for this
application.
The RECOMMENDED method to create a vendor ID is:
Vendor ID = UUID5(DNS_PREFIX, vendor domain name)
If the Vendor ID is a UUID, the RECOMMENDED method to create a Class
ID is:
Class ID = UUID5(Vendor ID, Class-Specific-Information)
If the Vendor ID is a CBOR PEN (see Section 8.7.5.3), the RECOMMENDED
method to create a Class ID is:
Class ID = UUID5(
UUID5(NAMESPACE_CBOR_PEN, CBOR_PEN),
Class-Specific-Information)
Class-specific-information is composed of a variety of data, for
example:
- Model number.
- Hardware revision.
- Bootloader version (for immutable bootloaders).
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8.7.5.3. suit-parameter-vendor-identifier
suit-parameter-vendor-identifier may be presented in one of two ways:
- A Private Enterprise Number
- A byte string containing a UUID ([RFC4122])
Private Enterprise Numbers are encoded as a relative OID, according
to the definition in [I-D.ietf-cbor-tags-oid]. All PENs are relative
to the IANA PEN: 1.3.6.1.4.1.
8.7.5.4. suit-parameter-class-identifier
A RFC 4122 UUID representing the class of the device or component.
The UUID is encoded as a 16 byte bstr, containing the raw bytes of
the UUID. It MUST be constructed as described in Section 8.7.5.2
8.7.5.5. suit-parameter-device-identifier
A RFC 4122 UUID representing the specific device or component. The
UUID is encoded as a 16 byte bstr, containing the raw bytes of the
UUID. It MUST be constructed as described in Section 8.7.5.2
8.7.5.6. suit-parameter-image-digest
A fingerprint computed over the component itself, encoded in the
SUIT_Digest Section 10 structure. The SUIT_Digest is wrapped in a
bstr, as required in Section 8.7.5.
8.7.5.7. suit-parameter-image-size
The size of the firmware image in bytes. This size is encoded as a
positive integer.
8.7.5.8. suit-parameter-use-before
An expiry date for the use of the manifest encoded as the positive
integer number of seconds since 1970-01-01. Implementations that use
this parameter MUST use a 64-bit internal representation of the
integer.
8.7.5.9. suit-parameter-component-offset
This parameter sets the offset in a component. Some components
support multiple possible Slots (offsets into a storage area). This
parameter describes the intended Slot to use, identified by its
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offset into the component's storage area. This offset MUST be
encoded as a positive integer.
8.7.5.10. suit-parameter-encryption-info
Encryption Info defines the mechanism that Fetch or Copy should use
to decrypt the data they transfer. SUIT_Parameter_Encryption_Info is
encoded as a COSE_Encrypt_Tagged or a COSE_Encrypt0_Tagged, wrapped
in a bstr.
8.7.5.11. suit-parameter-compression-info
SUIT_Compression_Info defines any information that is required for a
Recipient to perform decompression operations. SUIT_Compression_Info
is a map containing this data. The only element defined for the map
in this specification is the suit-compression-algorithm. This
document defines the following suit-compression-algorithm's: ZLIB
[RFC1950], Brotli [RFC7932], and ZSTD [I-D.kucherawy-rfc8478bis].
Additional suit-compression-algorithm's can be registered through the
IANA-maintained registry. If such a format requires more data than
an algorithm identifier, one or more new elements MUST be introduced
by specifying an element for SUIT_Compression_Info-extensions.
8.7.5.12. suit-parameter-unpack-info
SUIT_Unpack_Info defines the information required for a Recipient to
interpret a packed format. This document defines the use of the
following binary encodings: Intel HEX [HEX], Motorola S-record
[SREC], Executable and Linkable Format (ELF) [ELF], and Common Object
File Format (COFF) [COFF].
Additional packing formats can be registered through the IANA-
maintained registry.
8.7.5.13. suit-parameter-uri
A URI from which to fetch a resource, encoded as a text string. CBOR
Tag 32 is not used because the meaning of the text string is
unambiguous in this context.
8.7.5.14. suit-parameter-source-component
This parameter sets the source component to be used with either suit-
directive-copy (Section 8.7.7.9) or with suit-directive-swap
(Section 8.7.7.13). The current Component, as set by suit-directive-
set-component-index defines the destination, and suit-parameter-
source-component defines the source.
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8.7.5.15. suit-parameter-run-args
This parameter contains an encoded set of arguments for suit-
directive-run (Section 8.7.7.10). The arguments MUST be provided as
an implementation-defined bstr.
8.7.5.16. suit-parameter-minimum-battery
This parameter sets the minimum battery level in mWh. This parameter
is encoded as a positive integer. Used with suit-condition-minimum-
battery (Section 8.7.6.6).
8.7.5.17. suit-parameter-update-priority
This parameter sets the priority of the update. This parameter is
encoded as an integer. It is used along with suit-condition-update-
authorized (Section 8.7.6.7) to ask an application for permission to
initiate an update. This does not constitute a privilege inversion
because an explicit request for authorization has been provided by
the Update Authority in the form of the suit-condition-update-
authorized command.
Applications MAY define their own meanings for the update priority.
For example, critical reliability & vulnerability fixes MAY be given
negative numbers, while bug fixes MAY be given small positive
numbers, and feature additions MAY be given larger positive numbers,
which allows an application to make an informed decision about
whether and when to allow an update to proceed.
8.7.5.18. suit-parameter-version
Indicates allowable versions for the specified component. Allowable
versions can be specified, either with a list or with range matching.
This parameter is compared with version asserted by the current
component when suit-condition-version (Section 8.7.6.8) is invoked.
The current component may assert the current version in many ways,
including storage in a parameter storage database, in a metadata
object, or in a known location within the component itself.
The component version can be compared as:
- Greater.
- Greater or Equal.
- Equal.
- Lesser or Equal.
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- Lesser.
Versions are encoded as a CBOR list of integers. Comparisons are
done on each integer in sequence. Comparison stops after all
integers in the list defined by the manifest have been consumed OR
after a non-equal match has occurred. For example, if the manifest
defines a comparison, "Equal [1]", then this will match all version
sequences starting with 1. If a manifest defines both "Greater or
Equal [1,0]" and "Lesser [1,10]", then it will match versions 1.0.x
up to, but not including 1.10.
While the exact encoding of versions is application-defined, semantic
versions map conveniently. For example,
- 1.2.3 = [1,2,3].
- 1.2-rc3 = [1,2,-1,3].
- 1.2-beta = [1,2,-2].
- 1.2-alpha = [1,2,-3].
- 1.2-alpha4 = [1,2,-3,4].
suit-condition-version is OPTIONAL to implement.
Versions SHOULD be provided as follows:
1. The first integer represents the major number. This indicates
breaking changes to the component.
2. The second integer represents the minor number. This is
typically reserved for new features or large, non-breaking
changes.
3. The third integer is the patch version. This is typically
reserved for bug fixes.
4. The fourth integer is the build number.
Where Alpha (-3), Beta (-2), and Release Candidate (-1) are used,
they are inserted as a negative number between Minor and Patch
numbers. This allows these releases to compare correctly with final
releases. For example, Version 2.0, RC1 should be lower than Version
2.0.0 and higher than any Version 1.x. By encoding RC as -1, this
works correctly: [2,0,-1,1] compares as lower than [2,0,0].
Similarly, beta (-2) is lower than RC and alpha (-3) is lower than
RC.
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8.7.5.19. suit-parameter-wait-info
suit-directive-wait (Section 8.7.7.11) directs the manifest processor
to pause until a specified event occurs. The suit-parameter-wait-
info encodes the parameters needed for the directive.
The exact implementation of the pause is implementation-defined. For
example, this could be done by blocking on a semaphore, registering
an event handler and suspending the manifest processor, polling for a
notification, or aborting the update entirely, then restarting when a
notification is received.
suit-parameter-wait-info is encoded as a map of wait events. When
ALL wait events are satisfied, the Manifest Processor continues. The
wait events currently defined are described in the following table.
+------------------------------+---------+--------------------------+
| Name | Encodin | Description |
| | g | |
+------------------------------+---------+--------------------------+
| suit-wait-event- | int | Same as suit-parameter- |
| authorization | | update-priority |
| | | |
| suit-wait-event-power | int | Wait until power state |
| | | |
| suit-wait-event-network | int | Wait until network state |
| | | |
| suit-wait-event-other- | See | Wait for other device to |
| device-version | below | match version |
| | | |
| suit-wait-event-time | uint | Wait until time (seconds |
| | | since 1970-01-01) |
| | | |
| suit-wait-event-time-of-day | uint | Wait until seconds since |
| | | 00:00:00 |
| | | |
| suit-wait-event-time-of-day- | uint | Wait until seconds since |
| utc | | 00:00:00 UTC |
| | | |
| suit-wait-event-day-of-week | uint | Wait until days since |
| | | Sunday |
| | | |
| suit-wait-event-day-of-week- | uint | Wait until days since |
| utc | | Sunday UTC |
+------------------------------+---------+--------------------------+
suit-wait-event-other-device-version reuses the encoding of suit-
parameter-version-match. It is encoded as a sequence that contains
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an implementation-defined bstr identifier for the other device, and a
list of one or more SUIT_Parameter_Version_Match.
8.7.5.20. suit-parameter-uri-list
Indicates a list of URIs from which to fetch a resource. The URI
list is encoded as a list of text string, in priority order. CBOR
Tag 32 is not used because the meaning of the text string is
unambiguous in this context. The Recipient should attempt to fetch
the resource from each URI in turn, ruling out each, in order, if the
resource is inaccessible or it is otherwise undesirable to fetch from
that URI. suit-parameter-uri-list is consumed by suit-directive-
fetch-uri-list (Section 8.7.7.8).
8.7.5.21. suit-parameter-fetch-arguments
An implementation-defined set of arguments to suit-directive-fetch
(Section 8.7.7.7). Arguments are encoded in a bstr.
8.7.5.22. suit-parameter-strict-order
The Strict Order Parameter allows a manifest to govern when
directives can be executed out-of-order. This allows for systems
that have a sensitivity to order of updates to choose the order in
which they are executed. It also allows for more advanced systems to
parallelize their handling of updates. Strict Order defaults to
True. It MAY be set to False when the order of operations does not
matter. When arriving at the end of a command sequence, ALL commands
MUST have completed, regardless of the state of
SUIT_Parameter_Strict_Order. SUIT_Process_Dependency must preserve
and restore the state of SUIT_Parameter_Strict_Order. If
SUIT_Parameter_Strict_Order is returned to True, ALL preceding
commands MUST complete before the next command is executed.
See Section 6.7 for behavioral description of Strict Order.
8.7.5.23. suit-parameter-soft-failure
When executing a command sequence inside suit-directive-try-each
(Section 8.7.7.3) or suit-directive-run-sequence (Section 8.7.7.12)
and a condition failure occurs, the manifest processor aborts the
sequence. For suit-directive-try-each, if Soft Failure is True, the
next sequence in Try Each is invoked, otherwise suit-directive-try-
each fails with the condition failure code. In suit-directive-run-
sequence, if Soft Failure is True the suit-directive-run-sequence
simply halts with no side-effects and the Manifest Processor
continues with the following command, otherwise, the suit-directive-
run-sequence fails with the condition failure code.
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suit-parameter-soft-failure is scoped to the enclosing
SUIT_Command_Sequence. Its value is discarded when
SUIT_Command_Sequence terminates. It MUST NOT be set outside of
suit-directive-try-each or suit-directive-run-sequence.
When suit-directive-try-each is invoked, Soft Failure defaults to
True. An Update Author may choose to set Soft Failure to False if
they require a failed condition in a sequence to force an Abort.
When suit-directive-run-sequence is invoked, Soft Failure defaults to
False. An Update Author may choose to make failures soft within a
suit-directive-run-sequence.
8.7.5.24. suit-parameter-custom
This parameter is an extension point for any proprietary, application
specific conditions and directives. It MUST NOT be used in the
common sequence. This effectively scopes each custom command to a
particular Vendor Identifier/Class Identifier pair.
8.7.6. SUIT_Condition
Conditions are used to define mandatory properties of a system in
order for an update to be applied. They can be pre-conditions or
post-conditions of any directive or series of directives, depending
on where they are placed in the list. All Conditions specify a
Reporting Policy as described Section 8.7.4. Conditions include:
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+----------------+----------------------------------+---------------+
| Name | CDDL Structure | Reference |
+----------------+----------------------------------+---------------+
| Vendor | suit-condition-vendor-identifier | Section 8.7.6 |
| Identifier | | .1 |
| | | |
| Class | suit-condition-class-identifier | Section 8.7.6 |
| Identifier | | .1 |
| | | |
| Device | suit-condition-device-identifier | Section 8.7.6 |
| Identifier | | .1 |
| | | |
| Image Match | suit-condition-image-match | Section 8.7.6 |
| | | .2 |
| | | |
| Image Not | suit-condition-image-not-match | Section 8.7.6 |
| Match | | .3 |
| | | |
| Use Before | suit-condition-use-before | Section 8.7.6 |
| | | .4 |
| | | |
| Component | suit-condition-component-offset | Section 8.7.6 |
| Offset | | .5 |
| | | |
| Minimum | suit-condition-minimum-battery | Section 8.7.6 |
| Battery | | .6 |
| | | |
| Update | suit-condition-update-authorized | Section 8.7.6 |
| Authorized | | .7 |
| | | |
| Version | suit-condition-version | Section 8.7.6 |
| | | .8 |
| | | |
| Abort | suit-condition-abort | Section 8.7.6 |
| | | .9 |
| | | |
| Custom | suit-condition-custom | Section 8.7.6 |
| Condition | | .10 |
+----------------+----------------------------------+---------------+
The abstract description of these conditions is defined in
Section 6.4.
Conditions compare parameters against properties of the system.
These properties may be asserted in many different ways, including:
calculation on-demand, volatile definition in memory, static
definition within the manifest processor, storage in known location
within an image, storage within a key storage system, storage in One-
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Time-Programmable memory, inclusion in mask ROM, or inclusion as a
register in hardware. Some of these assertion methods are global in
scope, such as a hardware register, some are scoped to an individual
component, such as storage at a known location in an image, and some
assertion methods can be either global or component-scope, based on
implementation.
Each condition MUST report a result code on completion. If a
condition reports failure, then the current sequence of commands MUST
terminate. A subsequent command or command sequence MAY continue
executing if suit-parameter-soft-failure (Section 8.7.5.23) is set.
If a condition requires additional information, this MUST be
specified in one or more parameters before the condition is executed.
If a Recipient attempts to process a condition that expects
additional information and that information has not been set, it MUST
report a failure. If a Recipient encounters an unknown condition, it
MUST report a failure.
Condition labels in the positive number range are reserved for IANA
registration while those in the negative range are custom conditions
reserved for proprietary definition by the author of a manifest
processor. See Section 11 for more details.
8.7.6.1. suit-condition-vendor-identifier, suit-condition-class-
identifier, and suit-condition-device-identifier
There are three identifier-based conditions: suit-condition-vendor-
identifier, suit-condition-class-identifier, and suit-condition-
device-identifier. Each of these conditions match a RFC 4122
[RFC4122] UUID that MUST have already been set as a parameter. The
installing Recipient MUST match the specified UUID in order to
consider the manifest valid. These identifiers are scoped by
component in the manifest. Each component MAY match more than one
identifier. Care is needed to ensure that manifests correctly
identify their targets using these conditions. Using only a generic
class ID for a device-specific firmware could result in matching
devices that are not compatible.
The Recipient uses the ID parameter that has already been set using
the Set Parameters directive. If no ID has been set, this condition
fails. suit-condition-class-identifier and suit-condition-vendor-
identifier are REQUIRED to implement. suit-condition-device-
identifier is OPTIONAL to implement.
Each identifier condition compares the corresponding identifier
parameter to a parameter asserted to the Manifest Processor by the
Recipient. Identifiers MUST be known to the Manifest Processor in
order to evaluate compatibility.
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8.7.6.2. suit-condition-image-match
Verify that the current component matches the suit-parameter-image-
digest (Section 8.7.5.6) for the current component. The digest is
verified against the digest specified in the Component's parameters
list. If no digest is specified, the condition fails. suit-
condition-image-match is REQUIRED to implement.
8.7.6.3. suit-condition-image-not-match
Verify that the current component does not match the suit-parameter-
image-digest (Section 8.7.5.6). If no digest is specified, the
condition fails. suit-condition-image-not-match is OPTIONAL to
implement.
8.7.6.4. suit-condition-use-before
Verify that the current time is BEFORE the specified time. suit-
condition-use-before is used to specify the last time at which an
update should be installed. The recipient evaluates the current time
against the suit-parameter-use-before parameter (Section 8.7.5.8),
which must have already been set as a parameter, encoded as seconds
after 1970-01-01 00:00:00 UTC. Timestamp conditions MUST be
evaluated in 64 bits, regardless of encoded CBOR size. suit-
condition-use-before is OPTIONAL to implement.
8.7.6.5. suit-condition-component-offset
Verify that the offset of the current component matches the offset
set in suit-parameter-component-offset (Section 8.7.5.9). This
condition allows a manifest to select between several images to match
a target offset.
8.7.6.6. suit-condition-minimum-battery
suit-condition-minimum-battery provides a mechanism to test a
Recipient's battery level before installing an update. This
condition is primarily for use in primary-cell applications, where
the battery is only ever discharged. For batteries that are charged,
suit-directive-wait is more appropriate, since it defines a "wait"
until the battery level is sufficient to install the update. suit-
condition-minimum-battery is specified in mWh. suit-condition-
minimum-battery is OPTIONAL to implement. suit-condition-minimum-
battery consumes suit-parameter-minimum-battery (Section 8.7.5.16).
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8.7.6.7. suit-condition-update-authorized
Request Authorization from the application and fail if not
authorized. This can allow a user to decline an update. suit-
parameter-update-priority (Section 8.7.5.17) provides an integer
priority level that the application can use to determine whether or
not to authorize the update. Priorities are application defined.
suit-condition-update-authorized is OPTIONAL to implement.
8.7.6.8. suit-condition-version
suit-condition-version allows comparing versions of firmware.
Verifying image digests is preferred to version checks because
digests are more precise. suit-condition-version examines a
component's version against the version info specified in suit-
parameter-version (Section 8.7.5.18)
8.7.6.9. suit-condition-abort
Unconditionally fail. This operation is typically used in
conjunction with suit-directive-try-each (Section 8.7.7.3).
8.7.6.10. suit-condition-custom
suit-condition-custom describes any proprietary, application specific
condition. This is encoded as a negative integer, chosen by the
firmware developer. If additional information must be provided to
the condition, it should be encoded in a custom parameter (a nint) as
described in Section 8.7.5. SUIT_Condition_Custom is OPTIONAL to
implement.
8.7.7. SUIT_Directive
Directives are used to define the behavior of the recipient.
Directives include:
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+---------------+-------------------------------------+-------------+
| Name | CDDL Structure | Reference |
+---------------+-------------------------------------+-------------+
| Set Component | suit-directive-set-component-index | Section 8.7 |
| Index | | .7.1 |
| | | |
| Set | suit-directive-set-dependency-index | Section 8.7 |
| Dependency | | .7.2 |
| Index | | |
| | | |
| Try Each | suit-directive-try-each | Section 8.7 |
| | | .7.3 |
| | | |
| Process | suit-directive-process-dependency | Section 8.7 |
| Dependency | | .7.4 |
| | | |
| Set | suit-directive-set-parameters | Section 8.7 |
| Parameters | | .7.5 |
| | | |
| Override | suit-directive-override-parameters | Section 8.7 |
| Parameters | | .7.6 |
| | | |
| Fetch | suit-directive-fetch | Section 8.7 |
| | | .7.7 |
| | | |
| Fetch URI | suit-directive-fetch-uri-list | Section 8.7 |
| list | | .7.8 |
| | | |
| Copy | suit-directive-copy | Section 8.7 |
| | | .7.9 |
| | | |
| Run | suit-directive-run | Section 8.7 |
| | | .7.10 |
| | | |
| Wait For | suit-directive-wait | Section 8.7 |
| Event | | .7.11 |
| | | |
| Run Sequence | suit-directive-run-sequence | Section 8.7 |
| | | .7.12 |
| | | |
| Swap | suit-directive-swap | Section 8.7 |
| | | .7.13 |
| | | |
| Garbage | suit-directive-garbage-collect | Section 8.7 |
| Collect | | .8 |
+---------------+-------------------------------------+-------------+
The abstract description of these commands is defined in Section 6.4.
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When a Recipient executes a Directive, it MUST report a result code.
If the Directive reports failure, then the current Command Sequence
MUST be terminated.
8.7.7.1. suit-directive-set-component-index
Set Component Index defines the component to which successive
directives and conditions will apply. The supplied argument MUST be
one of three types:
1. An unsigned integer (REQUIRED to implement in parser)
2. A boolean (REQUIRED to implement in parser ONLY IF 2 or more
components supported)
3. An array of unsigned integers (REQUIRED to implement in parser
ONLY IF 3 or more components supported)
If the following commands apply to ONE component, an unsigned integer
index into the component list is used. If the following commands
apply to ALL components, then the boolean value "True" is used
instead of an index. If the following commands apply to more than
one, but not all components, then an array of unsigned integer
indices into the component list is used. See Section 6.5 for more
details.
If the following commands apply to NO components, then the boolean
value "False" is used. When suit-directive-set-dependency-index is
used, suit-directive-set-component-index = False is implied. When
suit-directive-set-component-index is used, suit-directive-set-
dependency-index = False is implied.
If component index is set to True when a command is invoked, then the
command applies to all components, in the order they appear in suit-
common-components. When the Manifest Processor invokes a command
while the component index is set to True, it must execute the command
once for each possible component index, ensuring that the command
receives the parameters corresponding to that component index.
8.7.7.2. suit-directive-set-dependency-index
Set Dependency Index defines the manifest to which successive
directives and conditions will apply. The supplied argument MUST be
either a boolean or an unsigned integer index into the dependencies,
or an array of unsigned integer indices into the list of
dependencies. If the following directives apply to ALL dependencies,
then the boolean value "True" is used instead of an index. If the
following directives apply to NO dependencies, then the boolean value
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"False" is used. When suit-directive-set-component-index is used,
suit-directive-set-dependency-index = False is implied. When suit-
directive-set-dependency-index is used, suit-directive-set-component-
index = False is implied.
If dependency index is set to True when a command is invoked, then
the command applies to all dependencies, in the order they appear in
suit-common-components. When the Manifest Processor invokes a
command while the dependency index is set to True, the Manifest
Processor MUST execute the command once for each possible dependency
index, ensuring that the command receives the parameters
corresponding to that dependency index. If the dependency index is
set to an array of unsigned integers, then the Manifest Processor
MUST execute the command once for each listed dependency index,
ensuring that the command receives the parameters corresponding to
that dependency index.
See Section 6.5 for more details.
Typical operations that require suit-directive-set-dependency-index
include setting a source URI or Encryption Information, invoking
"Fetch," or invoking "Process Dependency" for an individual
dependency.
8.7.7.3. suit-directive-try-each
This command runs several SUIT_Command_Sequence instances, one after
another, in a strict order. Use this command to implement a "try/
catch-try/catch" sequence. Manifest processors MAY implement this
command.
suit-parameter-soft-failure (Section 8.7.5.23) is initialized to True
at the beginning of each sequence. If one sequence aborts due to a
condition failure, the next is started. If no sequence completes
without condition failure, then suit-directive-try-each returns an
error. If a particular application calls for all sequences to fail
and still continue, then an empty sequence (nil) can be added to the
Try Each Argument.
The argument to suit-directive-try-each is a list of
SUIT_Command_Sequence. suit-directive-try-each does not specify a
reporting policy.
8.7.7.4. suit-directive-process-dependency
Execute the commands in the common section of the current dependency,
followed by the commands in the equivalent section of the current
dependency. For example, if the current section is "fetch payload,"
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this will execute "common" in the current dependency, then "fetch
payload" in the current dependency. Once this is complete, the
command following suit-directive-process-dependency will be
processed.
If the current dependency is False, this directive has no effect. If
the current dependency is True, then this directive applies to all
dependencies. If the current section is "common," then the command
sequence MUST be terminated with an error.
When SUIT_Process_Dependency completes, it forwards the last status
code that occurred in the dependency.
8.7.7.5. suit-directive-set-parameters
suit-directive-set-parameters allows the manifest to configure
behavior of future directives by changing parameters that are read by
those directives. When dependencies are used, suit-directive-set-
parameters also allows a manifest to modify the behavior of its
dependencies.
Available parameters are defined in Section 8.7.5.
If a parameter is already set, suit-directive-set-parameters will
skip setting the parameter to its argument. This provides the core
of the override mechanism, allowing dependent manifests to change the
behavior of a manifest.
suit-directive-set-parameters does not specify a reporting policy.
8.7.7.6. suit-directive-override-parameters
suit-directive-override-parameters replaces any listed parameters
that are already set with the values that are provided in its
argument. This allows a manifest to prevent replacement of critical
parameters.
Available parameters are defined in Section 8.7.5.
suit-directive-override-parameters does not specify a reporting
policy.
8.7.7.7. suit-directive-fetch
suit-directive-fetch instructs the manifest processor to obtain one
or more manifests or payloads, as specified by the manifest index and
component index, respectively.
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suit-directive-fetch can target one or more manifests and one or more
payloads. suit-directive-fetch retrieves each component and each
manifest listed in component-index and dependency-index,
respectively. If component-index or dependency-index is True,
instead of an integer, then all current manifest components/manifests
are fetched. The current manifest's dependent-components are not
automatically fetched. In order to pre-fetch these, they MUST be
specified in a component-index integer.
suit-directive-fetch typically takes no arguments unless one is
needed to modify fetch behavior. If an argument is needed, it must
be wrapped in a bstr and set in suit-parameter-fetch-arguments.
suit-directive-fetch reads the URI parameter to find the source of
the fetch it performs.
The behavior of suit-directive-fetch can be modified by setting one
or more of SUIT_Parameter_Encryption_Info,
SUIT_Parameter_Compression_Info, SUIT_Parameter_Unpack_Info. These
three parameters each activate and configure a processing step that
can be applied to the data that is transferred during suit-directive-
fetch.
8.7.7.8. suit-directive-fetch-uri-list
suit-directive-fetch-uri-list uses the same semantics as suit-
directive-fetch (Section 8.7.7.7), except that it iterates over the
URI List (Section 8.7.5.20) to select a URI to fetch from.
8.7.7.9. suit-directive-copy
suit-directive-copy instructs the manifest processor to obtain one or
more payloads, as specified by the component index. As described in
Section 6.5 component index may be a single integer, a list of
integers, or True. suit-directive-copy retrieves each component
specified by the current component-index, respectively. The current
manifest's dependent-components are not automatically copied. In
order to copy these, they MUST be specified in a component-index
integer.
The behavior of suit-directive-copy can be modified by setting one or
more of SUIT_Parameter_Encryption_Info,
SUIT_Parameter_Compression_Info, SUIT_Parameter_Unpack_Info. These
three parameters each activate and configure a processing step that
can be applied to the data that is transferred during suit-directive-
copy.
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suit-directive-copy reads its source from suit-parameter-source-
component (Section 8.7.5.14).
If either the source component parameter or the source component
itself is absent, this command fails.
8.7.7.10. suit-directive-run
suit-directive-run directs the manifest processor to transfer
execution to the current Component Index. When this is invoked, the
manifest processor MAY be unloaded and execution continues in the
Component Index. Arguments are provided to suit-directive-run
through suit-parameter-run-arguments (Section 8.7.5.15) and are
forwarded to the executable code located in Component Index in an
application-specific way. For example, this could form the Linux
Kernel Command Line if booting a Linux device.
If the executable code at Component Index is constructed in such a
way that it does not unload the manifest processor, then the manifest
processor may resume execution after the executable completes. This
allows the manifest processor to invoke suitable helpers and to
verify them with image conditions.
8.7.7.11. suit-directive-wait
suit-directive-wait directs the manifest processor to pause until a
specified event occurs. Some possible events include:
1. Authorization
2. External Power
3. Network availability
4. Other Device Firmware Version
5. Time
6. Time of Day
7. Day of Week
8.7.7.12. suit-directive-run-sequence
To enable conditional commands, and to allow several strictly ordered
sequences to be executed out-of-order, suit-directive-run-sequence
allows the manifest processor to execute its argument as a
SUIT_Command_Sequence. The argument must be wrapped in a bstr.
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When a sequence is executed, any failure of a condition causes
immediate termination of the sequence.
When suit-directive-run-sequence completes, it forwards the last
status code that occurred in the sequence. If the Soft Failure
parameter is true, then suit-directive-run-sequence only fails when a
directive in the argument sequence fails.
suit-parameter-soft-failure (Section 8.7.5.23) defaults to False when
suit-directive-run-sequence begins. Its value is discarded when
suit-directive-run-sequence terminates.
8.7.7.13. suit-directive-swap
suit-directive-swap instructs the manifest processor to move the
source to the destination and the destination to the source
simultaneously. Swap has nearly identical semantics to suit-
directive-copy except that suit-directive-swap replaces the source
with the current contents of the destination in an application-
defined way. As with suit-directive-copy, if the source component is
missing, this command fails.
If SUIT_Parameter_Compression_Info or SUIT_Parameter_Encryption_Info
are present, they MUST be handled in a symmetric way, so that the
source is decompressed into the destination and the destination is
compressed into the source. The source is decrypted into the
destination and the destination is encrypted into the source. suit-
directive-swap is OPTIONAL to implement.
8.7.8. suit-directive-garbage-collect
suit-directive-garbage-collect marks the current component as unused
in the current manifest. This can be used to remove temporary
storage or remove components that are no longer needed. Example use
cases:
- Temporary storage for encrypted download
- Temporary storage for verifying decompressed file before writing
to flash
- Removing Trusted Service no longer needed by Trusted Application
Once the current Command Sequence is complete, the manifest
processors checks each marked component to see whether any other
manifests have referenced it. Those marked components with no other
references are deleted. The manifest processor MAY choose to ignore
a Garbage Collect directive depending on device policy.
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suit-directive-garbage-collect is OPTIONAL to implement in manifest
processors.
8.7.9. Integrity Check Values
When the CoSWID, Text section, or any Command Sequence of the Update
Procedure is made severable, it is moved to the Envelope and replaced
with a SUIT_Digest. The SUIT_Digest is computed over the entire bstr
enclosing the Manifest element that has been moved to the Envelope.
Each element that is made severable from the Manifest is placed in
the Envelope. The keys for the envelope elements have the same
values as the keys for the manifest elements.
Each Integrity Check Value covers the corresponding Envelope Element
as described in Section 8.8.
8.8. Severable Elements
Because the manifest can be used by different actors at different
times, some parts of the manifest can be removed or "Severed" without
affecting later stages of the lifecycle. Severing of information is
achieved by separating that information from the signed container so
that removing it does not affect the signature. This means that
ensuring integrity of severable parts of the manifest is a
requirement for the signed portion of the manifest. Severing some
parts makes it possible to discard parts of the manifest that are no
longer necessary. This is important because it allows the storage
used by the manifest to be greatly reduced. For example, no text
size limits are needed if text is removed from the manifest prior to
delivery to a constrained device.
Elements are made severable by removing them from the manifest,
encoding them in a bstr, and placing a SUIT_Digest of the bstr in the
manifest so that they can still be authenticated. The SUIT_Digest
typically consumes 4 bytes more than the size of the raw digest,
therefore elements smaller than (Digest Bits)/8 + 4 SHOULD NOT be
severable. Elements larger than (Digest Bits)/8 + 4 MAY be
severable, while elements that are much larger than (Digest Bits)/8 +
4 SHOULD be severable.
Because of this, all command sequences in the manifest are encoded in
a bstr so that there is a single code path needed for all command
sequences.
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9. Access Control Lists
To manage permissions in the manifest, there are three models that
can be used.
First, the simplest model requires that all manifests are
authenticated by a single trusted key. This mode has the advantage
that only a root manifest needs to be authenticated, since all of its
dependencies have digests included in the root manifest.
This simplest model can be extended by adding key delegation without
much increase in complexity.
A second model requires an ACL to be presented to the Recipient,
authenticated by a trusted party or stored on the Recipient. This
ACL grants access rights for specific component IDs or Component
Identifier prefixes to the listed identities or identity groups. Any
identity can verify an image digest, but fetching into or fetching
from a Component Identifier requires approval from the ACL.
A third model allows a Recipient to provide even more fine-grained
controls: The ACL lists the Component Identifier or Component
Identifier prefix that an identity can use, and also lists the
commands and parameters that the identity can use in combination with
that Component Identifier.
10. SUIT Digest Container
RFC 8152 [RFC8152] provides containers for signature, MAC, and
encryption, but no basic digest container. The container needed for
a digest requires a type identifier and a container for the raw
digest data. Some forms of digest may require additional parameters.
These can be added following the digest.
The SUIT digest is a CBOR List containing two elements: a suit-
digest-algorithm-id and a bstr containing the bytes of the digest.
11. IANA Considerations
IANA is requested to:
- allocate CBOR tag 107 in the CBOR Tags registry for the SUIT
Envelope.
- allocate CBOR tag 1070 in the CBOR Tags registry for the SUIT
Manifest.
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- allocate media type application/suit-envelope in the Media Types
registry.
- setup several registries as described below.
IANA is requested to setup a registry for SUIT manifests. Several
registries defined in the subsections below need to be created.
For each registry, values 0-23 are Standards Action, 24-255 are IETF
Review, 256-65535 are Expert Review, and 65536 or greater are First
Come First Served.
Negative values -23 to 0 are Experimental Use, -24 and lower are
Private Use.
11.1. SUIT Commands
+-------+------------+-----------------------------------+----------+
| Label | Name | Reference | |
+-------+------------+-----------------------------------+----------+
| 1 | Vendor | Section 8.7.6.1 | |
| | Identifier | | |
| | | | |
| 2 | Class | Section 8.7.6.1 | |
| | Identifier | | |
| | | | |
| 3 | Image | Section 8.7.6.2 | |
| | Match | | |
| | | | |
| 4 | Use Before | Section 8.7.6.4 | |
| | | | |
| 5 | Component | Section 8.7.6.5 | |
| | Offset | | |
| | | | |
| 12 | Set | Section 8.7.7.1 | |
| | Component | | |
| | Index | | |
| | | | |
| 13 | Set | Section 8.7.7.2 | |
| | Dependency | | |
| | Index | | |
| | | | |
| 14 | Abort | | |
| | | | |
| 15 | Try Each | Section 8.7.7.3 | |
| | | | |
| 16 | Reserved | | |
| | | | |
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| 17 | Reserved | | |
| | | | |
| 18 | Process | suit-directive-process-dependency | Section |
| | Dependency | | 8.7.7.4 |
| | | | |
| 19 | Set | Section 8.7.7.5 | |
| | Parameters | | |
| | | | |
| 20 | Override | Section 8.7.7.6 | |
| | Parameters | | |
| | | | |
| 21 | Fetch | Section 8.7.7.7 | |
| | | | |
| 22 | Copy | Section 8.7.7.9 | |
| | | | |
| 23 | Run | Section 8.7.7.10 | |
| | | | |
| 24 | Device | Section 8.7.6.1 | |
| | Identifier | | |
| | | | |
| 25 | Image Not | Section 8.7.6.3 | |
| | Match | | |
| | | | |
| 26 | Minimum | Section 8.7.6.6 | |
| | Battery | | |
| | | | |
| 27 | Update | Section 8.7.6.7 | |
| | Authorized | | |
| | | | |
| 28 | Version | Section 8.7.6.8 | |
| | | | |
| 29 | Wait For | Section 8.7.7.11 | |
| | Event | | |
| | | | |
| 30 | Fetch URI | Section 8.7.7.8 | |
| | List | | |
| | | | |
| 31 | Swap | Section 8.7.7.13 | |
| | | | |
| 32 | Run | Section 8.7.7.12 | |
| | Sequence | | |
| | | | |
| 33 | Garbage | Section 8.7.8 | |
| | Collect | | |
| | | | |
| nint | Custom | Section 8.7.6.10 | |
| | Condition | | |
+-------+------------+-----------------------------------+----------+
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11.2. SUIT Parameters
+-------+------------------+---------------------------+
| Label | Name | Reference |
+-------+------------------+---------------------------+
| 1 | Vendor ID | Section 8.7.5.3 |
| | | |
| 2 | Class ID | Section 8.7.5.4 |
| | | |
| 3 | Image Digest | Section 8.7.5.6 |
| | | |
| 4 | Use Before | Section 8.7.5.8 |
| | | |
| 5 | Component Offset | Section 8.7.5.9 |
| | | |
| 12 | Strict Order | Section 8.7.5.22 |
| | | |
| 13 | Soft Failure | Section 8.7.5.23 |
| | | |
| 14 | Image Size | Section 8.7.5.7 |
| | | |
| 18 | Encryption Info | Section 8.7.5.10 |
| | | |
| 19 | Compression Info | Section 8.7.5.11 |
| | | |
| 20 | Unpack Info | Section 8.7.5.12 |
| | | |
| 21 | URI | Section 8.7.5.13 |
| | | |
| 22 | Source Component | Section 8.7.5.14 |
| | | |
| 23 | Run Args | Section 8.7.5.15 |
| | | |
| 24 | Device ID | Section 8.7.5.5 |
| | | |
| 26 | Minimum Battery | Section 8.7.5.16 |
| | | |
| 27 | Update Priority | Section 8.7.5.17 |
| | | |
| 28 | Version | {{suit-parameter-version} |
| | | |
| 29 | Wait Info | Section 8.7.5.19 |
| | | |
| 30 | URI List | Section 8.7.5.20 |
| | | |
| nint | Custom | Section 8.7.5.24 |
+-------+------------------+---------------------------+
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11.3. SUIT Text Values
+-------+----------------------+---------------+
| Label | Name | Reference |
+-------+----------------------+---------------+
| 1 | Manifest Description | Section 8.6.4 |
| | | |
| 2 | Update Description | Section 8.6.4 |
| | | |
| 3 | Manifest JSON Source | Section 8.6.4 |
| | | |
| 4 | Manifest YAML Source | Section 8.6.4 |
| | | |
| nint | Custom | Section 8.6.4 |
+-------+----------------------+---------------+
11.4. SUIT Component Text Values
+-------+----------------------------+---------------+
| Label | Name | Reference |
+-------+----------------------------+---------------+
| 1 | Vendor Name | Section 8.6.4 |
| | | |
| 2 | Model Name | Section 8.6.4 |
| | | |
| 3 | Vendor Domain | Section 8.6.4 |
| | | |
| 4 | Model Info | Section 8.6.4 |
| | | |
| 5 | Component Description | Section 8.6.4 |
| | | |
| 6 | Component Version | Section 8.6.4 |
| | | |
| 7 | Component Version Required | Section 8.6.4 |
| | | |
| nint | Custom | Section 8.6.4 |
+-------+----------------------------+---------------+
11.5. SUIT Algorithm Identifiers
11.5.1. SUIT Digest Algorithm Identifiers
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+-------+----------+------------+
| Label | Name | |
+-------+----------+------------+
| 1 | SHA224 | Section 10 |
| | | |
| 2 | SHA256 | Section 10 |
| | | |
| 3 | SHA384 | Section 10 |
| | | |
| 4 | SHA512 | Section 10 |
| | | |
| 5 | SHA3-224 | Section 10 |
| | | |
| 6 | SHA3-256 | Section 10 |
| | | |
| 7 | SHA3-384 | Section 10 |
| | | |
| 8 | SHA3-512 | Section 10 |
+-------+----------+------------+
11.5.2. SUIT Compression Algorithm Identifiers
+-------+--------+------------------+
| Label | Name | Reference |
+-------+--------+------------------+
| 1 | zlib | Section 8.7.5.11 |
| | | |
| 2 | Brotli | Section 8.7.5.11 |
| | | |
| 3 | zstd | Section 8.7.5.11 |
+-------+--------+------------------+
11.5.3. Unpack Algorithms
+-------+------+------------------+
| Label | Name | Reference |
+-------+------+------------------+
| 1 | HEX | Section 8.7.5.12 |
| | | |
| 2 | ELF | Section 8.7.5.12 |
| | | |
| 3 | COFF | Section 8.7.5.12 |
| | | |
| 4 | SREC | Section 8.7.5.12 |
+-------+------+------------------+
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12. Security Considerations
This document is about a manifest format protecting and describing
how to retrieve, install, and invoke firmware images and as such it
is part of a larger solution for delivering firmware updates to IoT
devices. A detailed security treatment can be found in the
architecture [I-D.ietf-suit-architecture] and in the information
model [I-D.ietf-suit-information-model] documents.
13. Acknowledgements
We would like to thank the following persons for their support in
designing this mechanism:
- Milosch Meriac
- Geraint Luff
- Dan Ros
- John-Paul Stanford
- Hugo Vincent
- Carsten Bormann
- Oeyvind Roenningstad
- Frank Audun Kvamtroe
- Krzysztof Chruściński
- Andrzej Puzdrowski
- Michael Richardson
- David Brown
- Emmanuel Baccelli
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
14.2. Informative References
[COFF] Wikipedia, ., "Common Object File Format (COFF)", 2020,
<https://en.wikipedia.org/wiki/COFF>.
[ELF] Wikipedia, ., "Executable and Linkable Format (ELF)",
2020, <https://en.wikipedia.org/wiki/
Executable_and_Linkable_Format>.
[HEX] Wikipedia, ., "Intel HEX", 2020,
<https://en.wikipedia.org/wiki/Intel_HEX>.
[I-D.ietf-cbor-tags-oid]
Bormann, C. and S. Leonard, "Concise Binary Object
Representation (CBOR) Tags for Object Identifiers", draft-
ietf-cbor-tags-oid-04 (work in progress), January 2021.
[I-D.ietf-sacm-coswid]
Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
Waltermire, "Concise Software Identification Tags", draft-
ietf-sacm-coswid-16 (work in progress), November 2020.
[I-D.ietf-suit-architecture]
Moran, B., Tschofenig, H., Brown, D., and M. Meriac, "A
Firmware Update Architecture for Internet of Things",
draft-ietf-suit-architecture-15 (work in progress),
January 2021.
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[I-D.ietf-suit-information-model]
Moran, B., Tschofenig, H., and H. Birkholz, "An
Information Model for Firmware Updates in IoT Devices",
draft-ietf-suit-information-model-08 (work in progress),
October 2020.
[I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Thaler, D., and D. Wheeler,
"Trusted Execution Environment Provisioning (TEEP)
Architecture", draft-ietf-teep-architecture-13 (work in
progress), November 2020.
[I-D.kucherawy-rfc8478bis]
Collet, Y. and M. Kucherawy, "Zstandard Compression and
the application/zstd Media Type", draft-kucherawy-
rfc8478bis-06 (work in progress), December 2020.
[RFC1950] Deutsch, P. and J-L. Gailly, "ZLIB Compressed Data Format
Specification version 3.3", RFC 1950,
DOI 10.17487/RFC1950, May 1996,
<https://www.rfc-editor.org/info/rfc1950>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7932] Alakuijala, J. and Z. Szabadka, "Brotli Compressed Data
Format", RFC 7932, DOI 10.17487/RFC7932, July 2016,
<https://www.rfc-editor.org/info/rfc7932>.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>.
[RFC8747] Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
Tschofenig, "Proof-of-Possession Key Semantics for CBOR
Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March
2020, <https://www.rfc-editor.org/info/rfc8747>.
[SREC] Wikipedia, ., "SREC (file format)", 2020,
<https://en.wikipedia.org/wiki/SREC_(file_format)>.
[YAML] "YAML Ain't Markup Language", 2020, <https://yaml.org/>.
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Appendix A. A. Full CDDL
In order to create a valid SUIT Manifest document the structure of
the corresponding CBOR message MUST adhere to the following CDDL data
definition.
SUIT_Envelope_Tagged = #6.48(SUIT_Envelope)
SUIT_Envelope = {
? suit-delegation => bstr .cbor SUIT_Delegation,
suit-authentication-wrapper => bstr .cbor SUIT_Authentication,
suit-manifest => bstr .cbor SUIT_Manifest,
SUIT_Severable_Manifest_Members,
* SUIT_Integrated_Payload,
* SUIT_Integrated_Dependency,
* $$SUIT_Envelope_Extensions,
* (int => bstr)
}
SUIT_Delegation = [ + [ + bstr .cbor CWT ] ]
CWT = SUIT_Authentication_Block
SUIT_Authentication = [
bstr .cbor SUIT_Digest,
* bstr .cbor SUIT_Authentication_Block
]
SUIT_Digest = [
suit-digest-algorithm-id : suit-digest-algorithm-ids,
suit-digest-bytes : bstr,
* $$SUIT_Digest-extensions
]
; Named Information Hash Algorithm Identifiers
suit-digest-algorithm-ids /= algorithm-id-sha224
suit-digest-algorithm-ids /= algorithm-id-sha256
suit-digest-algorithm-ids /= algorithm-id-sha384
suit-digest-algorithm-ids /= algorithm-id-sha512
suit-digest-algorithm-ids /= algorithm-id-sha3-224
suit-digest-algorithm-ids /= algorithm-id-sha3-256
suit-digest-algorithm-ids /= algorithm-id-sha3-384
suit-digest-algorithm-ids /= algorithm-id-sha3-512
SUIT_Authentication_Block /= COSE_Mac_Tagged
SUIT_Authentication_Block /= COSE_Sign_Tagged
SUIT_Authentication_Block /= COSE_Mac0_Tagged
SUIT_Authentication_Block /= COSE_Sign1_Tagged
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COSE_Mac_Tagged = any
COSE_Sign_Tagged = any
COSE_Mac0_Tagged = any
COSE_Sign1_Tagged = any
COSE_Encrypt_Tagged = any
COSE_Encrypt0_Tagged = any
SUIT_Severable_Manifest_Members = (
? suit-dependency-resolution => bstr .cbor SUIT_Command_Sequence,
? suit-payload-fetch => bstr .cbor SUIT_Command_Sequence,
? suit-install => bstr .cbor SUIT_Command_Sequence,
? suit-text => bstr .cbor SUIT_Text_Map,
? suit-coswid => bstr .cbor concise-software-identity,
* $$SUIT_severable-members-extensions,
)
SUIT_Integrated_Payload = (suit-integrated-payload-key => bstr)
SUIT_Integrated_Dependency = (
suit-integrated-payload-key => bstr .cbor SUIT_Envelope
)
suit-integrated-payload-key = nint / uint .ge 24
SUIT_Manifest_Tagged = #6.480(SUIT_Manifest)
SUIT_Manifest = {
suit-manifest-version => 1,
suit-manifest-sequence-number => uint,
suit-common => bstr .cbor SUIT_Common,
? suit-reference-uri => tstr,
SUIT_Severable_Manifest_Members,
SUIT_Severable_Members_Digests,
SUIT_Unseverable_Members,
* $$SUIT_Manifest_Extensions,
}
SUIT_Unseverable_Members = (
? suit-validate => bstr .cbor SUIT_Command_Sequence,
? suit-load => bstr .cbor SUIT_Command_Sequence,
? suit-run => bstr .cbor SUIT_Command_Sequence,
* $$unserverble-manifest-member-extensions,
)
SUIT_Severable_Members_Digests = (
? suit-dependency-resolution => SUIT_Digest,
? suit-payload-fetch => SUIT_Digest,
? suit-install => SUIT_Digest,
? suit-text => SUIT_Digest,
? suit-coswid => SUIT_Digest,
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* $$severable-manifest-members-digests-extensions
)
SUIT_Common = {
? suit-dependencies => SUIT_Dependencies,
? suit-components => SUIT_Components,
? suit-common-sequence => bstr .cbor SUIT_Common_Sequence,
* $$SUIT_Common-extensions,
}
SUIT_Dependencies = [ + SUIT_Dependency ]
SUIT_Components = [ + SUIT_Component_Identifier ]
concise-software-identity = any
SUIT_Dependency = {
suit-dependency-digest => SUIT_Digest,
? suit-dependency-prefix => SUIT_Component_Identifier,
* $$SUIT_Dependency-extensions,
}
SUIT_Component_Identifier = [* bstr]
SUIT_Common_Sequence = [
+ ( SUIT_Condition // SUIT_Common_Commands )
]
SUIT_Common_Commands //= (suit-directive-set-component-index, IndexArg)
SUIT_Common_Commands //= (suit-directive-set-dependency-index, IndexArg)
SUIT_Common_Commands //= (suit-directive-run-sequence,
bstr .cbor SUIT_Command_Sequence)
SUIT_Common_Commands //= (suit-directive-try-each,
SUIT_Directive_Try_Each_Argument)
SUIT_Common_Commands //= (suit-directive-set-parameters,
{+ SUIT_Parameters})
SUIT_Common_Commands //= (suit-directive-override-parameters,
{+ SUIT_Parameters})
IndexArg /= uint
IndexArg /= bool
IndexArg /= [+uint]
SUIT_Command_Sequence = [ + (
SUIT_Condition // SUIT_Directive // SUIT_Command_Custom
) ]
SUIT_Command_Custom = (suit-command-custom, bstr/tstr/int/nil)
SUIT_Condition //= (suit-condition-vendor-identifier, SUIT_Rep_Policy)
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SUIT_Condition //= (suit-condition-class-identifier, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-device-identifier, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-image-match, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-image-not-match, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-use-before, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-minimum-battery, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-update-authorized, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-version, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-component-offset, SUIT_Rep_Policy)
SUIT_Condition //= (suit-condition-abort, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-set-component-index, IndexArg)
SUIT_Directive //= (suit-directive-set-dependency-index, IndexArg)
SUIT_Directive //= (suit-directive-run-sequence,
bstr .cbor SUIT_Command_Sequence)
SUIT_Directive //= (suit-directive-try-each,
SUIT_Directive_Try_Each_Argument)
SUIT_Directive //= (suit-directive-process-dependency, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-set-parameters,
{+ SUIT_Parameters})
SUIT_Directive //= (suit-directive-override-parameters,
{+ SUIT_Parameters})
SUIT_Directive //= (suit-directive-fetch, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-copy, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-swap, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-run, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-wait, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-fetch-uri-list, SUIT_Rep_Policy)
SUIT_Directive //= (suit-directive-garbage-collect, SUIT_Rep_Policy)
SUIT_Directive_Try_Each_Argument = [
+ bstr .cbor SUIT_Command_Sequence,
nil / bstr .cbor SUIT_Command_Sequence
]
SUIT_Rep_Policy = uint .bits suit-reporting-bits
suit-reporting-bits = &(
suit-send-record-success : 0,
suit-send-record-failure : 1,
suit-send-sysinfo-success : 2,
suit-send-sysinfo-failure : 3
)
SUIT_Wait_Event = { + SUIT_Wait_Events }
SUIT_Wait_Events //= (suit-wait-event-authorization => int)
SUIT_Wait_Events //= (suit-wait-event-power => int)
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SUIT_Wait_Events //= (suit-wait-event-network => int)
SUIT_Wait_Events //= (suit-wait-event-other-device-version
=> SUIT_Wait_Event_Argument_Other_Device_Version)
SUIT_Wait_Events //= (suit-wait-event-time => uint); Timestamp
SUIT_Wait_Events //= (suit-wait-event-time-of-day
=> uint); Time of Day (seconds since 00:00:00)
SUIT_Wait_Events //= (suit-wait-event-day-of-week
=> uint); Days since Sunday
SUIT_Wait_Event_Argument_Other_Device_Version = [
other-device: bstr,
other-device-version: [ + SUIT_Parameter_Version_Match ]
]
SUIT_Parameters //= (suit-parameter-vendor-identifier =>
(RFC4122_UUID / cbor-pen))
cbor-pen = #6.112(bstr)
SUIT_Parameters //= (suit-parameter-class-identifier => RFC4122_UUID)
SUIT_Parameters //= (suit-parameter-image-digest
=> bstr .cbor SUIT_Digest)
SUIT_Parameters //= (suit-parameter-image-size => uint)
SUIT_Parameters //= (suit-parameter-use-before => uint)
SUIT_Parameters //= (suit-parameter-component-offset => uint)
SUIT_Parameters //= (suit-parameter-encryption-info
=> bstr .cbor SUIT_Encryption_Info)
SUIT_Parameters //= (suit-parameter-compression-info
=> bstr .cbor SUIT_Compression_Info)
SUIT_Parameters //= (suit-parameter-unpack-info
=> bstr .cbor SUIT_Unpack_Info)
SUIT_Parameters //= (suit-parameter-uri => tstr)
SUIT_Parameters //= (suit-parameter-source-component => uint)
SUIT_Parameters //= (suit-parameter-run-args => bstr)
SUIT_Parameters //= (suit-parameter-device-identifier => RFC4122_UUID)
SUIT_Parameters //= (suit-parameter-minimum-battery => uint)
SUIT_Parameters //= (suit-parameter-update-priority => uint)
SUIT_Parameters //= (suit-parameter-version =>
SUIT_Parameter_Version_Match)
SUIT_Parameters //= (suit-parameter-wait-info =>
bstr .cbor SUIT_Wait_Event)
SUIT_Parameters //= (suit-parameter-custom => int/bool/tstr/bstr)
SUIT_Parameters //= (suit-parameter-strict-order => bool)
SUIT_Parameters //= (suit-parameter-soft-failure => bool)
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SUIT_Parameters //= (suit-parameter-uri-list =>
bstr .cbor SUIT_URI_List)
RFC4122_UUID = bstr .size 16
SUIT_Parameter_Version_Match = [
suit-condition-version-comparison-type:
SUIT_Condition_Version_Comparison_Types,
suit-condition-version-comparison-value:
SUIT_Condition_Version_Comparison_Value
]
SUIT_Condition_Version_Comparison_Types /=
suit-condition-version-comparison-greater
SUIT_Condition_Version_Comparison_Types /=
suit-condition-version-comparison-greater-equal
SUIT_Condition_Version_Comparison_Types /=
suit-condition-version-comparison-equal
SUIT_Condition_Version_Comparison_Types /=
suit-condition-version-comparison-lesser-equal
SUIT_Condition_Version_Comparison_Types /=
suit-condition-version-comparison-lesser
suit-condition-version-comparison-greater = 1
suit-condition-version-comparison-greater-equal = 2
suit-condition-version-comparison-equal = 3
suit-condition-version-comparison-lesser-equal = 4
suit-condition-version-comparison-lesser = 5
SUIT_Condition_Version_Comparison_Value = [+int]
SUIT_Encryption_Info = COSE_Encrypt_Tagged/COSE_Encrypt0_Tagged
SUIT_Compression_Info = {
suit-compression-algorithm => SUIT_Compression_Algorithms,
* $$SUIT_Compression_Info-extensions,
}
SUIT_Compression_Algorithms /= SUIT_Compression_Algorithm_zlib
SUIT_Compression_Algorithms /= SUIT_Compression_Algorithm_brotli
SUIT_Compression_Algorithms /= SUIT_Compression_Algorithm_zstd
SUIT_Compression_Algorithm_zlib = 1
SUIT_Compression_Algorithm_brotli = 2
SUIT_Compression_Algorithm_zstd = 3
SUIT_Unpack_Info = {
suit-unpack-algorithm => SUIT_Unpack_Algorithms,
* $$SUIT_Unpack_Info-extensions,
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}
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Hex
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Elf
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Coff
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Srec
SUIT_Unpack_Algorithm_Hex = 1
SUIT_Unpack_Algorithm_Elf = 2
SUIT_Unpack_Algorithm_Coff = 3
SUIT_Unpack_Algorithm_Srec = 4
SUIT_URI_List = [+ tstr ]
SUIT_Text_Map = {
* SUIT_Component_Identifier => {
SUIT_Text_Component_Keys
},
SUIT_Text_Keys
}
SUIT_Text_Component_Keys = (
? suit-text-vendor-name => tstr,
? suit-text-model-name => tstr,
? suit-text-vendor-domain => tstr,
? suit-text-model-info => tstr,
? suit-text-component-description => tstr,
? suit-text-component-version => tstr,
? suit-text-version-required => tstr,
* $$suit-text-component-key-extensions
)
SUIT_Text_Keys = (
? suit-text-manifest-description => tstr,
? suit-text-update-description => tstr,
? suit-text-manifest-json-source => tstr,
? suit-text-manifest-yaml-source => tstr,
* $$suit-text-key-extensions
)
suit-delegation = 1
suit-authentication-wrapper = 2
suit-manifest = 3
algorithm-id-sha224 = 1
algorithm-id-sha256 = 2
algorithm-id-sha384 = 3
algorithm-id-sha512 = 4
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algorithm-id-sha3-224 = 5
algorithm-id-sha3-256 = 6
algorithm-id-sha3-384 = 7
algorithm-id-sha3-512 = 8
suit-manifest-version = 1
suit-manifest-sequence-number = 2
suit-common = 3
suit-reference-uri = 4
suit-dependency-resolution = 7
suit-payload-fetch = 8
suit-install = 9
suit-validate = 10
suit-load = 11
suit-run = 12
suit-text = 13
suit-coswid = 14
suit-dependencies = 1
suit-components = 2
suit-common-sequence = 4
suit-dependency-digest = 1
suit-dependency-prefix = 2
suit-command-custom = nint
suit-condition-vendor-identifier = 1
suit-condition-class-identifier = 2
suit-condition-image-match = 3
suit-condition-use-before = 4
suit-condition-component-offset = 5
suit-condition-abort = 14
suit-condition-device-identifier = 24
suit-condition-image-not-match = 25
suit-condition-minimum-battery = 26
suit-condition-update-authorized = 27
suit-condition-version = 28
suit-directive-set-component-index = 12
suit-directive-set-dependency-index = 13
suit-directive-try-each = 15
suit-directive-process-dependency = 18
suit-directive-set-parameters = 19
suit-directive-override-parameters = 20
suit-directive-fetch = 21
suit-directive-copy = 22
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suit-directive-run = 23
suit-directive-wait = 29
suit-directive-fetch-uri-list = 30
suit-directive-swap = 31
suit-directive-run-sequence = 32
suit-directive-garbage-collect = 33
suit-wait-event-authorization = 1
suit-wait-event-power = 2
suit-wait-event-network = 3
suit-wait-event-other-device-version = 4
suit-wait-event-time = 5
suit-wait-event-time-of-day = 6
suit-wait-event-day-of-week = 7
suit-parameter-vendor-identifier = 1
suit-parameter-class-identifier = 2
suit-parameter-image-digest = 3
suit-parameter-use-before = 4
suit-parameter-component-offset = 5
suit-parameter-strict-order = 12
suit-parameter-soft-failure = 13
suit-parameter-image-size = 14
suit-parameter-encryption-info = 18
suit-parameter-compression-info = 19
suit-parameter-unpack-info = 20
suit-parameter-uri = 21
suit-parameter-source-component = 22
suit-parameter-run-args = 23
suit-parameter-device-identifier = 24
suit-parameter-minimum-battery = 26
suit-parameter-update-priority = 27
suit-parameter-version = 28
suit-parameter-wait-info = 29
suit-parameter-uri-list = 30
suit-parameter-custom = nint
suit-compression-algorithm = 1
suit-unpack-algorithm = 1
suit-text-manifest-description = 1
suit-text-update-description = 2
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suit-text-manifest-json-source = 3
suit-text-manifest-yaml-source = 4
suit-text-vendor-name = 1
suit-text-model-name = 2
suit-text-vendor-domain = 3
suit-text-model-info = 4
suit-text-component-description = 5
suit-text-component-version = 6
suit-text-version-required = 7
Appendix B. B. Examples
The following examples demonstrate a small subset of the
functionality of the manifest. Even a simple manifest processor can
execute most of these manifests.
The examples are signed using the following ECDSA secp256r1 key:
-----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgApZYjZCUGLM50VBC
CjYStX+09jGmnyJPrpDLTz/hiXOhRANCAASEloEarguqq9JhVxie7NomvqqL8Rtv
P+bitWWchdvArTsfKktsCYExwKNtrNHXi9OB3N+wnAUtszmR23M4tKiW
-----END PRIVATE KEY-----
The corresponding public key can be used to verify these examples:
-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEhJaBGq4LqqvSYVcYnuzaJr6qi/Eb
bz/m4rVlnIXbwK07HypLbAmBMcCjbazR14vTgdzfsJwFLbM5kdtzOLSolg==
-----END PUBLIC KEY-----
Each example uses SHA256 as the digest function.
Note that reporting policies are declared for each non-flow-control
command in these examples. The reporting policies used in the
examples are described in the following tables.
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+-----------------------------+----------+
| Policy | Label |
+-----------------------------+----------+
| suit-send-record-on-success | Rec-Pass |
| | |
| suit-send-record-on-failure | Rec-Fail |
| | |
| suit-send-sysinfo-success | Sys-Pass |
| | |
| suit-send-sysinfo-failure | Sys-Fail |
+-----------------------------+----------+
+----------------------------+--------+---------+---------+---------+
| Command | Sys- | Sys- | Rec- | Rec- |
| | Fail | Pass | Fail | Pass |
+----------------------------+--------+---------+---------+---------+
| suit-condition-vendor- | 1 | 1 | 1 | 1 |
| identifier | | | | |
| | | | | |
| suit-condition-class- | 1 | 1 | 1 | 1 |
| identifier | | | | |
| | | | | |
| suit-condition-image-match | 1 | 1 | 1 | 1 |
| | | | | |
| suit-condition-component- | 0 | 1 | 0 | 1 |
| offset | | | | |
| | | | | |
| suit-directive-fetch | 0 | 0 | 1 | 0 |
| | | | | |
| suit-directive-copy | 0 | 0 | 1 | 0 |
| | | | | |
| suit-directive-run | 0 | 0 | 1 | 0 |
+----------------------------+--------+---------+---------+---------+
B.1. Example 0: Secure Boot
This example covers the following templates:
- Compatibility Check (Section 7.1)
- Secure Boot (Section 7.2)
It also serves as the minimum example.
{
/ authentication-wrapper / 2:bstr .cbor ([
digest: bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
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/ digest-bytes /
h'5c097ef64bf3bb9b494e71e1f2418eef8d466cc902f639a855ec9af3e9eddb99'
]),
signature: bstr .cbor (18([
/ protected / bstr .cbor ({
/ alg / 1:-7 / "ES256" /,
}),
/ unprotected / {
},
/ payload / F6 / nil /,
/ signature / h'a19fd1f23b17beed321cece7423dfb48c457b8
f1f6ac83577a3c10c6773f6f3a7902376b59540920b6c5f57bac5fc8543d8f5d3d974f
aa2e6d03daa534b443a7'
]))
]
]),
/ manifest / 3:bstr .cbor ({
/ manifest-version / 1:1,
/ manifest-sequence-number / 2:0,
/ common / 3:bstr .cbor ({
/ components / 2:[
[h'00']
],
/ common-sequence / 4:bstr .cbor ([
/ directive-override-parameters / 20,{
/ vendor-id /
1:h'fa6b4a53d5ad5fdfbe9de663e4d41ffe' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
/ class-id / 2:h'1492af1425695e48bf429b2d51f2ab45'
/ 1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'00112233445566778899aabbccddeeff0123456789abcdeffedcba9876543210'
]),
/ image-size / 14:34768,
} ,
/ condition-vendor-identifier / 1,15 ,
/ condition-class-identifier / 2,15
]),
}),
/ validate / 10:bstr .cbor ([
/ condition-image-match / 3,15
]),
/ run / 12:bstr .cbor ([
/ directive-run / 23,2
]),
}),
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}
Total size of Envelope without COSE authentication object: 159
Envelope:
a2025827815824820258205c097ef64bf3bb9b494e71e1f2418eef8d466c
c902f639a855ec9af3e9eddb99035871a50101020003585fa20281814100
0458568614a40150fa6b4a53d5ad5fdfbe9de663e4d41ffe02501492af14
25695e48bf429b2d51f2ab450358248202582000112233445566778899aa
bbccddeeff0123456789abcdeffedcba98765432100e1987d0010f020f0a
4382030f0c43821702
Total size of Envelope with COSE authentication object: 235
Envelope with COSE authentication object:
a2025873825824820258205c097ef64bf3bb9b494e71e1f2418eef8d466c
c902f639a855ec9af3e9eddb99584ad28443a10126a0f65840a19fd1f23b
17beed321cece7423dfb48c457b8f1f6ac83577a3c10c6773f6f3a790237
6b59540920b6c5f57bac5fc8543d8f5d3d974faa2e6d03daa534b443a703
5871a50101020003585fa202818141000458568614a40150fa6b4a53d5ad
5fdfbe9de663e4d41ffe02501492af1425695e48bf429b2d51f2ab450358
248202582000112233445566778899aabbccddeeff0123456789abcdeffe
dcba98765432100e1987d0010f020f0a4382030f0c43821702
B.2. Example 1: Simultaneous Download and Installation of Payload
This example covers the following templates:
- Compatibility Check (Section 7.1)
- Firmware Download (Section 7.3)
Simultaneous download and installation of payload. No secure boot is
present in this example to demonstrate a download-only manifest.
{
/ authentication-wrapper / 2:bstr .cbor ([
digest: bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'987eec85fa99fd31d332381b9810f90b05c2e0d4f284a6f4211207ed00fff750'
]),
signature: bstr .cbor (18([
/ protected / bstr .cbor ({
/ alg / 1:-7 / "ES256" /,
}),
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/ unprotected / {
},
/ payload / F6 / nil /,
/ signature / h'0008d2678ddda1afd6846cb9272f539a789e4c
ed4c874774e58dbe4cf1607e755668029ad6383d4e14c72083ba43002fe3f5cda48859
90c9b59135976b80ebc9'
]))
]
]),
/ manifest / 3:bstr .cbor ({
/ manifest-version / 1:1,
/ manifest-sequence-number / 2:1,
/ common / 3:bstr .cbor ({
/ components / 2:[
[h'00']
],
/ common-sequence / 4:bstr .cbor ([
/ directive-override-parameters / 20,{
/ vendor-id /
1:h'fa6b4a53d5ad5fdfbe9de663e4d41ffe' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
/ class-id / 2:h'1492af1425695e48bf429b2d51f2ab45'
/ 1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'00112233445566778899aabbccddeeff0123456789abcdeffedcba9876543210'
]),
/ image-size / 14:34768,
} ,
/ condition-vendor-identifier / 1,15 ,
/ condition-class-identifier / 2,15
]),
}),
/ install / 9:bstr .cbor ([
/ directive-set-parameters / 19,{
/ uri / 21:'http://example.com/file.bin',
} ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15
]),
/ validate / 10:bstr .cbor ([
/ condition-image-match / 3,15
]),
}),
}
Total size of Envelope without COSE authentication object: 194
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Envelope:
a202582781582482025820987eec85fa99fd31d332381b9810f90b05c2e0
d4f284a6f4211207ed00fff750035894a50101020103585fa20281814100
0458568614a40150fa6b4a53d5ad5fdfbe9de663e4d41ffe02501492af14
25695e48bf429b2d51f2ab450358248202582000112233445566778899aa
bbccddeeff0123456789abcdeffedcba98765432100e1987d0010f020f09
58258613a115781b687474703a2f2f6578616d706c652e636f6d2f66696c
652e62696e1502030f0a4382030f
Total size of Envelope with COSE authentication object: 270
Envelope with COSE authentication object:
a202587382582482025820987eec85fa99fd31d332381b9810f90b05c2e0
d4f284a6f4211207ed00fff750584ad28443a10126a0f658400008d2678d
dda1afd6846cb9272f539a789e4ced4c874774e58dbe4cf1607e75566802
9ad6383d4e14c72083ba43002fe3f5cda4885990c9b59135976b80ebc903
5894a50101020103585fa202818141000458568614a40150fa6b4a53d5ad
5fdfbe9de663e4d41ffe02501492af1425695e48bf429b2d51f2ab450358
248202582000112233445566778899aabbccddeeff0123456789abcdeffe
dcba98765432100e1987d0010f020f0958258613a115781b687474703a2f
2f6578616d706c652e636f6d2f66696c652e62696e1502030f0a4382030f
B.3. Example 2: Simultaneous Download, Installation, Secure Boot,
Severed Fields
This example covers the following templates:
- Compatibility Check (Section 7.1)
- Secure Boot (Section 7.2)
- Firmware Download (Section 7.3)
This example also demonstrates severable elements (Section 5.5), and
text (Section 8.6.4).
{
/ authentication-wrapper / 2:bstr .cbor ([
digest: bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'78fa7652e377d31dcd7e95730c885ef13b6ee394d586410aa5fd0aca1f299d34'
]),
signature: bstr .cbor (18([
/ protected / bstr .cbor ({
/ alg / 1:-7 / "ES256" /,
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}),
/ unprotected / {
},
/ payload / F6 / nil /,
/ signature / h'1aa5bf99688b5d6a1211fd9c99bdd409b64cd6
add316ff87029a81faf682f93c5fb94863eebdfd17a6fcfed729ffa9735a624ce7edb5
65cba26ff7a5bd6a779d'
]))
]
]),
/ manifest / 3:bstr .cbor ({
/ manifest-version / 1:1,
/ manifest-sequence-number / 2:2,
/ common / 3:bstr .cbor ({
/ components / 2:[
[h'00']
],
/ common-sequence / 4:bstr .cbor ([
/ directive-override-parameters / 20,{
/ vendor-id /
1:h'fa6b4a53d5ad5fdfbe9de663e4d41ffe' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
/ class-id / 2:h'1492af1425695e48bf429b2d51f2ab45'
/ 1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'00112233445566778899aabbccddeeff0123456789abcdeffedcba9876543210'
]),
/ image-size / 14:34768,
} ,
/ condition-vendor-identifier / 1,15 ,
/ condition-class-identifier / 2,15
]),
}),
/ install / 9:[
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'3ee96dc79641970ae46b929ccf0b72ba9536dd846020dbdc9f949d84ea0e18d2'
],
/ validate / 10:bstr .cbor ([
/ condition-image-match / 3,15
]),
/ run / 12:bstr .cbor ([
/ directive-run / 23,2
]),
/ text / 13:[
/ algorithm-id / 2 / "sha256" /,
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/ digest-bytes /
h'2bfc4d0cc6680be7dd9f5ca30aa2bb5d1998145de33d54101b80e2ca49faf918'
],
}),
/ install / 9:bstr .cbor ([
/ directive-set-parameters / 19,{
/ uri /
21:'http://example.com/very/long/path/to/file/file.bin',
} ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15
]),
/ text / 13:bstr .cbor ({
[h'00']:{
/ vendor-domain / 3:'arm.com',
/ component-description / 5:'This component is a
demonstration. The digest is a sample pattern, not a real one.',
}
}),
}
Total size of the Envelope without COSE authentication object or
Severable Elements: 233
Envelope:
a20258278158248202582078fa7652e377d31dcd7e95730c885ef13b6ee3
94d586410aa5fd0aca1f299d340358bba70101020203585fa20281814100
0458568614a40150fa6b4a53d5ad5fdfbe9de663e4d41ffe02501492af14
25695e48bf429b2d51f2ab450358248202582000112233445566778899aa
bbccddeeff0123456789abcdeffedcba98765432100e1987d0010f020f09
820258203ee96dc79641970ae46b929ccf0b72ba9536dd846020dbdc9f94
9d84ea0e18d20a4382030f0c438217020d820258202bfc4d0cc6680be7dd
9f5ca30aa2bb5d1998145de33d54101b80e2ca49faf918
Total size of the Envelope with COSE authentication object but
without Severable Elements: 309
Envelope:
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a20258738258248202582078fa7652e377d31dcd7e95730c885ef13b6ee3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Total size of Envelope with COSE authentication object and Severable
Elements: 892
Envelope with COSE authentication object: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B.4. Example 3: A/B images
This example covers the following templates:
- Compatibility Check (Section 7.1)
- Secure Boot (Section 7.2)
- Firmware Download (Section 7.3)
- A/B Image Template (Section 7.11)
{
/ authentication-wrapper / 2:bstr .cbor ([
digest: bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'ae0c1ea689c9800a843550f38796b6fdbd52a0c78be5d26011d8e784da43d47c'
]),
signature: bstr .cbor (18([
/ protected / bstr .cbor ({
/ alg / 1:-7 / "ES256" /,
}),
/ unprotected / {
},
/ payload / F6 / nil /,
/ signature / h'1296c87d168bb857495e6551730f9d6d3a6d81
ad6c908c72fbc52ddcb2e8011d20d217b3f1c028374eecbda5d2ca26d047270b397dca
a91a48a7c78cf376004e'
]))
]
]),
/ manifest / 3:bstr .cbor ({
/ manifest-version / 1:1,
/ manifest-sequence-number / 2:3,
/ common / 3:bstr .cbor ({
/ components / 2:[
[h'00']
],
/ common-sequence / 4:bstr .cbor ([
/ directive-override-parameters / 20,{
/ vendor-id /
1:h'fa6b4a53d5ad5fdfbe9de663e4d41ffe' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
/ class-id / 2:h'1492af1425695e48bf429b2d51f2ab45'
/ 1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
} ,
/ directive-try-each / 15,[
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bstr .cbor ([
/ directive-override-parameters / 20,{
/ offset / 5:33792,
} ,
/ condition-component-offset / 5,5 ,
/ directive-override-parameters / 20,{
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'00112233445566778899aabbccddeeff0123456789abcdeffedcba9876543210'
]),
/ image-size / 14:34768,
}
]) ,
bstr .cbor ([
/ directive-override-parameters / 20,{
/ offset / 5:541696,
} ,
/ condition-component-offset / 5,5 ,
/ directive-override-parameters / 20,{
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'0123456789abcdeffedcba987654321000112233445566778899aabbccddeeff'
]),
/ image-size / 14:76834,
}
])
] ,
/ condition-vendor-identifier / 1,15 ,
/ condition-class-identifier / 2,15
]),
}),
/ install / 9:bstr .cbor ([
/ directive-try-each / 15,[
bstr .cbor ([
/ directive-set-parameters / 19,{
/ offset / 5:33792,
} ,
/ condition-component-offset / 5,5 ,
/ directive-set-parameters / 19,{
/ uri / 21:'http://example.com/file1.bin',
}
]) ,
bstr .cbor ([
/ directive-set-parameters / 19,{
/ offset / 5:541696,
} ,
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/ condition-component-offset / 5,5 ,
/ directive-set-parameters / 19,{
/ uri / 21:'http://example.com/file2.bin',
}
])
] ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15
]),
/ validate / 10:bstr .cbor ([
/ condition-image-match / 3,15
]),
}),
}
Total size of Envelope without COSE authentication object: 330
Envelope: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 size of Envelope with COSE authentication object: 406
Envelope with COSE authentication object:
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a202587382582482025820ae0c1ea689c9800a843550f38796b6fdbd52a0
c78be5d26011d8e784da43d47c584ad28443a10126a0f658401296c87d16
8bb857495e6551730f9d6d3a6d81ad6c908c72fbc52ddcb2e8011d20d217
b3f1c028374eecbda5d2ca26d047270b397dcaa91a48a7c78cf376004e03
59011ba5010102030358aaa202818141000458a18814a20150fa6b4a53d5
ad5fdfbe9de663e4d41ffe02501492af1425695e48bf429b2d51f2ab450f
8258368614a105198400050514a203582482025820001122334455667788
99aabbccddeeff0123456789abcdeffedcba98765432100e1987d0583a86
14a1051a00084400050514a2035824820258200123456789abcdeffedcba
987654321000112233445566778899aabbccddeeff0e1a00012c22010f02
0f095861860f82582a8613a105198400050513a115781c687474703a2f2f
6578616d706c652e636f6d2f66696c65312e62696e582c8613a1051a0008
4400050513a115781c687474703a2f2f6578616d706c652e636f6d2f6669
6c65322e62696e1502030f0a4382030f
B.5. Example 4: Load and Decompress from External Storage
This example covers the following templates:
- Compatibility Check (Section 7.1)
- Secure Boot (Section 7.2)
- Firmware Download (Section 7.3)
- Install (Section 7.4)
- Load & Decompress (Section 7.8)
{
/ authentication-wrapper / 2:bstr .cbor ([
digest: bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'4b4c7c8c0fda76c9c9591a9db160918e2b3c96a58b0a5e4984fd4e8f9359a928'
]),
signature: bstr .cbor (18([
/ protected / bstr .cbor ({
/ alg / 1:-7 / "ES256" /,
}),
/ unprotected / {
},
/ payload / F6 / nil /,
/ signature / h'd88c4953fe5a0399e69ab37fe654d1f1b957a4
4a46fde3e9cffdf0cdaa0456ddce9f08bc2a59895ffd70adce0e4aee8690645dcd4b7b
77d401bd91e35aa115d2'
]))
]
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]),
/ manifest / 3:bstr .cbor ({
/ manifest-version / 1:1,
/ manifest-sequence-number / 2:4,
/ common / 3:bstr .cbor ({
/ components / 2:[
[h'00'] ,
[h'02'] ,
[h'01']
],
/ common-sequence / 4:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ directive-override-parameters / 20,{
/ vendor-id /
1:h'fa6b4a53d5ad5fdfbe9de663e4d41ffe' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
/ class-id / 2:h'1492af1425695e48bf429b2d51f2ab45'
/ 1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'00112233445566778899aabbccddeeff0123456789abcdeffedcba9876543210'
]),
/ image-size / 14:34768,
} ,
/ condition-vendor-identifier / 1,15 ,
/ condition-class-identifier / 2,15
]),
}),
/ payload-fetch / 8:bstr .cbor ([
/ directive-set-component-index / 12,1 ,
/ directive-set-parameters / 19,{
/ uri / 21:'http://example.com/file.bin',
} ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15
]),
/ install / 9:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ directive-set-parameters / 19,{
/ source-component / 22:1 / [h'02'] /,
} ,
/ directive-copy / 22,2 ,
/ condition-image-match / 3,15
]),
/ validate / 10:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ condition-image-match / 3,15
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]),
/ load / 11:bstr .cbor ([
/ directive-set-component-index / 12,2 ,
/ directive-set-parameters / 19,{
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'0123456789abcdeffedcba987654321000112233445566778899aabbccddeeff'
]),
/ image-size / 14:76834,
/ source-component / 22:0 / [h'00'] /,
/ compression-info / 19:1 / "gzip" /,
} ,
/ directive-copy / 22,2 ,
/ condition-image-match / 3,15
]),
/ run / 12:bstr .cbor ([
/ directive-set-component-index / 12,2 ,
/ directive-run / 23,2
]),
}),
}
Total size of Envelope without COSE authentication object: 287
Envelope: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Total size of Envelope with COSE authentication object: 363
Envelope with COSE authentication object:
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a2025873825824820258204b4c7c8c0fda76c9c9591a9db160918e2b3c96
a58b0a5e4984fd4e8f9359a928584ad28443a10126a0f65840d88c4953fe
5a0399e69ab37fe654d1f1b957a44a46fde3e9cffdf0cdaa0456ddce9f08
bc2a59895ffd70adce0e4aee8690645dcd4b7b77d401bd91e35aa115d203
58f1a801010204035867a20283814100814102814101045858880c0014a4
0150fa6b4a53d5ad5fdfbe9de663e4d41ffe02501492af1425695e48bf42
9b2d51f2ab450358248202582000112233445566778899aabbccddeeff01
23456789abcdeffedcba98765432100e1987d0010f020f085827880c0113
a115781b687474703a2f2f6578616d706c652e636f6d2f66696c652e6269
6e1502030f094b880c0013a116011602030f0a45840c00030f0b583a880c
0213a4035824820258200123456789abcdeffedcba987654321000112233
445566778899aabbccddeeff0e1a00012c22130116001602030f0c45840c
021702
B.6. Example 5: Two Images
This example covers the following templates:
- Compatibility Check (Section 7.1)
- Secure Boot (Section 7.2)
- Firmware Download (Section 7.3)
Furthermore, it shows using these templates with two images.
{
/ authentication-wrapper / 2:bstr .cbor ([
digest: bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'de7c7927a15bd2eda59cab1512875f17c9f1e9e23885ce1ac6d671eefcefa37a'
]),
signature: bstr .cbor (18([
/ protected / bstr .cbor ({
/ alg / 1:-7 / "ES256" /,
}),
/ unprotected / {
},
/ payload / F6 / nil /,
/ signature / h'8f5919c05ef786366ab4899db27a2e7412ef72
480372437757b1c1c9f8b2ed2a677a88db17fcfbb47d178c9e5620f14ac68a314ceabc
d20cbf54fbe89b8e83ad'
]))
]
]),
/ manifest / 3:bstr .cbor ({
/ manifest-version / 1:1,
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/ manifest-sequence-number / 2:5,
/ common / 3:bstr .cbor ({
/ components / 2:[
[h'00'] ,
[h'01']
],
/ common-sequence / 4:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ directive-override-parameters / 20,{
/ vendor-id /
1:h'fa6b4a53d5ad5fdfbe9de663e4d41ffe' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
/ class-id / 2:h'1492af1425695e48bf429b2d51f2ab45'
/ 1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'00112233445566778899aabbccddeeff0123456789abcdeffedcba9876543210'
]),
/ image-size / 14:34768,
} ,
/ condition-vendor-identifier / 1,15 ,
/ condition-class-identifier / 2,15 ,
/ directive-set-component-index / 12,1 ,
/ directive-override-parameters / 20,{
/ image-digest / 3:bstr .cbor ([
/ algorithm-id / 2 / "sha256" /,
/ digest-bytes /
h'0123456789abcdeffedcba987654321000112233445566778899aabbccddeeff'
]),
/ image-size / 14:76834,
}
]),
}),
/ install / 9:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ directive-set-parameters / 19,{
/ uri / 21:'http://example.com/file1.bin',
} ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15 ,
/ directive-set-component-index / 12,1 ,
/ directive-set-parameters / 19,{
/ uri / 21:'http://example.com/file2.bin',
} ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15
]),
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/ validate / 10:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ condition-image-match / 3,15 ,
/ directive-set-component-index / 12,1 ,
/ condition-image-match / 3,15
]),
/ run / 12:bstr .cbor ([
/ directive-set-component-index / 12,0 ,
/ directive-run / 23,2
]),
}),
}
Total size of Envelope without COSE authentication object: 304
Envelope:
a202582781582482025820de7c7927a15bd2eda59cab1512875f17c9f1e9
e23885ce1ac6d671eefcefa37a03590101a601010205035895a202828141
008141010458898c0c0014a40150fa6b4a53d5ad5fdfbe9de663e4d41ffe
02501492af1425695e48bf429b2d51f2ab45035824820258200011223344
5566778899aabbccddeeff0123456789abcdeffedcba98765432100e1987
d0010f020f0c0114a2035824820258200123456789abcdeffedcba987654
321000112233445566778899aabbccddeeff0e1a00012c2209584f900c00
13a115781c687474703a2f2f6578616d706c652e636f6d2f66696c65312e
62696e1502030f0c0113a115781c687474703a2f2f6578616d706c652e63
6f6d2f66696c65322e62696e1502030f0a49880c00030f0c01030f0c4584
0c001702
Total size of Envelope with COSE authentication object: 380
Envelope with COSE authentication object:
a202587382582482025820de7c7927a15bd2eda59cab1512875f17c9f1e9
e23885ce1ac6d671eefcefa37a584ad28443a10126a0f658408f5919c05e
f786366ab4899db27a2e7412ef72480372437757b1c1c9f8b2ed2a677a88
db17fcfbb47d178c9e5620f14ac68a314ceabcd20cbf54fbe89b8e83ad03
590101a601010205035895a202828141008141010458898c0c0014a40150
fa6b4a53d5ad5fdfbe9de663e4d41ffe02501492af1425695e48bf429b2d
51f2ab450358248202582000112233445566778899aabbccddeeff012345
6789abcdeffedcba98765432100e1987d0010f020f0c0114a20358248202
58200123456789abcdeffedcba987654321000112233445566778899aabb
ccddeeff0e1a00012c2209584f900c0013a115781c687474703a2f2f6578
616d706c652e636f6d2f66696c65312e62696e1502030f0c0113a115781c
687474703a2f2f6578616d706c652e636f6d2f66696c65322e62696e1502
030f0a49880c00030f0c01030f0c45840c001702
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Appendix C. C. Design Rational
In order to provide flexible behavior to constrained devices, while
still allowing more powerful devices to use their full capabilities,
the SUIT manifest encodes the required behavior of a Recipient
device. Behavior is encoded as a specialized byte code, contained in
a CBOR list. This promotes a flat encoding, which simplifies the
parser. The information encoded by this byte code closely matches
the operations that a device will perform, which promotes ease of
processing. The core operations used by most update and trusted
invocation operations are represented in the byte code. The byte
code can be extended by registering new operations.
The specialized byte code approach gives benefits equivalent to those
provided by a scripting language or conventional byte code, with two
substantial differences. First, the language is extremely high
level, consisting of only the operations that a device may perform
during update and trusted invocation of a firmware image. Second,
the language specifies linear behavior, without reverse branches.
Conditional processing is supported, and parallel and out-of-order
processing may be performed by sufficiently capable devices.
By structuring the data in this way, the manifest processor becomes a
very simple engine that uses a pull parser to interpret the manifest.
This pull parser invokes a series of command handlers that evaluate a
Condition or execute a Directive. Most data is structured in a
highly regular pattern, which simplifies the parser.
The results of this allow a Recipient to implement a very small
parser for constrained applications. If needed, such a parser also
allows the Recipient to perform complex updates with reduced
overhead. Conditional execution of commands allows a simple device
to perform important decisions at validation-time.
Dependency handling is vastly simplified as well. Dependencies
function like subroutines of the language. When a manifest has a
dependency, it can invoke that dependency's commands and modify their
behavior by setting parameters. Because some parameters come with
security implications, the dependencies also have a mechanism to
reject modifications to parameters on a fine-grained level.
Developing a robust permissions system works in this model too. The
Recipient can use a simple ACL that is a table of Identities and
Component Identifier permissions to ensure that operations on
components fail unless they are permitted by the ACL. This table can
be further refined with individual parameters and commands.
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Capability reporting is similarly simplified. A Recipient can report
the Commands, Parameters, Algorithms, and Component Identifiers that
it supports. This is sufficiently precise for a manifest author to
create a manifest that the Recipient can accept.
The simplicity of design in the Recipient due to all of these
benefits allows even a highly constrained platform to use advanced
update capabilities.
C.1. C.1 Design Rationale: Envelope
The Envelope is used instead of a COSE structure for several reasons:
1. This enables the use of Severable Elements (Section 8.8)
2. This enables modular processing of manifests, particularly with
large signatures.
3. This enables multiple authentication schemes.
4. This allows integrity verification by a dependent to be
unaffected by adding or removing authentication structures.
Modular processing is important because it allows a Manifest
Processor to iterate forward over an Envelope, processing Delegation
Chains and Authentication Blocks, retaining only intermediate values,
without any need to seek forward and backwards in a stream until it
gets to the Manifest itself. This allows the use of large, Post-
Quantum signatures without requiring retention of the signature
itself, or seeking forward and back.
Four authentication objects are supported by the Envelope:
- COSE_Sign_Tagged
- COSE_Sign1_Tagged
- COSE_Mac_Tagged
- COSE_Mac0_Tagged
The SUIT Envelope allows an Update Authority or intermediary to mix
and match any number of different authentication blocks it wants
without any concern for modifying the integrity of another
authentication block. This also allows the addition or removal of an
authentication blocks without changing the integrity check of the
Manifest, which is important for dependency handling. See
Section 6.2
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C.2. C.2 Byte String Wrappers
Byte string wrappers are used in several places in the suit manifest.
The primary reason for wrappers it to limit the parser extent when
invoked at different times, with a possible loss of context.
The elements of the suit envelope are wrapped both to set the extents
used by the parser and to simplify integrity checks by clearly
defining the length of each element.
The common block is re-parsed in order to find components identifiers
from their indices, to find dependency prefixes and digests from
their identifiers, and to find the common sequence. The common
sequence is wrapped so that it matches other sequences, simplifying
the code path.
A severed SUIT command sequence will appear in the envelope, so it
must be wrapped as with all envelope elements. For consistency,
command sequences are also wrapped in the manifest. This also allows
the parser to discern the difference between a command sequence and a
SUIT_Digest.
Parameters that are structured types (arrays and maps) are also
wrapped in a bstr. This is so that parser extents can be set
correctly using only a reference to the beginning of the parameter.
This enables a parser to store a simple list of references to
parameters that can be retrieved when needed.
Appendix D. D. Implementation Conformance Matrix
This section summarizes the functionality a minimal manifest
processor implementation needs to offer to claim conformance to this
specification, in the absence of an application profile standard
specifying otherwise.
The subsequent table shows the conditions.
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+-------------------+------------------+----------------+
| Name | Reference | Implementation |
+-------------------+------------------+----------------+
| Vendor Identifier | Section 8.7.5.2 | REQUIRED |
| | | |
| Class Identifier | Section 8.7.5.2 | REQUIRED |
| | | |
| Device Identifier | Section 8.7.5.2 | OPTIONAL |
| | | |
| Image Match | Section 8.7.6.2 | REQUIRED |
| | | |
| Image Not Match | Section 8.7.6.3 | OPTIONAL |
| | | |
| Use Before | Section 8.7.6.4 | OPTIONAL |
| | | |
| Component Offset | Section 8.7.6.5 | OPTIONAL |
| | | |
| Abort | Section 8.7.6.9 | OPTIONAL |
| | | |
| Minimum Battery | Section 8.7.6.6 | OPTIONAL |
| | | |
| Update Authorized | Section 8.7.6.7 | OPTIONAL |
| | | |
| Version | Section 8.7.6.8 | OPTIONAL |
| | | |
| Custom Condition | Section 8.7.6.10 | OPTIONAL |
+-------------------+------------------+----------------+
The subsequent table shows the directives.
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+-------------------+----------------+------------------------------+
| Name | Reference | Implementation |
+-------------------+----------------+------------------------------+
| Set Component | Section 8.7.7. | REQUIRED if more than one |
| Index | 1 | component |
| | | |
| Set Dependency | Section 8.7.7. | REQUIRED if dependencies |
| Index | 2 | used |
| | | |
| Try Each | Section 8.7.7. | OPTIONAL |
| | 3 | |
| | | |
| Process | Section 8.7.7. | OPTIONAL |
| Dependency | 4 | |
| | | |
| Set Parameters | Section 8.7.7. | OPTIONAL |
| | 5 | |
| | | |
| Override | Section 8.7.7. | REQUIRED |
| Parameters | 6 | |
| | | |
| Fetch | Section 8.7.7. | REQUIRED for Updater |
| | 7 | |
| | | |
| Copy | Section 8.7.7. | OPTIONAL |
| | 9 | |
| | | |
| Run | Section 8.7.7. | REQUIRED for Bootloader |
| | 10 | |
| | | |
| Wait For Event | Section 8.7.7. | OPTIONAL |
| | 11 | |
| | | |
| Run Sequence | Section 8.7.7. | OPTIONAL |
| | 12 | |
| | | |
| Swap | Section 8.7.7. | OPTIONAL |
| | 13 | |
| | | |
| Fetch URI List | Section 8.7.7. | OPTIONAL |
| | 8 | |
| | | |
| Garbage Collect | Section 8.7.8 | OPTIONAL |
+-------------------+----------------+------------------------------+
The subsequent table shows the parameters.
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+------------------+------------------+----------------------+
| Name | Reference | Implementation |
+------------------+------------------+----------------------+
| Vendor ID | Section 8.7.5.3 | REQUIRED |
| | | |
| Class ID | Section 8.7.5.4 | REQUIRED |
| | | |
| Image Digest | Section 8.7.5.6 | REQUIRED |
| | | |
| Image Size | Section 8.7.5.7 | REQUIRED |
| | | |
| Use Before | Section 8.7.5.8 | RECOMMENDED |
| | | |
| Component Offset | Section 8.7.5.9 | OPTIONAL |
| | | |
| Encryption Info | Section 8.7.5.10 | RECOMMENDED |
| | | |
| Compression Info | Section 8.7.5.11 | RECOMMENDED |
| | | |
| Unpack Info | Section 8.7.5.12 | RECOMMENDED |
| | | |
| URI | Section 8.7.5.13 | REQUIRED for Updater |
| | | |
| Source Component | Section 8.7.5.14 | OPTIONAL |
| | | |
| Run Args | Section 8.7.5.15 | OPTIONAL |
| | | |
| Device ID | Section 8.7.5.5 | OPTIONAL |
| | | |
| Minimum Battery | Section 8.7.5.16 | OPTIONAL |
| | | |
| Update Priority | Section 8.7.5.17 | OPTIONAL |
| | | |
| Version Match | Section 8.7.5.18 | OPTIONAL |
| | | |
| Wait Info | Section 8.7.5.19 | OPTIONAL |
| | | |
| URI List | Section 8.7.5.20 | OPTIONAL |
| | | |
| Strict Order | Section 8.7.5.22 | OPTIONAL |
| | | |
| Soft Failure | Section 8.7.5.23 | OPTIONAL |
| | | |
| Custom | Section 8.7.5.24 | OPTIONAL |
+------------------+------------------+----------------------+
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Authors' Addresses
Brendan Moran
Arm Limited
EMail: Brendan.Moran@arm.com
Hannes Tschofenig
Arm Limited
EMail: hannes.tschofenig@arm.com
Henk Birkholz
Fraunhofer SIT
EMail: henk.birkholz@sit.fraunhofer.de
Koen Zandberg
Inria
EMail: koen.zandberg@inria.fr
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