Signing HTTP Messages
draft-ietf-httpbis-message-signatures-02
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 9421.
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|---|---|---|---|
| Authors | Annabelle Backman , Justin Richer , Manu Sporny | ||
| Last updated | 2021-03-15 (Latest revision 2020-11-17) | ||
| Replaces | draft-richanna-http-message-signatures, draft-cavage-http-signatures | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-httpbis-message-signatures-02
HTTP A. Backman, Ed.
Internet-Draft Amazon
Intended status: Standards Track J. Richer
Expires: 16 September 2021 Bespoke Engineering
M. Sporny
Digital Bazaar
15 March 2021
Signing HTTP Messages
draft-ietf-httpbis-message-signatures-02
Abstract
This document describes a mechanism for creating, encoding, and
verifying digital signatures or message authentication codes over
content within an HTTP message. This mechanism supports use cases
where the full HTTP message may not be known to the signer, and where
the message may be transformed (e.g., by intermediaries) before
reaching the verifier.
Note to Readers
_RFC EDITOR: please remove this section before publication_
Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/
(https://lists.w3.org/Archives/Public/ietf-http-wg/).
Working Group information can be found at https://httpwg.org/
(https://httpwg.org/); source code and issues list for this draft can
be found at https://github.com/httpwg/http-extensions/labels/
signatures (https://github.com/httpwg/http-extensions/labels/
signatures).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 16 September 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Discussion . . . . . . . . . . . . . . . . . 4
1.2. HTTP Message Transformations . . . . . . . . . . . . . . 5
1.3. Safe Transformations . . . . . . . . . . . . . . . . . . 5
1.4. Conventions and Terminology . . . . . . . . . . . . . . . 6
1.5. Application of HTTP Message Signatures . . . . . . . . . 7
2. Identifying and Canonicalizing Content . . . . . . . . . . . 8
2.1. HTTP Headers . . . . . . . . . . . . . . . . . . . . . . 8
2.1.1. Canonicalized Structured HTTP Headers . . . . . . . . 9
2.1.2. Canonicalization Examples . . . . . . . . . . . . . . 9
2.2. Dictionary Structured Field Members . . . . . . . . . . . 10
2.2.1. Canonicalization Examples . . . . . . . . . . . . . . 10
2.3. List Prefixes . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1. Canonicalization Examples . . . . . . . . . . . . . . 11
2.4. Specialty Content Fields . . . . . . . . . . . . . . . . 12
2.4.1. Request Target . . . . . . . . . . . . . . . . . . . 12
2.4.2. Signature Parameters . . . . . . . . . . . . . . . . 13
3. HTTP Message Signatures . . . . . . . . . . . . . . . . . . . 14
3.1. Signature Metadata . . . . . . . . . . . . . . . . . . . 14
3.2. Creating a Signature . . . . . . . . . . . . . . . . . . 16
3.2.1. Choose and Set Signature Metadata Properties . . . . 16
3.2.2. Create the Signature Input . . . . . . . . . . . . . 18
3.2.3. Sign the Signature Input . . . . . . . . . . . . . . 19
3.3. Verifying a Signature . . . . . . . . . . . . . . . . . . 19
3.3.1. Enforcing Application Requirements . . . . . . . . . 20
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4. Including a Message Signature in a Message . . . . . . . . . 21
4.1. The 'Signature-Input' HTTP Header . . . . . . . . . . . . 21
4.2. The 'Signature' HTTP Header . . . . . . . . . . . . . . . 21
4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 22
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
5.1. HTTP Signature Algorithms Registry . . . . . . . . . . . 23
5.1.1. Registration Template . . . . . . . . . . . . . . . . 23
5.1.2. Initial Contents . . . . . . . . . . . . . . . . . . 24
5.2. HTTP Signature Metadata Parameters Registry . . . . . . . 25
5.2.1. Registration Template . . . . . . . . . . . . . . . . 25
5.2.2. Initial Contents . . . . . . . . . . . . . . . . . . 25
5.3. HTTP Signature Specialty Content Identifiers Registry . . 26
5.3.1. Registration Template . . . . . . . . . . . . . . . . 26
5.3.2. Initial Contents . . . . . . . . . . . . . . . . . . 26
6. Security Considerations . . . . . . . . . . . . . . . . . . . 27
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1. Normative References . . . . . . . . . . . . . . . . . . 27
7.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. Detecting HTTP Message Signatures . . . . . . . . . 29
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 29
B.1. Example Keys . . . . . . . . . . . . . . . . . . . . . . 29
B.1.1. Example Key RSA test . . . . . . . . . . . . . . . . 29
B.2. Example keyid Values . . . . . . . . . . . . . . . . . . 30
B.3. Test Cases . . . . . . . . . . . . . . . . . . . . . . . 31
B.3.1. Signature Generation . . . . . . . . . . . . . . . . 31
B.3.2. Signature Verification . . . . . . . . . . . . . . . 34
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 36
Document History . . . . . . . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39
1. Introduction
Message integrity and authenticity are important security properties
that are critical to the secure operation of many HTTP applications.
Application developers typically rely on the transport layer to
provide these properties, by operating their application over [TLS].
However, TLS only guarantees these properties over a single TLS
connection, and the path between client and application may be
composed of multiple independent TLS connections (for example, if the
application is hosted behind a TLS-terminating gateway or if the
client is behind a TLS Inspection appliance). In such cases, TLS
cannot guarantee end-to-end message integrity or authenticity between
the client and application. Additionally, some operating
environments present obstacles that make it impractical to use TLS,
or to use features necessary to provide message authenticity.
Furthermore, some applications require the binding of an application-
level key to the HTTP message, separate from any TLS certificates in
use. Consequently, while TLS can meet message integrity and
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authenticity needs for many HTTP-based applications, it is not a
universal solution.
This document defines a mechanism for providing end-to-end integrity
and authenticity for content within an HTTP message. The mechanism
allows applications to create digital signatures or message
authentication codes (MACs) over only that content within the message
that is meaningful and appropriate for the application. Strict
canonicalization rules ensure that the verifier can verify the
signature even if the message has been transformed in any of the many
ways permitted by HTTP.
The mechanism described in this document consists of three parts:
* A common nomenclature and canonicalization rule set for the
different protocol elements and other content within HTTP
messages.
* Algorithms for generating and verifying signatures over HTTP
message content using this nomenclature and rule set.
* A mechanism for attaching a signature and related metadata to an
HTTP message.
1.1. Requirements Discussion
HTTP permits and sometimes requires intermediaries to transform
messages in a variety of ways. This may result in a recipient
receiving a message that is not bitwise equivalent to the message
that was oringally sent. In such a case, the recipient will be
unable to verify a signature over the raw bytes of the sender's HTTP
message, as verifying digital signatures or MACs requires both signer
and verifier to have the exact same signed content. Since the raw
bytes of the message cannot be relied upon as signed content, the
signer and verifier must derive the signed content from their
respective versions of the message, via a mechanism that is resilient
to safe changes that do not alter the meaning of the message.
For a variety of reasons, it is impractical to strictly define what
constitutes a safe change versus an unsafe one. Applications use
HTTP in a wide variety of ways, and may disagree on whether a
particular piece of information in a message (e.g., the body, or the
"Date" header field) is relevant. Thus a general purpose solution
must provide signers with some degree of control over which message
content is signed.
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HTTP applications may be running in environments that do not provide
complete access to or control over HTTP messages (such as a web
browser's JavaScript environment), or may be using libraries that
abstract away the details of the protocol (such as the Java
HTTPClient library (https://openjdk.java.net/groups/net/httpclient/
intro.html)). These applications need to be able to generate and
verify signatures despite incomplete knowledge of the HTTP message.
1.2. HTTP Message Transformations
As mentioned earlier, HTTP explicitly permits and in some cases
requires implementations to transform messages in a variety of ways.
Implementations are required to tolerate many of these
transformations. What follows is a non-normative and non-exhaustive
list of transformations that may occur under HTTP, provided as
context:
* Re-ordering of header fields with different header field names
([MESSAGING], Section 3.2.2).
* Combination of header fields with the same field name
([MESSAGING], Section 3.2.2).
* Removal of header fields listed in the "Connection" header field
([MESSAGING], Section 6.1).
* Addition of header fields that indicate control options
([MESSAGING], Section 6.1).
* Addition or removal of a transfer coding ([MESSAGING],
Section 5.7.2).
* Addition of header fields such as "Via" ([MESSAGING],
Section 5.7.1) and "Forwarded" ([RFC7239], Section 4).
1.3. Safe Transformations
Based on the definition of HTTP and the requirements described above,
we can identify certain types of transformations that should not
prevent signature verification, even when performed on content
covered by the signature. The following list describes those
transformations:
* Combination of header fields with the same field name.
* Reordering of header fields with different names.
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* Conversion between different versions of the HTTP protocol (e.g.,
HTTP/1.x to HTTP/2, or vice-versa).
* Changes in casing (e.g., "Origin" to "origin") of any case-
insensitive content such as header field names, request URI
scheme, or host.
* Addition or removal of leading or trailing whitespace to a header
field value.
* Addition or removal of "obs-folds".
* Changes to the "request-target" and "Host" header field that when
applied together do not result in a change to the message's
effective request URI, as defined in Section 5.5 of [MESSAGING].
Additionally, all changes to content not covered by the signature are
considered safe.
1.4. 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.
The terms "HTTP message", "HTTP request", "HTTP response", "absolute-
form", "absolute-path", "effective request URI", "gateway", "header
field", "intermediary", "request-target", "sender", and "recipient"
are used as defined in [MESSAGING].
The term "method" is to be interpreted as defined in Section 4 of
[SEMANTICS].
For brevity, the term "signature" on its own is used in this document
to refer to both digital signatures and keyed MACs. Similarly, the
verb "sign" refers to the generation of either a digital signature or
keyed MAC over a given input string. The qualified term "digital
signature" refers specifically to the output of an asymmetric
cryptographic signing operation.
In addition to those listed above, this document uses the following
terms:
Signer:
The entity that is generating or has generated an HTTP Message
Signature.
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Verifier:
An entity that is verifying or has verified an HTTP Message
Signature against an HTTP Message. Note that an HTTP Message
Signature may be verified multiple times, potentially by different
entities.
The term "Unix time" is defined by [POSIX.1] section 4.16
(http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
V1_chap04.html#tag_04_16).
This document contains non-normative examples of partial and complete
HTTP messages. To improve readability, header fields may be split
into multiple lines, using the "obs-fold" syntax. This syntax is
deprecated in [MESSAGING], and senders MUST NOT generate messages
that include it.
Additionally, some examples use '\' line wrapping for long values
that contain no whitespace, as per [RFC8792].
1.5. Application of HTTP Message Signatures
HTTP Message Signatures are designed to be a general-purpose security
mechanism applicable in a wide variety of circumstances and
applications. In order to properly and safely apply HTTP Message
Signatures, an application or profile of this specification MUST
specify all of the following items:
* The set of content identifiers (Section 2) that are expected and
required. For example, an authorization protocol would mandate
that the "Authorization" header be covered to protect the
authorization credentials, as well as a "*created" field to allow
replay detection.
* A means of retrieving the key material used to verify the
signature. An application will usually use the "keyid" field of
the "Signature-Input" header value and define rules for resolving
a key from there.
* A means of determining the signature algorithm used to verify the
signature content is appropriate for the key material.
* A means of determining that a given key and algorithm presented in
the request are appropriate for the request being made. For
example, a server expecting only ECDSA signatures should know to
reject any RSA signatures; or a server expecting asymmetric
cryptography should know to reject any symmetric cryptography.
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The details of this kind of profiling are the purview of the
application and outside the scope of this specification.
2. Identifying and Canonicalizing Content
In order to allow signers and verifiers to establish which content is
covered by a signature, this document defines content identifiers for
data items covered by an HTTP Message Signature.
Some content within HTTP messages can undergo transformations that
change the bitwise value without altering meaning of the content (for
example, the merging together of header fields with the same name).
Message content must therefore be canonicalized before it is signed,
to ensure that a signature can be verified despite such intermediary
transformations. This document defines rules for each content
identifier that transform the identifier's associated content into
such a canonical form.
Content identifiers are defined using production grammar defined by
[RFC8941] section 4. The content identifier is an "sf-string" value.
The content identifier type MAY define parameters which are included
using the "parameters" rule.
content-identifier = sf-string parameters
Note that this means the value of the identifier itself is encased in
double quotes, with parameters following as a semicolon-separated
list, such as ""cache-control"", ""date"", or ""@signature-params"".
The following sections define content identifier types, their
parameters, their associated content, and their canonicalization
rules.
2.1. HTTP Headers
The content identifier for an HTTP header is the lowercased form of
its header field name. While HTTP header field names are case-
insensitive, implementations MUST use lowercased field names (e.g.,
"content-type", "date", "etag") when using them as content
identifiers.
Unless overridden by additional parameters and rules, the HTTP header
field value MUST be canonicalized with the following steps:
1. Create an ordered list of the field values of each instance of
the header field in the message, in the order that they occur (or
will occur) in the message.
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2. Strip leading and trailing whitespace from each item in the list.
3. Concatenate the list items together, with a comma "," and space "
" between each item.
The resulting string is the canonicalized value.
2.1.1. Canonicalized Structured HTTP Headers
If value of the the HTTP header in question is a structured field
[RFC8941], the content identifier MAY include the "sf" parameter. If
this parameter is included, the HTTP header value MUST be
canonicalized using the rules specified in [RFC8941] section 4. Note
that this process will replace any optional whitespace with a single
space.
The resulting string is used as the field value input in Section 2.1.
2.1.2. Canonicalization Examples
This section contains non-normative examples of canonicalized values
for header fields, given the following example HTTP message:
HTTP/1.1 200 OK
Server: www.example.com
Date: Tue, 07 Jun 2014 20:51:35 GMT
X-OWS-Header: Leading and trailing whitespace.
X-Obs-Fold-Header: Obsolete
line folding.
X-Empty-Header:
Cache-Control: max-age=60
Cache-Control: must-revalidate
The following table shows example canonicalized values for header
fields, given that message:
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+=====================+==================================+
| Header Field | Canonicalized Value |
+=====================+==================================+
| "cache-control" | max-age=60, must-revalidate |
+---------------------+----------------------------------+
| "date" | Tue, 07 Jun 2014 20:51:35 GMT |
+---------------------+----------------------------------+
| "server" | www.example.com |
+---------------------+----------------------------------+
| "x-empty-header" | |
+---------------------+----------------------------------+
| "x-obs-fold-header" | Obsolete line folding. |
+---------------------+----------------------------------+
| "x-ows-header" | Leading and trailing whitespace. |
+---------------------+----------------------------------+
Table 1: Non-normative examples of header field
canonicalization.
2.2. Dictionary Structured Field Members
An individual member in the value of a Dictionary Structured Field is
identified by using the parameter "key" on the content identifier for
the header. The value of this parameter is a the key being
identified, without any parameters present on that key in the
original dictionary.
An individual member in the value of a Dictionary Structured Field is
canonicalized by applying the serialization algorithm described in
Section 4.1.2 of [RFC8941] on a Dictionary containing only that
member.
2.2.1. Canonicalization Examples
This section contains non-normative examples of canonicalized values
for Dictionary Structured Field Members given the following example
header field, whose value is assumed to be a Dictionary:
X-Dictionary: a=1, b=2;x=1;y=2, c=(a b c)
The following table shows example canonicalized values for different
content identifiers, given that field:
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+======================+=====================+
| Content Identifier | Canonicalized Value |
+======================+=====================+
| "x-dictionary";key=a | 1 |
+----------------------+---------------------+
| "x-dictionary";key=b | 2;x=1;y=2 |
+----------------------+---------------------+
| "x-dictionary";key=c | (a, b, c) |
+----------------------+---------------------+
Table 2: Non-normative examples of
Dictionary member canonicalization.
2.3. List Prefixes
A prefix of a List Structured Field consisting of the first N members
in the field's value (where N is an integer greater than 0 and less
than or equal to the number of members in the List) is identified by
the parameter "prefix" with the value of N as an integer.
A list prefix value is canonicalized by applying the serialization
algorithm described in Section 4.1.1 of [RFC8941] on a List
containing only the first N members as specified in the list prefix,
in the order they appear in the original List.
2.3.1. Canonicalization Examples
This section contains non-normative examples of canonicalized values
for list prefixes given the following example header fields, whose
values are assumed to be Dictionaries:
X-List-A: (a b c d e f)
X-List-B: ()
The following table shows example canonicalized values for different
content identifiers, given those fields:
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+=====================+=====================+
| Content Identifier | Canonicalized Value |
+=====================+=====================+
| "x-list-a";prefix=0 | () |
+---------------------+---------------------+
| "x-list-a";prefix=1 | (a) |
+---------------------+---------------------+
| "x-list-a";prefix=3 | (a, b, c) |
+---------------------+---------------------+
| "x-list-a";prefix=6 | (a, b, c, d, e, f) |
+---------------------+---------------------+
| "x-list-b";prefix=0 | () |
+---------------------+---------------------+
Table 3: Non-normative examples of list
prefix canonicalization.
2.4. Specialty Content Fields
Content not found in an HTTP header can be included in the signature
base string by defining a content identifier and the canonicalization
method for its content.
To differentiate speciality content identifiers from HTTP headers,
specialty content identifiers MUST start with the "at" "@" character.
This specification defines the following specialty content
identifiers:
@request-target The target request endpoint. Section 2.4.1
@signature-params The signature metadata parameters for this
signature. Section 2.4.2
Additional specialty content identifiers MAY be defined and
registered in the HTTP Signatures Specialty Content Identifier
Registry. Section 5.3
2.4.1. Request Target
The request target endpoint, consisting of the request method and the
path and query of the effective request URI, is identified by the
"@request-target" identifier.
Its value is canonicalized as follows:
1. Take the lowercased HTTP method of the message.
2. Append a space " ".
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3. Append the path and query of the request target of the message,
formatted according to the rules defined for the :path pseudo-
header in [HTTP2], Section 8.1.2.3. The resulting string is the
canonicalized value.
2.4.1.1. Canonicalization Examples
The following table contains non-normative example HTTP messages and
their canonicalized "@request-target" values.
+=========================+=================+
|HTTP Message | @request-target |
+=========================+=================+
| POST /?param=value HTTP/1.1| post |
| Host: www.example.com | /?param=value |
+-------------------------+-----------------+
| POST /a/b HTTP/1.1 | post /a/b |
| Host: www.example.com | |
+-------------------------+-----------------+
| GET http://www.example.com/a/ HTTP/1.1| get /a/ |
+-------------------------+-----------------+
| GET http://www.example.com HTTP/1.1| get / |
+-------------------------+-----------------+
| CONNECT server.example.com:80 HTTP/1.1| connect / |
| Host: server.example.com| |
+-------------------------+-----------------+
| OPTIONS * HTTP/1.1 | options * |
| Host: server.example.com| |
+-------------------------+-----------------+
Table 4: Non-normative examples of "@request-target"
canonicalization.
2.4.2. Signature Parameters
The signature parameters special content is identified by the
"@signature-params" identifier.
Its canonicalized value is the serialization of the signature
parameters for this signature, including the covered content list
with all associated parameters. Section 3.1
Note that an HTTP message could contain multiple signatures, but only
the signature parameters used for the current signature are included.
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2.4.2.1. Canonicalization Examples
Given the following signature parameters:
+==============+=========================================+
| Property | Value |
+==============+=========================================+
| Algorithm | hs2019 |
+--------------+-----------------------------------------+
| Covered | "@request-target", "host", "date", |
| Content | "cache-control", "x-emptyheader", |
| | "x-example", "x-dictionary;key=b", |
| | "x-dictionary;key=a", "x-list;prefix=3" |
+--------------+-----------------------------------------+
| Creation | 1402174295 |
| Time | |
+--------------+-----------------------------------------+
| Expiration | 1402174595 |
| Time | |
+--------------+-----------------------------------------+
| Verification | The public key provided in |
| Key Material | Appendix B.1.1 and identified by the |
| | "keyid" value "test-key-a". |
+--------------+-----------------------------------------+
Table 5
The signature parameter value is defined as:
"@signature-params": ("@request-target" "host" "date" "cache-control" "x-empty-header" "x-example" "x-dictionary";key=b "x-dictionary";key=a "x-list";prefix=3); keyid="test-key-a"; alg="hs2019"; created=1402170695; expires=1402170995
3. HTTP Message Signatures
An HTTP Message Signature is a signature over a string generated from
a subset of the content in an HTTP message and metadata about the
signature itself. When successfully verified against an HTTP
message, it provides cryptographic proof that with respect to the
subset of content that was signed, the message is semantically
equivalent to the message for which the signature was generated.
3.1. Signature Metadata
HTTP Message Signatures have metadata properties that provide
information regarding the signature's generation and/or verification.
The following metadata properties are defined:
Algorithm:
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An HTTP Signature Algorithm defined in the HTTP Signature
Algorithms Registry defined in this document, represented as a
string. It describes the signing and verification algorithms for
the signature.
Creation Time:
A timestamp representing the point in time that the signature was
generated, represented as an integer. Sub-second precision is not
supported. A signature's Creation Time MAY be undefined,
indicating that it is unknown.
Expiration Time:
A timestamp representing the point in time at which the signature
expires, represented as an integer. An expired signature always
fails verification. A signature's Expiration Time MAY be
undefined, indicating that the signature does not expire.
Verification Key Material:
The key material required to verify the signature.
Covered Content:
An ordered list of content identifiers (Section 2) that indicates
the metadata and message content that is covered by the signature.
This list MUST NOT include the "@signature-params" content
identifier.
The signature metadata is serialized using the rules in [RFC8941]
section 4 as follows:
1. Let the output be an empty string.
2. Serialize the content identifiers as an ordered "inner-list"
according to [RFC8941] section 4.1.1.1 and append this to the
output.
3. Append the signature metadata as parameters according to
[RFC8941] section 4.1.1.2 in the any order, skipping fields that
are not available:
* "alg": Algorithm as an "sf-string" value.
* "keyid": Verification Key Material as an "sf-string" value.
* "created": Creation Time as an "sf-integer" timestamp value.
* "expires": Expiration Time as an "sf-integer" timestamp value.
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Note that the "inner-list" serialization is used instead of the "sf-
list" serialization in order to facilitate this value's inclusion in
the "Signature-Input" header's dictionary, as discussed in
Section 4.1.
The Table 6 values would be serialized as follows:
("@request-target" "host" "date" "cache-control" "x-empty-header" "x-example"); keyid="test-key-a"; alg="hs2019"; created=1402170695; expires=1402170995
3.2. Creating a Signature
In order to create a signature, a signer completes the following
process:
1. Choose key material and algorithm, and set metadata properties
Section 3.2.1
2. Create the Signature Input Section 3.2.2
3. Sign the Signature Input Section 3.2.3
The following sections describe each of these steps in detail.
3.2.1. Choose and Set Signature Metadata Properties
1. The signer chooses an HTTP Signature Algorithm from those
registered in the HTTP Signature Algorithms Registry defined by
this document, and sets the signature's Algorithm property to
that value. The signer MUST NOT choose an algorithm marked
"Deprecated". The mechanism by which the signer chooses an
algorithm is out of scope for this document.
2. The signer chooses key material to use for signing and
verification, and sets the signature's Verification Key Material
property to the key material required for verification. The
signer MUST choose key material that is appropriate for the
signature's Algorithm, and that conforms to any requirements
defined by the Algorithm, such as key size or format. The
mechanism by which the signer chooses key material is out of
scope for this document.
3. The signer sets the signature's Creation Time property to the
current time.
4. The signer sets the signature's Expiration Time property to the
time at which the signature is to expire, or to undefined if the
signature will not expire.
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5. The signer creates an ordered list of content identifiers
representing the message content and signature metadata to be
covered by the signature, and assigns this list as the
signature's Covered Content.
* Each identifier MUST be one of those defined in Section 2.
* This list MUST NOT be empty, as this would result in creating
a signature over the empty string.
* Signers SHOULD include "@request-target" in the list.
* Signers SHOULD include a date stamp, such as the "date"
header. Alternatively, the "created" signature metadata
parameter can fulfil this role.
* Further guidance on what to include in this list and in what
order is out of scope for this document. However, the list
order is significant and once established for a given
signature it MUST be preserved for that signature.
* Note that the signature metadata is not included in the
explicit list of covered content identifiers since its value
is always covered.
For example, given the following HTTP message:
GET /foo HTTP/1.1
Host: example.org
Date: Sat, 07 Jun 2014 20:51:35 GMT
X-Example: Example header
with some whitespace.
X-EmptyHeader:
X-Dictionary: a=1, b=2
X-List: (a b c d)
Cache-Control: max-age=60
Cache-Control: must-revalidate
The following table presents a non-normative example of metadata
values that a signer may choose:
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+==============+=========================================+
| Property | Value |
+==============+=========================================+
| Algorithm | hs2019 |
+--------------+-----------------------------------------+
| Covered | "@request-target", "host", "date", |
| Content | "cache-control", "x-emptyheader", |
| | "x-example", "x-dictionary;key=b", |
| | "x-dictionary;key=a", "x-list;prefix=3" |
+--------------+-----------------------------------------+
| Creation | 1402174295 |
| Time | |
+--------------+-----------------------------------------+
| Expiration | 1402174595 |
| Time | |
+--------------+-----------------------------------------+
| Verification | The public key provided in |
| Key Material | Appendix B.1.1 and identified by the |
| | "keyid" value "test-key-a". |
+--------------+-----------------------------------------+
Table 6: Non-normative example metadata values
3.2.2. Create the Signature Input
The Signature Input is a US-ASCII string containing the content that
will be signed. To create it, the signer or verifier concatenates
together entries for each identifier in the signature's Covered
Content in the order it occurs in the list, with each entry separated
by a newline ""\n"". An identifier's entry is a "sf-string" followed
with a colon "":"", a space "" "", and the identifier's canonicalized
value.
The signer or verifier then includes the signature metadata specialty
field "@signature-params" as the last entry in the covered content,
separated by a newline ""\n"". Section 2.4.2
If Covered Content contains an identifier for a header field that is
malformed or is not present in the message, the implementation MUST
produce an error.
If Covered Content contains an identifier for a Dictionary member
that references a header field using the "key" parameter that is not
present, is malformed in the message, or is not a Dictionary
Structured Field, the implementation MUST produce an error. If the
header field value does not contain the specified member, the
implementation MUST produce an error.
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If Covered Content contains an identifier for a List Prefix that
references a header field using the "prefix" parameter that is not
present, is malformed in the message, or is not a List Structured
Field, the implementation MUST produce an error. If the header field
value contains fewer than the specified number of members, the
implementation MUST produce an error.
For the non-normative example Signature metadata in Table 6, the
corresponding Signature Input is:
"@request-target": get /foo
"host": example.org
"date": Tue, 07 Jun 2014 20:51:35 GMT
"cache-control": max-age=60, must-revalidate
"x-emptyheader":
"x-example": Example header with some whitespace.
"x-dictionary";key=b: 2
"x-dictionary";key=a: 1
"x-list";prefix=3: (a, b, c)
"@signature-params": ("@request-target" "host" "date" "cache-control" "x-empty-header" "x-example" "x-dictionary";key=b "x-dictionary";key=b "x-list";prefix=3); keyid="test-key-a"; alg="hs2019"; created=1402170695; expires=1402170995
Figure 1: Non-normative example Signature Input
3.2.3. Sign the Signature Input
The signer signs the Signature Input using the signing algorithm
described by the signature's Algorithm property, and the key material
chosen by the signer. The signer then encodes the result of that
operation as a base 64-encoded string [RFC4648]. This string is the
signature value.
For the non-normative example Signature metadata in Section 3.2.1 and
Signature Input in Figure 1, the corresponding signature value is:
K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUeZx/Kdrq32DrfakQ6b
PsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibeoHyqU/yCjphSmEdd7WD+z
rchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4CaB8X/I5/+HLZLGvDiezqi6/7
p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg1Q7MpWYZs0soHjttq0uLIA3DIbQfL
iIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZgFquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==
Figure 2: Non-normative example signature value
3.3. Verifying a Signature
In order to verify a signature, a verifier MUST:
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1. Examine the signature's metadata to confirm that the signature
meets the requirements described in this document, as well as any
additional requirements defined by the application such as which
header fields or other content are required to be covered by the
signature.
2. Use the received HTTP message and the signature's metadata to
recreate the Signature Input, using the process described in
Section 3.2.2. The value of the "@signature-params" input is the
value of the signature input header field for this signature, not
including the signature's label.
3. Use the signature's Algorithm and Verification Key Material with
the recreated Signing Input to verify the signature value.
A signature with a Creation Time that is in the future or an
Expiration Time that is in the past MUST NOT be processed.
The verifier MUST ensure that a signature's Algorithm is appropriate
for the key material the verifier will use to verify the signature.
If the Algorithm is not appropriate for the key material (for
example, if it is the wrong size, or in the wrong format), the
signature MUST NOT be processed.
3.3.1. Enforcing Application Requirements
The verification requirements specified in this document are intended
as a baseline set of restrictions that are generally applicable to
all use cases. Applications using HTTP Message Signatures MAY impose
requirements above and beyond those specified by this document, as
appropriate for their use case.
Some non-normative examples of additional requirements an application
might define are:
* Requiring a specific set of header fields to be signed (e.g.,
Authorization, Digest).
* Enforcing a maximum signature age.
* Prohibiting the use of certain algorithms, or mandating the use of
an algorithm.
* Requiring keys to be of a certain size (e.g., 2048 bits vs. 1024
bits).
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Application-specific requirements are expected and encouraged. When
an application defines additional requirements, it MUST enforce them
during the signature verification process, and signature verification
MUST fail if the signature does not conform to the application's
requirements.
Applications MUST enforce the requirements defined in this document.
Regardless of use case, applications MUST NOT accept signatures that
do not conform to these requirements.
4. Including a Message Signature in a Message
Message signatures can be included within an HTTP message via the
"Signature-Input" and "Signature" HTTP header fields, both defined
within this specification. The "Signature" HTTP header field
contains signature values, while the "Signature-Input" HTTP header
field identifies the Covered Content and metadata that describe how
each signature was generated.
4.1. The 'Signature-Input' HTTP Header
The "Signature-Input" HTTP header field is a Dictionary Structured
Header [RFC8941] containing the metadata for zero or more message
signatures generated from content within the HTTP message. Each
member describes a single message signature. The member's name is an
identifier that uniquely identifies the message signature within the
context of the HTTP message. The member's value is the serialization
of the covered content including all signature metadata parameters,
described in Section 3.1.
Signature-Input: sig1=("@request-target" "host" "date"
"cache-control" "x-empty-header" "x-example"); keyid="test-key-a";
alg="hs2019"; created=1402170695; expires=1402170995
To facilitate signature validation, the "Signature-Input" header MUST
contain the same serialization value used in generating the signature
input.
4.2. The 'Signature' HTTP Header
The "Signature" HTTP header field is a Dictionary Structured Header
[RFC8941] containing zero or more message signatures generated from
content within the HTTP message. Each member's name is a signature
identifier that is present as a member name in the "Signature-Input"
Structured Header within the HTTP message. Each member's value is a
Byte Sequence containing the signature value for the message
signature identified by the member name. Any member in the
"Signature" HTTP header field that does not have a corresponding
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member in the HTTP message's "Signature-Input" HTTP header field MUST
be ignored.
Signature: sig1=:K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUe\
Zx/Kdrq32DrfakQ6bPsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibe\
oHyqU/yCjphSmEdd7WD+zrchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4\
CaB8X/I5/+HLZLGvDiezqi6/7p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg\
1Q7MpWYZs0soHjttq0uLIA3DIbQfLiIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZg\
FquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==:
4.3. Examples
The following is a non-normative example of "Signature-Input" and
"Signature" HTTP header fields representing the signature in
Figure 2:
# NOTE: '\' line wrapping per RFC 8792
Signature-Input: sig1=("@request-target" "host" "date"
"cache-control" "x-empty-header" "x-example"); keyid="test-key-a";
alg="hs2019"; created=1402170695; expires=1402170995
Signature: sig1=:K2qGT5srn2OGbOIDzQ6kYT+ruaycnDAAUpKv+ePFfD0RAxn/1BUe\
Zx/Kdrq32DrfakQ6bPsvB9aqZqognNT6be4olHROIkeV879RrsrObury8L9SCEibe\
oHyqU/yCjphSmEdd7WD+zrchK57quskKwRefy2iEC5S2uAH0EPyOZKWlvbKmKu5q4\
CaB8X/I5/+HLZLGvDiezqi6/7p2Gngf5hwZ0lSdy39vyNMaaAT0tKo6nuVw0S1MVg\
1Q7MpWYZs0soHjttq0uLIA3DIbQfLiIvK6/l0BdWTU7+2uQj7lBkQAsFZHoA96ZZg\
FquQrXRlmYOh+Hx5D9fJkXcXe5tmAg==:
Since "Signature-Input" and "Signature" are both defined as
Dictionary Structured Headers, they can be used to easily include
multiple signatures within the same HTTP message. For example, a
signer may include multiple signatures signing the same content with
different keys and/or algorithms to support verifiers with different
capabilities, or a reverse proxy may include information about the
client in header fields when forwarding the request to a service
host, and may also include a signature over those fields and the
client's signature. The following is a non-normative example of
header fields a reverse proxy might add to a forwarded request that
contains the signature in the above example:
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# NOTE: '\' line wrapping per RFC 8792
X-Forwarded-For: 192.0.2.123
Signature-Input: reverse_proxy_sig=("host" "date"
"signature";key=sig1 "x-forwarded-for"); keyid="test-key-a";
alg="hs2019"; created=1402170695; expires=1402170695
Signature: reverse_proxy_sig=:ON3HsnvuoTlX41xfcGWaOEVo1M3bJDRBOp0Pc/O\
jAOWKQn0VMY0SvMMWXS7xG+xYVa152rRVAo6nMV7FS3rv0rR5MzXL8FCQ2A35DCEN\
LOhEgj/S1IstEAEFsKmE9Bs7McBsCtJwQ3hMqdtFenkDffSoHOZOInkTYGafkoy78\
l1VZvmb3Y4yf7McJwAvk2R3gwKRWiiRCw448Nt7JTWzhvEwbh7bN2swc/v3NJbg/w\
JYyYVbelZx4IywuZnYFxgPl/qvqbAjeEVvaLKLgSMr11y+uzxCHoMnDUnTYhMrmOT\
4O8lBLfRFOcoJPKBdoKg9U0a96U2mUug1bFOozEVYFg==:
5. IANA Considerations
5.1. HTTP Signature Algorithms Registry
This document defines HTTP Signature Algorithms, for which IANA is
asked to create and maintain a new registry titled "HTTP Signature
Algorithms". Initial values for this registry are given in
Section 5.1.2. Future assignments and modifications to existing
assignment are to be made through the Expert Review registration
policy [RFC8126] and shall follow the template presented in
Section 5.1.1.
5.1.1. Registration Template
Algorithm Name:
An identifier for the HTTP Signature Algorithm. The name MUST be
an ASCII string consisting only of lower-case characters (""a"" -
""z""), digits (""0"" - ""9""), and hyphens (""-""), and SHOULD
NOT exceed 20 characters in length. The identifier MUST be unique
within the context of the registry.
Status:
A brief text description of the status of the algorithm. The
description MUST begin with one of "Active" or "Deprecated", and
MAY provide further context or explanation as to the reason for
the status.
Description:
A description of the algorithm used to sign the signing string
when generating an HTTP Message Signature, or instructions on how
to determine that algorithm. When the description specifies an
algorithm, it MUST include a reference to the document or
documents that define the algorithm.
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5.1.2. Initial Contents
(( MS: The references in this section are problematic as many of the
specifications that they refer to are too implementation specific,
rather than just pointing to the proper signature and hashing
specifications. A better approach might be just specifying the
signature and hashing function specifications, leaving implementers
to connect the dots (which are not that hard to connect). ))
5.1.2.1. hs2019
Algorithm Name:
"hs2019"
Status:
active
Description:
Derived from metadata associated with keyid. Recommend support
for:
* RSASSA-PSS [RFC8017] using SHA-512 [RFC6234]
* HMAC [RFC2104] using SHA-512 [RFC6234]
* ECDSA using curve P-256 DSS [FIPS186-4] and SHA-512 [RFC6234]
* Ed25519ph, Ed25519ctx, and Ed25519 [RFC8032]
5.1.2.2. rsa-sha1
Algorithm Name:
"rsa-sha1"
Status:
Deprecated; SHA-1 not secure.
Description:
RSASSA-PKCS1-v1_5 [RFC8017] using SHA-1 [RFC6234]
5.1.2.3. rsa-sha256
Algorithm Name:
"rsa-sha256"
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Status:
Deprecated; specifying signature algorithm enables attack vector.
Description:
RSASSA-PKCS1-v1_5 [RFC8017] using SHA-256 [RFC6234]
5.1.2.4. hmac-sha256
Algorithm Name:
"hmac-sha256"
Status:
Deprecated; specifying signature algorithm enables attack vector.
Description:
HMAC [RFC2104] using SHA-256 [RFC6234]
5.1.2.5. ecdsa-sha256
Algorithm Name:
"ecdsa-sha256"
Status:
Deprecated; specifying signature algorithm enables attack vector.
Description:
ECDSA using curve P-256 DSS [FIPS186-4] and SHA-256 [RFC6234]
5.2. HTTP Signature Metadata Parameters Registry
This document defines the "Signature-Input" Structured Header, whose
member values may have parameters containing metadata about a message
signature. IANA is asked to create and maintain a new registry
titled "HTTP Signature Metadata Parameters" to record and maintain
the set of parameters defined for use with member values in the
"Signature-Input" Structured Header. Initial values for this
registry are given in Section 5.2.2. Future assignments and
modifications to existing assignments are to be made through the
Expert Review registration policy [RFC8126] and shall follow the
template presented in Section 5.2.1.
5.2.1. Registration Template
5.2.2. Initial Contents
The table below contains the initial contents of the HTTP Signature
Metadata Parameters Registry. Each row in the table represents a
distinct entry in the registry.
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+=========+========+==============================+
| Name | Status | Reference(s) |
+=========+========+==============================+
| alg | Active | Section 3.1 of this document |
+---------+--------+------------------------------+
| created | Active | Section 3.1 of this document |
+---------+--------+------------------------------+
| expires | Active | Section 3.1 of this document |
+---------+--------+------------------------------+
| keyid | Active | Section 3.1 of this document |
+---------+--------+------------------------------+
Table 7: Initial contents of the HTTP Signature
Metadata Parameters Registry.
5.3. HTTP Signature Specialty Content Identifiers Registry
This document defines a method for canonicalizing HTTP message
content, including content that can be generated from the context of
the HTTP message outside of the HTTP headers. This content is
identified by a unique key. IANA is asked to create and maintain a
new registry typed "HTTP Signature Specialty Content Identifiers" to
record and maintain the set of non-header content identifiers and
their canonicalization method. Initial values for this registry are
given in Section 5.3.2. Future assignments and modifications to
existing assignments are to be made through the Expert Review
registration policy [RFC8126] and shall follow the template presented
in Section 5.3.1.
5.3.1. Registration Template
5.3.2. Initial Contents
The table below contains the initial contents of the HTTP Signature
Specialty Content Identifiers Registry.
+===================+========+================================+
| Name | Status | Reference(s) |
+===================+========+================================+
| @request-target | Active | Section 2.4.1 of this document |
+-------------------+--------+--------------------------------+
| @signature-params | Active | Section 2.4.2 of this document |
+-------------------+--------+--------------------------------+
Table 8: Initial contents of the HTTP Signature Specialty
Content Identifiers Registry.
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6. Security Considerations
(( TODO: need to dive deeper on this section; not sure how much of
what's referenced below is actually applicable, or if it covers
everything we need to worry about. ))
(( TODO: Should provide some recommendations on how to determine what
content needs to be signed for a given use case. ))
There are a number of security considerations to take into account
when implementing or utilizing this specification. A thorough
security analysis of this protocol, including its strengths and
weaknesses, can be found in [WP-HTTP-Sig-Audit].
7. References
7.1. Normative References
[FIPS186-4]
"Digital Signature Standard (DSS)", 2013,
<https://csrc.nist.gov/publications/detail/fips/186/4/
final>.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/rfc/rfc7540>.
[MESSAGING]
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/rfc/rfc7230>.
[POSIX.1] "The Open Group Base Specifications Issue 7, 2018
edition", 2018,
<https://pubs.opengroup.org/onlinepubs/9699919799/>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/rfc/rfc2104>.
[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/rfc/rfc2119>.
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[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/rfc/rfc8174>.
[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/rfc/rfc8792>.
[RFC8941] Nottingham, M. and P-H. Kamp, "Structured Field Values for
HTTP", RFC 8941, DOI 10.17487/RFC8941, February 2021,
<https://www.rfc-editor.org/rfc/rfc8941>.
[SEMANTICS]
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/rfc/rfc7231>.
7.2. Informative References
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/rfc/rfc4648>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/rfc/rfc6234>.
[RFC7239] Petersson, A. and M. Nilsson, "Forwarded HTTP Extension",
RFC 7239, DOI 10.17487/RFC7239, June 2014,
<https://www.rfc-editor.org/rfc/rfc7239>.
[RFC8017] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
"PKCS #1: RSA Cryptography Specifications Version 2.2",
RFC 8017, DOI 10.17487/RFC8017, November 2016,
<https://www.rfc-editor.org/rfc/rfc8017>.
[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/rfc/rfc8032>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>.
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[TLS] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.
[WP-HTTP-Sig-Audit]
"Security Considerations for HTTP Signatures", 2013,
<https://web-payments.org/specs/source/http-signatures-
audit/>.
Appendix A. Detecting HTTP Message Signatures
There have been many attempts to create signed HTTP messages in the
past, including other non-standard definitions of the "Signature"
header used within this specification. It is recommended that
developers wishing to support both this specification and other
historial drafts do so carefully and deliberately, as
incompatibilities between this specification and various versions of
other drafts could lead to problems.
It is recommended that implementers first detect and validate the
"Signature-Input" header defined in this specification to detect that
this standard is in use and not an alternative. If the "Signature-
Input" header is present, all "Signature" headers can be parsed and
interpreted in the context of this draft.
Appendix B. Examples
B.1. Example Keys
This section provides cryptographic keys that are referenced in
example signatures throughout this document. These keys MUST NOT be
used for any purpose other than testing.
B.1.1. Example Key RSA test
The following key is a 2048-bit RSA public and private key pair:
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-----BEGIN RSA PUBLIC KEY-----
MIIBCgKCAQEAhAKYdtoeoy8zcAcR874L8cnZxKzAGwd7v36APp7Pv6Q2jdsPBRrw
WEBnez6d0UDKDwGbc6nxfEXAy5mbhgajzrw3MOEt8uA5txSKobBpKDeBLOsdJKFq
MGmXCQvEG7YemcxDTRPxAleIAgYYRjTSd/QBwVW9OwNFhekro3RtlinV0a75jfZg
kne/YiktSvLG34lw2zqXBDTC5NHROUqGTlML4PlNZS5Ri2U4aCNx2rUPRcKIlE0P
uKxI4T+HIaFpv8+rdV6eUgOrB2xeI1dSFFn/nnv5OoZJEIB+VmuKn3DCUcCZSFlQ
PSXSfBDiUGhwOw76WuSSsf1D4b/vLoJ10wIDAQAB
-----END RSA PUBLIC KEY-----
-----BEGIN RSA PRIVATE KEY-----
MIIEqAIBAAKCAQEAhAKYdtoeoy8zcAcR874L8cnZxKzAGwd7v36APp7Pv6Q2jdsP
BRrwWEBnez6d0UDKDwGbc6nxfEXAy5mbhgajzrw3MOEt8uA5txSKobBpKDeBLOsd
JKFqMGmXCQvEG7YemcxDTRPxAleIAgYYRjTSd/QBwVW9OwNFhekro3RtlinV0a75
jfZgkne/YiktSvLG34lw2zqXBDTC5NHROUqGTlML4PlNZS5Ri2U4aCNx2rUPRcKI
lE0PuKxI4T+HIaFpv8+rdV6eUgOrB2xeI1dSFFn/nnv5OoZJEIB+VmuKn3DCUcCZ
SFlQPSXSfBDiUGhwOw76WuSSsf1D4b/vLoJ10wIDAQABAoIBAG/JZuSWdoVHbi56
vjgCgkjg3lkO1KrO3nrdm6nrgA9P9qaPjxuKoWaKO1cBQlE1pSWp/cKncYgD5WxE
CpAnRUXG2pG4zdkzCYzAh1i+c34L6oZoHsirK6oNcEnHveydfzJL5934egm6p8DW
+m1RQ70yUt4uRc0YSor+q1LGJvGQHReF0WmJBZHrhz5e63Pq7lE0gIwuBqL8SMaA
yRXtK+JGxZpImTq+NHvEWWCu09SCq0r838ceQI55SvzmTkwqtC+8AT2zFviMZkKR
Qo6SPsrqItxZWRty2izawTF0Bf5S2VAx7O+6t3wBsQ1sLptoSgX3QblELY5asI0J
YFz7LJECgYkAsqeUJmqXE3LP8tYoIjMIAKiTm9o6psPlc8CrLI9CH0UbuaA2JCOM
cCNq8SyYbTqgnWlB9ZfcAm/cFpA8tYci9m5vYK8HNxQr+8FS3Qo8N9RJ8d0U5Csw
DzMYfRghAfUGwmlWj5hp1pQzAuhwbOXFtxKHVsMPhz1IBtF9Y8jvgqgYHLbmyiu1
mwJ5AL0pYF0G7x81prlARURwHo0Yf52kEw1dxpx+JXER7hQRWQki5/NsUEtv+8RT
qn2m6qte5DXLyn83b1qRscSdnCCwKtKWUug5q2ZbwVOCJCtmRwmnP131lWRYfj67
B/xJ1ZA6X3GEf4sNReNAtaucPEelgR2nsN0gKQKBiGoqHWbK1qYvBxX2X3kbPDkv
9C+celgZd2PW7aGYLCHq7nPbmfDV0yHcWjOhXZ8jRMjmANVR/eLQ2EfsRLdW69bn
f3ZD7JS1fwGnO3exGmHO3HZG+6AvberKYVYNHahNFEw5TsAcQWDLRpkGybBcxqZo
81YCqlqidwfeO5YtlO7etx1xLyqa2NsCeG9A86UjG+aeNnXEIDk1PDK+EuiThIUa
/2IxKzJKWl1BKr2d4xAfR0ZnEYuRrbeDQYgTImOlfW6/GuYIxKYgEKCFHFqJATAG
IxHrq1PDOiSwXd2GmVVYyEmhZnbcp8CxaEMQoevxAta0ssMK3w6UsDtvUvYvF22m
qQKBiD5GwESzsFPy3Ga0MvZpn3D6EJQLgsnrtUPZx+z2Ep2x0xc5orneB5fGyF1P
WtP+fG5Q6Dpdz3LRfm+KwBCWFKQjg7uTxcjerhBWEYPmEMKYwTJF5PBG9/ddvHLQ
EQeNC8fHGg4UXU8mhHnSBt3EA10qQJfRDs15M38eG2cYwB1PZpDHScDnDA0=
-----END RSA PRIVATE KEY-----
B.2. Example keyid Values
The table below maps example "keyid" values to associated algorithms
and/or keys. These are example mappings that are valid only within
the context of examples in examples within this and future documents
that reference this section. Unless otherwise specified, within the
context of examples it should be assumed that the signer and verifier
understand these "keyid" mappings. These "keyid" values are not
reserved, and deployments are free to use them, with these
associations or others.
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+============+=================================+================+
| keyid | Algorithm | Verification |
| | | Key |
+============+=================================+================+
| test-key-a | "hs2019", using RSASSA-PSS | The public key |
| | [RFC8017] and SHA-512 [RFC6234] | specified in |
| | | Appendix B.1.1 |
+------------+---------------------------------+----------------+
| test-key-b | rsa-sha256 | The public key |
| | | specified in |
| | | Appendix B.1.1 |
+------------+---------------------------------+----------------+
Table 9
B.3. Test Cases
This section provides non-normative examples that may be used as test
cases to validate implementation correctness. These examples are
based on the following HTTP message:
POST /foo?param=value&pet=dog HTTP/1.1
Host: example.com
Date: Tue, 07 Jun 2014 20:51:35 GMT
Content-Type: application/json
Digest: SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Content-Length: 18
{"hello": "world"}
B.3.1. Signature Generation
B.3.1.1. hs2019 signature over minimal recommended content
This presents metadata for a Signature using "hs2019", over minimum
recommended data to sign:
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+==============+===================================+
| Property | Value |
+==============+===================================+
| Algorithm | "hs2019", using RSASSA-PSS |
| | [RFC8017] using SHA-512 [RFC6234] |
+--------------+-----------------------------------+
| Covered | @request-target |
| Content | |
+--------------+-----------------------------------+
| Creation | 8:51:35 PM GMT, June 7th, 2014 |
| Time | |
+--------------+-----------------------------------+
| Expiration | Undefined |
| Time | |
+--------------+-----------------------------------+
| Verification | The public key specified in |
| Key Material | Appendix B.1.1. |
+--------------+-----------------------------------+
Table 10
The Signature Input is:
"@request-target": post /foo?param=value&pet=dog
"@signature-params": ("@request-target"); keyid="test-key-a"; created=1402170695
The signature value is:
QaVaWYfF2da6tG66Xtd0GrVFChJ0fOWUe/C6kaYESPiYYwnMH9egOgyKqgLLY9NQJFk7b
QY834sHEUwjS5ByEBaO3QNwIvqEY1qAAU/2MX14tc9Yn7ELBnaaNHaHkV3xVO9KIuLT7V
6e4OUuGb1axfbXpMgPEql6CEFrn6K95CLuuKP5/gOEcBtmJp5L58gN4VvZrk2OVA6U971
YiEDNuDa4CwMcQMvcGssbc/L3OULTUffD/1VcPtdGImP2uvVQntpT8b2lBeBpfh8MuaV2
vtzidyBYFtAUoYhRWO8+ntqA1q2OK4LMjM2XgDScSVWvGdVd459A0wI9lRlnPap3zg==
A possible "Signature-Input" and "Signature" header containing this
signature is:
# NOTE: '\' line wrapping per RFC 8792
Signature-Input: sig1=("@request-target");
keyid="test-key-a"; created=1402170695
Signature: sig1=:QaVaWYfF2da6tG66Xtd0GrVFChJ0fOWUe/C6kaYESPiYYwnMH9eg\
OgyKqgLLY9NQJFk7bQY834sHEUwjS5ByEBaO3QNwIvqEY1qAAU/2MX14tc9Yn7ELB\
naaNHaHkV3xVO9KIuLT7V6e4OUuGb1axfbXpMgPEql6CEFrn6K95CLuuKP5/gOEcB\
tmJp5L58gN4VvZrk2OVA6U971YiEDNuDa4CwMcQMvcGssbc/L3OULTUffD/1VcPtd\
GImP2uvVQntpT8b2lBeBpfh8MuaV2vtzidyBYFtAUoYhRWO8+ntqA1q2OK4LMjM2X\
gDScSVWvGdVd459A0wI9lRlnPap3zg==:
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B.3.1.2. hs2019 signature covering all header fields
This presents metadata for a Signature using "hs2019" that covers all
header fields in the request:
+==============+============================================+
| Property | Value |
+==============+============================================+
| Algorithm | "hs2019", using RSASSA-PSS [RFC8017] using |
| | SHA-512 [RFC6234] |
+--------------+--------------------------------------------+
| Covered | "@request-target", "host", "date", |
| Content | "content-type", "digest", "content-length" |
+--------------+--------------------------------------------+
| Creation | 8:51:35 PM GMT, June 7th, 2014 |
| Time | |
+--------------+--------------------------------------------+
| Expiration | Undefined |
| Time | |
+--------------+--------------------------------------------+
| Verification | The public key specified in |
| Key Material | Appendix B.1.1. |
+--------------+--------------------------------------------+
Table 11
The Signature Input is:
"@request-target": post /foo?param=value&pet=dog
"host": example.com
"date": Tue, 07 Jun 2014 20:51:35 GMT
"content-type": application/json
"digest": SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
"content-length": 18
"@signature-params": ("@request-target" "host" "date" "content-type" "digest" "content-length"); keyid="test-key-a"; alg="hs2019"; created=1402170695
The signature value is:
B24UG4FaiE2kSXBNKV4DA91J+mElAhS3mncrgyteAye1GKMpmzt8jkHNjoudtqw3GngGY
3n0mmwjdfn1eA6nAjgeHwl0WXced5tONcCPNzLswqPOiobGeA5y4WE8iBveel30OKYVel
0lZ1OnXOmN5TIEIIPo9LrE+LzZis6A0HA1FRMtKgKGhT3N965pkqfhKbq/V48kpJKT8+c
Zs0TOn4HFMG+OIy6c9ofSBrXD68yxP6QYTz6xH0GMWawLyPLYR52j3I05fK1ylAb6K0ox
PxzQ5nwrLD+mUVPZ9rDs1En6fmOX9xfkZTblG/5D+s1fHHs9dDXCOVkT5dLS8DjdIA==
A possible "Signature-Input" and "Signature" header containing this
signature is:
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# NOTE: '\' line wrapping per RFC 8792
Signature-Input: sig1=("@request-target" "host" "date"
"content-type" "digest" "content-length"); keyid="test-key-a";
alg="hs2019"; created=1402170695
Signature: sig1=:B24UG4FaiE2kSXBNKV4DA91J+mElAhS3mncrgyteAye1GKMpmzt8\
jkHNjoudtqw3GngGY3n0mmwjdfn1eA6nAjgeHwl0WXced5tONcCPNzLswqPOiobGe\
A5y4WE8iBveel30OKYVel0lZ1OnXOmN5TIEIIPo9LrE+LzZis6A0HA1FRMtKgKGhT\
3N965pkqfhKbq/V48kpJKT8+cZs0TOn4HFMG+OIy6c9ofSBrXD68yxP6QYTz6xH0G\
MWawLyPLYR52j3I05fK1ylAb6K0oxPxzQ5nwrLD+mUVPZ9rDs1En6fmOX9xfkZTbl\
G/5D+s1fHHs9dDXCOVkT5dLS8DjdIA==:
B.3.2. Signature Verification
B.3.2.1. Minimal Required Signature Header
This presents a "Signature-Input" and "Signature" header containing
only the minimal required parameters:
# NOTE: '\' line wrapping per RFC 8792
Signature-Input: sig1=(); keyid="test-key-a"; created=1402170695
Signature: sig1=:cxieW5ZKV9R9A70+Ua1A/1FCvVayuE6Z77wDGNVFSiluSzR9TYFV\
vwUjeU6CTYUdbOByGMCee5q1eWWUOM8BIH04Si6VndEHjQVdHqshAtNJk2Quzs6WC\
2DkV0vysOhBSvFZuLZvtCmXRQfYGTGhZqGwq/AAmFbt5WNLQtDrEe0ErveEKBfaz+\
IJ35zhaj+dun71YZ82b/CRfO6fSSt8VXeJuvdqUuVPWqjgJD4n9mgZpZFGBaDdPiw\
pfbVZHzcHrumFJeFHWXH64a+c5GN+TWlP8NPg2zFdEc/joMymBiRelq236WGm5VvV\
9a22RW2/yLmaU/uwf9v40yGR/I1NRA==:
The corresponding signature metadata derived from this header field
is:
+=================+==========================================+
| Property | Value |
+=================+==========================================+
| Algorithm | "hs2019", using RSASSA-PSS using SHA-256 |
+-----------------+------------------------------------------+
| Covered Content | `` |
+-----------------+------------------------------------------+
| Creation Time | 8:51:35 PM GMT, June 7th, 2014 |
+-----------------+------------------------------------------+
| Expiration Time | Undefined |
+-----------------+------------------------------------------+
| Verification | The public key specified in |
| Key Material | Appendix B.1.1. |
+-----------------+------------------------------------------+
Table 12
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The corresponding Signature Input is:
"@signature-params": sig1=(); alg="hs2019"; keyid="test-key-a"; created=1402170695
B.3.2.2. Minimal Recommended Signature Header
This presents a "Signature-Input" and "Signature" header containing
only the minimal required and recommended parameters:
# NOTE: '\' line wrapping per RFC 8792
Signature-Input: sig1=(); alg="hs2019"; keyid="test-key-a";
created=1402170695
Signature: sig1=:cxieW5ZKV9R9A70+Ua1A/1FCvVayuE6Z77wDGNVFSiluSzR9TYFV\
vwUjeU6CTYUdbOByGMCee5q1eWWUOM8BIH04Si6VndEHjQVdHqshAtNJk2Quzs6WC\
2DkV0vysOhBSvFZuLZvtCmXRQfYGTGhZqGwq/AAmFbt5WNLQtDrEe0ErveEKBfaz+\
IJ35zhaj+dun71YZ82b/CRfO6fSSt8VXeJuvdqUuVPWqjgJD4n9mgZpZFGBaDdPiw\
pfbVZHzcHrumFJeFHWXH64a+c5GN+TWlP8NPg2zFdEc/joMymBiRelq236WGm5VvV\
9a22RW2/yLmaU/uwf9v40yGR/I1NRA==:
The corresponding signature metadata derived from this header field
is:
+=================+==========================================+
| Property | Value |
+=================+==========================================+
| Algorithm | "hs2019", using RSASSA-PSS using SHA-512 |
+-----------------+------------------------------------------+
| Covered Content | `` |
+-----------------+------------------------------------------+
| Creation Time | 8:51:35 PM GMT, June 7th, 2014 |
+-----------------+------------------------------------------+
| Expiration Time | Undefined |
+-----------------+------------------------------------------+
| Verification | The public key specified in |
| Key Material | Appendix B.1.1. |
+-----------------+------------------------------------------+
Table 13
The corresponding Signature Input is:
"@signature-params": sig1=(); alg="rsa-sha256"; keyid="test-key-b"
B.3.2.3. Minimal Signature Header using rsa-sha256
This presents a minimal "Signature-Input" and "Signature" header for
a signature using the "rsa-sha256" algorithm:
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# NOTE: '\' line wrapping per RFC 8792
Signature: sig1=("date"); alg=rsa-sha256; keyid="test-key-b"
Signature: sig1=:HtXycCl97RBVkZi66ADKnC9c5eSSlb57GnQ4KFqNZplOpNfxqk62\
JzZ484jXgLvoOTRaKfR4hwyxlcyb+BWkVasApQovBSdit9Ml/YmN2IvJDPncrlhPD\
VDv36Z9/DiSO+RNHD7iLXugdXo1+MGRimW1RmYdenl/ITeb7rjfLZ4b9VNnLFtVWw\
rjhAiwIqeLjodVImzVc5srrk19HMZNuUejK6I3/MyN3+3U8tIRW4LWzx6ZgGZUaEE\
P0aBlBkt7Fj0Tt5/P5HNW/Sa/m8smxbOHnwzAJDa10PyjzdIbywlnWIIWtZKPPsoV\
oKVopUWEU3TNhpWmaVhFrUL/O6SN3w==:
The corresponding signature metadata derived from this header field
is:
+===========================+==========================+
| Property | Value |
+===========================+==========================+
| Algorithm | rsa-sha256 |
+---------------------------+--------------------------+
| Covered Content | date |
+---------------------------+--------------------------+
| Creation Time | Undefined |
+---------------------------+--------------------------+
| Expiration Time | Undefined |
+---------------------------+--------------------------+
| Verification Key Material | The public key specified |
| | in Appendix B.1.1. |
+---------------------------+--------------------------+
Table 14
The corresponding Signature Input is:
"date": Tue, 07 Jun 2014 20:51:35 GMT
"@signature-params": ("date"); alg=rsa-sha256; keyid="test-key-b"
Acknowledgements
This specification was initially based on the draft-cavage-http-
signatures internet draft. The editors would like to thank the
authors of that draft, Mark Cavage and Manu Sporny, for their work on
that draft and their continuing contributions.
The editor would also like to thank the following individuals for
feedback on and implementations of the draft-cavage-http-signatures
draft (in alphabetical order): Mark Adamcin, Mark Allen, Paul
Annesley, Karl Boehlmark, Stephane Bortzmeyer, Sarven Capadisli, Liam
Dennehy, ductm54, Stephen Farrell, Phillip Hallam-Baker, Eric Holmes,
Andrey Kislyuk, Adam Knight, Dave Lehn, Dave Longley, James H.
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Manger, Ilari Liusvaara, Mark Nottingham, Yoav Nir, Adrian Palmer,
Lucas Pardue, Roberto Polli, Julian Reschke, Michael Richardson,
Wojciech Rygielski, Adam Scarr, Cory J. Slep, Dirk Stein, Henry
Story, Lukasz Szewc, Chris Webber, and Jeffrey Yasskin
Document History
_RFC EDITOR: please remove this section before publication_
* draft-ietf-httpbis-message-signatures
- Since -02
- -02
o Removed editorial comments on document sources.
o Removed in-document issues list in favor of tracked issues.
o Replaced unstructured "Signature" header with "Signature-
Input" and "Signature" Dictionary Structured Header Fields.
o Defined content identifiers for individual Dictionary
members, e.g., ""x-dictionary-field";key=member-name".
o Defined content identifiers for first N members of a List,
e.g., ""x-list-field":prefix=4".
o Fixed up examples.
o Updated introduction now that it's adopted.
o Defined specialty content identifiers and a means to extend
them.
o Required signature parameters to be included in signature.
o Added guidance on backwards compatibility, detection, and
use of signature methods.
- -01
o Strengthened requirement for content identifiers for header
fields to be lower-case (changed from SHOULD to MUST).
o Added real example values for Creation Time and Expiration
Time.
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o Minor editorial corrections and readability improvements.
- -00
o Initialized from draft-richanna-http-message-signatures-00,
following adoption by the working group.
* draft-richanna-http-message-signatures
- -00
o Converted to xml2rfc v3 and reformatted to comply with RFC
style guides.
o Removed Signature auth-scheme definition and related
content.
o Removed conflicting normative requirements for use of
algorithm parameter. Now MUST NOT be relied upon.
o Removed Extensions appendix.
o Rewrote abstract and introduction to explain context and
need, and challenges inherent in signing HTTP messages.
o Rewrote and heavily expanded algorithm definition, retaining
normative requirements.
o Added definitions for key terms, referenced RFC 7230 for
HTTP terms.
o Added examples for canonicalization and signature generation
steps.
o Rewrote Signature header definition, retaining normative
requirements.
o Added default values for algorithm and expires parameters.
o Rewrote HTTP Signature Algorithms registry definition.
Added change control policy and registry template. Removed
suggested URI.
o Added IANA HTTP Signature Parameter registry.
o Added additional normative and informative references.
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o Added Topics for Working Group Discussion section, to be
removed prior to publication as an RFC.
Authors' Addresses
Annabelle Backman (editor)
Amazon
P.O. Box 81226
Seattle, WA 98108-1226
United States of America
Email: richanna@amazon.com
URI: https://www.amazon.com/
Justin Richer
Bespoke Engineering
Email: ietf@justin.richer.org
URI: https://bspk.io/
Manu Sporny
Digital Bazaar
203 Roanoke Street W.
Blacksburg, VA 24060
United States of America
Email: msporny@digitalbazaar.com
URI: https://manu.sporny.org/
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