drip S. Card
Internet-Draft A. Wiethuechter
Intended status: Informational AX Enterprize
Expires: 6 May 2021 R. Moskowitz
HTT Consulting
S. Zhao (Editor)
Tencent
A. Gurtov
Linköping University
2 November 2020
Drone Remote Identification Protocol (DRIP) Architecture
draft-ietf-drip-arch-05
Abstract
This document defines an architecture for protocols and services to
support Unmanned Aircraft System Remote Identification and tracking
(UAS RID), plus RID-related communications, including required
architectural building blocks and their interfaces.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 6 May 2021.
Copyright Notice
Copyright (c) 2020 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Overview UAS Remote ID (RID) and RID Standardization . . 3
1.2. Overview of Types of UAS Remote ID . . . . . . . . . . . 4
1.2.1. Network RID . . . . . . . . . . . . . . . . . . . . . 4
1.2.2. Broadcast RID . . . . . . . . . . . . . . . . . . . . 5
1.3. Overview of USS Interoperability . . . . . . . . . . . . 5
1.4. Overview of DRIP Archicture . . . . . . . . . . . . . . . 6
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Definitions and Abbreviations . . . . . . . . . . . . . . . . 8
3.1. Additional Definitions . . . . . . . . . . . . . . . . . 8
3.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 8
4. HHIT for UAS RID . . . . . . . . . . . . . . . . . . . . . . 9
5. DRIP RID Entities (WAS Entities and their interfaces) . . . . 10
5.1. Private Information Registry . . . . . . . . . . . . . . 10
5.1.1. Background . . . . . . . . . . . . . . . . . . . . . 10
5.1.2. Proposed Approach . . . . . . . . . . . . . . . . . . 11
5.2. Public Information Registry . . . . . . . . . . . . . . . 11
5.2.1. Background . . . . . . . . . . . . . . . . . . . . . 11
5.2.2. Proposed Approach . . . . . . . . . . . . . . . . . . 11
5.3. CS-RID concept . . . . . . . . . . . . . . . . . . . . . 11
5.3.1. Proposed optional CS-RID SDSP . . . . . . . . . . . . 12
5.3.2. Proposed optional CS-RID Finder . . . . . . . . . . . 12
6. UAS Remote Identifiers . . . . . . . . . . . . . . . . . . . 13
6.1. Background . . . . . . . . . . . . . . . . . . . . . . . 13
6.2. Proposed Approach . . . . . . . . . . . . . . . . . . . . 13
7. DRIP Transactions enabling Trustworthy . . . . . . . . . . . 14
8. Privacy for Broadcast PII . . . . . . . . . . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. Security Considerations . . . . . . . . . . . . . . . . . . . 16
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
12.1. Normative References . . . . . . . . . . . . . . . . . . 16
12.2. Informative References . . . . . . . . . . . . . . . . . 17
Appendix A. Overview of Unmanned Aircraft Systems (UAS)
Traffic . . . . . . . . . . . . . . . . . . . . . . . . . 20
A.1. Operation Concept . . . . . . . . . . . . . . . . . . . . 20
A.2. UAS Service Supplier (USS) . . . . . . . . . . . . . . . 21
A.3. UTM Use Cases for UAS Operations . . . . . . . . . . . . 21
A.4. Automatic Dependent Surveillance Broadcast (ADS-B) . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
This document describes a natural Internet and MAC-layer broadcast-
based architecture for Unmanned Aircraft System Remote Identification
and tracking (UAS RID), conforming to proposed regulations and
external technical standards, satisfying the requirements listed in
the companion requirements document [I-D.ietf-drip-reqs].
Many considerations (especially safety) dictate that UAS be remotely
identifiable. Civil Aviation Authorities (CAAs) worldwide are
mandating Unmanned Aircraft Systems (UAS) Remote Identification
(RID). CAAs currently (2020) promulgate performance-based
regulations that do not specify techniques, but rather cite industry
consensus technical standards as acceptable means of compliance.
1.1. Overview UAS Remote ID (RID) and RID Standardization
A RID is an application enabler for a UAS to be identified by a UTM/
USS or third parties entities such as law enforcement. Many safety
and other considerations dictate that UAS be remotely identifiable.
CAAs worldwide are mandating UAS RID. The European Union Aviation
Safety Agency (EASA) has published [Delegated] and [Implementing]
Regulations. The FAA has published a Notice of Proposed Rule Making
[NPRM]. CAAs currently promulgate performance-based regulations that
do not specify techniques, but rather cite industry consensus
technical standards as acceptable means of compliance.
ASTM
ASTM International, Technical Committee F38 (UAS), Subcommittee
F38.02 (Aircraft Operations), Work Item WK65041, developed the new
ASTM [F3411-19] Standard Specification for Remote ID and Tracking.
ASTM defines one set of RID information and two means, MAC-layer
broadcast and IP-layer network, of communicating it. If a UAS
uses both communication methods, generally the same information
must provided via both means. The [F3411-19] is sighted by FAA in
its RID [NPRM] as "one potential means of compliance" to a Remote
ID rule.
3GPP
3GPP provides UA service in the LTE network since release 15 in
published technical specification [TS-36.777]. Start from its
release 16, it completed the UAS RID requirement study in
[TS-22.825] and proposed use cases in the mobile network and the
services that can be offered based on RID and ongoing release 17
specification works on enhanced UAS service requirement and
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provides the protocol and application architecture support which
is applicable for both 4G and 5G network. ATIS's recent report
[ATIS-I-0000074] proposes architecture approaches for the 3GPP
network to support UAS and one of which is put RID in higher 3GPP
protocol stack such as using ASTM remote ID [F3411-19].
1.2. Overview of Types of UAS Remote ID
1.2.1. Network RID
Network RID defines a RID data dictionary and data flow: from a UAS
via unspecified means to a Network Remote ID Service Provider (Net-
RID SP); from the Net-RID SP to an integrated, or over the Internet
to a separate, Network Remote ID Display Provider (Net- RID DP); from
the Net-RID DP via the Internet to Network Remote ID clients in
response to their queries (expected typically, but not specified
exclusively, to be web based) specifying airspace volumes of
interest. Network RID depends upon connectivity, in several
segments, via the Internet, from the UAS to the Observer.
The Network RID is illustrated in Figure 1 below.
x x UA
xxxxx ********************
| * ------*---+------------+
| * / * | NET_Rid_SP |
| * ------------/ +---*--+------------+
| RF */ | *
| * INTERNET | * +------------+
| /* +---*--| NET_Rid_DP |
| / * +----*--+------------+
+ / * | *
x / ****************|*** x
xxxxx | xxxxx
x +------- x
x x
x x Operator (GCS) Observer x x
x x x x
Figure 1
Via the direct Radio Frequency (RF) link between the UA and GCS:
Command and Control (C2) flows from the GCS to the UA; for all but
the simplest hobby aircraft, position and status flow from the UA to
the GCS. Via the Internet, through three distinct segments, Network
RID information flows from the UAS (comprising the UA and its GCS) to
the Observer.
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1.2.2. Broadcast RID
Broadcast RID defines a set of RID messages and how the UA transmits
them locally directly one-way, over Bluetooth or Wi-Fi. Broadcast
RID should need Internet (or other Wide Area Network) connectivity
only for UAS registry information lookup using the locally directly
received UAS ID as a key. Broadcast RID should be functionally
usable in situations with no Internet connectivity.
The Broadcast RID is illustrated in Figure 2 below.
Editor's note: Is there a need to add interconnections between
B-RID and N-RID in the drawing
x x UA
xxxxx
|
|
| app messages directly over
| one-way RF data link (no IP)
|
|
+
x
xxxxx
x
x
x x Observer's device (e.g. smartphone)
x x
Figure 2
Editor's note: the following may more clarification:
* what Broadcast RID can do w/ & w/o Observer Internet connectivity
* How Broadcast RID transmits public info (obviating some registry
lookups)
* how Network RID is "less constrained" than Broadcast RID
1.3. Overview of USS Interoperability
Editor's Note: Show how DRIP RID is an enabler of USS
Interoperability Figure 3
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+-------+
| DSS |
+-------+
/ \
/ \
/ \
+-------+ +-------+
| USS-1 | <----------> | USS-2 |
+-------+ +-------+
Figure 3
1.4. Overview of DRIP Archicture
The requirements document also provides an extended introduction to
the problem space, use cases, etc. Only a brief summary of that
introduction will be restated here as context, with reference to the
general architecture shown in Figure 4 below.
General x x Public
Public xxxxx xxxxx Safety
Observer x x Observer
x x
x x ---------+ +---------- x x
x x | | x x
| |
+ +
xxxxxxxxxx
x x
+----------+x Internet x+------------+
| x x |
UA1 x | xxxxxxxxxx | x UA2
Pilot xxxxx + + + xxxxx Pilot
Operator x | | | x Operator
x | | | x
x x | | | x x
x x | | | x x
| | |
+----------+ | | | +----------+
| |------+ | +-------| |
| Public | | | Private |
| Registry | +-----+ | Registry |
| | | DNS | | |
+----------+ +-----+ +----------+
Figure 4
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Editor's note: the archteture may need more clarification, and
address the following:
* add network RID and broadcast RID in the picture (since those are
the focus points)
* connectivity requirements among UA, GCS, SP, DP (if necessary) ...
DRIP will enable leveraging existing Internet resources (standard
protocols, services, infrastructure and business models) to meet UAS
RID and closely related needs. DRIP will specify how to apply IETF
standards, complementing [F3411-19] and other external standards, to
satisfy UAS RID requirements. DRIP will update existing and develop
new protocol standards as needed to accomplish the foregoing.
This document will outline the UAS RID architecture into which DRIP
must fit, and an architecture for DRIP itself. This includes
presenting the gaps between the CAAs' Concepts of Operations and
[F3411-19] as it relates to use of Internet technologies and UA
direct RF communications. Issues include, but are not limited to:
* Mechanisms to leverage Domain Name System (DNS: [RFC1034]) and
Extensible Provisioning Protocol (EPP [RFC5731]) technology to
provide for private (Section 5.1) and public (Section 5.2)
Information Registry.
* Trustworthy Remote ID and trust in RID messages Section 6
* Privacy in RID messages (PII protection) Section 8
Eiditor's Note: The following aspects are not covered in this
draft, yet. We may consider add sections for each of them if
necessary.
* UA -> Ground communications including Broadcast RID
* Broadcast RID 'harvesting' and secure forwarding into the UTM
* Secure UAS -> Net-RID SP communications
* Secure Observer -> Pilot communications
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2. Conventions
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 above.
3. Definitions and Abbreviations
3.1. Additional Definitions
Editor's Note: to be updated.
This document uses terms defined in [I-D.ietf-drip-reqs].
Editor's note: in order to make it self-contain, listing terms
used in this draft should be okie, comments?
3.2. Abbreviations
Editor's Note: to be updated.
ADS-B: Automatic Dependent Surveillance Broadcast
DSS: Discovery & Synchronization Service
EdDSA: Edwards-Curve Digital Signature Algorithm
GCS: Ground Control Station
HHIT: Hierarchical HIT Registries
HIP: Host Identity Protocol
HIT: Host Identity Tag
RID: Remote ID
Net-RID SP: Network RID Service Provider
Net-RID DP: Network RID Display Provider.
PII: Personally Identifiable Information
RF: Radio Frequency
SDSP: Supplemental Data Service Provider
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UA: Unmanned Aircraft
UAS: Unmanned Aircraft System
USS: UAS Service Supplier
UTM: UAS Traffic Management
4. HHIT for UAS RID
Editor's note: I think we should explain HHIT designs for UAS RID
first and give readers a direct imporession what this draft is
offering. This is one of Daniel's comment, we shall focus on
solutions, without repeating too much of details from a sepecifc
draft.
This document describes the use of Hierarchical Host Identity Tags
(HHITs) as self-asserting IPv6 addresses and thereby a trustable
Identifier for use as the UAS Remote ID. HHITs self-attest to the
included explicit hierarchy that provides Registrar discovery for
3rd-party ID attestation.
HITs are statistically unique through the cryptographic hash feature
of second-preimage resistance. The cryptographically-bound addition
of the Hierarchy and a HHIT registration process (TBD; e.g. based on
Extensible Provisioning Protocol, [RFC5730]) provide complete, global
HHIT uniqueness. This is in contrast to general IDs (e.g. a UUID or
device serial number) as the subject in an X.509 certificate.
other pointers: (mostly list how HHIT satisfy the reqs-)
* Why DRIP RID should/MUST/May be a HHIT?
* HHIT RID format, metadate, and other useful info
* HHIT RID registar workflow
* HHIT Users (operator/USS/NETRID-SP?)
- expand on different uses of & relationship between optional
manufacturer-assigned HI & subsequent single-use HIs
* how security is guaranteed
- call X.509 PKI not "standard" but "classical", describe it to
justify why it won't work here
- explain continuing role of some kind of CA even w/o X.509 PKI
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Editors' note: this is also one of the Michael's comment, we
can address it here
* how DNS lookup may happen (Reverse DNS?)
* ....
5. DRIP RID Entities (WAS Entities and their interfaces)
Editor: This section descrips the DRIP RID ecosystem such as RID
design philosophy, PII registration, Still not sure this is a good
title since here mainly talks about regiter, maybe use this seciton
focus on HHIT RID registration?? I also have suggestion to move the
CS-RID to a seperated section
Any DRIP solutions for UAS RID must fit into the UTM (or U-space)
system. This implies interaction with entities including UA, GCS,
USS, Net-RID SP, Net-RID DP, Observers, Operators, Pilots In Command,
Remote Pilots, possibly SDSP, etc. The only additional entities
introduced in this document are registries, required but not
specified by the regulations and [RFC7401], and optionally CS-RID
SDSP and Finder nodes.
UAS registries hold both public and private UAS information. The
public information is primarily pointers to the repositories of, and
keys for looking up, the private information. Given these different
uses, and to improve scalability, security and simplicity of
administration, the public and private information can be stored in
different registries, indeed different types of registry.
Editor's note: what are differences & relationships among public &
private registries, DP, SP, USS
5.1. Private Information Registry
5.1.1. Background
The private information required for UAS RID is similar to that
required for Internet domain name registration. Thus a DRIP RID
solution can leverage existing Internet resources: registration
protocols, infrastructure and business models, by fitting into an ID
structure compatible with DNS names. This implies some sort of
hierarchy, for scalability, and management of this hierarchy. It is
expected that the private registry function will be provided by the
same organizations that run USS, and likely integrated with USS.
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5.1.2. Proposed Approach
A DRIP UAS ID MUST be amenable to handling as an Internet domain name
(at an arbitrary level in the hierarchy), MUST be registered in at
least a pseudo-domain (e.g. .ip6.arpa for reverse lookup), and MAY be
registered as a sub-domain (for forward lookup).
A DRIP private information registry MUST support essential Internet
domain name registry operations (e.g. add, delete, update, query)
using interoperable open standard protocols. It SHOULD support the
Extensible Provisioning Protocol (EPP) and the Registry Data Access
Protocol (RDAP) with access controls. It MAY use XACML to specify
those access controls. It MUST be listed in a DNS: that DNS MAY be
private; but absent any compelling reasons for use of private DNS,
SHOULD be the definitive public Internet DNS hierarchy. The DRIP
private information registry in which a given UAS is registered MUST
be findable, starting from the UAS ID, using the methods specified in
[RFC7484]. A DRIP private information registry MAY support WebFinger
as specified in [RFC7033].
5.2. Public Information Registry
5.2.1. Background
The public information required to be made available by UAS RID is
transmitted as cleartext to local observers in Broadcast RID and is
served to a client by a Net-RID DP in Network RID. Therefore, while
IETF can offer e.g. [RFC6280] as one way to implement Network RID,
the only public information required to support essential DRIP
functions for UAS RID is that required to look up Internet domain
hosts, services, etc.
5.2.2. Proposed Approach
A DRIP public information registry MUST be a standard DNS server, in
the definitive public Internet DNS hierarchy. It MUST support NS,
MX, SRV, TXT, AAAA, PTR, CNAME and HIP RR (the last per [RFC8005])
types. If a DRIP public information registry lists, in a HIP RR, any
HIP RVS servers for a given DRIP UAS ID, those RVS servers MUST
restrict relay services per AAA policy; this may require extensions
to [RFC8004].
5.3. CS-RID concept
Editor's Note: if CS-RID is optional, may be added in separately
section stating optional features Maybe add the CS into
architecture diagram
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ASTM anticipated that regulators would require both Broadcast RID and
Network RID for large UAS, but allow RID requirements for small UAS
to be satisfied with the operator's choice of either Broadcast RID or
Network RID. The EASA initially specified Broadcast RID for UAS of
essentially all UAS and is now considering Network RID also. The FAA
NPRM requires both for Standard RID and specifies Network RID only
for Limited RID. One obvious opportunity is to enhance the
architecture with gateways from Broadcast RID to Network RID. This
provides the best of both and gives regulators and operators
flexibility. Such gateways could be pre-positioned (e.g. around
airports and other sensitive areas) and/or crowdsourced (as nothing
more than a smartphone with a suitable app is needed). As Broadcast
RID media have limited range, gateways receiving messages claiming
locations far from the gateway can alert authorities or a SDSP to the
failed sanity check possibly indicating intent to deceive.
Surveillance SDSPs can use messages with precise date/time/position
stamps from the gateways to multilaterate UA location, independent of
the locations claimed in the messages, which are entirely operator
self-reported in UAS RID and UTM. Further, gateways with additional
sensors (e.g. smartphones with cameras) can provide independent
information on the UA type and size, confirming or refuting those
claims made in the RID messages. CS-RID would be an option, beyond
baseline DRIP functionality; if implemented, it adds two more entity
types.
5.3.1. Proposed optional CS-RID SDSP
A CS-RID SDSP MUST appear (i.e. present the same interface) to a Net-
RID SP as a Net-RID DP. A CS-RID SDSP MUST appear to a Net-RID DP as
a Net-RID SP. A CS-RID SDSP MUST NOT present a standard GCS-facing
interface as if it were a Net-RID SP. A CS-RID SDSP MUST NOT present
a standard client-facing interface as if it were a Net-RID DP. A CS-
RID SDSP MUST present a TBD interface to a CS-RID Finder; this
interface SHOULD be based upon but readily distinguishable from that
between a GCS and a Net-RID SP.
5.3.2. Proposed optional CS-RID Finder
A CS-RID Finder MUST present a TBD interface to a CS-RID SDSP; this
interface SHOULD be based upon but readily distinguishable from that
between a GCS and a Net-RID SP. A CS-RID Finder must implement,
integrate, or accept outputs from, a Broadcast RID receiver. A CS-
RID Finder MUST NOT interface directly with a GCS, Net-RID SP, Net-
RID DP or Network RID client.
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6. UAS Remote Identifiers
6.1. Background
A DRIP UA ID needs to be "Trustworthy". This means that within the
framework of the RID messages, an observer can establish that the RID
used does uniquely belong to the UA. That the only way for any other
UA to assert this RID would be to steal something from within the UA.
The RID is self-generated by the UAS (either UA or GCS) and
registered with the USS.
Within the limitations of Broadcast RID, this is extremely
challenging as:
* An RID can at most be 20 characters
* The ASTM Basic RID message (the message containing the RID) is 25
characters; only 3 characters are currently unused
* The ASTM Authentication message, with some changes from [F3411-19]
can carry 224 bytes of payload.
Standard approaches like X.509 and PKI will not fit these
constraints, even using the new EdDSA algorithm. An example of a
technology that will fit within these limitations is an enhancement
of the Host Identity Tag (HIT) of HIPv2 [RFC7401] introducing
hierarchy as defined in HHIT [I-D.moskowitz-hip-hierarchical-hit];
using Hierarchical HITs for UAS RID is outlined in HHIT based UAS RID
[I-D.ietf-drip-rid]. As PKI with X.509 is being used in other
systems with which UAS RID must interoperate (e.g. the UTM Discovery
and Synchronization Service and the UTM InterUSS protocol) mappings
between the more flexible but larger X.509 certificates and the HHIT
based structures must be devised.
By using the EdDSA HHIT suite, self-assertions of the RID can be done
in as little as 84 bytes. Third-party assertions can be done in 200
bytes. An observer would need Internet access to validate a self-
assertion claim. A third-party assertion can be validated via a
small credential cache in a disconnected environment. This third-
party assertion is possible when the third-party also uses HHITs for
its identity and the UA has the public key for that HHIT.
6.2. Proposed Approach
A DRIP UAS ID MUST be a HHIT. It SHOULD be self-generated by the UAS
(either UA or GCS) and MUST be registered with the Private
Information Registry identified in its hierarchy fields. Each UAS ID
HHIT MUST NOT be used more than once, with one exception as follows.
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Each UA MAY be assigned, by its manufacturer, a single HI and derived
HHIT encoded as a hardware serial number per [CTA2063A]. Such a
static HHIT SHOULD be used only to bind one-time use UAS IDs (other
HHITs) to the unique UA. Depending upon implementation, this may
leave a HI private key in the possession of the manufacturer (see
Security Considerations).
Each UA equipped for Broadcast RID MUST be provisioned not only with
its HHIT but also with the HI public key from which the HHIT was
derived and the corresponding private key, to enable message
signature. Each UAS equipped for Network RID MUST be provisioned
likewise; the private key SHOULD reside only in the ultimate source
of Network RID messages (i.e. on the UA itself if the GCS is merely
relaying rather than sourcing Network RID messages). Each observer
device MUST be provisioned with public keys of the UAS RID root
registries and MAY be provisioned with public keys or certificates
for subordinate registries.
Operators and Private Information Registries MUST possess and other
UTM entities MAY possess UAS ID style HHITs. When present, such
HHITs SHOULD be used with HIP to strongly mutually authenticate and
optionally encrypt communications.
7. DRIP Transactions enabling Trustworthy
Each Operator MUST generate a Host Identity of the Operator (HIo) and
derived Hierarchical HIT of the Operator (HHITo), register them with
a Private Information Registry along with whatever Operator data
(inc. PII) is required by the cognizant CAA and the registry, and
obtain a Certificate from the Registry on the Operator (Cro) signed
with the Host Identity of the Registry private key (HIr(priv))
proving such registration.
To add an UA, an Operator MUST generate a Host Identity of the
Aircraft (HIa) and derived Hierarchical HIT of the Aircraft (HHITa),
create a Certificate from the Operator on the Aircraft (Coa) signed
with the Host Identity of the Operator private key (HIo(priv)) to
associate the UA with its Operator, register them with a Private
Information Registry along with whatever UAS data is required by the
cognizant CAA and the registry, obtain a Certificate from the
Registry on the Operator and Aircraft ("Croa") signed with the
HIr(priv) proving such registration, and obtain a Certificate from
the Registry on the Aircraft (Cra) signed with HIr(priv) proving UA
registration in that specific registry while preserving Operator
privacy. The operator then MUST provision the UA with HIa,
HIa(priv), HHITa and Cra.
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UA engaging in Broadcast RID MUST use HIa(priv) to sign Auth Messages
and MUST periodically broadcast Cra. UAS engaging in Network RID MUST
use HIa(priv) to sign Auth Messages. Observers MUST use HIa from
received Cra to verify received Broadcast RID Auth messages.
Observers without Internet connectivity MAY use Cra to identify the
trust class of the UAS based on known registry vetting. Observers
with Internet connectivity MAY use HHITa to perform lookups in the
Public Information Registry and MAY then query the Private
Information Registry, which MUST enforce AAA policy on Operator PII
and other sensitive information.
8. Privacy for Broadcast PII
Editor's ntoe: move this to a subsction of Operator Privacy?
Broadcast RID messages may contain PII. This may be information
about the UA such as its destination or Operator information such as
GCS location. There is no absolute "right" in hiding PII, as there
will be times (e.g., disasters) and places (buffer zones around
airports and sensitive facilities) where policy may mandate all
information be sent as cleartext. Otherwise, the modern general
position (consistent with, e.g., the EU General Data Protection
Regulation) is to hide PII unless otherwise instructed. While some
have argued that a system like that of automobile registration plates
should suffice for UAS, others have argued persuasively that each
generation of new identifiers should take advantage of advancing
technology to protect privacy, to the extent compatible with the
transparency needed to protect safety.
A viable architecture for PII protection would be symmetric
encryption of the PII using a key known to the UAS and a USS service.
An authorized Observer may send the encrypted PII along with the
Remote ID (to their UAS display service) to get the plaintext. The
authorized Observer may send the Remote ID (to their UAS display
service) and receive the key to directly decrypt all PII content from
the UA.
PII is protected unless the UAS is informed otherwise. This may come
from operational instructions to even permit flying in a space/time.
It may be special instructions at the start or during an operation.
PII protection should not be used if the UAS loses connectivity to
the USS. The USS always has the option to abort the operation if PII
protection is disallowed.
An authorized observer may instruct a UAS via the USS that conditions
have changed mandating no PII protection or land the UA.
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9. IANA Considerations
Editor's note: placeholder
10. Security Considerations
DRIP is all about safety and security, so content pertaining to such
is not limited to this section. The security provided by asymmetric
cryptographic techniques depends upon protection of the private keys.
A manufacturer that embeds a private key in an UA may have retained a
copy. A manufacturer whose UA are configured by a closed source
application on the GCS which communicates over the Internet with the
factory may be sending a copy of a UA or GCS self-generated key back
to the factory. Keys may be extracted from a GCS or UA; the RID
sender of a small harmless UA (or the entire UA) could be carried by
a larger dangerous UA as a "false flag." Compromise of a registry
private key could do widespread harm. Key revocation procedures are
as yet to be determined. These risks are in addition to those
involving Operator key management practices.
11. Acknowledgements
The work of the FAA's UAS Identification and Tracking (UAS ID)
Aviation Rulemaking Committee (ARC) is the foundation of later ASTM
and proposed IETF DRIP WG efforts. The work of ASTM F38.02 in
balancing the interests of diverse stakeholders is essential to the
necessary rapid and widespread deployment of UAS RID. IETF
volunteers who have contributed to this draft include Amelia
Andersdotter and Mohamed Boucadair.
12. References
12.1. Normative References
[I-D.ietf-drip-reqs]
Card, S., Wiethuechter, A., Moskowitz, R., and A. Gurtov,
"Drone Remote Identification Protocol (DRIP)
Requirements", Work in Progress, Internet-Draft, draft-
ietf-drip-reqs-06, 1 November 2020, <http://www.ietf.org/
internet-drafts/draft-ietf-drip-reqs-06.txt>.
[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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[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>.
12.2. Informative References
[ATIS-I-0000074]
ATIS, "Report on UAS in 3GPP", n.d.,
<https://access.atis.org/apps/group_public/
download.php/48760/ATIS-I-0000074.pdf>.
[CTA2063A] ANSI, "Small Unmanned Aerial Systems Serial Numbers",
2019.
[Delegated]
European Union Aviation Safety Agency (EASA), "EU
Commission Delegated Regulation 2019/945 of 12 March 2019
on unmanned aircraft systems and on third-country
operators of unmanned aircraft systems", 2019.
[F3411-19] ASTM, "Standard Specification for Remote ID and Tracking",
2019.
[I-D.ietf-drip-rid]
Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov,
"UAS Remote ID", Work in Progress, Internet-Draft, draft-
ietf-drip-rid-04, 1 November 2020, <http://www.ietf.org/
internet-drafts/draft-ietf-drip-rid-04.txt>.
[I-D.maeurer-raw-ldacs]
Maeurer, N., Graeupl, T., and C. Schmitt, "L-band Digital
Aeronautical Communications System (LDACS)", Work in
Progress, Internet-Draft, draft-maeurer-raw-ldacs-06, 2
October 2020, <http://www.ietf.org/internet-drafts/draft-
maeurer-raw-ldacs-06.txt>.
[I-D.moskowitz-drip-crowd-sourced-rid]
Moskowitz, R., Card, S., Wiethuechter, A., Zhao, S., and
H. Birkholz, "Crowd Sourced Remote ID", Work in Progress,
Internet-Draft, draft-moskowitz-drip-crowd-sourced-rid-04,
20 May 2020, <http://www.ietf.org/internet-drafts/draft-
moskowitz-drip-crowd-sourced-rid-04.txt>.
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[I-D.moskowitz-drip-secure-nrid-c2]
Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov,
"Secure UAS Network RID and C2 Transport", Work in
Progress, Internet-Draft, draft-moskowitz-drip-secure-
nrid-c2-01, 27 September 2020, <http://www.ietf.org/
internet-drafts/draft-moskowitz-drip-secure-nrid-
c2-01.txt>.
[I-D.moskowitz-hip-hhit-registries]
Moskowitz, R., Card, S., and A. Wiethuechter,
"Hierarchical HIT Registries", Work in Progress, Internet-
Draft, draft-moskowitz-hip-hhit-registries-02, 9 March
2020, <http://www.ietf.org/internet-drafts/draft-
moskowitz-hip-hhit-registries-02.txt>.
[I-D.moskowitz-hip-hierarchical-hit]
Moskowitz, R., Card, S., and A. Wiethuechter,
"Hierarchical HITs for HIPv2", Work in Progress, Internet-
Draft, draft-moskowitz-hip-hierarchical-hit-05, 13 May
2020, <http://www.ietf.org/internet-drafts/draft-
moskowitz-hip-hierarchical-hit-05.txt>.
[I-D.moskowitz-hip-new-crypto]
Moskowitz, R., Card, S., and A. Wiethuechter, "New
Cryptographic Algorithms for HIP", Work in Progress,
Internet-Draft, draft-moskowitz-hip-new-crypto-05, 26 July
2020, <http://www.ietf.org/internet-drafts/draft-
moskowitz-hip-new-crypto-05.txt>.
[I-D.moskowitz-orchid-cshake]
Moskowitz, R., Card, S., and A. Wiethuechter, "Using
cSHAKE in ORCHIDs", Work in Progress, Internet-Draft,
draft-moskowitz-orchid-cshake-01, 21 May 2020,
<http://www.ietf.org/internet-drafts/draft-moskowitz-
orchid-cshake-01.txt>.
[I-D.wiethuechter-drip-auth]
Wiethuechter, A., Card, S., and R. Moskowitz, "DRIP
Authentication Formats", Work in Progress, Internet-Draft,
draft-wiethuechter-drip-auth-04, 21 September 2020,
<http://www.ietf.org/internet-drafts/draft-wiethuechter-
drip-auth-04.txt>.
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[I-D.wiethuechter-drip-identity-claims]
Wiethuechter, A., Card, S., and R. Moskowitz, "DRIP
Identity Claims", Work in Progress, Internet-Draft, draft-
wiethuechter-drip-identity-claims-02, 26 October 2020,
<http://www.ietf.org/internet-drafts/draft-wiethuechter-
drip-identity-claims-02.txt>.
[Implementing]
European Union Aviation Safety Agency (EASA), "EU
Commission Implementing Regulation 2019/947 of 24 May 2019
on the rules and procedures for the operation of unmanned
aircraft", 2019.
[LAANC] United States Federal Aviation Administration (FAA), "Low
Altitude Authorization and Notification Capability", n.d.,
<https://www.faa.gov/uas/programs_partnerships/
data_exchange/>.
[NPRM] United States Federal Aviation Administration (FAA),
"Notice of Proposed Rule Making on Remote Identification
of Unmanned Aircraft Systems", 2019.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[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>.
[RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
STD 69, RFC 5730, DOI 10.17487/RFC5730, August 2009,
<https://www.rfc-editor.org/info/rfc5730>.
[RFC5731] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)
Domain Name Mapping", STD 69, RFC 5731,
DOI 10.17487/RFC5731, August 2009,
<https://www.rfc-editor.org/info/rfc5731>.
[RFC6280] Barnes, R., Lepinski, M., Cooper, A., Morris, J.,
Tschofenig, H., and H. Schulzrinne, "An Architecture for
Location and Location Privacy in Internet Applications",
BCP 160, RFC 6280, DOI 10.17487/RFC6280, July 2011,
<https://www.rfc-editor.org/info/rfc6280>.
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[RFC7033] Jones, P., Salgueiro, G., Jones, M., and J. Smarr,
"WebFinger", RFC 7033, DOI 10.17487/RFC7033, September
2013, <https://www.rfc-editor.org/info/rfc7033>.
[RFC7401] Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
Henderson, "Host Identity Protocol Version 2 (HIPv2)",
RFC 7401, DOI 10.17487/RFC7401, April 2015,
<https://www.rfc-editor.org/info/rfc7401>.
[RFC7484] Blanchet, M., "Finding the Authoritative Registration Data
(RDAP) Service", RFC 7484, DOI 10.17487/RFC7484, March
2015, <https://www.rfc-editor.org/info/rfc7484>.
[RFC8004] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", RFC 8004, DOI 10.17487/RFC8004,
October 2016, <https://www.rfc-editor.org/info/rfc8004>.
[RFC8005] Laganier, J., "Host Identity Protocol (HIP) Domain Name
System (DNS) Extension", RFC 8005, DOI 10.17487/RFC8005,
October 2016, <https://www.rfc-editor.org/info/rfc8005>.
[TS-22.825]
3GPP, "UAS RID requirement study", n.d.,
<https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=3527>.
[TS-36.777]
3GPP, "UAV service in the LTE network", n.d.,
<https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=3231>.
[U-Space] European Organization for the Safety of Air Navigation
(EUROCONTROL), "U-space Concept of Operations", 2019,
<https://www.sesarju.eu/sites/default/files/documents/u-
space/CORUS%20ConOps%20vol2.pdf>.
Appendix A. Overview of Unmanned Aircraft Systems (UAS) Traffic
A.1. Operation Concept
The National Aeronautics and Space Administration (NASA) and FAAs'
effort of integrating UAS's operation into the national airspace
system (NAS) leads to the development of the concept of UTM and the
ecosystem around it. The UTM concept was initially presented in
2013. The eventual development and implementation are conducted by
the UTM research transition team which is the joint workforce by FAA
and NASA. World efforts took place afterward. The Single European
Sky ATM Research (SESAR) started the CORUS project to research its
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UTM counterpart concept, namely [U-Space]. This effort is led by the
European Organization for the Safety of Air Navigation (Eurocontrol).
Both NASA and SESAR have published the UTM concept of operations to
guide the development of their future air traffic management (ATM)
system and make sure safe and efficient integrations of manned and
unmanned aircraft into the national airspace.
The UTM composes of UAS operation infrastructure, procedures and
local regulation compliance policies to guarantee UAS's safe
integration and operation. The main functionality of a UTM includes,
but is not limited to, providing means of communication between UAS
operators and service providers and a platform to facilitate
communication among UAS service providers.
A.2. UAS Service Supplier (USS)
A USS plays an important role to fulfill the key performance
indicators (KPIs) that a UTM has to offer. Such Entity acts as a
proxy between UAS operators and UTM service providers. It provides
services like real-time UAS traffic monitor and planning,
aeronautical data archiving, airspace and violation control,
interacting with other third-party control entities, etc. A USS can
coexist with other USS(s) to build a large service coverage map which
can load-balance, relay and share UAS traffic information.
The FAA works with UAS industry shareholders and promotes the Low
Altitude Authorization and Notification Capability [LAANC] program
which is the first implementation to realize UTM's functionality.
The LAANC program can automate the UAS's fly plan application and
approval process for airspace authorization in real-time by checking
against multiple aeronautical databases such as airspace
classification and fly rules associated with it, FAA UAS facility
map, special use airspace, Notice to airman (NOTAM) and Temporary
flight rule (TFR).
A.3. UTM Use Cases for UAS Operations
This section illustrates a couple of use case scenarios where UAS
participation in UTM has significant safety improvement.
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1. For a UAS participating in UTM and takeoff or land in a
controlled airspace (e.g., Class Bravo, Charlie, Delta and Echo
in United States), the USS where UAS is currently communicating
with is responsible for UAS's registration, authenticating the
UAS's fly plan by checking against designated UAS fly map
database, obtaining the air traffic control (ATC) authorization
and monitor the UAS fly path in order to maintain safe boundary
and follow the pre-authorized route.
2. For a UAS participating in UTM and take off or land in an
uncontrolled airspace (ex. Class Golf in the United States),
pre-fly authorization must be obtained from a USS when operating
beyond-visual-of-sight (BVLOS) operation. The USS either accepts
or rejects received intended fly plan from the UAS. Accepted UAS
operation may share its current fly data such as GPS position and
altitude to USS. The USS may keep the UAS operation status near
real-time and may keep it as a record for overall airspace air
traffic monitor.
A.4. Automatic Dependent Surveillance Broadcast (ADS-B)
The ADS-B is the de facto technology used in manned aviation for
sharing locaiton infomraiton, which is a ground and satellite based
system designed in the early 2000s. Broadcast RID is conceptually
similar to ADS-B. However, for numerous technical and regulatory
reasons, ADS-B itself is not suitable for low-flying small UA.
Technical reasons include: needing RF-LOS to large, expensive (hence
scarce) ground stations; needing both a satellite receiver and 1090
MHz transceiver onboard CSWaP constrained UA; the limited bandwidth
of both uplink and downlink, which are adequate for the current
manned aviation traffic volume, but would likely be saturated by
large numbers of UAS, endangering manned aviation; etc.
Understanding these technical shortcomings, regulators world-wide
have ruled out use of ADS-B for the small UAS for which UAS RID and
DRIP are intended.
Authors' Addresses
Stuart W. Card
AX Enterprize
4947 Commercial Drive
Yorkville, NY, 13495
United States of America
Email: stu.card@axenterprize.com
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Adam Wiethuechter
AX Enterprize
4947 Commercial Drive
Yorkville, NY, 13495
United States of America
Email: adam.wiethuechter@axenterprize.com
Robert Moskowitz
HTT Consulting
na
Oak Park, MI, 48237
United States of America
Email: rgm@labs.htt-consult.com
Shuai Zhao
Tencent
2747 Park Blvd
Palo Alto, 94588
United States of America
Email: shuai.zhao@ieee.org
Andrei Gurtov
Linköping University
IDA
SE-58183 Linköping Linköping
Sweden
Email: gurtov@acm.org
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