Aircraft to Anything AdHoc Broadcasts and Session
draft-moskowitz-drip-a2x-adhoc-session-04
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Robert Moskowitz , Stuart W. Card , Andrei Gurtov | ||
| Last updated | 2024-04-25 | ||
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draft-moskowitz-drip-a2x-adhoc-session-04
DRIP R. Moskowitz
Internet-Draft HTT Consulting
Intended status: Standards Track S. Card
Expires: 27 October 2024 AX Enterprize
A. Gurtov
Linköping University
25 April 2024
Aircraft to Anything AdHoc Broadcasts and Session
draft-moskowitz-drip-a2x-adhoc-session-04
Abstract
Aircraft-to-anything (A2X) communications are often single broadcast
messages that to be trustable, need to be signed with expensive (in
cpu and payload size) asymmetric cryptography. There are also
frequent cases of extended exchanges between two devices where trust
can be maintained via a lower cost symmetric key protect flow.
This document shows both how to secure A2X broadcast messages with
DRIP Entity Tags (DET) and DRIP Endorsement objects and to leverage
these to create an AdHoc session key for just such a communication
flow.
There is also provision for DETs within X.509 certificates, encoded
in c509, as an alternative DET trust model.
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
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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 27 October 2024.
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Copyright Notice
Copyright (c) 2024 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 Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. X.509 Certificate in place of DET Endorsements . . . . . 4
2. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Terminology . . . . . . . . . . . . . . . . 4
2.2. Notation . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
3. Broadcast A2X messaging . . . . . . . . . . . . . . . . . . . 5
3.1. The Compressed DRIP HDA Endorsement of UA DET . . . . . . 5
3.2. Full UA Signed Evidence of the A2X message . . . . . . . 6
3.3. Compressed UA Signed Evidence of the A2X message . . . . 6
3.4. IPv6 datagram for A2X message via SCHC . . . . . . . . . 7
4. Using full Endorsement messaging to set up a A2A session . . 7
4.1. Session Key Derivation . . . . . . . . . . . . . . . . . 9
4.2. A2A Secure Message . . . . . . . . . . . . . . . . . . . 9
4.3. Selection of Nonced Messages . . . . . . . . . . . . . . 10
4.4. SCHC compression of DTLS datagram . . . . . . . . . . . . 11
5. A2X Messages . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Wireless Transport for A2X messaging . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8.1. Potentially static EC keys for ECDH . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 14
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
Aircraft-to-anything (A2X) communications are currently an open area
of debate and research. There are questions as to whether air-to-
ground-to-air or air-to-air will prevail as the driving force and
thus the impetus for solutions. One real need is in air-to-air
Detect And Avoid (DAA). There are current DAA approaches for
commercial/general aviation over Automatic Dependent
Surveillance–Broadcast (ADS-B); this is unlikely to scale to the
needs of Unmanned Aircraft (UA). UA-to-UA and UA - to - General
Aviation will drive a different solution.
ADS-B cannot, directly, be secured. The data framing is too
constrained, and the Manifest approach in [drip-authentication] is
also not possible within the ADS-B constraints. This is considered
an acceptable risk, as these large airframes can support radar
systems to validate presense reported by ADS-B along with crew visual
sighting. Neither of these are options in UA-to-anything and thus a
trustable messaging environment is needed.
Although all aspects of this document is applicable to all aircraft,
the language will be Uncrewed Aircraft (UA) slanted. This is to
avoid any confusion within the body of the document about what type
of aircraft is under discussion.
A prevailing current approach for UA-to-anything messaging is to
leverage the Broadcast Remote ID (B-RID) messages, as they provide
situational awareness in the Vector/Location ASTM messages
[F3411-22a]. But this message is not adequate by itself for
situational awareness as it does not identify the UA (other than the
wireless media MAC address). Thus although it is possible for UAs
act on a set of B-RID messages, this document will define specific,
singular, messages that are directly actionable by listening UAs.
The messages defined in this document leverage the DRIP Entity Tags
(DET) [RFC9374] and its underlying Ed25519 keypair. It also relies
on DET endorsement hierarchy for trust in the DETs.
ECDSA as in the ICAO defined International Aviation Common (IAC) PKI
can be used in DETs (DET Suite ID of 3). With point-compression, the
P-256 keys would have Host Idenities (HI) 1 byte larger than Ed25519
(i.e. 33 bytes). This increase may still be usable. It would also
facilitate DAA between civil/general aviation and UAs.
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1.1. X.509 Certificate in place of DET Endorsements
The DRIP DET public Key Infrastructure, Section 4.1 of [drip-dki]
defines X.509 certificates to "shadow" the DET Endorsements. These
X.509 certificates are much larger than the DET Endorsements (e.g.
240 bytes). This may be too large for some transmission media.
There is an alternative C509 encoding for these X.509 certificates
per [C509-Certificates]. These C509 certificates in initial testing
are ~180 bytes. This is still larger than the DET Endorsements, but
may be small enough.
Author's Note: More content is needed for those that wish to
implement c509.
2. Terms and Definitions
2.1. Requirements 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.
2.2. Notation
|
Signifies concatenation of information (e.g., X | Y is the
concatenation of X with Y).
Ltrunc (x, K)
Denotes the lowest order K bits of the input x.
2.3. Definitions
This document uses the terms defined in Section 2.2 of Drip
Requirements and Terminology [RFC9153] and in Section 2 of Drip
Architecture [RFC9434]. The following new terms are used in the
document:
A2X
Communications from an aircraft to any other device. Be it
another aircraft or some ground equipment.
cSHAKE customizable SHAKE function (cSHAKE) [NIST.SP.800-185]:
Extends the SHAKE scheme [NIST.FIPS.202] to allow users to
customize their use of the SHAKE function.
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KECCAK Message Authentication Code (KMAC) [NIST.SP.800-185]:
A Pseudo Random Function (PRF) and keyed hash function based on
KECCAK.
3. Broadcast A2X messaging
The basic view of Aircraft-to-Anything (A2X) communications is
broadcast based. What is there within radio range of a UA? In most
situations, the UA has no apriori knowledge of other systems around
it. Thus the UA would just broadcast any information of general
knowledge, like "Hello, I am me and I am here. Oh, and I am out of
fuel and crashing."
Thus the first concern is to be able to create a single, trusted
message from the UA for all devices around it. The following
sections detail the pieces of such a trusted message.
3.1. The Compressed DRIP HDA Endorsement of UA DET
The DRIP HDA Endorsement of UA DET is a DRIP Link authentication
message as defined in Section 4.2 of [drip-authentication]. It is
the primary trust proof of UA DETs. This object is 136 bytes, but in
the specific context where the UA DET has the same first 64 bits as
the HDA DET (typical case), the 16 byte UA DET can be derived from
the HDA DET and the UA HI, compressing the object to 120 bytes.
+=======+===============+=====================================+
| Bytes | Name | Explanation |
+=======+===============+=====================================+
| 4 | VNB Timestamp | Current time at signing, set by HDA |
+-------+---------------+-------------------------------------+
| 4 | VNA Timestamp | Timestamp denoting recommended time |
| | | to trust Endorsement, set by HDA |
+-------+---------------+-------------------------------------+
| 32 | HI of UA | Host Identity of UA |
+-------+---------------+-------------------------------------+
| 16 | DET of HDA | DRIP Entity Tag of HDA |
+-------+---------------+-------------------------------------+
| 64 | Signature by | Signature over preceding fields |
| | HDA | using the keypair of the HDA DET |
+-------+---------------+-------------------------------------+
Table 1: 120-Byte Compressed HDA on UA Endorsement
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3.2. Full UA Signed Evidence of the A2X message
The UA can now fully endorse a A2X message by signing it, along with
the HDA Compressed Endorsement of the UA (Section 3.1). A Message ID
field is needed to distinguish all the multiple messages for this
datagram. The message also needs a Until timestamp for a total of
189 bytes plus n bytes of the actual message:
+=======+===============+=================================+
| Bytes | Name | Explanation |
+=======+===============+=================================+
| 4 | VNA Timestamp | Timestamp denoting recommended |
| | | time to trust Evidence |
+-------+---------------+---------------------------------+
| 1 | Message ID | A2X Message ID Number |
+-------+---------------+---------------------------------+
| n | A2X Message | Actual A2X Message |
+-------+---------------+---------------------------------+
| 120 | HDA/UA | Compressed HDA on UA |
| | Endorsement | Endorsement |
+-------+---------------+---------------------------------+
| 64 | Signature by | Signature over preceding fields |
| | UA | using the keypair of the UA DET |
+-------+---------------+---------------------------------+
Table 2: 189+n Byte Full UA Signed A2X message
3.3. Compressed UA Signed Evidence of the A2X message
The UA also has the option to send a A2X message without the HDA
Endorsement (Section 3.1). These shorter messages can be alternated
with the full messages, based on an assumption that the other parties
will receive the full endorsed message either prior or after this
shorter message format. Or a block of these shorter messages could
be sent based on other assumptions. This message is 85 bytes plus n
bytes of the actual message, with the average overhead of the 2
messages (1:1 transmission) is 137 bytes:
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+=======+===============+=================================+
| Bytes | Name | Explanation |
+=======+===============+=================================+
| 4 | VNA Timestamp | Timestamp denoting recommended |
| | | time to trust Evidence |
+-------+---------------+---------------------------------+
| 1 | Message ID | A2X Message ID Number |
+-------+---------------+---------------------------------+
| n | A2X Message | Actual A2X Message |
+-------+---------------+---------------------------------+
| 16 | DET of UA | DRIP Entity Tag of UA |
+-------+---------------+---------------------------------+
| 64 | Signature by | Signature over preceding fields |
| | UA | using the keypair of the UA DET |
+-------+---------------+---------------------------------+
Table 3: 85+n Byte Compressed UA Signed A2X message
3.4. IPv6 datagram for A2X message via SCHC
All the pieces are present in these messages for a SCHC [RFC8724]
process to expand them to multicast addressed IPv6 datagrams. The
destination IPv6 address would be ff02::1 (all nodes), the source
address is the UA DET. The protocol would be UDP with the port
numbers are still TBD and completely up to the receiving UA.
Thus the A2X application would just be an IPv6 application and A2X
could be this broadcast method or a datagram that actually was routed
over an IPv6 network. There is no transmission cost to this, just
the SCHC mechanism. It is completely up to the receiving UA and the
sending UA needs not be concerned if this is how its messages are
processed.
4. Using full Endorsement messaging to set up a A2A session
The Ed25519 keys used for DETs can be converted to Curve25519 keys
per [RFC7748] for use in an X25519 ECDH key establishment. The P-256
keys in ECDSA can be directly used in an ECDH key establishment
[NIST.SP.800-56Ar3]. However, these keys are not enough for key
establishment, nonces are needed to make each encounter has a unique
session key. These nonces need to be at least 16 bytes each (from
each party in the session). The security concerns of using
potentially static, rather than ephemeral EC keys is discussed in
Section 8.1.
One use case for this is in DAA. There may be a number of messages
between two UA during the DAA event. The DAA event would probably
start when each party receives a Vector/Location message showing a
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potential encounter. If we use the ASTM F3411-22a Vector/Location
message, less the timestamp information, along with a 16 byte nonce,
we have the beginning of the additional information for this ECDH key
establishment and use of the key in a authenticated session.
+=======+===============+=================================+
| Bytes | Name | Explanation |
+=======+===============+=================================+
| 4 | VNA Timestamp | Timestamp denoting recommended |
| | | time to trust Evidence |
+-------+---------------+---------------------------------+
| 1 | Message ID | A2X Message ID Number |
+-------+---------------+---------------------------------+
| 16 | Nonce | Random Session Nonce |
+-------+---------------+---------------------------------+
| 20 | Vector/ | Extracted from ASTM Vector/ |
| | Location | Location message |
+-------+---------------+---------------------------------+
| 120 | HDA/UA | Compressed HDA on UA |
| | Endorsement | Endorsement |
+-------+---------------+---------------------------------+
| 64 | Signature by | Signature over preceding fields |
| | UA | using the keypair of the UA DET |
+-------+---------------+---------------------------------+
Table 4: 225-Byte Nonce enabled A2A message
Such an authenticated session would look much like DTLS, needing a
Connection ID to map in the systems to the symmetric connection keys
and ending in a keyed-MAC. Note that authentication may be enough
and encryption of the message content will rarely be of value. If
specific data elements need confidentiality, they can be encrypted in
place using AES-CFB.
Carefully constructed, though still random, nonces can be used to
construct a 1-byte Connection ID as follows. Each V/L message
includes a 16 byte nonce that changes regularly, say once a second.
In a 16 (or 32) nonce window, the first 4 bits of the nonce MUST be
unique. Then the Connection ID can be: .
ConnectionID = ltrunc(othernonce,4)|ltrunc(mynonce,4)
Figure 1
Note that there is no provision in the above message for specifying
the session protection algorithm. Table 5, below, does a KMAC on the
message; this does not provide for crypto agility.
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Note that a 1-byte approach could be support of 64 possible
algorithms and the above message provide a list of 4 choices in order
of preference. This is similar to the DH_GROUP_LIST in the HIPv2 I1
message; at least this list would be protected from tamper by the
message signature.
4.1. Session Key Derivation
Each UA converts its Ed25519 private key to an Curve25519 private
key. Likewise it converts the received Ed25519 key to an Curve25519
public key (e.g. [Ed25519_Curve25519]). These are then used for
each UA to compute the X25519 derived shared secret. Alternatively a
P-256 key may be used.
Note that there is no way for one party to use P-256 and the other
Curve25519. This method is reserved for cases where both have the
same key algorithm.
Here, KMAC from [NIST.SP.800-185] is used with x25519. This is a
single pass using the underlying cSHAKE function. The function call
is:
OKM = KMAC128(salt | info, IKM, 128, S)
Where
IKM = X25519 ECDH secret | sort(HI-my | HI-other)
salt = sort(nonce-my | nonce-other)
info = sort(DET-my | DET-other)
S = the byte string 01001011 | 01000100 | 01000110
which is the characters "K", "D", and "F"
in 8-bit ASCII.
Figure 2: Session Key Derivation Function
Note that that for P-256, HKDF with SHA2 would be used. TBA.
4.2. A2A Secure Message
Now a session message would be (33 bytes plus n bytes of the actual
message):
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+=======+=================+=======================================+
| Bytes | Name | Explanation |
+=======+=================+=======================================+
| 16 | Destination DET | DRIP Entity Tag of the destination UA |
+-------+-----------------+---------------------------------------+
| 1 | Connection ID | Source UA Connection ID |
+-------+-----------------+---------------------------------------+
| 1 | Sequence Number | Source UA Sequence Number |
+-------+-----------------+---------------------------------------+
| 1 | Message ID | A2X Message ID Number |
+-------+-----------------+---------------------------------------+
| n | A2A Message | Actual A2A Message |
+-------+-----------------+---------------------------------------+
| 12 | MAC by Source | KMAC on message by Source UA |
+-------+-----------------+---------------------------------------+
Table 5: 31+n Byte A2A secure message
Author's Note: Probably should explicitly include the source DET
(rather than a SCHC expansion rule) or at least make it explicit ver
part of the SCHC expansion rules. This is to protect against cases
where multiple UA connected to one destination UA and how to manage
ConnectionID to avoid collisions in this 1-byte ID.
4.3. Selection of Nonced Messages
Author's Note: This section needs the state machine clearly drawn
out. Otherwise too hard to follow and implement correctly.
In theory once one UA sends its Nonce Enabled A2A message and
received a Nonce Enabled A2A message from a nearby UA, it can
immediately set up and use the A2A secure messages in Section 4.2.
In practice messages will not be received and one UA may operate on
the basis that a secure session is possible when the other UA does
not have the needed information for the secure session. This section
will detail a procedure for UAs to follow to reach that point of
common knowledge and thus transition to a secure session.
The Connection ID shown in Figure 1 is unidirectional. It is part of
a tuple (Source DET, Destination DET, Connection ID) that contains
the operational state of the unidirectional secure messages (e.g.
session key, sequence number). Each UA in the secure session link
MUST have this tuple, but may have multiple such (at least two, one
for each direction) and could be using one Connection ID and session
for sending and another for receiving. the basis for the tuple for
the secured messaging.
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A Connection ID MUST NOT have each 4-bit component the same; this
would break the unidirectional feather of the secure connection.
When a UA receives a Nonce Enabled A2A message, it MUST send its own
and the contained nonce MUST NOT have the same first 4 bits as the
one received. After sending its Nonce Enabled A2A message, it MAY
immediately switch to a secure session mode.
If a UA receives a secure session message (addressed to its DET), but
does not have the security tuple for the contained Connection ID and
thus the source DET, it MUST continue to use the Nonce Enabled A2A
messages. A UA that receives a Nonce Enabled A2A message MUST work
on the basis that the sending UA does not have similar from it. The
UA MUST send a Nonce Enabled A2A message and switch to these two
messages as
This process MAY be repeated for 4 attempts. At which point it
should be assumed something is interfering with message transmissions
and act accordingly.
4.4. SCHC compression of DTLS datagram
Author Note: the above datagram was produced from a full IPv6|DTLS
message. The MACing is on this original message. The receiver needs
to reverse the SCHC before authenticating the message, but this might
be a DOS risk.
TBD
5. A2X Messages
Below are the initial defined messages for use in A2X.
+====+=======+=================+==============================+
| ID | Bytes | Name | Explanation |
+====+=======+=================+==============================+
| 1 | 20 | Location/Vector | ASTM Location/Vector Message |
| | | | less timestamp fields |
+----+-------+-----------------+------------------------------+
| 2 | 36 | L/V and Nonce | Msg 1 plus Nonce |
+----+-------+-----------------+------------------------------+
Table 6: A2X Messages
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6. Wireless Transport for A2X messaging
Author's Note: Still need work on what wireless technologies are
practical for this approach and even if it is appropriate to discuss
actual wireless transport here. There are messages here that are too
large for the ASTM Remote ID BT4 limit of 200 bytes, but may well fit
into the practical limits of 250 bytes over BT5 and WiFi Beacons. It
is even possible of a multi-RF approach, separating the large
messages from the short ones.
Author's Note: We define here a new ASTM Auth message content that is
only sent over BT5 and WiFi Beacons.
Author's Note: Using SCHC as an Ethertype we can position these
messages to work over multiple wireless tech. Most noteably IEEE
802.11ah (HiLo) with 802.11bc (Enhanced Broadcast Service). Also
802.16 and 802.15.16t (Licensed Narrowband) addendum to 802.16.
TBD
7. IANA Considerations
TBD
8. Security Considerations
Author's note: We need to have a discussion on the size of the MAC in
the A2A (Table 5) message. Currently a 12-byte MAC is specified.
Considering this is an authentication MAC and the messages are
timestamped, an 8-byte MAC should be adequate. But the discussion on
this is needed and other examples of 8-byte authentication MACs
provided.
TBD
8.1. Potentially static EC keys for ECDH
In Section 4 the UA Identity keys are used in a ECDH key derivation
operation. The common practice is to use "right now" ephemeral EC
keys. This is not practical in this case, as there is very limited
time and bandwidth to carry out a full key exchange. Another factor
is in most cases the data protected with the derived key is of only
immediate value, rarely having any historical worth.
Additionally these Identity keys are normally specific to this
mission; new keys are typically used for each flight. Thus, in large
measure, they are ephemeral.
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Finally, most uses of this approach is only to authenticate an
extended exchange between two UA rather than the more bandwidth
costly digitally signed messages.
Thus, all factors considered, ECDH key establishment with these
Identity keys are practical and within reasonable security bounds.
9. References
9.1. Normative References
[NIST.FIPS.202]
Dworkin, M. J. and National Institute of Standards and
Technology, "SHA-3 Standard: Permutation-Based Hash and
Extendable-Output Functions", DOI 10.6028/nist.fips.202,
July 2015, <https://doi.org/10.6028/nist.fips.202>.
[NIST.SP.800-185]
Kelsey, J., Change, S., Perlner, R., and National
Institute of Standards and Technology, "SHA-3 derived
functions: cSHAKE, KMAC, TupleHash and ParallelHash",
DOI 10.6028/nist.sp.800-185, December 2016,
<https://doi.org/10.6028/nist.sp.800-185>.
[NIST.SP.800-56Ar3]
Barker, E., Chen, L., Roginsky, A., Vassilev, A., Davis,
R., and National Institute of Standards and Technology,
"Recommendation for pair-wise key-establishment schemes
using discrete logarithm cryptography",
DOI 10.6028/nist.sp.800-56ar3, April 2018,
<https://doi.org/10.6028/nist.sp.800-56ar3>.
[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>.
[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>.
[RFC9153] Card, S., Ed., Wiethuechter, A., Moskowitz, R., and A.
Gurtov, "Drone Remote Identification Protocol (DRIP)
Requirements and Terminology", RFC 9153,
DOI 10.17487/RFC9153, February 2022,
<https://www.rfc-editor.org/info/rfc9153>.
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[RFC9374] Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov,
"DRIP Entity Tag (DET) for Unmanned Aircraft System Remote
ID (UAS RID)", RFC 9374, DOI 10.17487/RFC9374, March 2023,
<https://www.rfc-editor.org/info/rfc9374>.
[RFC9434] Card, S., Wiethuechter, A., Moskowitz, R., Zhao, S., Ed.,
and A. Gurtov, "Drone Remote Identification Protocol
(DRIP) Architecture", RFC 9434, DOI 10.17487/RFC9434, July
2023, <https://www.rfc-editor.org/info/rfc9434>.
9.2. Informative References
[C509-Certificates]
Mattsson, J. P., Selander, G., Raza, S., Höglund, J., and
M. Furuhed, "CBOR Encoded X.509 Certificates (C509
Certificates)", Work in Progress, Internet-Draft, draft-
ietf-cose-cbor-encoded-cert-09, 4 March 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-cose-
cbor-encoded-cert-09>.
[drip-authentication]
Wiethuechter, A., Card, S. W., and R. Moskowitz, "DRIP
Entity Tag Authentication Formats & Protocols for
Broadcast Remote ID", Work in Progress, Internet-Draft,
draft-ietf-drip-auth-49, 21 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-drip-
auth-49>.
[drip-dki] Moskowitz, R. and S. W. Card, "The DRIP DET public Key
Infrastructure", Work in Progress, Internet-Draft, draft-
moskowitz-drip-dki-09, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-moskowitz-
drip-dki-09>.
[Ed25519_Curve25519]
Libsodium Documentation, "Ed25519 to Curve25519", 2021,
<https://libsodium.gitbook.io/doc/advanced/
ed25519-curve25519>.
[F3411-22a]
ASTM International, "Standard Specification for Remote ID
and Tracking - F3411−22a", July 2022,
<https://www.astm.org/f3411-22a.html>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
for Security", RFC 7748, DOI 10.17487/RFC7748, January
2016, <https://www.rfc-editor.org/info/rfc7748>.
Moskowitz, et al. Expires 27 October 2024 [Page 14]
Internet-Draft A2X AdHoc sessions April 2024
[RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
Zuniga, "SCHC: Generic Framework for Static Context Header
Compression and Fragmentation", RFC 8724,
DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/info/rfc8724>.
Acknowledgments
Adam Wiethuechter of AX Enterprize provided review and implementation
insights.
Authors' Addresses
Robert Moskowitz
HTT Consulting
Oak Park, MI 48237
United States of America
Email: rgm@labs.htt-consult.com
Stuart W. Card
AX Enterprize
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: stu.card@axenterprize.com
Andrei Gurtov
Linköping University
IDA
SE-58183 Linköping
Sweden
Email: gurtov@acm.org
Moskowitz, et al. Expires 27 October 2024 [Page 15]