DRIP Entity Tag (DET) for Unmanned Aircraft System Remote Identification (UAS RID)
draft-ietf-drip-rid-15
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 9374.
|
|
|---|---|---|---|
| Authors | Robert Moskowitz , Stuart W. Card , Adam Wiethuechter , Andrei Gurtov | ||
| Last updated | 2021-12-08 | ||
| Replaces | draft-ietf-drip-uas-rid | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
IOTDIR Early review
(of
-07)
by Michael Richardson
Almost ready
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | In WG Last Call | |
| Associated WG milestones |
|
||
| Document shepherd | Mohamed Boucadair | ||
| Shepherd write-up | Show Last changed 2021-12-02 | ||
| IESG | IESG state | Became RFC 9374 (Proposed Standard) | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | mohamed.boucadair@orange.com |
draft-ietf-drip-rid-15
DRIP R. Moskowitz
Internet-Draft HTT Consulting
Updates: 7401, 7343 (if approved) S. Card
Intended status: Standards Track A. Wiethuechter
Expires: 11 June 2022 AX Enterprize, LLC
A. Gurtov
Linköping University
8 December 2021
DRIP Entity Tag (DET) for Unmanned Aircraft System Remote Identification
(UAS RID)
draft-ietf-drip-rid-15
Abstract
This document describes the use of Hierarchical Host Identity Tags
(HHITs), updating both [RFC7401] and [RFC7343], as self-asserting
IPv6 addresses and thereby a trustable identifier for use as the
Unmanned Aircraft System Remote Identification and tracking (UAS
RID). Within the context of RID, HHITs will be called DRIP Entity
Tags (DET). HHITs self-attest to the included explicit hierarchy
that provides Registrar discovery for 3rd-party identifier
attestation.
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/.
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 11 June 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Terminology . . . . . . . . . . . . . . . . 4
2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
3. The Hierarchical Host Identity Tag (HHIT) . . . . . . . . . . 5
3.1. HHIT Prefix for RID Purposes . . . . . . . . . . . . . . 6
3.2. HHIT Suite IDs . . . . . . . . . . . . . . . . . . . . . 6
3.2.1. 8-bit HIT Suite IDs . . . . . . . . . . . . . . . . . 7
3.3. The Hierarchy ID (HID) . . . . . . . . . . . . . . . . . 7
3.3.1. The Registered Assigning Authority (RAA) . . . . . . 7
3.3.2. The Hierarchical HIT Domain Authority (HDA) . . . . . 8
3.4. Edward Digital Signature Algorithm for HITs . . . . . . . 8
3.4.1. HOST_ID . . . . . . . . . . . . . . . . . . . . . . . 8
3.4.2. HIT_SUITE_LIST . . . . . . . . . . . . . . . . . . . 10
3.5. ORCHIDs for Hierarchical HITs . . . . . . . . . . . . . . 10
3.5.1. Adding additional information to the ORCHID . . . . . 11
3.5.2. ORCHID Encoding . . . . . . . . . . . . . . . . . . . 12
3.5.3. ORCHID Decoding . . . . . . . . . . . . . . . . . . . 14
3.5.4. Decoding ORCHIDs for HIPv2 . . . . . . . . . . . . . 14
4. Hierarchical HITs as Remote ID DRIP Entity Tags (DET) . . . . 14
4.1. Nontransferablity of DETs . . . . . . . . . . . . . . . . 15
4.2. Encoding HHITs in CTA 2063-A Serial Numbers . . . . . . . 15
4.3. Remote ID DET as one class of Hierarchical HITs . . . . . 16
4.4. Hierarchy in ORCHID Generation . . . . . . . . . . . . . 16
4.5. DRIP Entity Tag (DET) Registry . . . . . . . . . . . . . 17
4.6. Remote ID Authentication using DETs . . . . . . . . . . . 17
5. DRIP Entity Tags (DETs) in DNS . . . . . . . . . . . . . . . 18
6. Other UTM uses of HHITs beyond DET . . . . . . . . . . . . . 19
7. DRIP Requirements addressed . . . . . . . . . . . . . . . . . 19
8. DET Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9.1. IANA CGA registry update . . . . . . . . . . . . . . . . 20
9.2. IANA HIP registry updates . . . . . . . . . . . . . . . . 20
9.3. IANA IPSECKEY registry update . . . . . . . . . . . . . . 21
9.4. New IPv6 prefix needed for DETs . . . . . . . . . . . . . 21
10. Security Considerations . . . . . . . . . . . . . . . . . . . 22
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10.1. DET Trust . . . . . . . . . . . . . . . . . . . . . . . 23
10.2. Collision risks with DETs . . . . . . . . . . . . . . . 24
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
11.1. Normative References . . . . . . . . . . . . . . . . . . 24
11.2. Informative References . . . . . . . . . . . . . . . . . 25
Appendix A. EU U-Space RID Privacy Considerations . . . . . . . 28
Appendix B. Calculating Collision Probabilities . . . . . . . . 29
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30
1. Introduction
[drip-requirements] describes an Unmanned Aircraft System Remote
Identification and tracking (UAS ID) as unique (ID-4), non-spoofable
(ID-5), and identify a registry where the ID is listed (ID-2); all
within a 20 character identifier (ID-1).
This document describes the use of Hierarchical Host Identity Tags
(HHITs) (Section 3) as self-asserting IPv6 addresses and thereby a
trustable identifier for use as the UAS Remote ID. HHITs include
explicit hierarchy to enable DNS HHIT queries (Host ID for
authentication, e.g., [drip-authentication]) and for Extensible
Provisioning Protocol (EPP) Registrar discovery [RFC7484] for 3rd-
party identification attestation (e.g., [drip-authentication]).
This addition of hierarchy to HITs requires updates to both [RFC7401]
and [RFC7343].
HHITs as used within the context of UAS will be labeled as DRIP
Entity Tags (DET). Throughout this document HHIT and DET will be
used appropriately. HHIT will be used when covering the technology,
and DET for their context within UAS RID.
HHITs are statistically unique through the cryptographic hash feature
of second-preimage resistance. The cryptographically-bound addition
of the hierarchy and a HHIT registration process [drip-registries]
provide complete, global HHIT uniqueness. This contrasts with using
general identifiers (e.g., a Universally Unique IDentifiers (UUID)
[RFC4122] or device serial numbers) as the subject in an X.509
[RFC5280] certificate.
In a multi Certificate Authority (multi-CA) PKI alternative to HHITs,
a Remote ID as the Subject (Section 4.1.2.6 of [RFC5280]) can occur
in multiple CAs, possibly fraudulently. CAs within the PKI would
need to implement an approach to enforce assurance of the uniqueness
achieved with HHITs.
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Hierarchical HITs provide self-attestation of the HHIT registry. A
HHIT can only be in a single registry within a registry system (e.g.,
EPP and DNS).
Hierarchical HITs are valid, though non-routable, IPv6 addresses
[RFC8200]. As such, they fit in many ways within various IETF
technologies.
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. Notations
| Signifies concatenation of information - e.g., X | Y is the
concatenation of X and Y.
2.3. Definitions
This document uses the terms defined in [drip-requirements]. The
following new terms are used in the document:
cSHAKE (The customizable SHAKE function [NIST.SP.800-185]):
Extends the SHAKE [NIST.FIPS.202] scheme to allow users to
customize their use of the SHAKE function.
HDA (Hierarchical HIT Domain Authority):
The 16-bit field that identifies the HHIT Domain Authority under a
Registered Assigning Authority (RAA).
HHIT
Hierarchical Host Identity Tag. A HIT with extra hierarchical
information not found in a standard HIT [RFC7401].
HI
Host Identity. The public key portion of an asymmetric key pair
as defined in [RFC9063].
HID (Hierarchy ID):
The 32-bit field providing the HIT Hierarchy ID.
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HIP (Host Identity Protocol)
The origin of HI, HIT, and HHIT, required for DRIP.
HIT
Host Identity Tag. A 128-bit handle on the HI. HITs are valid
IPv6 addresses.
Keccak (KECCAK Message Authentication Code):
The family of all sponge functions with a KECCAK-f permutation as
the underlying function and multi-rate padding as the padding
rule. In particular all the functions referenced from
[NIST.FIPS.202] and [NIST.SP.800-185].
KMAC (KECCAK Message Authentication Code [NIST.SP.800-185]):
A Pseudo Random Function (PRF) and keyed hash function based on
KECCAK.
RAA (Registered Assigning Authority):
The 16 bit field identifying the business or organization that
manages a registry of HDAs.
RVS (Rendezvous Server):
A Rendezvous Server such as the HIP Rendezvous Server for enabling
mobility, as defined in [RFC8004].
SHAKE (Secure Hash Algorithm KECCAK [NIST.FIPS.202]):
A secure hash that allows for an arbitrary output length.
XOF (eXtendable-Output Function [NIST.FIPS.202]):
A function on bit strings (also called messages) in which the
output can be extended to any desired length.
3. The Hierarchical Host Identity Tag (HHIT)
The Hierarchical HIT (HHIT) is a small but important enhancement over
the flat HIT space, constructed as an Overlay Routable Cryptographic
Hash IDentifier (ORCHID) [RFC7343]. By adding two levels of
hierarchical administration control, the HHIT provides for device
registration/ownership, thereby enhancing the trust framework for
HITs.
HHITs represent the HI in only a 64-bit hash and use the other 32
bits to create a hierarchical administration organization for HIT
domains. Hierarchical HIT construction is defined in Section 3.5.
The input values for the Encoding rules are described in
Section 3.5.1.
A HHIT is built from the following fields:
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* p = IANA prefix (max 28 bit)
* 32 bit Hierarchy ID (HID)
* s = 4 (or 8) bit HIT Suite ID
* ORCHID hash (96 - prefix length - Suite ID length bits, e.g., 64)
See Section 3.5
16 bits| 16 bits 4 or 8 bits
+-------+-------+ +--------------+
| RAA | HDA | | HIT Suite ID |
+-------+-------+ +--------------+
\ | ____/ ___________/
\ \ _/ _____/
\ \/ /
| p bits | 32 bits |s | o=96-p-s bits |
+--------------+------------+---+------------------------+
| IANA Prefix | HID |HSI| ORCHID hash |
+--------------+------------+---+------------------------+
Figure 1: HHIT Format
The Context ID for the ORCHID hash is:
Context ID := 0x00B5 A69C 795D F5D5 F008 7F56 843F 2C40
Context IDs are allocated out of the namespace introduced for
Cryptographically Generated Addresses (CGA) Type Tags [RFC3972].
A python script is available for generating HHITs [hhit-gen].
3.1. HHIT Prefix for RID Purposes
A unique IANA IPv6 prefix, no larger than 28 bits, for HHITs is
recommended. It clearly separates the flat-space HIT processing from
HHIT processing per Section 3.5.
Without a unique prefix, the first 4 bits of the RRA would be
interpreted as the HIT Suite ID per HIPv2 [RFC7401].
3.2. HHIT Suite IDs
The HIT Suite IDs specify the HI and hash algorithms. Any HIT Suite
ID can be used for HHITs. The 8-bit format is supported (only when
the first 4 bits are set to zeros), but this reduces the ORCHID hash
length.
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3.2.1. 8-bit HIT Suite IDs
Support for 8 bit HIT Suite IDs is allowed in Section 5.2.10 of
[RFC7401], but not specified in how ORCHIDs are generated with these
longer ORCHID Generation Algorithms (OGAs). Section 3.5 provides the
algorithmic flexibility, allowing for HDA custom HIT Suite IDs as
follows:
HIT Suite Four-bit ID Eight-bit encoding
HDA Assigned 1 NA TBD4 (suggested value 0x0E)
HDA Assigned 2 NA TBD5 (suggested value 0x0F)
This feature, for example, may be used for large-scale experimenting
with post quantum computing hashes or similar domain specific needs.
Note that currently there is no support for domain-specific HI
algorithms.
3.3. The Hierarchy ID (HID)
The Hierarchy ID (HID) provides the structure to organize HITs into
administrative domains. HIDs are further divided into two fields:
* 16-bit Registered Assigning Authority (RAA)
* 16-bit Hierarchical HIT Domain Authority (HDA)
3.3.1. The Registered Assigning Authority (RAA)
An RAA is a business or organization that manages a registry of HDAs.
For example, the Federal Aviation Authority (FAA) could be an RAA.
The RAA is a 16-bit field (65,536 RAAs) assigned by ICAO. An RAA
must provide a set of services to allocate HDAs to organizations. It
must have a public policy on what is necessary to obtain an HDA. The
RAA need not maintain any HIP related services. It must maintain a
DNS zone minimally for discovering HID RVS servers.
The ICAO registration process will be available from ICAO. Once ICAO
accepts an RAA, it will assign a number and create a zone delegation
under the uas.icao.int. DNS zone for the RAA.
As HHITs may be used in many different domains, RAA should be
allocated in blocks with consideration on the likely size of a
particular usage. Alternatively, different prefixes can be used to
separate different domains of use of HHTs.
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This DNS zone may be a PTR for its RAA. It may be a zone in an HHIT
specific DNS zone. Assume that the RAA is 100. The PTR record could
be constructed as follows:
100.hhit.arpa IN PTR raa.bar.com.
3.3.2. The Hierarchical HIT Domain Authority (HDA)
An HDA may be an ISP or any third party that takes on the business to
provide RVS and other needed services such as those required for HIP-
enabled devices.
The HDA is an 16-bit field (65,536 HDAs per RAA) assigned by an RAA.
An HDA should maintain a set of RVS servers for UAS clients that may
use HIP. How this is done and scales to the potentially millions of
customers are outside the scope of this document. This service
should be discoverable through the DNS zone maintained by the HDA's
RAA.
An RAA may assign a block of values to an individual organization.
This is completely up to the individual RAA's published policy for
delegation. Such policy is out of scope.
3.4. Edward Digital Signature Algorithm for HITs
The Edwards-Curve Digital Signature Algorithm (EdDSA) [RFC8032] is
specified here for use as Host Identities (HIs) per HIPv2 [RFC7401].
The intent in this document is to add EdDSA as a HI algortihm for
DETs, but doing so impacts the HIP parameters used in a HIP exchange.
As such the following update HIP parameters. Other than the HIP DNS
RR, these should not be needed in a DRIP implementation that does not
use HIP.
See Section 3.2 for use of the HIT Suite in the context of this
document.
3.4.1. HOST_ID
The HOST_ID parameter specifies the public key algorithm, and for
elliptic curves, a name. The HOST_ID parameter is defined in
Section 5.2.19 of [RFC7401].
Algorithm
profiles Values
EdDSA TBD1 (suggested value 13) [RFC8032] (RECOMMENDED)
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3.4.1.1. HIP Parameter support for EdDSA
The addition of EdDSA as a HI algorithm requires a subfield in the
HIP HOST_ID parameter Section 5.2.9 of [RFC7401] as was done for
ECDSA when used in a HIP exchange.
For HIP hosts that implement EdDSA as the algorithm, the following
EdDSA curves are represented by the following fields:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EdDSA Curve | /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Public Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
EdDSA Curve Curve label
Public Key Represented in Octet-string format [RFC8032]
Figure 2
For hosts that implement EdDSA as a HIP algorithm the following EdDSA
curves are required:
Algorithm Curve Values
EdDSA RESERVED 0
EdDSA EdDSA25519 1 [RFC8032] (RECOMMENDED)
EdDSA EdDSA25519ph 2 [RFC8032]
EdDSA EdDSA448 3 [RFC8032] (RECOMMENDED)
EdDSA EdDSA448ph 4 [RFC8032]
3.4.1.2. HIP DNS RR support for EdDSA
The HIP DNS RR (Resource Record) is defined in [RFC8005]. It uses
the values defined for the 'Algorithm Type' of the IPSECKEY RR
[RFC4025] for its PK Algorithm field.
The new EdDSA HI will use [RFC8080] for the IPSECKEY RR encoding:
Value Description
TBD2 (suggested value 4)
An EdDSA key is present, in the format defined in [RFC8080]
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3.4.2. HIT_SUITE_LIST
The HIT_SUITE_LIST parameter contains a list of the supported HIT
suite IDs of the HIP Responder. Based on the HIT_SUITE_LIST, the HIP
Initiator can determine which source HIT Suite IDs are supported by
the Responder. The HIT_SUITE_LIST parameter is defined in
Section 5.2.10 of [RFC7401].
The following HIT Suite ID is defined, and the relationship between
the four-bit ID value used in the OGA ID field and the eight-bit
encoding within the HIT_SUITE_LIST ID field is clarified:
HIT Suite 4-bit ID 8-bit encoding
RESERVED 0 0x00
EdDSA/cSHAKE128 TBD3 (suggested value 5) 0x50 (RECOMMENDED)
The following table provides more detail on the above HIT Suite
combination.
The output of cSHAKE128 is variable per the needs of a specific
ORCHID construction. It is at most 96 bits long and is directly used
in the ORCHID (without truncation).
+=======+===========+=========+===========+====================+
| Index | Hash | HMAC | Signature | Description |
| | function | | algorithm | |
| | | | family | |
+=======+===========+=========+===========+====================+
| 5 | cSHAKE128 | KMAC128 | EdDSA | EdDSA HI hashed |
| | | | | with cSHAKE128, |
| | | | | output is variable |
+-------+-----------+---------+-----------+--------------------+
Table 1: HIT Suites
3.5. ORCHIDs for Hierarchical HITs
This section improves on ORCHIDv2 [RFC7343] with three enhancements:
* Optional Info field between the Prefix and OGA ID.
* Increased flexibility on the length of each component in the
ORCHID construction, provided the resulting ORCHID is 128 bits.
* Use of cSHAKE, NIST SP 800-185 [NIST.SP.800-185], for the hashing
function.
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The Keccak [Keccak] based cSHAKE XOF hash function is a variable
output length hash function. As such it does not use the truncation
operation that other hashes need. The invocation of cSHAKE specifies
the desired number of bits in the hash output. Further, cSHAKE has a
parameter 'S' as a customization bit string. This parameter will be
used for including the ORCHID Context Identifier in a standard
fashion.
This ORCHID construction includes the fields in the ORCHID in the
hash to protect them against substitution attacks. It also provides
for inclusion of additional information, in particular the
hierarchical bits of the Hierarchical HIT, in the ORCHID generation.
This should be viewed as an addendum to ORCHIDv2 [RFC7343], as it can
produce ORCHIDv2 output.
3.5.1. Adding additional information to the ORCHID
ORCHIDv2 [RFC7343] is currently defined as consisting of three
components:
ORCHID := Prefix | OGA ID | Encode_96( Hash )
where:
Prefix : A constant 28-bit-long bitstring value
(IANA IPv6 assigned).
OGA ID : A 4-bit long identifier for the Hash_function
in use within the specific usage context. When
used for HIT generation this is the HIT Suite ID.
Encode_96( ) : An extraction function in which output is obtained
by extracting the middle 96-bit-long bitstring
from the argument bitstring.
This addendum will be constructed as follows:
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ORCHID := Prefix (p) | Info (n) | OGA ID (o) | Hash (m)
where:
Prefix (p) : An IANA IPv6 assigned prefix (max 28-bit-long).
Info (n) : n bits of information that define a use of the
ORCHID. n can be zero, that is no additional
information.
OGA ID (o) : A 4 or 8 bit long identifier for the Hash_function
in use within the specific usage context. When
used for HIT generation this is the HIT Suite ID.
Hash (m) : An extraction function in which output is m bits.
p + n + o + m = 128 bits
With a 28-bit IPv6 Prefix, the remaining 100 bits can be divided in
any manner between the additional information, OGA ID, and the hash
output. Care must be taken in determining the size of the hash
portion, taking into account risks like pre-image attacks. Thus 64
bits as used in Hierarchical HITs may be as small as is acceptable.
Note that if a 8-bit OGA is used, the hash will be 4 bits shorter.
This will result in a greater risk of pre-image attacks and a
corresponding greater need to manage HHIT registration and require
look up of the HI from a trusted source.
3.5.2. ORCHID Encoding
This addendum adds a different encoding process to that currently
used in ORCHIDv2. The input to the hash function explicitly includes
all the header content plus the Context ID. The header content
consists of the Prefix, the Additional Information, and OGA ID (HIT
Suite ID). Secondly, the length of the resulting hash is set by sum
of the length of the ORCHID header fields. For example, a 28-bit
Prefix with 32 bits for the HID and 4 bits for the OGA ID leaves 64
bits for the hash length.
To achieve the variable length output in a consistent manner, the
cSHAKE hash is used. For this purpose, cSHAKE128 is appropriate.
The the cSHAKE function call for this addendum is:
cSHAKE128(Input, L, "", Context ID)
Input := Prefix | Additional Information | OGA ID | HOST_ID
L := Length in bits of hash portion of ORCHID
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For full Suite ID support (those that use fixed length hashes like
SHA256), the following hashing can be used (Note: this does NOT
produce output Identical to ORCHIDv2 for Prefix of /28 and Additional
Information of ZERO length):
Hash[L](Context ID | Input)
Input := Prefix | Additional Information | OGA ID | HOST_ID
L := Length in bits of hash portion of ORCHID
Hash[L] := An extraction function in which output is obtained
by extracting the middle L-bit-long bitstring
from the argument bitstring.
Hierarchical HIT uses the same context as all other HIPv2 HIT Suites
as they are clearly separated by the distinct HIT Suite ID.
3.5.2.1. Encoding ORCHIDs for HIPv2
This section is included to provide backwards compatibility for
ORCHIDv2 [RFC7343] as used in HIPv2 [RFC7401].
For HIPv2, the Prefix is 2001:20::/28. Info is zero-length (i.e.,
not included), and OGA ID is length 4. Thus the HI Hash is length
96. Further the Prefix and OGA ID are not included in the hash
calculation. Thus the following ORCHID calculations for fixed output
length hashes are used:
Hash[L](Context ID | Input)
Input := HOST_ID
L := 96
Context ID := 0xF0EF F02F BFF4 3D0F E793 0C3C 6E61 74EA
Hash[L] := An extraction function in which output is obtained
by extracting the middle L-bit-long bitstring
from the argument bitstring.
For variable output length hashes use:
Hash[L](Context ID | Input)
Input := HOST_ID
L := 96
Context ID := 0xF0EF F02F BFF4 3D0F E793 0C3C 6E61 74EA
Hash[L] := The L bit output from the hash function
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Then the ORCHID is constructed as follows:
Prefix | OGA ID | Hash Output
3.5.3. ORCHID Decoding
With this addendum, the decoding of an ORCHID is determined by the
Prefix and OGA ID (HIT Suite ID). ORCHIDv2 [RFC7343] decoding is
selected when the Prefix is: 2001:20::/28.
For Hierarchical HITs, the decoding is determined by the presence of
the HHIT Prefix as specified Section 9.4.
3.5.4. Decoding ORCHIDs for HIPv2
This section is included to provide backwards compatibility for
ORCHIDv2 [RFC7343] as used for HIPv2 [RFC7401].
HIPv2s are identified by a Prefix of 2001:20::/28. The next 4 bits
are the OGA ID. The remaining 96 bits are the HI Hash.
4. Hierarchical HITs as Remote ID DRIP Entity Tags (DET)
Hierarchical HITs are a refinement on the Host Identity Tag (HIT) of
HIPv2. HHITs require a new ORCHID mechanism as described in
Section 3.5.
HHITs for UAS ID (called, DETs) also use the new EdDSA/SHAKE128 HIT
suite defined in Section 3.4 (GEN-2 in [drip-requirements]). This
hierarchy, cryptographically embedded within the HHIT, provides the
information for finding the UA's HHIT registry (ID-3 in
[drip-requirements]).
ASTM Standard Specification for Remote ID and Tracking [F3411]
specifies four UAS ID types:
TYPE-1 A static, manufacturer assigned, hardware serial number per
ANSI/CTA-2063-A "Small Unmanned Aerial System Serial Numbers"
[CTA2063A].
TYPE-2 A CAA assigned (presumably static) ID.
TYPE-3 A UTM system assigned UUID [RFC4122]. These can be dynamic,
but do not need to be.
TYPE-4 Specific Session ID (SSI)
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Note that Types 1 - 3 allow for an UAS ID with a maximum length of 20
bytes, the SSI (Type 4) uses the first byte of the ID for the SSI
value, thus restricting the UAS ID to a maximum of 19 bytes. The SSI
values initially assigned (as per 2021) are:
ID 1 IETF - DRIP Drone Remote Identification Protocol (DRIP) entity
ID.
ID 2 3GPP - IEEE 1609.2-2016 HashedID8
4.1. Nontransferablity of DETs
A HI and its HHIT SHOULD NOT be transferable between UA or even
between replacement electronics (e.g., replacement of damaged
controller CPU) for a UA. The private key for the HI SHOULD be held
in a cryptographically secure component.
4.2. Encoding HHITs in CTA 2063-A Serial Numbers
In some cases, it is advantageous to encode HHITs as a CTA 2063-A
Serial Number [CTA2063A]. For example, the FAA Remote ID Rules
[FAA_RID] state that a Remote ID Module (i.e., not integrated with UA
controller) must only use "the serial number of the unmanned
aircraft"; CTA 2063-A meets this requirement.
Encoding an HHIT within the CTA 2063-A format is not simple. The CTA
2063-A format is defined as:
Serial Number := MFR Code | Length Code | MFR SN
where:
MFR Code : 4 character code assigned by ICAO.
Length Code : 1 character Hex encoding of MFR SN length (1-F).
MFR SN : Alphanumeric code (0-9, A-Z except O and I).
Maximum length of 15 characters.
There is no place for the HID; there will need to be a mapping
service from Manufacturer Code to HID. The HIT Suite ID and ORCHID
hash will take 14 characters (as described below), leaving 1
character to distinguish encoded DETs from other manufacturer use of
CTA 2063-A Serial Numbers.
A character in a CTA 2063-A Serial Number "shall include any
combination of digits and uppercase letters, except the letters O and
I, but may include all digits". This would allow for a Base34
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encoding of the binary HIT Suite ID and ORCHID hash. Although,
programmatically, such a conversion is not hard, other technologies
(e.g., credit card payment systems) that have used such odd base
encoding have had performance challenges. Thus here a Base32
encoding will be used by also excluding the letters Z and S (too
similar to the digits 2 and 5).
The low-order 68 bits (HIT Suite ID | ORCHID hash) of the HHIT SHALL
be left-padded with 2 bits of zeros. This 70-bit number will be
encoded into 14 characters using the digit/letters above. The
manufacturer MUST use a Length Code of F (15). The first character
after the Length Code MUST be 'Z', followed by the 14 characters of
the encoded HIT Suite ID and ORCHID hash. This construct allows the
manufacturer to construct other MFR SN of length 15 by avoiding
starting them with 'Z'.
Using the sample DET from Section 5 that is for HDA=20 under RAA=10
and having the ICAO CTA MFR Code of 8653, the 20-character CTA 2063-A
Serial Number would be:
8653FZ2T7B8RA85D19LX
A mapping service (e.g., DNS) MUST provide a trusted (e.g., via
DNSSEC) conversion of the 4-character Manufacturer Code to high-order
60 bits (Prefix | HID) of the HHIT. Definition of this mapping
service is currently out of scope of this document.
It should be noted that this encoding would only be used in the Basic
ID Message. The HHIT DET will still be used in the Authentication
Messages.
4.3. Remote ID DET as one class of Hierarchical HITs
UAS Remote ID DET may be one of a number of uses of HHITs. However,
it is out of the scope of the document to elaborate on other uses of
HHITs. As such these follow-on uses need to be considered in
allocating the RAAs Section 3.3.1 or HHIT prefix assignments
Section 9.
4.4. Hierarchy in ORCHID Generation
ORCHIDS, as defined in [RFC7343], do not cryptographically bind an
IPv6 prefix nor the Orchid Generation Algorithm (OGA) ID (the HIT
Suite ID) to the hash of the HI. The rational at the time of
developing ORCHID was attacks against these fields are DoS attacks
against protocols using ORCHIDs and thus up to those protocols to
address the issue.
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HHITs, as defined in Section 3.5, cryptographically bind all content
in the ORCHID through the hashing function. A recipient of a DET
that has the underlying HI can directly trust and act on all content
in the HHIT. This provides a strong, self-attestation for using the
hierarchy to find the DET Registry based on the HID.
4.5. DRIP Entity Tag (DET) Registry
DETs are registered to HDAs. A registration process,
[drip-registries], ensures DET global uniqueness (ID-4 in
[drip-requirements]). It also provides the mechanism to create UAS
public/private data that are associated with the DET (REG-1 and REG-2
in [drip-requirements]).
The two levels of hierarchy within the DET allows for CAAs to have
their own Registered Assigning Authority (RAA) for their National Air
Space (NAS). Within the RAA, the CAAs can delegate HDAs as needed.
There may be other RAAs allowed to operate within a given NAS; this
is a policy decision by the CAA.
4.6. Remote ID Authentication using DETs
The EdDSA25519 HI (Section 3.4) underlying the DET can be used in an
84-byte self-proof attestation (timestamp, HHIT, and signature of
these) to provide proof of Remote ID ownership (GEN-1 in
[drip-requirements]). In practice, the Wrapper and Manifest
authentication formats in the ASTM Authentication Message (Msg Type
0x2) [drip-authentication] implicitly provide this self-attestation.
A lookup service like DNS can provide the HI and registration proof
(GEN-3 in [drip-requirements]).
Similarly, for Observers without Internet access, a 200-byte offline
self-attestation could provide the same Remote ID ownership proof.
This attestation would contain the HDA's signing of the UA's HHIT,
itself signed by the UA's HI. Only a small cache that contains the
HDA's HI/HHIT and HDA meta-data is needed by the Observer. However,
such an object would just fit in the ASTM Authentication Message with
no room for growth. In practice [drip-authentication] provides this
offline self-attestation in two authentication messages: the HDA's
certification of the UA's HHIT registration in a Link authentication
message whose hash is sent in a Manifest authentication message.
Hashes of any previously sent ASTM messages can be placed in a
Manifest authentication message (GEN-2 in [drip-requirements]). When
a Location/Vector Message (Msg Type 0x1) hash along with the hash of
the HDA's UA HHIT attestation are sent in a Manifest authentication
message and the Observer can visually see a UA at the claimed
location, the Observer has a very strong proof of the UA's Remote ID.
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All this behavior and how to mix these authentication messages into
the flow of UA operation messages are detailed in
[drip-authentication].
5. DRIP Entity Tags (DETs) in DNS
There are two approaches for storing and retrieving DETs using DNS.
* As FQDNs in ".icao.int.".
* Reverse DNS lookups as IPv6 addresses per [RFC8005].
A DET can be used to construct an FQDN that points to the USS that
has the public/private information for the UA (REG-1 and REG-2 in
[drip-requirements]). For example, the USS for the HHIT could be
found via the following: Assume the RAA is 100 and the HDA is 50.
The PTR record is constructed as follows:
100.50.det.uas.icao.int IN PTR foo.uss.icao.int.
The individual DETs may be potentially too numerous (e.g., 60 - 600M)
and dynamic (e.g., new DETs every minute for some HDAs) to store in a
signed, DNS zone. The HDA SHOULD provide DNS service for its zone
and provide the HHIT detail response. A secure connection (e.g., DNS
over TLS) to the authoritative zone may be a viable alternative to
DNSSEC.
The DET reverse lookup can be a standard IPv6 reverse look up, or it
can leverage off the HHIT structure. If we assume a prefix of
2001:30::/28, the RAA is 10 and the HDA is 20, the DET is:
2001:30:a0:145:a3ad:1952:ad0:a69e
A DET reverse lookup could be to:
a69e.ad0.1952.a3ad.145.a0.30.2001.20.10.det.arpa.
or:
a3ad1952ad0a69e.5.20.10.30.2001.det.remoteid.icao.int.
A 'standard' ip6.arpa RR has the advantage of only one Registry
service supported.
$ORIGIN 5.4.1.0.0.a.0.0.0.3.0.0.1.0.0.2.ip6.arpa.
e.9.6.a.0.d.a.0.2.5.9.1.d.a.3.a IN PTR
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6. Other UTM uses of HHITs beyond DET
HHITs might be used within the UTM architecture beyond DET (and USS
in UA ID registration and authentication). For example as a GCS HHIT
ID. The GCS may use its HIIT if it is the source of Network Remote
ID for securing the transport and for secure C2 transport (e.g.,
[drip-secure-nrid-c2]).
Observers may have their own HHITs to facilitate UAS information
retrieval (e.g., for authorization to private UAS data). They could
also use their HHIT for establishing a HIP connection with the UA
Pilot for direct communications per authorization (this use is
currently outside the scope of this document). Further, they can be
used by FINDER observers, (e.g., [crowd-sourced-rid]).
7. DRIP Requirements addressed
This document in the previous sections provides the details to
solutions for GEN 1 - 3, ID 1 - 5, and REG 1 - 2 as described in
[drip-requirements].
8. DET Privacy
There is no expectation of privacy for DETs; it is not part of the
Privacy Normative Requirements, Section 4.3.1, of
[drip-requirements]. DETs are broadcast in the clear over the open
air via Bluetooth and Wi-Fi. They will be collected and collated
with other public information about the UAS. This will include DET
registration information and location and times of operations for a
DET. A DET can be for the life of a UA if there is no concern about
DET/UA activity harvesting.
Further, the MAC address of the wireless interface used for Remote ID
broadcasts are a target for UA operation aggregation that may not be
mitigated through address randomization. For Bluetooth 4 Remote ID
messaging, the MAC address is used by observers to link the Basic ID
Message that contains the RID with other Remote ID messages, thus
must be constant for a UA operation. This message linkage use of MAC
addresses may not be needed with the Bluetooth 5 or Wi-Fi PHYs.
These PHYs provide for a larger message payload and can use the
Message Pack (Msg Type 0xF) and the Authentication Message to
transmit the RID with other Remote ID messages. However, it is not
mandatory to send the RID in a Message Pack or Authentication
Message, so allowance for using the MAC address for UA message
linking must be maintained. That is, the MAC address should be
stable for at least a UA operation.
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Finally, it is not adequate to simply change the DET and MAC for a UA
per operation to defeat historically tracking a UA's activity.
Any changes to the UA MAC may have impacts to C2 setup and use. A
constant GCS MAC may well defeat any privacy gains in UA MAC and RID
changes. UA/GCS binding is complicated with changing MAC addresses;
historically UAS design assumed these to be "forever" and made setup
a one-time process. Additionally, if IP is used for C2, a changing
MAC may mean a changing IP address to further impact the UAS
bindings. Finally, an encryption wrapper's identifier (such as ESP
[RFC4303] SPI) would need to change per operation to insure operation
tracking separation.
Creating and maintaining UAS operational privacy is a multifaceted
problem. Many communication pieces need to be considered to truly
create a separation between UA operations. Simply changing the UAS
RID only starts the changes that need to be implemented.
9. IANA Considerations
9.1. IANA CGA registry update
This document requests IANA to make the following change to the IANA
"CGA Extension Type Tags registry [IANA-CGA] registry:
Context ID:
The Context ID (Section 3) shares the namespace introduced for CGA
Type Tags. Defining new Context IDs follow the rules in Section 8
of [RFC3972].
9.2. IANA HIP registry updates
This document requests IANA to make the following changes to the IANA
"Host Identity Protocol (HIP) Parameters" [IANA-HIP] registry:
Host ID:
This document defines the new EdDSA Host ID with value TBD1
(suggested: 13) (Section 3.4.1) in the "HI Algorithm" subregistry
of the "Host Identity Protocol (HIP) Parameters" registry.
EdDSA Curve Label:
This document specifies a new algorithm-specific subregistry named
"EdDSA Curve Label". The values for this subregistry are defined
in Section 3.4.1.1.
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HIT Suite ID:
This document defines the new HIT Suite of EdDSA/cSHAKE with value
TBD3 (suggested: 5) (Section 3.4.2) in the "HIT Suite ID"
subregistry of the "Host Identity Protocol (HIP) Parameters"
registry.
HIT Suite ID eight-bit encoding:
This document defines the first eight-bit encoded HIT Suite IDs as
defined in Section 5.2.10 of [RFC7401]. These are the new HDA
domain HIT Suites with values TBD4 and TBD5 (suggested values:
0x0E and 0x0F) (Section 3.2.1). IANA is requested to expand the
"HIT Suite ID" subregistry of the "Host Identity Protocol (HIP)
Parameters" registry to show both the four-bit and eight-bit
values as shown in Section 5.2.10 of [RFC7401] and add these new
values that only have 8-bit representations.
9.3. IANA IPSECKEY registry update
This document requests IANA to make the following change to the
"IPSECKEY Resource Record Parameters" [IANA-IPSECKEY] registry:
IPSECKEY:
This document defines the new IPSECKEY value TBD2 (suggested: 4)
(Section 3.4.1.2) in the "Algorithm Type Field" subregistry of the
"IPSECKEY Resource Record Parameters" registry.
9.4. New IPv6 prefix needed for DETs
Since the DET format is not compatible with [RFC7343], IANA is
requested to allocate a new prefix following this template for the
IPv6 Special-Purpose Address Registry.
Address Block:
IANA is requested to allocate a new 28-bit prefix out of the IANA
IPv6 Special Purpose Address Block, namely 2001::/23, as per
[RFC6890] (suggested: 2001:30::/28).
Name:
This block should be named "DRIP Device Entity Tags (DET) Prefix".
RFC:
This document.
Allocation Date:
Date this document published.
Termination Date:
Forever.
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Source:
False.
Destination:
False.
Forwardable:
False.
Globally Reachable:
False.
Reserved-by-Protocol:
False?
10. Security Considerations
The 64-bit hash in HHITs presents a real risk of second pre-image
cryptographic hash attack Section 10.2. There are no known (to the
authors) studies of hash size to cryptographic hash attacks. A
Python script is available to randomly generate 1M HHITs that did not
produce a hash collision which is a simpler attack than a first or
second pre-image attack.
However, with today's computing power, producing 2^64 EdDSA keypairs
and then generating the corresponding HHIT is economically feasible.
Consider that a *single* bitcoin mining ASIC can do on the order of
2^46 sha256 hashes a second or about 2^62 hashes in a single day.
The point being, 2^64 is not prohibitive, especially as this can be
done in parallel.
Now it should be noted that the 2^64 attempts is for stealing a
specific HHIT. Consider a scenario of a street photography company
with 1,024 UAs (each with its own HHIT); you'd be happy stealing any
one of them. Then rather than needing to satisfy a 64-bit condition
on the cSHAKE128 output, you need only satisfy what is equivalent to
a 54-bit condition (since you have 2^10 more opportunities for
success).
Thus, although the probability of a collision or pre-image attack is
low in a collection of 1,024 HHITs out of a total population of 2^64,
per Section 10.2, it is computationally and economically feasible.
Thus the HHIT registration and HHIT/HI registration validation is
strongly recommended.
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The DET Registry services effectively block attempts to "take over"
or "hijack" a DET. It does not stop a rogue attempting to
impersonate a known DET. This attack can be mitigated by the
receiver of the DET using DNS to find the HI for the DET. As such,
use of DNSSEC and DNS over TLS by the DET registries is recommended.
The 60-bit hash for DETs with 8-bit OGAs have a greater hash attack
risk. As such its use should be restricted to testing and to small,
well managed UAS/USS.
Another mitigation of HHIT hijacking is if the HI owner (UA) supplies
an object containing the HHIT and signed by the HI private key of the
HDA such as discussed in Section 4.6.
The two risks with hierarchical HITs are the use of an invalid HID
and forced HIT collisions. The use of a DNS zone (e.g., "det.arpa.")
is a strong protection against invalid HIDs. Querying an HDA's RVS
for a HIT under the HDA protects against talking to unregistered
clients. The Registry service [drip-registries], through its HHIT
uniqueness enforcement, provides against forced or accidental HHIT
hash collisions.
Cryptographically Generated Addresses (CGAs) provide an assurance of
uniqueness. This is two-fold. The address (in this case the UAS ID)
is a hash of a public key and a Registry hierarchy naming. Collision
resistance (more important that it implied second-preimage
resistance) makes it statistically challenging to attacks. A
registration process ([drip-registries]) within the HDA provides a
level of assured uniqueness unattainable without mirroring this
approach.
The second aspect of assured uniqueness is the digital signing
(attestation) process of the DET by the HI private key and the
further signing (attestation) of the HI public key by the Registry's
key. This completes the ownership process. The observer at this
point does not know what owns the DET, but is assured, other than the
risk of theft of the HI private key, that this UAS ID is owned by
something and is properly registered.
10.1. DET Trust
The DET in the ASTM Basic ID Message (Msg Type 0x0, the actual Remote
ID message) does not provide any assertion of trust. The best that
might be done within this Basic ID Message is 4 bytes truncated from
a HI signing of the HHIT (the UA ID field is 20 bytes and a HHIT is
16). This is not trustable; that is, too open to a hash attack.
Minimally, it takes 84 bytes, Section 4.6, to prove ownership of a
DET with a full EdDSA signature. Thus, no attempt has been made to
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add DET trust directly within the very small Basic ID Message.
The ASTM Authentication Message (Msg Type 0x2) as shown in
Section 4.6 can provide practical actual ownership proofs. These
attestations include timestamps to defend against replay attacks.
But in themselves, they do not prove which UA sent the message. They
could have been sent by a dog running down the street with a
Broadcast Remote ID module strapped to its back.
Proof of UA transmission comes when the Authentication Message
includes proofs for the ASTM Location/Vector Message (Msg Type 0x1)
and the observer can see the UA or that information is validated by
ground multilateration [crowd-sourced-rid]. Only then does an
observer gain full trust in the DET of the UA.
DETs obtained via the Network RID path provides a different approach
to trust. Here the UAS SHOULD be securely communicating to the USS
(see [drip-secure-nrid-c2]), thus asserting DET trust.
10.2. Collision risks with DETs
The 64-bit hash size does have an increased risk of collisions over
the 96-bit hash size used for the other HIT Suites. There is a 0.01%
probability of a collision in a population of 66 million. The
probability goes up to 1% for a population of 663 million. See
Appendix B for the collision probability formula.
However, this risk of collision is within a single "Additional
Information" value, i.e., a RAA/HDA domain. The UAS/USS registration
process should include registering the DET and MUST reject a
collision, forcing the UAS to generate a new HI and thus HHIT and
reapplying to the DET registration process.
11. References
11.1. Normative References
[IANA-CGA] IANA, "Cryptographically Generated Addresses (CGA) Message
Type Name Space", <https://www.iana.org/assignments/cga-
message-types/cga-message-types.xhtml>.
[IANA-HIP] IANA, "Host Identity Protocol (HIP) Parameters",
<https://www.iana.org/assignments/hip-parameters/hip-
parameters.xhtml>.
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[IANA-IPSECKEY]
IANA, "IPSECKEY Resource Record Parameters",
<https://www.iana.org/assignments/ipseckey-rr-parameters/
ipseckey-rr-parameters.xhtml>.
[NIST.FIPS.202]
Dworkin, M., "SHA-3 Standard: Permutation-Based Hash and
Extendable-Output Functions", National Institute of
Standards and Technology report,
DOI 10.6028/nist.fips.202, July 2015,
<https://doi.org/10.6028/nist.fips.202>.
[NIST.SP.800-185]
Kelsey, J., Change, S., and R. Perlner, "SHA-3 derived
functions: cSHAKE, KMAC, TupleHash and ParallelHash",
National Institute of Standards and Technology report,
DOI 10.6028/nist.sp.800-185, December 2016,
<https://doi.org/10.6028/nist.sp.800-185>.
[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>.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153,
RFC 6890, DOI 10.17487/RFC6890, April 2013,
<https://www.rfc-editor.org/info/rfc6890>.
[RFC7343] Laganier, J. and F. Dupont, "An IPv6 Prefix for Overlay
Routable Cryptographic Hash Identifiers Version 2
(ORCHIDv2)", RFC 7343, DOI 10.17487/RFC7343, September
2014, <https://www.rfc-editor.org/info/rfc7343>.
[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>.
[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>.
[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>.
11.2. Informative References
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[cfrg-comment]
"A CFRG review of draft-ietf-drip-rid", September 2021,
<https://mailarchive.ietf.org/arch/msg/cfrg/
tAJJq60W6TlUv7_pde5cw5TDTCU/>.
[corus] CORUS, "U-space Concept of Operations", September 2019,
<https://www.sesarju.eu/node/3411>.
[crowd-sourced-rid]
Moskowitz, R., Card, S. W., Wiethuechter, A., Zhao, S.,
and H. Birkholz, "Crowd Sourced Remote ID", Work in
Progress, Internet-Draft, draft-moskowitz-drip-crowd-
sourced-rid-06, 26 May 2021,
<https://datatracker.ietf.org/doc/html/draft-moskowitz-
drip-crowd-sourced-rid-06>.
[CTA2063A] ANSI/CTA, "Small Unmanned Aerial Systems Serial Numbers",
September 2019, <https://shop.cta.tech/products/small-
unmanned-aerial-systems-serial-numbers>.
[drip-authentication]
Wiethuechter, A., Card, S., and R. Moskowitz, "DRIP
Authentication Formats for Broadcast Remote ID", Work in
Progress, Internet-Draft, draft-ietf-drip-auth-03, 8
November 2021, <https://datatracker.ietf.org/doc/html/
draft-ietf-drip-auth-03>.
[drip-registries]
Wiethuechter, A., Card, S., and R. Moskowitz, "DRIP
Registries", Work in Progress, Internet-Draft, draft-
wiethuechter-drip-registries-01, 22 October 2021,
<https://datatracker.ietf.org/doc/html/draft-wiethuechter-
drip-registries-01>.
[drip-requirements]
Card, S. W., Wiethuechter, A., Moskowitz, R., and A.
Gurtov, "Drone Remote Identification Protocol (DRIP)
Requirements", Work in Progress, Internet-Draft, draft-
ietf-drip-reqs-18, 8 September 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-drip-
reqs-18>.
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[drip-secure-nrid-c2]
Moskowitz, R., Card, S. W., Wiethuechter, A., and A.
Gurtov, "Secure UAS Network RID and C2 Transport", Work in
Progress, Internet-Draft, draft-moskowitz-drip-secure-
nrid-c2-04, 21 October 2021,
<https://datatracker.ietf.org/doc/html/draft-moskowitz-
drip-secure-nrid-c2-04>.
[F3411] ASTM International, "Standard Specification for Remote ID
and Tracking",
<http://www.astm.org/cgi-bin/resolver.cgi?F3411>.
[FAA_RID] United States Federal Aviation Administration (FAA),
"Remote Identification of Unmanned Aircraft", 2021,
<https://www.govinfo.gov/content/pkg/FR-2021-01-15/
pdf/2020-28948.pdf>.
[hhit-gen] "Python script to generate HHITs", September 2021,
<https://github.com/ietf-wg-drip/draft-ietf-drip-
rid/blob/master/hhit-gen.py>.
[Keccak] Bertoni, G., Daemen, J., Peeters, M., Van Assche, G., and
R. Van Keer, "The Keccak Function",
<https://keccak.team/index.html>.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, DOI 10.17487/RFC3972, March 2005,
<https://www.rfc-editor.org/info/rfc3972>.
[RFC4025] Richardson, M., "A Method for Storing IPsec Keying
Material in DNS", RFC 4025, DOI 10.17487/RFC4025, March
2005, <https://www.rfc-editor.org/info/rfc4025>.
[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>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/info/rfc4303>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
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[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>.
[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/info/rfc8032>.
[RFC8080] Sury, O. and R. Edmonds, "Edwards-Curve Digital Security
Algorithm (EdDSA) for DNSSEC", RFC 8080,
DOI 10.17487/RFC8080, February 2017,
<https://www.rfc-editor.org/info/rfc8080>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC9063] Moskowitz, R., Ed. and M. Komu, "Host Identity Protocol
Architecture", RFC 9063, DOI 10.17487/RFC9063, July 2021,
<https://www.rfc-editor.org/info/rfc9063>.
Appendix A. EU U-Space RID Privacy Considerations
EU is defining a future of airspace management known as U-space
within the Single European Sky ATM Research (SESAR) undertaking.
Concept of Operation for EuRopean UTM Systems (CORUS) project
proposed low-level Concept of Operations [corus] for UAS in EU. It
introduces strong requirements for UAS privacy based on European GDPR
regulations. It suggests that UAs are identified with agnostic IDs,
with no information about UA type, the operators or flight
trajectory. Only authorized persons should be able to query the
details of the flight with a record of access.
Due to the high privacy requirements, a casual observer can only
query U-space if it is aware of a UA seen in a certain area. A
general observer can use a public U-space portal to query UA details
based on the UA transmitted "Remote identification" signal. Direct
remote identification (DRID) is based on a signal transmitted by the
UA directly. Network remote identification (NRID) is only possible
for UAs being tracked by U-Space and is based on the matching the
current UA position to one of the tracks.
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The project lists "E-Identification" and "E-Registrations" services
as to be developed. These services can follow the privacy mechanism
proposed in this document. If an "agnostic ID" above refers to a
completely random identifier, it creates a problem with identity
resolution and detection of misuse. On the other hand, a classical
HIT has a flat structure which makes its resolution difficult. The
Hierarchical HITs provide a balanced solution by associating a
registry with the UA identifier. This is not likely to cause a major
conflict with U-space privacy requirements, as the registries are
typically few at a country level (e.g., civil personal, military, law
enforcement, or commercial).
Appendix B. Calculating Collision Probabilities
The accepted formula for calculating the probability of a collision
is:
p = 1 - e^{-k^2/(2n)}
P Collision Probability
n Total possible population
k Actual population
The following table provides the approximate population size for a
collision for a given total population.
Deployed Population
Total With Collision Risk of
Population .01% 1%
2^96 4T 42T
2^72 1B 10B
2^68 250M 2.5B
2^64 66M 663M
2^60 16M 160M
Acknowledgments
Dr. Gurtov is an adviser on Cybersecurity to the Swedish Civil
Aviation Administration.
Quynh Dang of NIST gave considerable guidance on using Keccak and the
NIST supporting documents. Joan Deamen of the Keccak team was
especially helpful in many aspects of using Keccak. Nicholas
Gajcowski [cfrg-comment] provided a concise hash pre-image security
assessment via the CFRG list.
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Many thanks to Michael Richardson for the iotdir review, Magnus
Nystrom for the secdir review and DRIP co-chair and draft shepherd,
Mohamed Boucadair for his extensive comments and help on document
clarity.
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, LLC
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: stu.card@axenterprize.com
Adam Wiethuechter
AX Enterprize, LLC
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: adam.wiethuechter@axenterprize.com
Andrei Gurtov
Linköping University
IDA
SE-58183 Linköping
Sweden
Email: gurtov@acm.org
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