COSE O. Steele
Internet-Draft Transmute
Intended status: Standards Track H. Birkholz
Expires: 3 September 2024 Fraunhofer SIT
A. Delignat-Lavaud
C. Fournet
Microsoft
2 March 2024
COSE Receipts
draft-ietf-cose-merkle-tree-proofs-04
Abstract
COSE (CBOR Object Signing and Encryption) Receipts prove properties
of a verifiable data structure to a verifier. Verifiable data
structures and associated proof types enable security properties,
such as minimal disclosure, transparency and non-equivocation.
Transparency helps maintain trust over time, and has been applied to
certificates, end to end encrypted messaging systems, and supply
chain security. This specification enables concise transparency
oriented systems, by building on CBOR (Concise Binary Object
Representation) and COSE. The extensibility of the approach is
demonstrated by providing CBOR encodings for RFC9162.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the CBOR Object Signing
and Encryption Working Group mailing list (cose@ietf.org), which is
archived at https://mailarchive.ietf.org/arch/browse/cose/.
Source for this draft and an issue tracker can be found at
https://github.com/cose-wg/draft-ietf-cose-merkle-tree-proofs.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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This Internet-Draft will expire on 3 September 2024.
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document authors. All rights reserved.
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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. Requirements Notation . . . . . . . . . . . . . . . . . . 3
2. CBOR Tags . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Verifiable Data Structures in CBOR . . . . . . . . . . . . . 5
4.1. Structures . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Parameters . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.1. Registration Requirements . . . . . . . . . . . . . . 8
5. RFC9162_SHA256 . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Verifiable Data Structure . . . . . . . . . . . . . . . . 8
5.2. Inclusion Proof . . . . . . . . . . . . . . . . . . . . . 8
5.2.1. Receipt of Inclusion . . . . . . . . . . . . . . . . 9
5.3. Consistency Proof . . . . . . . . . . . . . . . . . . . . 11
5.3.1. Receipt of Consistency . . . . . . . . . . . . . . . 12
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14
6.1. Log Length . . . . . . . . . . . . . . . . . . . . . . . 14
6.2. Header Parameters . . . . . . . . . . . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7.1. Choice of Signature Algorithms . . . . . . . . . . . . . 15
7.2. Validity Period . . . . . . . . . . . . . . . . . . . . . 15
7.3. Status Updates . . . . . . . . . . . . . . . . . . . . . 15
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9.1. Additions to Existing Registries . . . . . . . . . . . . 16
9.1.1. New Entries to the COSE Header Parameters Registry . 16
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9.1.2. COSE Verifiable Data Structures . . . . . . . . . . . 16
9.1.3. COSE Verifiable Data Structure Parameters . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Implementation Status . . . . . . . . . . . . . . . 20
A.1. Implementer . . . . . . . . . . . . . . . . . . . . . . . 20
A.2. Implementation Name . . . . . . . . . . . . . . . . . . . 20
A.3. Implementation URL . . . . . . . . . . . . . . . . . . . 20
A.4. Maturity . . . . . . . . . . . . . . . . . . . . . . . . 20
A.5. Coverage and Version Compatibility . . . . . . . . . . . 21
A.6. License . . . . . . . . . . . . . . . . . . . . . . . . . 21
A.7. Implementation Dependencies . . . . . . . . . . . . . . . 21
A.8. Contact . . . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
Merkle trees are one of many verifiable data structures that enable
tamper evident secure information storage, through their ability to
protect the integrity of batches of documents or collections of
statements. Merkle trees can be constructed from simple operations
such as concatenation and digest via a cryptographic hash function,
however, more advanced constructions enable proofs of different
properties of the underlying verifiable data structure. Verifiable
data structure proofs can be used to prove a document is in a
database (proof of inclusion), that a database is append only (proof
of consistency), that a smaller set of statements are contained in a
large set of statements (proof of disclosure, a special case of proof
of inclusion), or proof that certain data is not yet present in a
database (proofs of non inclusion). Differences in the
representation of verifiable data structures, and verifiable data
structure proof types, can increase the burden for implementers, and
create interoperability challenges for transparency services. This
document describes how to convey verifiable data structures, and
associated proof types in COSE envelopes. For conciseness, we refer
to a COSE object securing a verifiable data structure and its
associated proof types, as a COSE Receipt.
1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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2. CBOR Tags
Editorial Note (To be removed by RFC Editor).
This section will be removed before the document is completed, its
purpose is to track the TBD code points references throughout the
draft.
-111 is TBD_1: A requested cose header parameter representing the
verifiable data structure used.
-222 is TBD_2: A requested cose header parameter representing the
verifiable data structure parameters map (proofs map).
The other codepoints are assigned from the registries established in
this draft, they are therefore not marked TBD.
3. Terminology
Verifiable Data Structure (vds): A data structure which supports one
or more Proof Types. This property is conceptually similar to
"alg" (1), it described an algorithm used to maintain the
verifiable data structure, for example a binary merkle tree
algorithm.
Verifiable Data Structure Parameters (vdp): Parameters to a
verifiable data structure that are used to prove properties, such
as authentication, inclusion, consistency, and freshness.
Parameters can include multiple proofs of a given type, or
multiple types of proof (inclusion and consistency). This
property is conceptually similar to COSE Header Parameter "epk"
(-1) or CBOR Web Token (CWT) claim "cnf" (8), it is applied to a
verifiable data structure, to confirm a property. For example an
encrypted messsage might be decrypted using epk and a private key,
a digital signature for authentication might be verified using cnf
and the (CWT) claim "nonce" and "audience", and an inclusion proof
for a binary merkle tree might be verified with vdp and some entry
that is being tested or inclusion in the tree.
Proof Type: A verifiable process, that proves properties of a
Verifiable Data Structure.
Proof Value: An encoding of a Proof Type in CBOR.
Entry: An entry in a verifiable data structure for which proofs can
be derived.
Receipt: A COSE Object containing the header parameters necessary to
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convey a proof types for verifiable data structures.
4. Verifiable Data Structures in CBOR
This section describes representations of verifiable data structure
proofs in CBOR. For example, construction of a merkle tree leaf, or
an inclusion proof from a leaf to a merkle root, might have several
different representations, depending on the verifiable data structure
used. Differences in representations are necessary to support
efficient verification, unique security or privacy properties, and
for compatibility with specific implementations. In order to improve
interoperability we define two extension points for enabling
verifiable data structures with COSE, and we provide concrete
examples for the structures and proofs defined in [RFC9162]. The
design of these structures is influenced by the conventions
established for COSE Keys.
4.1. Structures
Similar to COSE Key Types (https://www.iana.org/assignments/cose/
cose.xhtml#key-type), different verifiable data structures support
different algorithms. As EC2 keys (1: 2) support both digital
signature and key agreement algorithms, RFC9162_SHA256 (TBD_1 : 1)
supports both inclusion and consistency proofs.
This document establishes a registry of verifiable data structure
algorithms, with the following initial contents:
* Name: The name of the verifiable data structure
* Value: The identifier for the verifiable data structure
* Description: The identifier for the verifiable data structure
* Reference: Where the verifiable data structure is defined
+================+=======+===========================+===========+
| Name | Value | Description | Reference |
+================+=======+===========================+===========+
| N/A | 0 | N/A | N/A |
+----------------+-------+---------------------------+-----------+
| RFC9162_SHA256 | 1 | SHA256 Binary Merkle Tree | [RFC9162] |
+----------------+-------+---------------------------+-----------+
Table 1: COSE Verifiable Data Structures
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When desigining new verifiable data structures, please request the
next available positive integer as your requested assignment, for
example:
+================+================+===============+===============+
| Name | Value | Description | Reference |
+================+================+===============+===============+
| N/A | 0 | N/A | N/A |
+----------------+----------------+---------------+---------------+
| RFC9162_SHA256 | 1 | SHA256 Binary | [RFC9162] |
| | | Merkle Tree | |
+----------------+----------------+---------------+---------------+
| Your name | TBD (requested | tbd | Your |
| | assignment 2) | | specification |
+----------------+----------------+---------------+---------------+
Table 2: How to register new structures
4.2. Parameters
Similar to COSE Key Type Parameters
(https://www.iana.org/assignments/cose/cose.xhtml#key-type-
parameters), as EC2 keys (1: 2) keys require and give meaning to
specific parameters, such as -1 (crv), -2 (x), -3 (y), -4 (d),
RFC9162_SHA256 (TBD_1 : 1) supports both (-1) inclusion and (-2)
consistency proofs.
This document establishes a registry of verifiable data structure
algorithms, with the following initial contents:
+============+=============+=====+=======+=============+===========+
| Verifiable | Name |Label| CBOR | Description | Reference |
| Data | | | Type | | |
| Structure | | | | | |
+============+=============+=====+=======+=============+===========+
| 1 | inclusion |-1 | array | Proof of | Section |
| | proofs | | (of | inclusion | 5.2 |
| | | | bstr) | | |
+------------+-------------+-----+-------+-------------+-----------+
| 1 | consistency |-2 | array | Proof of | Section |
| | proofs | | (of | append only | 5.3 |
| | | | bstr) | property | |
+------------+-------------+-----+-------+-------------+-----------+
Table 3: COSE Verifiable Data Structure Parameters
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Proof types are specific to their associated "verifiable data
structure", for example, different Merkle trees might support
different representations of "inclusion proof" or "consistency
proof". Implementers should not expect interoperability accross
"verifiable data structures", but they should expect conceptually
similar properties across the different registered proof types. For
example, 2 different merkle tree based verifiable data structures
might both support proofs of inclusion. Protocols requiring proof of
inclusion ought to be able to preserve their functionality, while
switching from one verifiable data structure to another, so long as
both structures support the same proof types. Security analysis
SHOULD be conducted prior to migrating to new structures to ensure
the new security and privacy assumptions are acceptable for the use
case. When designing new verifiable data structure parameters (or
proof types), please start with -1, and count down for each proof
type supported by your verifiable data structure:
+==========+===========+=====+=====+===========+==================+
|Verifiable|Name |Label|CBOR |Description|Reference |
|Data | | |Type | | |
|Structure | | | | | |
+==========+===========+=====+=====+===========+==================+
|1 |inclusion |-1 |array|Proof of |Section 5.2 |
| |proofs | |(of |inclusion | |
| | | |bstr)| | |
+----------+-----------+-----+-----+-----------+------------------+
|1 |consistency|-2 |array|Proof of |Section 5.3 |
| |proofs | |(of |append only| |
| | | |bstr)|property | |
+----------+-----------+-----+-----+-----------+------------------+
|TBD |new proof |-1 |tbd |tbd |Your_Specification|
|(requested|type | | | | |
|assignment| | | | | |
|2) | | | | | |
+----------+-----------+-----+-----+-----------+------------------+
|TBD |new proof |-2 |tbd |tbd |Your_Specification|
|(requested|type | | | | |
|assignment| | | | | |
|2) | | | | | |
+----------+-----------+-----+-----+-----------+------------------+
|TBD |new proof |-3 |tbd |tbd |Your_Specification|
|(requested|type | | | | |
|assignment| | | | | |
|2) | | | | | |
+----------+-----------+-----+-----+-----------+------------------+
Table 4: How to register new parameters
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4.2.1. Registration Requirements
Each specification MUST define how to encode the verifiable data
structure and its parameters (also called proof types) in CBOR. Each
specification MUST define how to produce and consume the supported
proof types. See Section 5 as an example.
5. RFC9162_SHA256
This section defines how the data structures described in [RFC9162]
are mapped to the terminology defined in this document, using CBOR
and COSE.
5.1. Verifiable Data Structure
The integer identifier for this Verifiable Data Structure is 1. The
string identifier for this Verifiable Data Structure is
"RFC9162_SHA256". See Table 1. See [RFC9162], 2.1.1. Definition of
the Merkle Tree, for a complete description of this verifiable data
structure.
5.2. Inclusion Proof
See [RFC9162], 2.1.3.1. Generating an Inclusion Proof, for a
complete description of this verifiable data structure proof type.
The CBOR representation of an inclusion proof for RFC9162_SHA256 is:
inclusion-proof = bstr .cbor [
; tree size at current merkle root
tree-size: int
; index of leaf in tree
leaf-index: int
; path from leaf to current merkle root
inclusion-path: [ + bstr ]
]
Figure 1: CBOR Encoded RFC9162 Inclusion Proof
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5.2.1. Receipt of Inclusion
In a signed inclusion proof, the previous merkle tree root, maps to
tree-size-1, and is a detached payload. Profiles of proof signatures
are encouraged to make additional protected header parameters
mandatory, to ensure that claims are processed with their intended
semantics. One way to include this information in the COSE structure
is use of the typ (type) Header Parameter, see
[I-D.ietf-cose-typ-header-parameter] and the similar guidance
provided in [I-D.ietf-cose-cwt-claims-in-headers]. The protected
header for an RFC9162_SHA256 inclusion proof signature is:
protected-header-map = {
&(alg: 1) => int
&(vds: -111) => int
* cose-label => cose-value
}
Figure 2: Protected Header for a Receipt of Inclusion
* alg (label: 1): REQUIRED. Signature algorithm identifier. Value
type: int.
* vds (label: -111): REQUIRED. verifiable data structure algorithm
identifier. Value type: int.
The unprotected header for an RFC9162_SHA256 inclusion proof
signature is:
inclusion-proofs = [ + inclusion-proof ]
verifiable-proofs = {
&(inclusion-proof: -1) => inclusion-proofs
}
unprotected-header-map = {
&(vdp: -222) => verifiable-proofs
* cose-label => cose-value
}
Figure 3: A Verifiable Data Structure Proofs in an Unprotected Header
* vdp (label: -222): REQUIRED. Verifiable data structure proofs.
Value type: Map.
* inclusion-proof (label: -1): REQUIRED. Inclusion proofs. Value
type: Array of bstr.
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The payload of an RFC9162_SHA256 inclusion proof signature is the
previous Merkle tree hash as defined in [RFC9162]. The payload MUST
be detached. Detaching the payload forces verifiers to recompute the
root from the inclusion proof signature, this protects against
implementation errors where the signature is verified but the merkle
root does not match the inclusion proof. The CBOR Extended
Diagnostic Notation (EDN) for a Receipt containing an inclusion proof
for RFC9162_SHA256 is:
18( / COSE Sign 1 /
[
h'a4012604...6d706c65', / Protected /
{ / Unprotected /
-222: { / Proofs /
-1: [ / Inclusion proofs (1) /
h'83080783...32568964', / Inclusion proof 1 /
]
},
},
nil, / Detached payload /
h'2e34df43...8d74d55e' / Signature /
]
)
Figure 4: Example inclusion receipt
The CBOR Extended Diagnostic Notation (EDN) for the Protected Header
in the example above is:
{ / Protected /
1: -7, / Algorithm /
4: h'4930714e...7163316b', / Key identifier /
-111: 1, / Verifiable Data Structure /
}
Figure 5: Example inclusion receipt decoded protected header
The vds in the protected header is necessary to understand the vdp in
the unprotected header.
The CBOR Extended Diagnostic Notation (EDN) for the inclusion proof
in the Unprotected Header is:
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[ / Inclusion proof 1 /
8, / Tree size /
7, / Leaf index /
[ / Inclusion hashes (3) /
h'2a8d7dfc...15d10b22' / Intermediate hash 1 /
h'75f177fd...2e73a8ab' / Intermediate hash 2 /
h'0bdaaed3...32568964' / Intermediate hash 3 /
]
]
Figure 6: Example inclusion receipt decoded inclusion proof
The vds in the protected header is necessary to understand the
inclusion proof structure in the unprotected header.
The inclusion proof and signature are verified in order. First the
verifiers applies the inclusion proof to a possible entry (set
member) bytes. If this process fails, the inclusion proof may have
been tampered with. If this process succeeds, the result is a merkle
root, which in the attached as the COSE Sign1 payload. Second the
verifier checks the signature of the COSE Sign1. If the resulting
signature verifies, the Receipt has proved inclusion of the entry in
the verifiable data structure. If the resulting signature does not
verify, the signature may have been tampered with. It is recommended
that implementations return a single boolean result for Receipt
verification operations, to reduce the chance of accepting a valid
signature over an invalid inclusion proof.
5.3. Consistency Proof
See [RFC9162], 2.1.4.1. Generating a Consistency Proof, for a
complete description of this verifiable data structure proof type.
The cbor representation of a consistency proof for RFC9162_SHA256 is:
consistency-proof = bstr .cbor [
; previous merkle root tree size
tree-size-1: int
; latest merkle root tree size
tree-size-2: int
; path from previous merkle root to latest merkle root.
consistency-path: [ + bstr ]
]
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Figure 7: CBOR Encoded RFC9162 Consistency Proof
Editors note: tree-size-1, could be omitted, if an inclusion-proof is
always present, since the inclusion proof contains, tree-size-1.
5.3.1. Receipt of Consistency
In a signed consistency proof, the latest merkle tree root, maps to
tree-size-2, and is an attached payload.
The protected header for an RFC9162_SHA256 consistency proof
signature is:
protected-header-map = {
&(alg: 1) => int
&(vds: -111) => int
* cose-label => cose-value
}
Figure 8: Protected Header for a Receipt of Consistency
* alg (label: 1): REQUIRED. Signature algorithm identifier. Value
type: int.
* vds (label: TBD_1): REQUIRED. Verifiable data structure algorithm
identifier. Value type: int.
The unprotected header for an RFC9162_SHA256 consistency proof
signature is:
consistency-proofs = [ + consistency-proof ]
verifiable-proofs = {
&(consistency-proof: -2) => consistency-proofs
}
unprotected-header-map = {
&(vdp: -222) => verifiable-proofs
* cose-label => cose-value
}
* vdp (label: -222): REQUIRED. Verifiable data structure proofs.
Value type: Map.
* consistency-proof (label: -2): REQUIRED. Consistency proofs.
Value type: Array of bstr.
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The payload of an RFC9162_SHA256 consistency proof signature is: The
latest Merkle tree hash as defined in [RFC9162]. The payload MUST be
attached.
The CBOR Extended Diagnostic Notation (EDN) for a Receipt containing
a consistency proof for RFC9162_SHA256 is:
18( / COSE Sign 1 /
[
h'a3012604...392b6601', / Protected /
{ / Unprotected /
-222: { / Proofs /
-2: [ / Consistency proofs (1) /
h'83040682...2e73a8ab', / Consistency proof 1 /
]
},
},
h'430b6fd7...f74c7fc4', / Payload (Attached) /
h'd97befea...f30631cb' / Signature /
]
)
Figure 9: Example consistency receipt
The vds in the protected header is necessary to understand the vdp in
the unprotected header.
The CBOR Extended Diagnostic Notation (EDN) for the Protected Header
in the example above is:
{ / Protected /
1: -7, / Algorithm /
4: h'68747470...6d706c65', / Key identifier /
-111: 1, / Verifiable Data Structure /
}
Figure 10: Example consistency receipt decoded protected header
The CBOR Extended Diagnostic Notation (EDN) for the consistency proof
in the Unprotected Header is:
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[ / Consistency proof 1 /
4, / Tree size 1 /
6, / Tree size 2 /
[ / Consistency hashes (2) /
h'0bdaaed3...32568964' / Intermediate hash 1 /
h'75f177fd...2e73a8ab' / Intermediate hash 2 /
]
]
Figure 11: Example consistency receipt decoded consistency proof
The vds in the protected header is necessary to understand the
consistency proof structure in the unprotected header.
The signature and consistency proof are verified in order.
First the verifier checks the signature on the COSE Sign1. If the
verification fails, the consistency proof is not checked. Second the
consistency proof is checked by applying a previous inclusion proof,
to the consistency proof. If the verification fails, the append only
property of the verifiable data structure is not assured. This
approach is specific to RFC9162_SHA256, different verifiable data
structures may not support consistency proofs. It is recommended
that implementations return a single boolean result for Receipt
verification operations, to reduce the chance of accepting a valid
signature over an invalid consistency proof.
6. Privacy Considerations
See the privacy considerations section of:
* [RFC9162]
* [RFC9053]
6.1. Log Length
Some structures and proofs leak the size of the log at the time of
inclusion. In the case that a log only stores certain kinds of
information, this can reveal details that could impact reputation.
For example, if a transparency log only stored breach notices, a
receipt for a breach notice would reveal the number of previous
breaches at the time the notice was made transparent.
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6.2. Header Parameters
Additional header parameters can reveal information about the
transparency service or its log entries. A privacy analysis MUST be
performed for all mandatory fields in profiles based on this
specification.
7. Security Considerations
See the security considerations section of:
* [RFC9162]
* [RFC9053]
7.1. Choice of Signature Algorithms
A security analysis MUST be performed to ensure that the digital
signature algorithm alg has the appropriate strength to secure
receipts.
It is recommended to select signature algorithms that share
cryptographic components with the verifiable data structure used, for
example: Both RFC9162_SHA256 and ES256 depend on the sha-256 hash
function.
7.2. Validity Period
In some cases, receipts MAY include strict validity periods, for
example, activation not too far in the future, or expiration, not too
far in the past. See the iat, nbf, and exp claims in [RFC8392], for
one way to accomplish this. The details of expressing validity
periods are out of scope for this document.
7.3. Status Updates
In some cases, receipts should be "revocable" or "suspendible", after
being issued, regardless of their validity period. The details of
expressing statuses are out of scope for this document.
8. Acknowledgements
We would like to thank Maik Riechert, Jon Geater, Mike Jones, Mike
Prorock, Ilari Liusvaara, for their contributions (some of which
substantial) to this draft and to the initial set of implementations.
9. IANA Considerations
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9.1. Additions to Existing Registries
9.1.1. New Entries to the COSE Header Parameters Registry
This document requests IANA to add new values to the 'COSE
Algorithms' and to the 'COSE Header Algorithm Parameters' registries
in the 'Standards Action With Expert Review category.
9.1.1.1. COSE Header Algorithm Parameters
* Name: vds
* Label: TBD_1
* Value type: int
* Value registry: https://www.iana.org/assignments/cose/
cose.xhtml#header-parameters
* Description: Algorithm name for verifiable data structure, used to
produce verifiable data structure proofs.
* Name: vdp
* Label: TBD_2
* Value type: int
* Value registry: https://www.iana.org/assignments/cose/
cose.xhtml#header-parameters
* Description: Location for verifiable data structure proofs in COSE
Header Parameters.
9.1.2. COSE Verifiable Data Structures
IANA will be asked to establish a registry of verifiable data
structure identifiers, named "COSE Verifiable Data Structures" to be
administered under a Specification Required policy [RFC8126].
Template:
* Name: The name of the verifiable data structure
* Value: The identifier for the verifiable data structure
* Description: A brief description of the verifiable data structure
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* Reference: Where the verifiable data structure is defined
Initial contents: Provided in Table 1
9.1.2.1. Expert Review
This IANA registries is established under a Specification Required
policy.
This section gives some general guidelines for what the experts
should be looking for, but they are being designated as experts for a
reason, so they should be given substantial latitude.
Expert reviewers should take into consideration the following points:
* Point squatting should be discouraged. Reviewers are encouraged
to get sufficient information for registration requests to ensure
that the usage is not going to duplicate one that is already
registered, and that the point is likely to be used in
deployments.
* Specifications are required for all point assignments. Early
assignment before a specification is available is considered to be
permissible, however, such registrations MUST be marked
provisional by prefixing the entry with "PROVISIONAL: ".
Provisional assignments to expired drafts MUST be removed from the
registry.
* Points assigned in this registry MUST have references that match
the COSE Verifiable Data Structure Parameters registry. It is not
permissible to assign points in this registry, for which no
Verifiable Data Structure Parameters entries exist.
9.1.3. COSE Verifiable Data Structure Parameters
IANA will be asked to establish a registry of verifiable data
structure parameters, named "COSE Verifiable Data Structure
Parameters" to be administered under a Specification Required policy
[RFC8126].
Template:
* Verifiable Data Structure: The identifier for the verifiable data
structure
* Name: The name of the proof type
* Label: The integer of the proof type
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* CBOR Type: The cbor data type of the proof
* Description: The description of the proof type
* Reference: Where the proof type is defined
Initial contents: Provided in Table 3
9.1.3.1. Expert Review
This IANA registries is established under a Specification Required
policy.
This section gives some general guidelines for what the experts
should be looking for, but they are being designated as experts for a
reason, so they should be given substantial latitude.
Expert reviewers should take into consideration the following points:
* Point squatting should be discouraged. Reviewers are encouraged
to get sufficient information for registration requests to ensure
that the usage is not going to duplicate one that is already
registered, and that the point is likely to be used in
deployments.
* Specifications are required for all point assignments. Early
assignment before a specification is available is considered to be
permissible, however, such registrations MUST be marked
provisional by prefixing the entry with "PROVISIONAL: ".
Provisional assignments to expired drafts MUST be removed from the
registry.
* Points assigned in this registry MUST have references that match
the COSE Verifiable Data Structures registry. It is not
permissible to assign points in this registry, for which no
Verifiable Data Structure entry exists.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
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[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, .
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, .
[RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053,
August 2022, .
[RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate
Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162,
December 2021, .
10.2. Informative References
[BCP205] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
.
[I-D.ietf-cose-cwt-claims-in-headers]
Looker, T. and M. B. Jones, "CBOR Web Token (CWT) Claims
in COSE Headers", Work in Progress, Internet-Draft, draft-
ietf-cose-cwt-claims-in-headers-10, 29 November 2023,
.
[I-D.ietf-cose-typ-header-parameter]
Jones, M. B. and O. Steele, "COSE "typ" (type) Header
Parameter", Work in Progress, Internet-Draft, draft-ietf-
cose-typ-header-parameter-03, 26 February 2024,
.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, .
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Appendix A. Implementation Status
Note to RFC Editor: Please remove this section as well as references
to [BCP205] before AUTH48.
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [BCP205].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [BCP205], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
A.1. Implementer
An open-source implementation was initiated and is maintained by the
Transmute Industries Inc. - Transmute.
A.2. Implementation Name
An application demonstrating the concepts is available at COSE SCITT
Receipts (https://github.com/transmute-industries/cose?tab=readme-ov-
file#scitt-receipts)
A.3. Implementation URL
An open-source implementation is available at:
* https://github.com/transmute-industries/cose
A.4. Maturity
The code's level of maturity is considered to be "prototype".
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A.5. Coverage and Version Compatibility
The current version ('main') implements the verifiable data structure
algorithm, inclusion proof and consistency proof concepts of this
draft.
A.6. License
The project and all corresponding code and data maintained on GitHub
are provided under the Apache License, version 2.
A.7. Implementation Dependencies
The implementation uses the Concise Binary Object Representation
[RFC7049] (https://cbor.io/).
The implementation uses the CBOR Object Signing and Encryption
[RFC9053], maintained at: - https://github.com/erdtman/cose-js
The implementation uses an implementation of [RFC9162], maintained
at:
* https://github.com/transmute-industries/rfc9162/tree/main/src/
CoMETRE
A.8. Contact
Orie Steele (orie@transmute.industries)
Authors' Addresses
Orie Steele
Transmute
United States
Email: orie@transmute.industries
Henk Birkholz
Fraunhofer SIT
Rheinstrasse 75
64295 Darmstadt
Germany
Email: henk.birkholz@sit.fraunhofer.de
Antoine Delignat-Lavaud
Microsoft
United Kingdom
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Email: antdl@microsoft.com
Cedric Fournet
Microsoft
United Kingdom
Email: fournet@microsoft.com
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