LAMPS M. Ounsworth
Internet-Draft J. Gray
Intended status: Standards Track Entrust
Expires: 4 September 2025 M. Pala
OpenCA Labs
J. Klaussner
Bundesdruckerei GmbH
S. Fluhrer
Cisco Systems
3 March 2025
Composite ML-DSA for use in X.509 Public Key Infrastructure and CMS
draft-ietf-lamps-pq-composite-sigs-04
Abstract
This document defines combinations of ML-DSA [FIPS.204] in hybrid
with traditional algorithms RSASSA-PKCS1-v1_5, RSASSA-PSS, ECDSA,
Ed25519, and Ed448. These combinations are tailored to meet security
best practices and regulatory requirements. Composite ML-DSA is
applicable in any application that uses X.509, PKIX, and CMS data
structures and protocols that accept ML-DSA, but where the operator
wants extra protection against breaks or catastrophic bugs in ML-DSA.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at https://lamps-
wg.github.io/draft-composite-sigs/draft-ietf-lamps-pq-composite-
sigs.html. Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-ietf-lamps-pq-composite-sigs/.
Discussion of this document takes place on the LAMPS Working Group
mailing list (mailto:spams@ietf.org), which is archived at
https://datatracker.ietf.org/wg/lamps/about/. Subscribe at
https://www.ietf.org/mailman/listinfo/spams/.
Source for this draft and an issue tracker can be found at
https://github.com/lamps-wg/draft-composite-sigs.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1. Changes in -04 . . . . . . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Conventions and Terminology . . . . . . . . . . . . . . . 5
2.2. Composite Design Philosophy . . . . . . . . . . . . . . . 6
3. Overview of the Composite ML-DSA Signature Scheme . . . . . . 7
3.1. Pure vs Pre-hashed modes . . . . . . . . . . . . . . . . 8
4. Composite ML-DSA Functions . . . . . . . . . . . . . . . . . 8
4.1. Key Generation . . . . . . . . . . . . . . . . . . . . . 8
4.2. Pure Signature Mode . . . . . . . . . . . . . . . . . . . 10
4.2.1. Composite-ML-DSA.Sign . . . . . . . . . . . . . . . . 10
4.2.2. Composite-ML-DSA.Verify . . . . . . . . . . . . . . . 12
4.3. PreHash-Signature Mode . . . . . . . . . . . . . . . . . 14
4.3.1. HashComposite-ML-DSA-Sign signature mode . . . . . . 14
4.3.2. HashComposite-ML-DSA-Verify . . . . . . . . . . . . . 16
4.4. SerializeKey and DeserializeKey . . . . . . . . . . . . . 19
4.5. SerializeSignatureValue and DeSerializeSignatureValue . . 22
4.6. ML-DSA public key, private key and signature sizes for
serialization and deserialization . . . . . . . . . . . . 25
5. Composite Key Structures . . . . . . . . . . . . . . . . . . 26
5.1. CompositeMLDSAPublicKey . . . . . . . . . . . . . . . . . 26
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5.2. CompositeMLDSAPrivateKey . . . . . . . . . . . . . . . . 27
5.3. Encoding Rules . . . . . . . . . . . . . . . . . . . . . 28
5.4. Key Usage Bits . . . . . . . . . . . . . . . . . . . . . 29
6. Composite Signature Structures . . . . . . . . . . . . . . . 29
6.1. sa-CompositeSignature . . . . . . . . . . . . . . . . . . 29
6.2. CompositeSignatureValue . . . . . . . . . . . . . . . . . 30
7. Algorithm Identifiers . . . . . . . . . . . . . . . . . . . . 30
7.1. PureComposite-ML-DSA Algorithm Identifiers . . . . . . . 30
7.2. HashComposite-ML-DSA Algorithm Identifiers . . . . . . . 31
7.3. Domain Separators . . . . . . . . . . . . . . . . . . . . 33
7.4. Rationale for choices . . . . . . . . . . . . . . . . . . 36
7.5. RSASSA-PSS . . . . . . . . . . . . . . . . . . . . . . . 36
7.5.1. RSA2048-PSS . . . . . . . . . . . . . . . . . . . . . 36
7.5.2. RSA3072-PSS . . . . . . . . . . . . . . . . . . . . . 37
7.5.3. RSA4096-PSS . . . . . . . . . . . . . . . . . . . . . 38
8. Use in CMS . . . . . . . . . . . . . . . . . . . . . . . . . 38
8.1. Underlying Components . . . . . . . . . . . . . . . . . . 39
8.2. SignedData Conventions . . . . . . . . . . . . . . . . . 39
8.3. Signature generation and verification . . . . . . . . . . 40
8.4. Certificate Conventions . . . . . . . . . . . . . . . . . 40
8.5. SMIMECapabilities Attribute Conventions . . . . . . . . . 41
9. ASN.1 Module . . . . . . . . . . . . . . . . . . . . . . . . 41
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 54
10.1. Object Identifier Allocations . . . . . . . . . . . . . 55
10.1.1. Module Registration - SMI Security for PKIX Module
Identifier . . . . . . . . . . . . . . . . . . . . . 55
10.1.2. Object Identifier Registrations - SMI Security for
PKIX Algorithms . . . . . . . . . . . . . . . . . . . 55
11. Security Considerations . . . . . . . . . . . . . . . . . . . 60
11.1. Why Hybrids? . . . . . . . . . . . . . . . . . . . . . . 60
11.2. Non-separability, EUF-CMA and SUF . . . . . . . . . . . 61
11.3. Key Reuse . . . . . . . . . . . . . . . . . . . . . . . 63
11.4. Policy for Deprecated and Acceptable Algorithms . . . . 63
11.5. Use of Prefix to for attack mitigation . . . . . . . . . 65
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 65
12.1. Normative References . . . . . . . . . . . . . . . . . . 65
12.2. Informative References . . . . . . . . . . . . . . . . . 67
Appendix A. Samples . . . . . . . . . . . . . . . . . . . . . . 69
A.1. Message Format Examples . . . . . . . . . . . . . . . . . 69
A.1.1. Example of MLDSA44-ECDSA-P256 with Context: . . . . . 69
A.1.2. Example of MLDSA44-ECDSA-P256 without a Context . . . 70
A.1.3. Example of HashMLDSA44-ECDSA-P256-SHA256 with
Context . . . . . . . . . . . . . . . . . . . . . . . 70
A.1.4. Example of HashMLDSA44-ECDSA-P256-SHA256 without
Context . . . . . . . . . . . . . . . . . . . . . . . 70
A.2. Composite Signature Examples . . . . . . . . . . . . . . 71
Appendix B. Component Algorithm Reference . . . . . . . . . . . 71
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Appendix C. Component AlgorithmIdentifiers for Public Keys and
Signatures . . . . . . . . . . . . . . . . . . . . . . . 73
Appendix D. Implementation Considerations . . . . . . . . . . . 79
D.1. FIPS certification . . . . . . . . . . . . . . . . . . . 79
D.2. Backwards Compatibility . . . . . . . . . . . . . . . . . 79
D.2.1. Hybrid Extensions (Keys and Signatures) . . . . . . . 80
Appendix E. Intellectual Property Considerations . . . . . . . . 80
Appendix F. Contributors and Acknowledgements . . . . . . . . . 80
F.1. Making contributions . . . . . . . . . . . . . . . . . . 81
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 81
1. Changes in -04
Interop-affecting changes:
* Remove the ASN.1 SEQUENCE Wrapping around the Public Keys, Private
Keys and Composite Signature Value
* Added a prefix into the message format to allow traditional
verifiers to detect if a composite signature has been stripped
* Added a fixed 4-byte length value to identify the length of the
first ML-DSA component so keys and signatures can be separated
* Issued new prototype OIDs for testing purposes since the above
changes break backwards compatiblity with version -03
* Added support for a MLDSA65-ECDSA-P256 combination because P256 is
a widely supported EC algorithm
* Added support for a MLDSA87-RSA4096-PSS combination at the request
of Microsoft and because we want a RSA combination complaint with
CNSA 2.0
* When used in CMS, all composite combinations make use of the
SHA-512 digest algorithm
Editorial changes: * Added normative language to make it clear that
key reuse is prohibited * Updated the security considerations section
* Added Message format examples * Additional editing changes as
needed
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2. Introduction
The advent of quantum computing poses a significant threat to current
cryptographic systems. Traditional cryptographic algorithms such as
RSA, Diffie-Hellman, DSA, and their elliptic curve variants are
vulnerable to quantum attacks. During the transition to post-quantum
cryptography (PQC), there is considerable uncertainty regarding the
robustness of both existing and new cryptographic algorithms. While
we can no longer fully trust traditional cryptography, we also cannot
immediately place complete trust in post-quantum replacements until
they have undergone extensive scrutiny and real-world testing to
uncover and rectify potential implementation flaws.
Unlike previous migrations between cryptographic algorithms, the
decision of when to migrate and which algorithms to adopt is far from
straightforward. Even after the migration period, it may be
advantageous for an entity's cryptographic identity to incorporate
multiple public-key algorithms to enhance security.
Cautious implementers may opt to combine cryptographic algorithms in
such a way that an attacker would need to break all of them
simultaneously to compromise the protected data. These mechanisms
are referred to as Post-Quantum/Traditional (PQ/T) Hybrids
[I-D.ietf-pquip-pqt-hybrid-terminology].
Certain jurisdictions are already recommending or mandating that PQC
lattice schemes be used exclusively within a PQ/T hybrid framework.
The use of Composite scheme provides a straightforward implementation
of hybrid solutions compatible with (and advocated by) some
governments and cybersecurity agencies [BSI2021].
Composite ML-DSA is applicable in any application that would
otherwise use ML-DSA, but wants the protection against breaks or
catastrophic bugs in ML-DSA.
2.1. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. These words may also appear in this
document in lower case as plain English words, absent their normative
meanings.
This document is consistent with the terminology defined in
[I-D.ietf-pquip-pqt-hybrid-terminology]. In addition, the following
terminology is used throughout this document:
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*ALGORITHM*: The usage of the term "algorithm" within this document
generally refers to any function which has a registered Object
Identifier (OID) for use within an ASN.1 AlgorithmIdentifier. This
loosely, but not precisely, aligns with the definitions of
"cryptographic algorithm" and "cryptographic scheme" given in
[I-D.ietf-pquip-pqt-hybrid-terminology].
*BER*: Basic Encoding Rules (BER) as defined in [X.690].
*CLIENT*: Any software that is making use of a cryptographic key.
This includes a signer, verifier, encrypter, decrypter. This is not
meant to imply any sort of client-server relationship between the
communicating parties.
*DER*: Distinguished Encoding Rules as defined in [X.690].
*PKI*: Public Key Infrastructure, as defined in [RFC5280].
*PUBLIC / PRIVATE KEY*: The public and private portion of an
asymmetric cryptographic key, making no assumptions about which
algorithm.
*SIGNATURE*: A digital cryptographic signature, making no assumptions
about which algorithm.
2.2. Composite Design Philosophy
[I-D.ietf-pquip-pqt-hybrid-terminology] defines composites as:
_Composite Cryptographic Element_: A cryptographic element that
incorporates multiple component cryptographic elements of the same
type in a multi-algorithm scheme.
Composite keys, as defined here, follow this definition and should be
regarded as a single key that performs a single cryptographic
operation such as key generation, signing, verifying, encapsulating,
or decapsulating -- using its internal sequence of component keys as
if they form a single key. This generally means that the complexity
of combining algorithms can and should be handled by the
cryptographic library or cryptographic module, and the single
composite public key, private key, ciphertext and signature can be
carried in existing fields in protocols such as PKCS#10 [RFC2986],
CMP [RFC4210], X.509 [RFC5280], CMS [RFC5652], and the Trust Anchor
Format [RFC5914]. In this way, composites achieve "protocol
backwards-compatibility" in that they will drop cleanly into any
protocol that accepts an analogous single-algorithm cryptographic
scheme without requiring any modification of the protocol to handle
multiple algorithms.
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3. Overview of the Composite ML-DSA Signature Scheme
Composite schemes are defined as cryptographic primitives that
consist of three algorithms:
* KeyGen() -> (pk, sk): A probabilistic key generation algorithm,
which generates a public key pk and a secret key sk.
* Sign(sk, Message) -> (signature): A signing algorithm which takes
as input a secret key sk and a Message, and outputs a signature
* Verify(pk, Message, signature) -> true or false: A verification
algorithm which takes as input a public key, a Message, and a
signature and outputs true if the signature verifies correctly.
Thus it proves the Message was signed with the secret key
associated with the public key and verifies the integrity of the
Message. If the signature and public key cannot verify the
Message, it returns false.
We define the following algorithms which we use to serialize and
deserialize the public and private keys
* SerializeKey(key) -> bytes: Produce a byte string encoding the
public or private key.
* DeserializeKey(bytes) -> pk: Parse a byte string to recover a
public or private key. This function can fail if the input byte
string is malformed.
We define the following algorithms which are used to serialize and
deseralize the composite signature value
* SerializeSignatureValue(CompositeSignatureValue) -> bytes: Produce
a byte string encoding the CompositeSignatureValue.
* DeserializeSignatureValue(bytes) -> pk: Parse a byte string to
recover a CompositeSignatureValue. This function can fail if the
input byte string is malformed.
A composite signature allows the security properties of the two
underlying algorithms to be combined via standard signature
operations Sign() and Verify().
This specification uses the Post-Quantum signature scheme ML-DSA as
specified in [FIPS.204] and [I-D.ietf-lamps-dilithium-certificates].
For Traditional signature schemes, this document uses the RSASSA-
PKCS1-v1_5 and RSASSA-PSS algorithms defined in [RFC8017], the
Elliptic Curve Digital Signature Algorithm ECDSA scheme defined in
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section 6 of [FIPS.186-5], and Ed25519 / Ed448 which are defined in
[RFC8410]. A simple "signature combiner"function which prepends a
domain separator value specific to the composite algorithm is used to
bind the two component signatures to the composite algorithm and
achieve weak non-separability.
3.1. Pure vs Pre-hashed modes
In [FIPS.204] NIST defined ML-DSA to have both pure and pre-hashed
signing modes, referred to as "ML-DSA" and "HashML-DSA" respectively.
Following this, this document defines "Composite-ML-DSA" and
"HashComposite-ML-DSA" which mirror the external functions defined in
[FIPS.204].
4. Composite ML-DSA Functions
4.1. Key Generation
To generate a new keypair for Composite schemes, the KeyGen() -> (pk,
sk) function is used. The KeyGen() function calls the two key
generation functions of the component algorithms for the Composite
keypair in no particular order. Multi-process or multi-threaded
applications might choose to execute the key generation functions in
parallel for better key generation performance.
The following process is used to generate composite keypair values:
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KeyGen() -> (pk, sk)
Explicit inputs:
None
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSASSA-PSS"
or "Ed25519".
Output:
(pk, sk) The composite keypair.
Key Generation Process:
1. Generate component keys
(mldsaPK, mldsaSK) = ML-DSA.KeyGen()
(tradPK, tradSK) = Trad.KeyGen()
2. Check for component key gen failure
if NOT (mldsaPK, mldsaSK) or NOT (tradPK, tradSK):
output "Key generation error"
3. Encode the component keys into composite structures
pk = CompositeSignaturePublicKey(mldsaPK, tradPK)
sk = CompositeSignaturePrivateKey(mldsaSK, tradSK)
4. Output the composite keys
return (pk, sk)
Figure 1: Composite KeyGen(pk, sk)
The structures CompositeSignaturePublicKey and
CompositeSignaturePrivateKey are described in Section 5.1 and
Section 5.2 respectively and are used here as placeholders since
implementations MAY use their own internal key representations in
cases where interoperability is not required.
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In order to ensure fresh keys, the key generation functions MUST be
executed for both component algorithms. Compliant parties MUST NOT
use, import or export component keys that are used in other contexts,
combinations, or by themselves as keys for standalone algorithm use.
For more details on the security considerations around key reuse, see
section Section 11.3.
Note that in step 2 above, both component key generation processes
are invoked, and no indication is given about which one failed. This
SHOULD be done in a timing-invariant way to prevent side-channel
attackers from learning which component algorithm failed.
4.2. Pure Signature Mode
This mode mirrors ML-DSA defined in Sections 5.2 and 5.3 of
[FIPS.204].
In the pure mode the Domain separator value is concatenated with the
length of the context in bytes, the context, and the message to be
signed. After that, the signature process for each component
algorithm is invoked and the values are then placed in the
CompositeSignatureValue structure defined in Section 6.1.
A composite signature's value MUST include two signature components
and MUST be in the same order as the components from the
corresponding signing key.
4.2.1. Composite-ML-DSA.Sign
This mode mirrors ML-DSA.Sign(sk, M, ctx) defined in Algorithm 2 in
Section 5.2 of [FIPS.204].
Composite-ML-DSA.Sign (sk, M, ctx) -> (signature)
Explicit inputs:
sk Composite private key consisting of signing private keys for
each component.
M The Message to be signed, an octet string.
ctx The Message context string used in the composite signature
combiner, which defaults to the empty string.
Implicit inputs:
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ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSASSA-PSS with id-sha256"
or "Ed25519".
Domain Domain separator value for binding the signature to the
Composite OID. See section on Domain Separators below.
Prefix The prefix String which is the byte encoding of the String
"CompositeAlgorithmSignatures2025" which in hex is
436F6D706F73697465416C676F726974686D5369676E61747572657332303235
Output:
signature The composite signature, a CompositeSignatureValue.
Signature Generation Process:
1. If len(ctx) > 255:
return error
2. Compute the Message M'.
M' = Prefix || Domain || len(ctx) || ctx || M
3. Separate the private key into component keys.
(mldsaSK, tradSK) = sk
4. Generate the 2 component signatures independently, by calculating
the signature over M' according to their algorithm specifications.
mldsaSig = ML-DSA.Sign( mldsaSK, M', ctx=Domain )
tradSig = Trad.Sign( tradSK, M' )
5. If either ML-DSA.Sign() or Trad.Sign() return an error, then this
process must return an error.
if NOT mldsaSig or NOT tradSig:
output "Signature generation error"
6. Encode each component signature into a CompositeSignatureValue.
signature = CompositeSignatureValue(mldsaSig, tradSig)
7. Output signature
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return signature
Figure 2: Composite-ML-DSA.Sign(sk, M, ctx)
It is possible to use component private keys stored in separate
software or hardware keystores. Variations in the process to
accommodate particular private key storage mechanisms are considered
to be conformant to this document so long as it produces the same
output and error handling as the process sketched above.
Note that in step 5 above, both component signature processes are
invoked, and no indication is given about which one failed. This
SHOULD be done in a timing-invariant way to prevent side-channel
attackers from learning which component algorithm failed.
Note that there are two different context strings ctx here: the first
is the application context that is passed in to Composite-ML-DSA.Sign
and bound to the composite signature combiner. The second is the ctx
that is passed down into the underlying ML-DSA.Sign and here
Composite-ML-DSA itself is the application that we wish to bind, and
outer ctx is already contained within the M' message.
4.2.2. Composite-ML-DSA.Verify
This mode mirrors ML-DSA.Verify(pk, M, signature, ctx) defined in
Algorithm 3 in Section 5.3 of [FIPS.204].
Compliant applications MUST output "Valid signature" (true) if and
only if all component signatures were successfully validated, and
"Invalid signature" (false) otherwise.
Composite-ML-DSA.Verify(pk, M, signature, ctx)
Explicit inputs:
pk Composite public key consisting of verification public keys
for each component.
M Message whose signature is to be verified,
an octet string.
signature CompositeSignatureValue containing the component
signature values (mldsaSig and tradSig) to be verified.
ctx The Message context string used in the composite signature
combiner, which defaults to the empty string.
Implicit inputs:
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ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSASSA-PSS with id-sha256"
or "Ed25519".
Domain Domain separator value for binding the signature to the
Composite OID. See section on Domain Separators below.
Prefix The prefix String which is the byte encoding of the String
"CompositeAlgorithmSignatures2025" which in hex is
436F6D706F73697465416C676F726974686D5369676E61747572657332303235
Output:
Validity (bool) "Valid signature" (true) if the composite
signature is valid, "Invalid signature"
(false) otherwise.
Signature Verification Process:
1. If len(ctx) > 255
return error
2. Separate the keys and signatures
(pk1, pk2) = pk
(s1, s2) = signature
If Error during Desequencing, or if any of the component
keys or signature values are not of the correct key type or
length for the given component algorithm then output
"Invalid signature" and stop.
3. Compute the Message M'.
M' = Prefix || Domain || len(ctx) || ctx || M
4. Check each component signature individually, according to its
algorithm specification.
If any fail, then the entire signature validation fails.
if not ML-DSA.Verify( pk1, M', s1, ctx=Domain) then
output "Invalid signature"
if not Trad.Verify( pk2, M', s2) then
output "Invalid signature"
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if all succeeded, then
output "Valid signature"
Figure 3: Composite-ML-DSA.Verify(pk, Message, signature, Context)
Note that in step 4 above, the function fails early if the first
component fails to verify. Since no private keys are involved in a
signature verification, there are no timing attacks to consider, so
this is ok.
4.3. PreHash-Signature Mode
This mode mirrors HashML-DSA defined in Section 5.4 of [FIPS.204].
In the pre-hash mode the Domain separator Section 7.3 is concatenated
with the length of the context in bytes, the context, an additional
DER encoded value that represents the OID of the Hash function and
finally the hash of the message to be signed. After that, the
signature process for each component algorithm is invoked and the
values are then placed in the CompositeSignatureValue structure
defined in Section 6.1.
A composite signature's value MUST include two signature components
and MUST be in the same order as the components from the
corresponding signing key.
Note that there are two different context strings ctx here: the first
is the application context that is passed in to Composite-ML-DSA.Sign
and bound to the composite signature combiner. The second is the ctx
that is passed down into the underlying ML-DSA.Sign and here
Composite-ML-DSA itself is the application that we wish to bind, and
outer ctx is already contained within the M' message.
4.3.1. HashComposite-ML-DSA-Sign signature mode
This mode mirrors HashML-DSA.Sign(sk, M, ctx, PH) defined in
Algorithm 4 Section 5.4.1 of [FIPS.204].
In the pre-hash mode the Domain separator (see Section 7.3) is
concatenated with the length of the context in bytes, the context, an
additional DER encoded value that indicates which Hash function was
used for the pre-hash and finally the pre-hashed message PH(M).
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HashComposite-ML-DSA.Sign (sk, M, ctx, PH) -> (signature)
Explicit inputs:
sk Composite private key consisting of signing private keys for
each component.
M The Message to be signed, an octet string.
ctx The Message context string used in the composite signature
combiner, which defaults to the empty string.
PH The Message Digest Algorithm for pre-hashing. See
section on pre-hashing the message below.
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSASSA-PSS with id-sha256"
or "Ed25519".
Prefix The prefix String which is the byte encoding of the String
"CompositeAlgorithmSignatures2025" which in hex is
436F6D706F73697465416C676F726974686D5369676E61747572657332303235
Domain Domain separator value for binding the signature to the
Composite OID. See section on Domain Separators below.
HashOID The DER Encoding of the Object Identifier of the
PreHash algorithm (PH) which is passed into the function.
Output:
signature The composite signature, a CompositeSignatureValue.
Signature Generation Process:
1. If len(ctx) > 255:
return error
2. Compute the Message format M'.
M' := Prefix || Domain || len(ctx) || ctx || HashOID || PH(M)
3. Separate the private key into component keys.
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(mldsaSK, tradSK) = sk
4. Generate the 2 component signatures independently, by calculating
the signature over M' according to their algorithm specifications.
mldsaSig = ML-DSA.Sign( mldsaSK, M', ctx=Domain )
tradSig = Trad.Sign( tradSK, M' )
5. If either ML-DSA.Sign() or Trad.Sign() return an error, then this
process must return an error.
if NOT mldsaSig or NOT tradSig:
output "Signature generation error"
6. Encode each component signature into a CompositeSignatureValue.
signature := CompositeSignatureValue(mldsaSig, tradSig)
7. Output signature
return signature
Figure 4: HashComposite-ML-DSA.Sign(sk, M, ctx, PH)
It is possible to use component private keys stored in separate
software or hardware keystores. Variations in the process to
accommodate particular private key storage mechanisms are considered
to be conformant to this document so long as it produces the same
output and error handling as the process sketched above.
Note that in step 5 above, both component signature processes are
invoked, and no indication is given about which one failed. This
SHOULD be done in a timing-invariant way to prevent side-channel
attackers from learning which component algorithm failed.
Note that there are two different context strings ctx here: the first
is the application context that is passed in to Composite-ML-DSA.Sign
and bound to the composite signature combiner. The second is the ctx
that is passed down into the underlying ML-DSA.Sign and here
Composite-ML-DSA itself is the application that we wish to bind, and
outer ctx is already contained within the M' message.
4.3.2. HashComposite-ML-DSA-Verify
This mode mirrors HashML-DSA.Verify(pk, M, signature, ctx, PH)
defined in Section 5.4.1 of [FIPS.204].
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Compliant applications MUST output "Valid signature" (true) if and
only if all component signatures were successfully validated, and
"Invalid signature" (false) otherwise.
HashComposite-ML-DSA.Verify(pk, M, signature, ctx, PH)
Explicit inputs:
pk Composite public key consisting of verification public
keys for each component.
M Message whose signature is to be verified, an octet
string.
signature CompositeSignatureValue containing the component
signature values (mldsaSig and tradSig) to be verified.
ctx The Message context string used in the composite signature
combiner, which defaults to the empty string.
PH The Message Digest Algorithm for pre-hashing. See
section on pre-hashing the message below.
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSASSA-PSS with id-sha256"
or "Ed25519".
Prefix The prefix String which is the byte encoding of the String
"CompositeAlgorithmSignatures2025" which in hex is
436F6D706F73697465416C676F726974686D5369676E61747572657332303235
Domain Domain separator value for binding the signature to the
Composite OID. See section on Domain Separators below.
HashOID The DER Encoding of the Object Identifier of the
PreHash algorithm (PH) which is passed into the function.
Output:
Validity (bool) "Valid signature" (true) if the composite
signature is valid, "Invalid signature"
(false) otherwise.
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Signature Verification Process:
1. If len(ctx) > 255
return error
2. Separate the keys and signatures
(pk1, pk2) = pk
(s1, s2) = signature
If Error during Desequencing, or if any of the component
keys or signature values are not of the correct key type or
length for the given component algorithm then output
"Invalid signature" and stop.
3. Compute a Hash of the Message.
M' = Prefix || Domain || len(ctx) || ctx || HashOID || PH(M)
4. Check each component signature individually, according to its
algorithm specification.
If any fail, then the entire signature validation fails.
if not ML-DSA.Verify( pk1, M', s1, ctx=Domain ) then
output "Invalid signature"
if not Trad.Verify( pk2, M', s2 ) then
output "Invalid signature"
if all succeeded, then
output "Valid signature"
Figure 5: HashComposite-ML-DSA.Verify(pk, M, signature, ctx, PH)
Note that in step 4 above, the function fails early if the first
component fails to verify. Since no private keys are involved in a
signature verification, there are no timing attacks to consider, so
this is ok.
Note that there are two different context strings ctx here: the first
is the application context that is passed in to Composite-ML-DSA.Sign
and bound to the composite signature combiner. The second is the ctx
that is passed down into the underlying ML-DSA.Sign and here
Composite-ML-DSA itself is the application that we wish to bind, and
outer ctx is already contained within the M' message.
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4.4. SerializeKey and DeserializeKey
Each component key is serialized according to their respective
standard as shown in Appendix B and concatenated together using a
fixed 4-byte length field denoting the length in bytes of the first
component key, as shown below.
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Composite-ML-DSA.SerializeKey(key) -> bytes
Explicit Input:
key Composite ML-DSA public key or private key
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSA" or "ECDSA".
IntegerToBytes A function that takes an Integer and converts it to
a byte representation of size byteLength. See definition in
[FIPS.204]
Output:
bytes The encoded public key or private key
Serialization Process:
1. Separate the keys
(mldsaKey, tradKey) = key
2. Serialize each of the constituent public keys
The component keys are serialized according to their respective standard
as shown in the component algorithm appendix.
mldsaEncodedKey = MLDSA.SerializeKey(mldsaKey)
tradEncodedKey = Trad.SerializeKey(tradKey)
3. Calculate the length encoding of the mldsaEncodedPK
If (mldsaEncodeKey.length) > 2^32
then output "message too long" and stop.
encodedLength = IntegerToBytes(mldsaEncodeKey.length, 4)
4. Combine and output the encoded public key
bytes = encodedLength || mldsaEncodedPK || tradEncodedPK
output bytes
Figure 6: Composite SerializeKey(pk)
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Deserialization reverses this process, raising an error in the event
that the input is malformed. Each component key is deserialized
according to their respective standard as shown in Appendix B.
Composite-ML-DSA.DeserializeKey(bytes) -> pk
Explicit Input:
bytes An encoded public key or private key
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSA" or "ECDSA".
Output:
key The composite ML-DSA public key or private key
Deserialization Process:
1. Validate the length of the the input byte string
if bytes is not the correct length:
output "Deserialization error"
2. Parse each constituent encoded key.
The first 4 bytes encodes the length of mldsaEncodedKey, which MAY
be used to separate the mldsaEncodedKey and tradEncodedKey, and then
is to be discarded. This length SHOULD be checked against the
expected length value as per ML-DSA.
(mldsaEncodedKey, tradEncodedKey) = bytes
3. Deserialize the constituent public or private keys
The component keys are deserialized according to their respective standard
as shown in the component algorithm appendix.
mldsaKey = MLDSA.DeserializeKey(mldsaEncodedKey)
tradKey = Trad.DeserializeKey(tradEncodedKey)
4. If either ML-DSA.DeserializeKey() or
Trad.DeserializeKey() return an error,
then this process must return an error.
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if NOT mldsaKey or NOT tradKey:
output "Deserialization error"
5. Output the composite ML-DSA key
output (mldsaPK, tradPK)
Figure 7: Composite DeserializeKey(bytes)
4.5. SerializeSignatureValue and DeSerializeSignatureValue
Each component signature is serialized according to their respective
standard as shown in Appendix B and concatenated together using a
fixed 4-byte length field denoting the length in bytes of the first
component signature, as shown below.
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Composite-ML-DSA.SerializeSignatureValue(CompositeSignatureValue) -> bytes
Explicit Input:
CompositeSignatureValue The Composite Signature Value obtained from Composite-ML-DSA.Sign()
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSA" or "ECDSA".
IntegerToBytes A function that takes an Integer and converts it to
a byte representation of size byteLength. See definition in
[FIPS.204]
Output:
bytes The encoded CompositeSignatureValue
Serialization Process:
1. Separate the signatures
(mldsaSig, tradSig) = CompositeSignatureValue
2. Serialize each of the constituent signatures
The component signatures are serialized according to their respective standard
as shown in the component algorithm appendix.
mldsaEncodedSignature = ML-DSA.SerializeSignature(mldsaSig)
tradEncodedSignature = Trad.SerializeSignature(tradSig)
3. Calculate the length encoding of the mldsaEncodedSignature
If (mldsaEncodeKey.length) > 2^32
then output "message too long" and stop.
encodedLength = IntegerToBytes(mldsaEncodeKey.length, 4)
encodedLength = IntegerToBytes(mldsaEncodedSignature.length, 4)
4. Combine and output the encoded composite signature
bytes = encodedLength || mldsaEncodedSignature || tradEncodedSignature
output bytes
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Figure 8: Composite SerializeSignatureValue(CompositeSignatureValue)
Deserialization reverses this process, raising an error in the event
that the input is malformed. Each component signature is
deserialized according to their respective standard as shown in
Appendix B.
Composite-ML-DSA.DeserializeSignatureValue(bytes) -> CompositeSignatureValue
Explicit Input:
bytes An encoded CompositeSignatureValue
Implicit inputs:
ML-DSA A placeholder for the specific ML-DSA algorithm and
parameter set to use, for example, could be "ML-DSA-65".
Trad A placeholder for the specific traditional algorithm and
parameter set to use, for example "RSA" or "ECDSA".
Output:
CompositeSignatureValue The CompositeSignatureValue
Deserialization Process:
1. Validate the length of the the input byte string
if bytes is not the correct length:
output "Deserialization error"
2. Parse each constituent encoded signature.
The first 4 bytes encodes the length of mldsaEncodedSignature, which MAY
be used to separate the mldsaEncodedSignature and tradEncodedSignature,
and then is to be discarded. The mldsaEncodedSignature length SHOULD
be checked against the expected length value as per ML-DSA.
(mldsaEncodedSignature, tradEncodedSignature) = bytes
3. Deserialize the constituent signature values
The component signatures are deserialized according to their respective standard
as shown in the component algorithm appendix.
mldsaSig = ML-DSA.DeserializeSignature(mldsaEncodedSignature)
tradSig = Trad.DeserializeSignature(tradEncodedSignature)
4. If either ML-DSA.DeserializeSignature() or
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Trad.DeserializeSignature() return an error,
then this process must return an error.
if NOT mldsaSig or NOT tradSig:
output "Deserialization error"
5. Output the CompositeSignatureValue
output (mldsaSig, tradSig)
Figure 9: Composite DeserializeSignatureValue(bytes)
4.6. ML-DSA public key, private key and signature sizes for
serialization and deserialization
As noted above, the composite public key, composite private key and
composite signature value serialization and deserialization methods
use a fixed 4-byte length value to indicate the size of the first
component. This is to allow the separation of the first component
from the second component. It is RECOMMENDED that the length
specified for the first component be checked against the values from
the table below to ensure the encoding has been done propertly.
If future composite combinations make use of algorithms where the
first component uses variable length keys or signatures, then this
fixed 4-byte length value can be used to ensure the components are
correctly deserialized.
The following table shows the possible length values in bytes for the
public, private and signature sizes for ML-DSA which can be used to
deserialzie the components.
+===========+============+====================+===========+
| Algorithm | Public key | Private key | Signature |
+===========+============+====================+===========+
| ML-DSA-44 | 1312 | 32 or 2560 or 2592 | 2420 |
+-----------+------------+--------------------+-----------+
| ML-DSA-65 | 1952 | 32 or 4032 or 4064 | 3309 |
+-----------+------------+--------------------+-----------+
| ML-DSA-87 | 2592 | 32 or 4896 or 4928 | 4627 |
+-----------+------------+--------------------+-----------+
Table 1: ML-DSA Key and Signature Sizes in bytes
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5. Composite Key Structures
In order to form composite public keys and signature values, we
define ASN.1-based composite encodings such that these structures can
be used as a drop-in replacement for existing public key and
signature fields such as those found in PKCS#10 [RFC2986], CMP
[RFC4210], X.509 [RFC5280], CMS [RFC5652].
5.1. CompositeMLDSAPublicKey
The wire encoding of a Composite ML-DSA public key is:
CompositeMLDSAPublicKey ::= BIT STRING
Since RSA and ECDSA component public keys are themselves in a DER
encoding, the following show the internal structure of the various
public key types used in this specification:
When a CompositeMLDSAPublicKey is used with an RSA public key, the
BIT STRING is generated by the concatenation of a raw ML-DSA key
according to [I-D.ietf-lamps-dilithium-certificates], and an
RSAPublicKey (which is a DER encoded RSAPublicKey).
When a CompositeMLDSAPublicKey is used with an EC public key, the BIT
STRING is generated by the concatenation of a raw ML-DSA key
according to [I-D.ietf-lamps-dilithium-certificates] and an
ECDSAPublicKey (which is a DER encoded ECPoint).
When a CompositeMLDSAPublicKey is used with an Edwards public key,
the BIT STRING is generated by the concatenation of a raw ML-DSA key
according to [I-D.ietf-lamps-dilithium-certificates] and a raw
Edwards public key according to [RFC8410].
Some applications may need to reconstruct the SubjectPublicKeyInfo
objects corresponding to each component public key. Table 2 or
Table 3 in Section 7 provides the necessary mapping between composite
and their component algorithms for doing this reconstruction.
When the CompositeMLDSAPublicKey must be provided in octet string or
bit string format, the data structure is encoded as specified in
Section 5.3.
Component keys of a CompositeMLDSAPublicKey MUST NOT be used in any
other type of key or as a standalone key. For more details on the
security considerations around key reuse, see section Section 11.3.
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The following ASN.1 Information Object Class is defined to allow for
compact definitions of each composite algorithm, leading to a smaller
overall ASN.1 module.
pk-CompositeSignature {OBJECT IDENTIFIER:id, PublicKeyType}
PUBLIC-KEY ::= {
IDENTIFIER id
KEY PublicKeyType
PARAMS ARE absent
CERT-KEY-USAGE { digitalSignature, nonRepudiation, keyCertSign, cRLSign}
}
As an example, the public key type id-MLDSA44-ECDSA-P256 is defined
as:
id-MLDSA44-ECDSA-P256 PUBLIC-KEY ::=
pk-CompositeSignature{
id-MLDSA44-ECDSA-P256,
CompositeMLDSAPublicKey }
The full set of key types defined by this specification can be found
in the ASN.1 Module in Section 9.
5.2. CompositeMLDSAPrivateKey
When a Composite ML-DSA private key is to be exported from a
cryptographic module, it uses an analogous definition to the public
keys:
CompositeMLDSAPrivateKey ::= OCTET STRING
Each element of the CompositeMLDSAPrivateKey is an OCTET STRING
according to the encoding of the underlying algorithm specification
and will decode into the respective private key structures in an
analogous way to the public key structures defined in Section 5.1.
The ASN.1 module in this document does not provide helper classes for
private keys. The PrivateKey for each component algorithm MUST be in
the same order as defined in Section 5.1.
Use cases that require an interoperable encoding for composite
private keys will often need to place a CompositeMLDSAPrivateKey
inside a OneAsymmetricKey structure defined in [RFC5958], such as
when private keys are carried in PKCS #12 [RFC7292], CMP [RFC4210] or
CRMF [RFC4211]. The definition of OneAsymmetricKey is copied here
for convenience:
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OneAsymmetricKey ::= SEQUENCE {
version Version,
privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
privateKey PrivateKey,
attributes [0] Attributes OPTIONAL,
...,
[[2: publicKey [1] PublicKey OPTIONAL ]],
...
}
...
PrivateKey ::= OCTET STRING
-- Content varies based on type of key. The
-- algorithm identifier dictates the format of
-- the key.
When a CompositeMLDSAPrivateKey is conveyed inside a OneAsymmetricKey
structure (version 1 of which is also known as PrivateKeyInfo)
[RFC5958], the privateKeyAlgorithm field SHALL be set to the
corresponding composite algorithm identifier defined according to
Section 7 and its parameters field MUST be absent. The privateKey
field SHALL contain the CompositeMLDSAPrivateKey, and the publicKey
field remains OPTIONAL. If the publicKey field is present, it MUST
be a CompositeMLDSAPublicKey.
Some applications may need to reconstruct the OneAsymmetricKey
objects corresponding to each component private key. Section 7
provides the necessary mapping between composite and their component
algorithms for doing this reconstruction.
Component keys of a CompositeMLDSAPrivateKey MUST NOT be used in any
other type of key or as a standalone key. For more details on the
security considerations around key reuse, see section Section 11.3.
5.3. Encoding Rules
Many protocol specifications will require that the composite public
key and composite private key data structures be represented by an
octet string or bit string.
When an octet string is required, the DER encoding of the composite
data structure SHALL be used directly.
When a bit string is required, the octets of the DER encoded
composite data structure SHALL be used as the bits of the bit string,
with the most significant bit of the first octet becoming the first
bit, and so on, ending with the least significant bit of the last
octet becoming the last bit of the bit string.
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In the interests of simplicity and avoiding compatibility issues,
implementations that parse these structures MAY accept both BER and
DER.
5.4. Key Usage Bits
When any of the Composite ML-DSA AlgorithmIdentifier appears in the
SubjectPublicKeyInfo field of an X.509 certificate [RFC5280], the key
usage certificate extension MUST only contain only signing-type key
usages.
The normal keyUsage rules for signing-type keys from [RFC5280] apply,
and are reproduced here for completeness.
For Certification Authority (CA) certificates that carry a composite
public key, any combination of the following values MAY be present
and any other values MUST NOT be present:
digitalSignature;
nonRepudiation;
keyCertSign; and
cRLSign.
For End Entity certificates, any combination of the following values
MAY be present and any other values MUST NOT be present:
digitalSignature; and
nonRepudiation;
Composite ML-DSA keys MUST NOT be used in a "dual usage" mode because
even if the traditional component key supports both signing and
encryption, the post-quantum algorithms do not and therefore the
overall composite algorithm does not.
6. Composite Signature Structures
6.1. sa-CompositeSignature
The ASN.1 algorithm object for a composite signature is:
sa-CompositeSignature{OBJECT IDENTIFIER:id,
PUBLIC-KEY:publicKeyType }
SIGNATURE-ALGORITHM ::= {
IDENTIFIER id
VALUE CompositeSignatureValue
PARAMS ARE absent
PUBLIC-KEYS {publicKeyType}
}
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6.2. CompositeSignatureValue
The output of a Composite ML-DSA algorithm is the DER encoding of the
following structure:
The CompositeSignatureValue is the DER encoding of a concatenation of
the signature values from the underlying component algorithms. It is
represented in ASN.1 as follows:
CompositeSignatureValue ::= BIT STRING
The order of the component signature values is the same as the order
defined in Section 5.1.
7. Algorithm Identifiers
This table summarizes the list of Composite ML-DSA algorithms and
lists the OID and the two component algorithms. Domain separator
values are defined below in Section 7.3.
EDNOTE: these are prototyping OIDs to be replaced by IANA.
<CompSig>.1 is equal to 2.16.840.1.114027.80.8.1.1
7.1. PureComposite-ML-DSA Algorithm Identifiers
Pure Composite-ML-DSA Signature public key types:
+======================+============+=========+=======================+
|Composite Signature |OID |First |Second Algorithm |
|Algorithm | |Algorithm| |
+======================+============+=========+=======================+
|id-MLDSA44-RSA2048-PSS|<CompSig>.60|id-ML- |id-RSASSA-PSS with id- |
| | |DSA-44 |sha256 |
+----------------------+------------+---------+-----------------------+
|id- |<CompSig>.61|id-ML- |sha256WithRSAEncryption|
|MLDSA44-RSA2048-PKCS15| |DSA-44 | |
+----------------------+------------+---------+-----------------------+
|id-MLDSA44-Ed25519 |<CompSig>.62|id-ML- |id-Ed25519 |
| | |DSA-44 | |
+----------------------+------------+---------+-----------------------+
|id-MLDSA44-ECDSA-P256 |<CompSig>.63|id-ML- |ecdsa-with-SHA256 with |
| | |DSA-44 |secp256r1 |
+----------------------+------------+---------+-----------------------+
|id-MLDSA65-RSA3072-PSS|<CompSig>.64|id-ML- |id-RSASSA-PSS with id- |
| | |DSA-65 |sha256 |
+----------------------+------------+---------+-----------------------+
|id- |<CompSig>.65|id-ML- |sha256WithRSAEncryption|
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|MLDSA65-RSA3072-PKCS15| |DSA-65 | |
+----------------------+------------+---------+-----------------------+
|id-MLDSA65-RSA4096-PSS|<CompSig>.66|id-ML- |id-RSASSA-PSS with id- |
| | |DSA-65 |sha384 |
+----------------------+------------+---------+-----------------------+
|id- |<CompSig>.67|id-ML- |sha384WithRSAEncryption|
|MLDSA65-RSA4096-PKCS15| |DSA-65 | |
+----------------------+------------+---------+-----------------------+
|id-MLDSA65-ECDSA-P256 |<CompSig>.68|id-ML- |ecdsa-with-SHA256 with |
| | |DSA-65 |secp256r1 |
+----------------------+------------+---------+-----------------------+
|id-MLDSA65-ECDSA-P384 |<CompSig>.69|id-ML- |ecdsa-with-SHA384 with |
| | |DSA-65 |secp384r1 |
+----------------------+------------+---------+-----------------------+
|id-MLDSA65-ECDSA- |<CompSig>.70|id-ML- |ecdsa-with-SHA256 with |
|brainpoolP256r1 | |DSA-65 |brainpoolP256r1 |
+----------------------+------------+---------+-----------------------+
|id-MLDSA65-Ed25519 |<CompSig>.71|id-ML- |id-Ed25519 |
| | |DSA-65 | |
+----------------------+------------+---------+-----------------------+
|id-MLDSA87-ECDSA-P384 |<CompSig>.72|id-ML- |ecdsa-with-SHA384 with |
| | |DSA-87 |secp384r1 |
+----------------------+------------+---------+-----------------------+
|id-MLDSA87-ECDSA- |<CompSig>.73|id-ML- |ecdsa-with-SHA384 with |
|brainpoolP384r1 | |DSA-87 |brainpoolP384r1 |
+----------------------+------------+---------+-----------------------+
|id-MLDSA87-Ed448 |<CompSig>.74|id-ML- |id-Ed448 |
| | |DSA-87 | |
+----------------------+------------+---------+-----------------------+
|id-MLDSA87-RSA4096-PSS|<CompSig>.75|id-ML- |id-RSASSA-PSS with id- |
| | |DSA-87 |sha384 |
+----------------------+------------+---------+-----------------------+
Table 2: Pure ML-DSA Composite Signature Algorithms
See the ASN.1 module in section Section 9 for the explicit
definitions of the above Composite ML-DSA algorithms.
Full specifications for the referenced algorithms can be found in
Appendix B.
7.2. HashComposite-ML-DSA Algorithm Identifiers
HashComposite-ML-DSA Signature public key types:
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+=================================+============+=========+=======================+======+
|Composite Signature Algorithm |OID |First |Second Algorithm |Pre- |
| | |Algorithm| |Hash |
+=================================+============+=========+=======================+======+
|id-HashMLDSA44-RSA2048-PSS-SHA256|<CompSig>.80|id-ML- |id-RSASSA-PSS with id- |id- |
| | |DSA-44 |sha256 |sha256|
+---------------------------------+------------+---------+-----------------------+------+
|id- |<CompSig>.81|id-ML- |sha256WithRSAEncryption|id- |
|HashMLDSA44-RSA2048-PKCS15-SHA256| |DSA-44 | |sha256|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA44-Ed25519-SHA512 |<CompSig>.82|id-ML- |id-Ed25519 |id- |
| | |DSA-44 | |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA44-ECDSA-P256-SHA256 |<CompSig>.83|id-ML- |ecdsa-with-SHA256 with |id- |
| | |DSA-44 |secp256r1 |sha256|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA65-RSA3072-PSS-SHA512|<CompSig>.84|id-ML- |id-RSASSA-PSS with id- |id- |
| | |DSA-65 |sha256 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id- |<CompSig>.85|id-ML- |sha256WithRSAEncryption|id- |
|HashMLDSA65-RSA3072-PKCS15-SHA512| |DSA-65 | |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA65-RSA4096-PSS-SHA512|<CompSig>.86|id-ML- |id-RSASSA-PSS with id- |id- |
| | |DSA-65 |sha384 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id- |<CompSig>.87|id-ML- |sha384WithRSAEncryption|id- |
|HashMLDSA65-RSA4096-PKCS15-SHA512| |DSA-65 | |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA65-ECDSA-P256-SHA512 |<CompSig>.88|id-ML- |ecdsa-with-SHA256 with |id- |
| | |DSA-65 |secp256r1 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA65-ECDSA-P384-SHA512 |<CompSig>.89|id-ML- |ecdsa-with-SHA384 with |id- |
| | |DSA-65 |secp384r1 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA65-ECDSA- |<CompSig>.90|id-ML- |ecdsa-with-SHA256 with |id- |
|brainpoolP256r1-SHA512 | |DSA-65 |brainpoolP256r1 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA65-Ed25519-SHA512 |<CompSig>.91|id-ML- |id-Ed25519 |id- |
| | |DSA-65 | |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA87-ECDSA-P384-SHA512 |<CompSig>.92|id-ML- |ecdsa-with-SHA384 with |id- |
| | |DSA-87 |secp384r1 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA87-ECDSA- |<CompSig>.93|id-ML- |ecdsa-with-SHA384 with |id- |
|brainpoolP384r1-SHA512 | |DSA-87 |brainpoolP384r1 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA87-Ed448-SHA512 |<CompSig>.94|id-ML- |id-Ed448 |id- |
| | |DSA-87 | |sha512|
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+---------------------------------+------------+---------+-----------------------+------+
|id-HashMLDSA87-RSA4096-PSS-SHA512|<CompSig>.95|id-ML- |id-RSASSA-PSS with id- |id- |
| | |DSA-87 |sha384 |sha512|
+---------------------------------+------------+---------+-----------------------+------+
Table 3: Hash ML-DSA Composite Signature Algorithms
See the ASN.1 module in Section 9 for the explicit definitions of the
above Composite ML-DSA algorithms.
The Pre-Hash algorithm is used as the PH algorithm and the DER
Encoded OID value of this Hash is used as HashOID for the Message
format in step 2 of HashComposite-ML-DSA.Sign in section
Section 4.3.1 and HashComposite-ML-DSA.Verify in Section 4.3.2.
Full specifications for the referenced algorithms can be found in
Appendix B.
7.3. Domain Separators
As mentioned above, the OID input value is used as a domain separator
for the Composite Signature Generation and verification process and
is the DER encoding of the OID. The following table shows the HEX
encoding for each Signature Algorithm.
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+==================================+============================+
| Composite Signature Algorithm | Domain Separator (in Hex |
| | encoding) |
+==================================+============================+
| id-MLDSA44-RSA2048-PSS | 060B6086480186FA6B5008013C |
+----------------------------------+----------------------------+
| id-MLDSA44-RSA2048-PKCS15 | 060B6086480186FA6B5008013D |
+----------------------------------+----------------------------+
| id-MLDSA44-Ed25519 | 060B6086480186FA6B5008013E |
+----------------------------------+----------------------------+
| id-MLDSA44-ECDSA-P256 | 060B6086480186FA6B5008013F |
+----------------------------------+----------------------------+
| id-MLDSA65-RSA3072-PSS | 060B6086480186FA6B50080140 |
+----------------------------------+----------------------------+
| id-MLDSA65-RSA3072-PKCS15 | 060B6086480186FA6B50080141 |
+----------------------------------+----------------------------+
| id-MLDSA65-RSA4096-PSS | 060B6086480186FA6B50080142 |
+----------------------------------+----------------------------+
| id-MLDSA65-RSA4096-PKCS15 | 060B6086480186FA6B50080143 |
+----------------------------------+----------------------------+
| id-MLDSA65-ECDSA-P256 | 060B6086480186FA6B50080144 |
+----------------------------------+----------------------------+
| id-MLDSA65-ECDSA-P384 | 060B6086480186FA6B50080145 |
+----------------------------------+----------------------------+
| id-MLDSA65-ECDSA-brainpoolP256r1 | 060B6086480186FA6B50080146 |
+----------------------------------+----------------------------+
| id-MLDSA65-Ed25519 | 060B6086480186FA6B50080147 |
+----------------------------------+----------------------------+
| id-MLDSA87-ECDSA-P384 | 060B6086480186FA6B50080148 |
+----------------------------------+----------------------------+
| id-MLDSA87-ECDSA-brainpoolP384r1 | 060B6086480186FA6B50080149 |
+----------------------------------+----------------------------+
| id-MLDSA87-Ed448 | 060B6086480186FA6B5008014A |
+----------------------------------+----------------------------+
| id-MLDSA87-RSA4096-PSS | 060B6086480186FA6B5008014B |
+----------------------------------+----------------------------+
Table 4
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+===================================+============================+
| Composite Signature Algorithm | Domain Separator (in Hex |
| | encoding) |
+===================================+============================+
| id-HashMLDSA44-RSA2048-PSS-SHA256 | 060B6086480186FA6B50080150 |
+-----------------------------------+----------------------------+
| id- | 060B6086480186FA6B50080151 |
| HashMLDSA44-RSA2048-PKCS15-SHA256 | |
+-----------------------------------+----------------------------+
| id-HashMLDSA44-Ed25519-SHA512 | 060B6086480186FA6B50080152 |
+-----------------------------------+----------------------------+
| id-HashMLDSA44-ECDSA-P256-SHA256 | 060B6086480186FA6B50080153 |
+-----------------------------------+----------------------------+
| id-HashMLDSA65-RSA3072-PSS-SHA512 | 060B6086480186FA6B50080154 |
+-----------------------------------+----------------------------+
| id- | 060B6086480186FA6B50080155 |
| HashMLDSA65-RSA3072-PKCS15-SHA512 | |
+-----------------------------------+----------------------------+
| id-HashMLDSA65-RSA4096-PSS-SHA512 | 060B6086480186FA6B50080156 |
+-----------------------------------+----------------------------+
| id- | 060B6086480186FA6B50080157 |
| HashMLDSA65-RSA4096-PKCS15-SHA512 | |
+-----------------------------------+----------------------------+
| id-HashMLDSA65-ECDSA-P256-SHA512 | 060B6086480186FA6B50080158 |
+-----------------------------------+----------------------------+
| id-HashMLDSA65-ECDSA-P384-SHA512 | 060B6086480186FA6B50080159 |
+-----------------------------------+----------------------------+
| id-HashMLDSA65-ECDSA- | 060B6086480186FA6B5008015A |
| brainpoolP256r1-SHA512 | |
+-----------------------------------+----------------------------+
| id-HashMLDSA65-Ed25519-SHA512 | 060B6086480186FA6B5008015B |
+-----------------------------------+----------------------------+
| id-HashMLDSA87-ECDSA-P384-SHA512 | 060B6086480186FA6B5008015C |
+-----------------------------------+----------------------------+
| id-HashMLDSA87-ECDSA- | 060B6086480186FA6B5008015D |
| brainpoolP384r1-SHA512 | |
+-----------------------------------+----------------------------+
| id-HashMLDSA87-Ed448-SHA512 | 060B6086480186FA6B5008015E |
+-----------------------------------+----------------------------+
| id-HashMLDSA87-RSA4096-PSS-SHA512 | 060B6086480186FA6B5008015F |
+-----------------------------------+----------------------------+
Table 5: Hash ML-DSA Composite Signature Domain Separators
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7.4. Rationale for choices
In generating the list of Composite algorithms, the following general
guidance was used, however during development of this specification
several algorithms were added by direct request even though they do
not fit this guidance.
* Pair equivalent levels.
* NIST-P-384 is CNSA approved [CNSA2.0] for all classification
levels.
* 521 bit curve not widely used.
SHA2 is used throughout in order to facilitate implementations that
do not have easy access to SHA3 outside of the ML-DSA function.
At the higher security levels of pre-hashed Composite ML-DSA, for
example id-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512, the 384-bit
elliptic curve component is used with SHA2-384 which is its pre-hash
(ie the pre-hash that is considered to be internal to the ECDSA
component), yet SHA2-512 is used as the pre-hash for the overall
composite because in this case the pre-hash must not weaken the ML-
DSA-87 component against a collision attack.
7.5. RSASSA-PSS
Use of RSASSA-PSS [RFC8017] requires extra parameters to be
specified, which differ for each security level.
Also note that this specification fixes the Public Key OID of RSASSA-
PSS to id-RSASSA-PSS (1.2.840.113549.1.1.10), although most
implementations also would accept rsaEncryption
(1.2.840.113549.1.1.1).
7.5.1. RSA2048-PSS
The RSA component keys MUST be generated at the 2048-bit security
level in order to match that of ML-DSA-44.
As with the other composite signature algorithms, when id-
MLDSA44-RSA2048-PSS and id-HashMLDSA44-RSA2048-PSS-SHA256 is used in
an AlgorithmIdentifier, the parameters MUST be absent. id-
MLDSA44-RSA2048-PSS and id-HashMLDSA44-RSA2048-PSS-SHA256 SHALL
instantiate RSASSA-PSS with the following parameters:
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+==========================+=========+
| RSASSA-PSS Parameter | Value |
+==========================+=========+
| Mask Generation Function | mgf1 |
+--------------------------+---------+
| Mask Generation params | SHA-256 |
+--------------------------+---------+
| Message Digest Algorithm | SHA-256 |
+--------------------------+---------+
| Salt Length in bits | 256 |
+--------------------------+---------+
Table 6: RSASSA-PSS 2048 Parameters
where:
* Mask Generation Function (mgf1) is defined in [RFC8017]
* SHA-256 is defined in [RFC6234].
7.5.2. RSA3072-PSS
The RSA component keys MUST be generated at the 3072-bit security
level in order to match that of ML-DSA-65.
As with the other composite signature algorithms, when id-
MLDSA65-RSA3072-PSS or id-HashMLDSA65-RSA3072-PSS-SHA512 is used in
an AlgorithmIdentifier, the parameters MUST be absent. id-
MLDSA65-RSA3072-PSS or id-HashMLDSA65-RSA3072-PSS-SHA512 SHALL
instantiate RSASSA-PSS with the following parameters:
+==========================+=========+
| RSASSA-PSS Parameter | Value |
+==========================+=========+
| Mask Generation Function | mgf1 |
+--------------------------+---------+
| Mask Generation params | SHA-256 |
+--------------------------+---------+
| Message Digest Algorithm | SHA-256 |
+--------------------------+---------+
| Salt Length in bits | 256 |
+--------------------------+---------+
Table 7: RSASSA-PSS 3072 Parameters
where:
* Mask Generation Function (mgf1) is defined in [RFC8017]
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* SHA-256 is defined in [RFC6234].
7.5.3. RSA4096-PSS
The RSA component keys MUST be generated at the 4096-bit security
level in order to match that of ML-DSA-65.
As with the other composite signature algorithms, when id-
MLDSA65-RSA4096-PSS or id-HashMLDSA65-RSA4096-PSS-SHA384 is used in
an AlgorithmIdentifier, the parameters MUST be absent. id-
MLDSA65-RSA4096-PSS or id-HashMLDSA65-RSA4096-PSS-SHA384 SHALL
instantiate RSASSA-PSS with the following parameters:
+==========================+=========+
| RSASSA-PSS Parameter | Value |
+==========================+=========+
| Mask Generation Function | mgf1 |
+--------------------------+---------+
| Mask Generation params | SHA-384 |
+--------------------------+---------+
| Message Digest Algorithm | SHA-384 |
+--------------------------+---------+
| Salt Length in bits | 384 |
+--------------------------+---------+
Table 8: RSASSA-PSS 4096 Parameters
where:
* Mask Generation Function (mgf1) is defined in [RFC8017]
* SHA-384 is defined in [RFC6234].
8. Use in CMS
[EDNOTE: The convention in LAMPS is to specify algorithms and their
CMS conventions in separate documents. Here we have presented them
in the same document, but this section has been written so that it
can easily be moved to a stand-alone document.]
Composite Signature algorithms MAY be employed for one or more
recipients in the CMS signed-data content type [RFC5652].
All recommendations for using Composite ML-DSA in CMS are fully
aligned with the use of ML-DSA in CMS [I-D.ietf-lamps-cms-ml-dsa].
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8.1. Underlying Components
A compliant implementation MUST support SHA-512 [FIPS180] for all
composite variants in this document. Implementations MAY also
support other algorithms for the SignerInfo digestAlgorithm and
SHOULD use algorithms that produce a hash value of a size that is at
least twice the collision strength of the internal commitment hash
used by ML-DSA.
Note: The Hash ML-DSA Composite identifiers are relevant here because
this algorithm operation mode is not provided in CMS, which is
consistent with [I-D.ietf-lamps-cms-ml-dsa].
8.2. SignedData Conventions
As specified in CMS [RFC5652], the digital signature is produced from
the message digest and the signer's private key. The signature is
computed over different values depending on whether signed attributes
are absent or present.
When signed attributes are absent, the composite signature is
computed over the content of the signed-data. The "content" of a
signed-data is the value of the encapContentInfo eContent OCTET
STRING. The tag and length octets are not included. When signed
attributes are present, a hash is computed over the content using the
hash function specified in Section 8.1, and then a message-digest
attribute is constructed to contain the resulting hash value, and
then the result of DER encoding the set of signed attributes, which
MUST include a content-type attribute and a message-digest attribute,
and then the composite signature is computed over the DER-encoded
output. In summary:
IF (signed attributes are absent)
THEN Composite-ML-DSA.Sign(content)
ELSE message-digest attribute = Hash(content);
Composite-ML-DSA.Sign(DER(SignedAttributes))
When using Composite Signatures, the fields in the SignerInfo are
used as follows:
digestAlgorithm: Per Section 5.3 of [RFC5652], the digestAlgorithm
contains the one-way hash function used by the CMS signer. To ensure
collision resistance, the identified message digest algorithm SHOULD
produce a hash value of a size that is at least twice the collision
strength of the internal commitment hash used by ML-DSA component
algorithm of the Composite Signature.
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signatureAlgorithm: The signatureAlgorithm MUST contain one of the
the Composite Signature algorithm identifiers as specified in
Section 8.1}
signature: The signature field contains the signature value resulting
from the composite signing operation of the specified
signatureAlgorithm.
8.3. Signature generation and verification
Composite signatures have a context string input that can be used to
ensure that different signatures are generated for different
application contexts. When using composite signatures for CMS, the
context string is the empty string.
8.4. Certificate Conventions
The conventions specified in this section augment RFC 5280 [RFC5280].
The willingness to accept a composite Signature Algorithm MAY be
signaled by the use of the SMIMECapabilities Attribute as specified
in Section 2.5.2. of [RFC8551] or the SMIMECapabilities certificate
extension as specified in [RFC4262].
The intended application for the public key MAY be indicated in the
key usage certificate extension as specified in Section 4.2.1.3 of
[RFC5280]. If the keyUsage extension is present in a certificate
that conveys a composite Signature public key, then the key usage
extension MUST contain only the following value:
digitalSignature
nonRepudiation
keyCertSign
cRLSign
The keyEncipherment and dataEncipherment values MUST NOT be present.
That is, a public key intended to be employed only with a composite
signature algorithm MUST NOT also be employed for data encryption.
This requirement does not carry any particular security
consideration; only the convention that signature keys be identified
with 'digitalSignature','nonRepudiation','keyCertSign' or 'cRLSign'
key usages.
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8.5. SMIMECapabilities Attribute Conventions
Section 2.5.2 of [RFC8551] defines the SMIMECapabilities attribute to
announce a partial list of algorithms that an S/MIME implementation
can support. When constructing a CMS signed-data content type
[RFC5652], a compliant implementation MAY include the
SMIMECapabilities attribute.
The SMIMECapability SEQUENCE representing a composite signature
Algorithm MUST include the appropriate object identifier as per
Section 8.1 in the capabilityID field.
9. ASN.1 Module
<CODE STARTS>
Composite-MLDSA-2025
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-composite-mldsa-2025(TBDMOD) }
DEFINITIONS IMPLICIT TAGS ::= BEGIN
EXPORTS ALL;
IMPORTS
PUBLIC-KEY, SIGNATURE-ALGORITHM, SMIME-CAPS, AlgorithmIdentifier{}
FROM AlgorithmInformation-2009 -- RFC 5912 [X509ASN1]
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-algorithmInformation-02(58) }
;
--
-- Object Identifiers
--
-- Defined in ITU-T X.690
der OBJECT IDENTIFIER ::=
{joint-iso-itu-t asn1(1) ber-derived(2) distinguished-encoding(1)}
--
-- Signature Algorithm
--
--
-- Composite Signature basic structures
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--
--
-- When a CompositeMLDSAPublicKey is used with an RSA public key, the BIT STRING is generated
-- by the concatenation of a raw ML-DSA key according to {{I-D.ietf-lamps-dilithium-certificates}},
-- and an RSAPublicKey (which is a DER encoded RSAPublicKey).
-- When a CompositeMLDSAPublicKey is used with an EC public key, the BIT STRING is generated
-- by the concatenation of a raw ML-DSA key according to {{I-D.ietf-lamps-dilithium-certificates}}
-- and an ECDSAPublicKey according to [RFC5480].
-- When a CompositeMLDSAPublicKey is used with an Edwards public key, the BIT STRING is generated
-- by the concatenation of a raw ML-DSA key according to {{I-D.ietf-lamps-dilithium-certificates}}
-- and a raw Edwards public key according to [RFC8410].
CompositeMLDSAPublicKey ::= BIT STRING
--
-- When a CompositeMLDSAPrivateKey is used with an RSA public key, the OCTET STRING is generated
-- by the concatenation of an ML-DSA private key according to {{I-D.ietf-lamps-dilithium-certificates}},
-- and an RSAPrivateKey (which is a DER encoded RSAPrivateKey).
-- When a CompositeMLDSAPrivateKey is used with an EC public key, the OCTET STRING is generated
-- by the concatenation of an ML-DSA private key according to {{I-D.ietf-lamps-dilithium-certificates}},
-- and an ECDSAPrivateKey according to [RFC5915].
-- When a CompositeMLDSAPrivateKey is used with an Edwards public key, the OCTET STRING is generated
-- by the concatenation of an ML-DSA private key according to {{I-D.ietf-lamps-dilithium-certificates}},
-- and a raw Edwards private key according to [RFC8410].
CompositeMLDSAPrivateKey ::= OCTET STRING
-- Composite Signature Value is just an BIT STRING and is a concatenation of the component signature
-- algorithms.
CompositeSignatureValue ::= BIT STRING
--
-- Information Object Classes
--
pk-CompositeSignature {OBJECT IDENTIFIER:id, PublicKeyType}
PUBLIC-KEY ::= {
IDENTIFIER id
KEY PublicKeyType
PARAMS ARE absent
CERT-KEY-USAGE { digitalSignature, nonRepudiation, keyCertSign, cRLSign}
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}
sa-CompositeSignature{OBJECT IDENTIFIER:id,
PUBLIC-KEY:publicKeyType }
SIGNATURE-ALGORITHM ::= {
IDENTIFIER id
VALUE CompositeSignatureValue
PARAMS ARE absent
PUBLIC-KEYS {publicKeyType}
}
-- PURE Version of OIDS
-- TODO: OID to be replaced by IANA
id-MLDSA44-RSA2048-PSS OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 60 }
pk-MLDSA44-RSA2048-PSS PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA44-RSA2048-PSS,
CompositeMLDSAPublicKey}
sa-MLDSA44-RSA2048-PSS SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA44-RSA2048-PSS,
pk-MLDSA44-RSA2048-PSS }
-- TODO: OID to be replaced by IANA
id-MLDSA44-RSA2048-PKCS15 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 61 }
pk-MLDSA44-RSA2048-PKCS15 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA44-RSA2048-PKCS15,
CompositeMLDSAPublicKey}
sa-MLDSA44-RSA2048-PKCS15 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA44-RSA2048-PKCS15,
pk-MLDSA44-RSA2048-PKCS15 }
-- TODO: OID to be replaced by IANA
id-MLDSA44-Ed25519 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 62 }
pk-MLDSA44-Ed25519 PUBLIC-KEY ::=
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pk-CompositeSignature{ id-MLDSA44-Ed25519,
CompositeMLDSAPublicKey}
sa-MLDSA44-Ed25519 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA44-Ed25519,
pk-MLDSA44-Ed25519 }
-- TODO: OID to be replaced by IANA
id-MLDSA44-ECDSA-P256 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 63 }
pk-MLDSA44-ECDSA-P256 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA44-ECDSA-P256,
CompositeMLDSAPublicKey}
sa-MLDSA44-ECDSA-P256 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA44-ECDSA-P256,
pk-MLDSA44-ECDSA-P256 }
-- TODO: OID to be replaced by IANA
id-MLDSA65-RSA3072-PSS OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 64 }
pk-MLDSA65-RSA3072-PSS PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-RSA3072-PSS,
CompositeMLDSAPublicKey}
sa-MLDSA65-RSA3072-PSS SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-RSA3072-PSS,
pk-MLDSA65-RSA3072-PSS }
-- TODO: OID to be replaced by IANA
id-MLDSA65-RSA3072-PKCS15 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 65 }
pk-MLDSA65-RSA3072-PKCS15 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-RSA3072-PKCS15,
CompositeMLDSAPublicKey}
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sa-MLDSA65-RSA3072-PKCS15 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-RSA3072-PKCS15,
pk-MLDSA65-RSA3072-PKCS15 }
-- TODO: OID to be replaced by IANA
id-MLDSA65-RSA4096-PSS OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 66 }
pk-MLDSA65-RSA4096-PSS PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-RSA4096-PSS,
CompositeMLDSAPublicKey}
sa-MLDSA65-RSA4096-PSS SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-RSA4096-PSS,
pk-MLDSA65-RSA4096-PSS }
-- TODO: OID to be replaced by IANA
id-MLDSA65-RSA4096-PKCS15 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 67 }
pk-MLDSA65-RSA4096-PKCS15 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-RSA4096-PKCS15,
CompositeMLDSAPublicKey}
sa-MLDSA65-RSA4096-PKCS15 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-RSA4096-PKCS15,
pk-MLDSA65-RSA4096-PKCS15 }
-- TODO: OID to be replaced by IANA
id-MLDSA65-ECDSA-P256 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 68 }
pk-MLDSA65-ECDSA-P256 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-ECDSA-P256,
CompositeMLDSAPublicKey}
sa-MLDSA65-ECDSA-P256 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-ECDSA-P256,
pk-MLDSA65-ECDSA-P256 }
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-- TODO: OID to be replaced by IANA
id-MLDSA65-ECDSA-P384 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 69 }
pk-MLDSA65-ECDSA-P384 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-ECDSA-P384,
CompositeMLDSAPublicKey}
sa-MLDSA65-ECDSA-P384 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-ECDSA-P384,
pk-MLDSA65-ECDSA-P384 }
-- TODO: OID to be replaced by IANA
id-MLDSA65-ECDSA-brainpoolP256r1 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 70 }
pk-MLDSA65-ECDSA-brainpoolP256r1 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-ECDSA-brainpoolP256r1,
CompositeMLDSAPublicKey}
sa-MLDSA65-ECDSA-brainpoolP256r1 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-ECDSA-brainpoolP256r1,
pk-MLDSA65-ECDSA-brainpoolP256r1 }
-- TODO: OID to be replaced by IANA
id-MLDSA65-Ed25519 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 71 }
pk-MLDSA65-Ed25519 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA65-Ed25519,
CompositeMLDSAPublicKey}
sa-MLDSA65-Ed25519 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA65-Ed25519,
pk-MLDSA65-Ed25519 }
-- TODO: OID to be replaced by IANA
id-MLDSA87-ECDSA-P384 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 72 }
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pk-MLDSA87-ECDSA-P384 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA87-ECDSA-P384,
CompositeMLDSAPublicKey}
sa-MLDSA87-ECDSA-P384 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA87-ECDSA-P384,
pk-MLDSA87-ECDSA-P384 }
-- TODO: OID to be replaced by IANA
id-MLDSA87-ECDSA-brainpoolP384r1 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 73 }
pk-MLDSA87-ECDSA-brainpoolP384r1 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA87-ECDSA-brainpoolP384r1,
CompositeMLDSAPublicKey}
sa-MLDSA87-ECDSA-brainpoolP384r1 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA87-ECDSA-brainpoolP384r1,
pk-MLDSA87-ECDSA-brainpoolP384r1 }
-- TODO: OID to be replaced by IANA
id-MLDSA87-Ed448 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 74 }
pk-MLDSA87-Ed448 PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA87-Ed448,
CompositeMLDSAPublicKey}
sa-MLDSA87-Ed448 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA87-Ed448,
pk-MLDSA87-Ed448 }
-- TODO: OID to be replaced by IANA
id-MLDSA87- OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 75 }
pk-MLDSA87-RSA4096-PSS PUBLIC-KEY ::=
pk-CompositeSignature{ id-MLDSA87-RSA4096-PSS,
CompositeMLDSAPublicKey}
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sa-MLDSA87-RSA4096-PSS SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-MLDSA87-RSA4096-PSS,
pk-MLDSA87-RSA4096-PSS }
-- PreHash Version of the OIDs
-- TODO: OID to be replaced by IANA
id-HashMLDSA44-RSA2048-PSS-SHA256 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 80 }
pk-HashMLDSA44-RSA2048-PSS-SHA256 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA44-RSA2048-PSS-SHA256,
CompositeMLDSAPublicKey}
sa-HashMLDSA44-RSA2048-PSS-SHA256 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA44-RSA2048-PSS-SHA256,
pk-HashMLDSA44-RSA2048-PSS-SHA256 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA44-RSA2048-PKCS15-SHA256 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 81 }
pk-HashMLDSA44-RSA2048-PKCS15-SHA256 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA44-RSA2048-PKCS15-SHA256,
CompositeMLDSAPublicKey}
sa-HashMLDSA44-RSA2048-PKCS15-SHA256 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA44-RSA2048-PKCS15-SHA256,
pk-HashMLDSA44-RSA2048-PKCS15-SHA256 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA44-Ed25519-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 82 }
pk-HashMLDSA44-Ed25519-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA44-Ed25519-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA44-Ed25519-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA44-Ed25519-SHA512,
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pk-HashMLDSA44-Ed25519-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA44-ECDSA-P256-SHA256 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 83 }
pk-HashMLDSA44-ECDSA-P256-SHA256 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA44-ECDSA-P256-SHA256,
CompositeMLDSAPublicKey}
sa-HashMLDSA44-ECDSA-P256-SHA256 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA44-ECDSA-P256-SHA256,
pk-HashMLDSA44-ECDSA-P256-SHA256 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-RSA3072-PSS-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 84 }
pk-HashMLDSA65-RSA3072-PSS-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-RSA3072-PSS-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-RSA3072-PSS-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-RSA3072-PSS-SHA512,
pk-HashMLDSA65-RSA3072-PSS-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-RSA3072-PKCS15-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 85 }
pk-HashMLDSA65-RSA3072-PKCS15-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-RSA3072-PKCS15-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-RSA3072-PKCS15-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-RSA3072-PKCS15-SHA512,
pk-HashMLDSA65-RSA3072-PKCS15-SHA512 }
-- TODO: OID to be replaced by IANA
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id-HashMLDSA65-RSA4096-PSS-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 86 }
pk-HashMLDSA65-RSA4096-PSS-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-RSA4096-PSS-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-RSA4096-PSS-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-RSA4096-PSS-SHA512,
pk-HashMLDSA65-RSA4096-PSS-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-RSA4096-PKCS15-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 87 }
pk-HashMLDSA65-RSA4096-PKCS15-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-RSA4096-PKCS15-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-RSA4096-PKCS15-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-RSA4096-PKCS15-SHA512,
pk-HashMLDSA65-RSA4096-PKCS15-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-ECDSA-P256-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 88 }
pk-HashMLDSA65-ECDSA-P256-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-ECDSA-P256-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-ECDSA-P256-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-ECDSA-P256-SHA512,
pk-HashMLDSA65-ECDSA-P256-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-ECDSA-P384-SHA512 OBJECT IDENTIFIER ::= {
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joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 89 }
pk-HashMLDSA65-ECDSA-P384-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-ECDSA-P384-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-ECDSA-P384-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-ECDSA-P384-SHA512,
pk-HashMLDSA65-ECDSA-P384-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 90 }
pk-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512,
pk-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA65-Ed25519-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 91 }
pk-HashMLDSA65-Ed25519-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA65-Ed25519-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA65-Ed25519-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA65-Ed25519-SHA512,
pk-HashMLDSA65-Ed25519-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA87-ECDSA-P384-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 92 }
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pk-HashMLDSA87-ECDSA-P384-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA87-ECDSA-P384-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA87-ECDSA-P384-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA87-ECDSA-P384-SHA512,
pk-HashMLDSA87-ECDSA-P384-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 93 }
pk-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512,
pk-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA87-Ed448-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 94 }
pk-HashMLDSA87-Ed448-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA87-Ed448-SHA512,
CompositeMLDSAPublicKey}
sa-HashMLDSA87-Ed448-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA87-Ed448-SHA512,
pk-HashMLDSA87-Ed448-SHA512 }
-- TODO: OID to be replaced by IANA
id-HashMLDSA87-RSA4096-PSS-SHA512 OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) country(16) us(840) organization(1)
entrust(114027) algorithm(80) composite(8) signature(1) 95 }
pk-HashMLDSA87-RSA4096-PSS-SHA512 PUBLIC-KEY ::=
pk-CompositeSignature{ id-HashMLDSA87-RSA4096-PSS-SHA512,
CompositeMLDSAPublicKey}
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sa-HashMLDSA87-RSA4096-PSS-SHA512 SIGNATURE-ALGORITHM ::=
sa-CompositeSignature{
id-HashMLDSA87-RSA4096-PSS-SHA512,
pk-HashMLDSA87-RSA4096-PSS-SHA512 }
SignatureAlgorithmSet SIGNATURE-ALGORITHM ::= {
sa-MLDSA44-RSA2048-PSS |
sa-MLDSA44-RSA2048-PKCS15 |
sa-MLDSA44-Ed25519 |
sa-MLDSA44-ECDSA-P256 |
sa-MLDSA65-RSA3072-PSS |
sa-MLDSA65-RSA3072-PKCS15 |
sa-MLDSA65-RSA4096-PSS |
sa-MLDSA65-RSA4096-PKCS15 |
sa-MLDSA65-ECDSA-P256 |
sa-MLDSA65-ECDSA-P384 |
sa-MLDSA65-ECDSA-brainpoolP256r1 |
sa-MLDSA65-Ed25519 |
sa-MLDSA87-ECDSA-P384 |
sa-MLDSA87-ECDSA-brainpoolP384r1 |
sa-MLDSA87-Ed448 |
sa-MLDSA87-RSA4096-PSS |
sa-HashMLDSA44-RSA2048-PSS-SHA256 |
sa-HashMLDSA44-RSA2048-PKCS15-SHA256 |
sa-HashMLDSA44-Ed25519-SHA512 |
sa-HashMLDSA44-ECDSA-P256-SHA256 |
sa-HashMLDSA65-RSA3072-PSS-SHA512 |
sa-HashMLDSA65-RSA3072-PKCS15-SHA512 |
sa-HashMLDSA65-RSA4096-PSS-SHA512 |
sa-HashMLDSA65-RSA4096-PKCS15-SHA512 |
sa-HashMLDSA65-ECDSA-P256-SHA512 |
sa-HashMLDSA65-ECDSA-P384-SHA512 |
sa-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512 |
sa-HashMLDSA65-Ed25519-SHA512 |
sa-HashMLDSA87-ECDSA-P384-SHA512 |
sa-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512 |
sa-HashMLDSA87-Ed448-SHA512 |
sa-HashMLDSA87-RSA4096-PSS-SHA512,
... }
--
-- Expand the S/MIME capabilities set used by CMS [RFC5911]
--
-- TODO: this doesn't compile, error:
-- "The referenced object in the 'ValueFromObject'
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-- syntax with the field '&smimeCaps' is invalid or does not exist."
-- We need help from an SMIME expert
SMimeCaps SMIME-CAPS ::= {
sa-MLDSA44-RSA2048-PSS.&smimeCaps |
sa-MLDSA44-RSA2048-PKCS15.&smimeCaps |
sa-MLDSA44-Ed25519.&smimeCaps |
sa-MLDSA44-ECDSA-P256.&smimeCaps |
sa-MLDSA65-RSA3072-PSS.&smimeCaps |
sa-MLDSA65-RSA3072-PKCS15.&smimeCaps |
sa-MLDSA65-RSA4096-PSS.&smimeCaps |
sa-MLDSA65-RSA4096-PKCS15.&smimeCaps |
sa-MLDSA65-ECDSA-P256.&smimeCaps |
sa-MLDSA65-ECDSA-P384.&smimeCaps |
sa-MLDSA65-ECDSA-brainpoolP256r1.&smimeCaps |
sa-MLDSA65-Ed25519.&smimeCaps |
sa-MLDSA87-ECDSA-P384.&smimeCaps |
sa-MLDSA87-ECDSA-brainpoolP384r1.&smimeCaps |
sa-MLDSA87-Ed448.&smimeCaps |
sa-MLDSA87-RSA4096-PSS.&smimeCaps |
sa-HashMLDSA44-RSA2048-PSS-SHA256.&smimeCaps |
sa-HashMLDSA44-RSA2048-PKCS15-SHA256.&smimeCaps |
sa-HashMLDSA44-Ed25519-SHA512.&smimeCaps |
sa-HashMLDSA44-ECDSA-P256-SHA256.&smimeCaps |
sa-HashMLDSA65-RSA3072-PSS-SHA512.&smimeCaps |
sa-HashMLDSA65-RSA3072-PKCS15-SHA512.&smimeCaps |
sa-HashMLDSA65-RSA4096-PSS-SHA512.&smimeCaps |
sa-HashMLDSA65-RSA4096-PKCS15-SHA512.&smimeCaps |
sa-HashMLDSA65-ECDSA-P256-SHA512.&smimeCaps |
sa-HashMLDSA65-ECDSA-P384-SHA512.&smimeCaps |
sa-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512.&smimeCaps |
sa-HashMLDSA65-Ed25519-SHA512.&smimeCaps |
sa-HashMLDSA87-ECDSA-P384-SHA512.&smimeCaps |
sa-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512.&smimeCaps |
sa-HashMLDSA87-Ed448-SHA512.&smimeCaps |
sa-HashMLDSA87-RSA4096-PSS-SHA512.&smimeCaps,
... }
END
<CODE ENDS>
10. IANA Considerations
IANA is requested to allocate a value from the "SMI Security for PKIX
Module Identifier" registry [RFC7299] for the included ASN.1 module,
and allocate values from "SMI Security for PKIX Algorithms" to
identify the fourteen Algorithms defined within.
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10.1. Object Identifier Allocations
EDNOTE to IANA: OIDs will need to be replaced in both the ASN.1
module and in Table 2 and Table 3.
10.1.1. Module Registration - SMI Security for PKIX Module Identifier
* Decimal: IANA Assigned - *Replace TBDMOD*
* Description: Composite-Signatures-2023 - id-mod-composite-
signatures
* References: This Document
10.1.2. Object Identifier Registrations - SMI Security for PKIX
Algorithms
* id-MLDSA44-RSA2048-PSS
- Decimal: IANA Assigned
- Description: id-MLDSA44-RSA2048-PSS
- References: This Document
* id-MLDSA44-RSA2048-PKCS15
- Decimal: IANA Assigned
- Description: id-MLDSA44-RSA2048-PKCS15
- References: This Document
* id-MLDSA44-Ed25519
- Decimal: IANA Assigned
- Description: id-MLDSA44-Ed25519
- References: This Document
* id-MLDSA44-ECDSA-P256
- Decimal: IANA Assigned
- Description: id-MLDSA44-ECDSA-P256
- References: This Document
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* id-MLDSA65-RSA3072-PSS
- Decimal: IANA Assigned
- Description: id-MLDSA65-RSA3072-PSS
- References: This Document
* id-MLDSA65-RSA3072-PKCS15
- Decimal: IANA Assigned
- Description: id-MLDSA65-RSA3072-PKCS15
- References: This Document
* id-MLDSA65-RSA4096-PSS
- Decimal: IANA Assigned
- Description: id-MLDSA65-RSA4096-PSS
- References: This Document
* id-MLDSA65-RSA4096-PKCS15
- Decimal: IANA Assigned
- Description: id-MLDSA65-RSA4096-PKCS15
- References: This Document
* id-MLDSA65-ECDSA-P256
- Decimal: IANA Assigned
- Description: id-MLDSA65-ECDSA-P256
- References: This Document
* id-MLDSA65-ECDSA-P384
- Decimal: IANA Assigned
- Description: id-MLDSA65-ECDSA-P384
- References: This Document
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* id-MLDSA65-ECDSA-brainpoolP256r1
- Decimal: IANA Assigned
- Description: id-MLDSA65-ECDSA-brainpoolP256r1
- References: This Document
* id-MLDSA65-Ed25519
- Decimal: IANA Assigned
- Description: id-MLDSA65-Ed25519
- References: This Document
* id-MLDSA87-ECDSA-P384
- Decimal: IANA Assigned
- Description: id-MLDSA87-ECDSA-P384
- References: This Document
* id-MLDSA87-ECDSA-brainpoolP384r1
- Decimal: IANA Assigned
- Description: id-MLDSA87-ECDSA-brainpoolP384r1
- References: This Document
* id-MLDSA87-Ed448
- Decimal: IANA Assigned
- Description: id-MLDSA87-Ed448
- References: This Document
* id-MLDSA87-RSA4096-PSS
- Decimal: IANA Assigned
- Description: id-MLDSA87-RSA4096-PSS
- References: This Document
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* id-HashMLDSA44-RSA2048-PSS-SHA256
- Decimal: IANA Assigned
- Description: id-HashMLDSA44-RSA2048-PSS-SHA256
- References: This Document
* id-HashMLDSA44-RSA2048-PKCS15-SHA256
- Decimal: IANA Assigned
- Description: id-HashMLDSA44-RSA2048-PKCS15-SHA256
- References: This Document
* id-HashMLDSA44-Ed25519-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA44-Ed25519-SHA512
- References: This Document
* id-HashMLDSA44-ECDSA-P256-SHA256
- Decimal: IANA Assigned
- Description: id-HashMLDSA44-ECDSA-P256-SHA256
- References: This Document
* id-HashMLDSA65-RSA3072-PSS-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-RSA3072-PSS-SHA512
- References: This Document
* id-HashMLDSA65-RSA3072-PKCS15-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-RSA3072-PKCS15-SHA512
- References: This Document
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* id-HashMLDSA65-RSA4096-PSS-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-RSA4096-PSS-SHA512
- References: This Document
* id-HashMLDSA65-RSA4096-PKCS15-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-RSA4096-PKCS15-SHA512
- References: This Document
* id-HashMLDSA65-ECDSA-P256-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-ECDSA-P256-SHA512
- References: This Document
* id-HashMLDSA65-ECDSA-P384-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-ECDSA-P384-SHA512
- References: This Document
* id-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-ECDSA-brainpoolP256r1-SHA512
- References: This Document
* id-HashMLDSA65-Ed25519-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA65-Ed25519-SHA512
- References: This Document
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* id-HashMLDSA87-ECDSA-P384-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA87-ECDSA-P384-SHA512
- References: This Document
* id-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA87-ECDSA-brainpoolP384r1-SHA512
- References: This Document
* id-HashMLDSA87-Ed448-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA87-Ed448-SHA512
- References: This Document
* id-HashMLDSA87-RSA4096-PSS-SHA512
- Decimal: IANA Assigned
- Description: id-HashMLDSA87-RSA4096-PSS-SHA512
- References: This Document
11. Security Considerations
11.1. Why Hybrids?
In broad terms, a PQ/T Hybrid can be used either to provide dual-
algorithm security or to provide migration flexibility. Let's
quickly explore both.
Dual-algorithm security. The general idea is that the data is
proctected by two algorithms such that an attacker would need to
break both in order to compromise the data. As with most of
cryptography, this property is easy to state in general terms, but
becomes more complicated when expressed in formalisms. Section 11.2
goes into more detail here. One common counter-argument against PQ/T
hybrid signatures is that if an attacker can forge one of the
component algorithms, then why attack the hybrid-signed message at
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all when they could simply forge a completely new message? The
answer to this question must be found outside the cryptographic
primitives themselves, and instead in policy; once an algorithm is
known to be broken it ought to be disallowed for single-algorithm use
by cryptographic policy, while hybrids involving that algorithm may
continue to be used and to provide value.
Migration flexibility. Some PQ/T hybrids exist to provide a sort of
"OR" mode where the client can choose to use one algorithm or the
other or both. The intention is that the PQ/T hybrid mechanism
builds in backwards compatibility to allow legacy and upgraded
clients to co-exist and communicate. The Composites presented in
this specification do not provide this since they operate in a strict
"AND" mode, but they do provide codebase migration flexibility.
Consider that an organization has today a mature, validated,
certified, hardened implementation of RSA or ECC. Composites allow
them to add to this an ML-DSA implementation which immediately starts
providing benefits against long-term document integrity attacks even
if that ML-DSA implemtation is still experimental, non-validated,
non-certified, non-hardened implementation. More details of
obtaining FIPS certification of a composite algorithm can be found in
Appendix D.1.
11.2. Non-separability, EUF-CMA and SUF
The signature combiner defined in this document is Weakly Non-
Separable (WNS), as defined in
[I-D.ietf-pquip-hybrid-signature-spectrums], since the forged message
M’ will include the composite domain separator as evidence. The
prohibition on key reuse between composite and single-algorithm
contexts discussed in Section 11.3 further strengthens the non-
separability in practice, but does not achieve Strong Non-
Separability (SNS) since policy mechanisms such as this are outside
the definition of SNS.
Unforgeability properties are somewhat more nuanced. We recall first
the definitions of Exitential Unforgeability under Chosen Message
Attack (EUF-CMA) and Strong Unforgeability (SUF).The classic EUF-CMA
game is in reference to a pair of algorithms ( Sign(), Verify() )
where the attacker has access to a signing oracle using the Sign()
and must produce a message-signature pair (m', s') that is accepted
by the verifier using Verify() and where m was never signed by the
oracle. SUF requires that the attacker cannot construct a new
signature to an already-signed message.
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The pair ( CompositeML-DSA.Sign(), CompositeML-DSA.Verify() ) is EUF-
CMA secure so long as at least one component algorithm is EUF-CMA
secure since any attempt to modify the message would cause the EUF-
CMA secure component to fail its Verify() which in turn will cause
CompositeML-DSA.Verify() to fail.
CompositeML-DSA only achieves SUF security if both components are SUF
secure, which is not a useful property; the argument is that if the
first component algorithm is not SUF secure then by definition it
admits at least one (m, s1*) pair where s1* was not produced by the
honest signer and it then can be combined with an honestly-signed (m,
s2) signature over the same message m to create (m, (s1*, s2)) which
violates SUF for the composite algorithm. Of the traditional
signature component algorithms used in this specification, only
Ed25519 and Ed448 are SUF secure and therefore applications that
require SUF security to be maintained even in the event that ML-DSA
is broken SHOULD use it in composite with Ed25519 or Ed448.
In addition to the classic EUF-CMA game, we should also consider a
“cross-protocol” version of the EUF-CMA game that is relevant to
hybrids. Specifically, we want to consider a modified version of the
EUF-CMA game where the attacker has access to either a signing oracle
over the two component algorithms in isolation, Trad.Sign() and ML-
DSA.Sign(), and attempts to fraudulently present them as a composite,
or where the attacker has access to a composite oracle for signing
and then attempts to split the signature back into components and
present them to either ML-DSA.Verify() or Trad.Verify().
In the case of CompositeML-DSA, a specific message forgery exists for
a cross-protocol EUF-CMA attack, namely introduced by the prefix
construction added to M. This applies to use of individual component
signing oracles with fraudulent presentation of the signature to a
composite verification oracle, and use of a composite signing oracle
with fraudulent splitting of the signature for presentation to
component verification oracle(s) of either ML-DSA.Verify() or
Trad.Verify(). In the first case, an attacker with access to signing
oracles for the two component algorithms can sign M’ and then
trivially assemble a composite. In the second case, the message M’
(containing the composite domain separator) can be presented as
having been signed by a standalone component algorithm. However, use
of the context string for domain separation enables Weak Non-
Separability and auditable checks on hybrid use, which is deemed a
reasonable trade-off. Moreover and very importantly, the cross-
protocol EUF-CMA attack in either direction is foiled if implementors
strictly follow the prohibition on key reuse presented in
Section 11.3 since there cannot exist simultaneously composite and
non-composite signers and verifiers for the same keys.
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11.3. Key Reuse
When using single-algorithm cryptography, the best practice is to
always generate fresh key material for each purpose, for example when
renewing a certificate, or obtaining both a TLS and S/MIME
certificate for the same device, however in practice key reuse in
such scenarios is not always catastrophic to security and therefore
often tolerated, despite cross-protocol attacks having been shown.
(citation needed here)
Within the broader context of PQ / Traditional hybrids, we need to
consider new attack surfaces that arise due to the hybrid
constructions that did not exist in single-algorithm contexts. One
of these is key reuse where the component keys within a hybrid are
also used by themselves within a single-algorithm context. For
example, it might be tempting for an operator to take an already-
deployed RSA key pair and combine it with an ML-DSA key pair to form
a hybrid key pair for use in a hybrid algorithm. Within a hybrid
signature context this leads to a class of attacks referred to as
"stripping attacks" discussed in Section 11.2 and may also open up
risks from further cross-protocol attacks. Despite the weak non-
separability property offered by the composite signature combiner,
key reuse MUST be avoided to prevent the introduction of EUF-CMA
vulnerabilities.
In addition, there is a further implication to key reuse regarding
certificate revocation. Upon receiving a new certificate enrollment
request, many certification authorities will check if the requested
public key has been previously revoked due to key compromise. Often
a CA will perform this check by using the public key hash.
Therefore, even if both components of a composite have been
previously revoked, the CA may only check the hash of the combined
composite key and not find the revocations. Therefore, because the
possibilty of key reuse exists even though forbidden in this
specification, CAs performing revocation checks on a composite key
SHOULD also check both component keys independently to verify that
the component keys have not been revoked.
11.4. Policy for Deprecated and Acceptable Algorithms
Traditionally, a public key, certificate, or signature contains a
single cryptographic algorithm. If and when an algorithm becomes
deprecated (for example, RSA-512, or SHA1), then clients performing
signatures or verifications should be updated to adhere to
appropriate policies.
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In the composite model this is less obvious since implementers may
decide that certain cryptographic algorithms have complementary
security properties and are acceptable in combination even though one
or both algorithms are deprecated for individual use. As such, a
single composite public key or certificate may contain a mixture of
deprecated and non-deprecated algorithms.
Since composite algorithms are registered independently of their
component algorithms, their deprecation can be handled independently
from that of their component algorithms. For example a cryptographic
policy might continue to allow id-MLDSA65-ECDSA-P256-SHA512 even
after ECDSA-P256 is deprecated.
When considering stripping attacks, one need consider the case where
an attacker has fully compromised one of the component algorithms to
the point that they can produce forged signatures that appear valid
under one of the component public keys, and thus fool a victim
verifier into accepting a forged signature. The protection against
this attack relies on the victim verifier trusting the pair of public
keys as a single composite key, and not trusting the individual
component keys by themselves.
Specifically, in order to achieve this non-separability property,
this specification makes two assumptions about how the verifier will
establish trust in a composite public key:
1. This specification assumes that all of the component keys within
a composite key are freshly generated for the composite; ie a
given public key MUST NOT appear as a component within a
composite key and also within single-algorithm constructions.
2. This specification assumes that composite public keys will be
bound in a structure that contains a signature over the public
key (for example, an X.509 Certificate [RFC5280]), which is
chained back to a trust anchor, and where that signature
algorithm is at least as strong as the composite public key that
it is protecting.
There are mechanisms within Internet PKI where trusted public keys do
not appear within signed structures -- such as the Trust Anchor
format defined in [RFC5914]. In such cases, it is the responsibility
of implementers to ensure that trusted composite keys are distributed
in a way that is tamper-resistant and does not allow the component
keys to be trusted independently.
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11.5. Use of Prefix to for attack mitigation
The Prefix value specified in the message format calculated in
Section 4 can be used by a traditional verifier to detect if the
composite signature has been stripped apart. An attacker would need
to compute M' = Prefix || Domain || len(ctx) || ctx || M or M' :=
Prefix || Domain || len(ctx) || ctx || HashOID || PH(M). Since the
Prefix is the constant String "CompositeAlgorithmSignatures2025"
(Byte encoding
436F6D706F73697465416C676F726974686D5369676E61747572657332303235 ) a
traditional verifier can check if the Message starts with this prefix
and reject the message.
12. References
12.1. Normative References
[FIPS.186-5]
National Institute of Standards and Technology (NIST),
"Digital Signature Standard (DSS)", February 2023,
<https://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.186-5.pdf>.
[FIPS.204] National Institute of Standards and Technology (NIST),
"Module-Lattice-Based Digital Signature Standard", August
2024, <https://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.204.pdf>.
[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>.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986,
DOI 10.17487/RFC2986, November 2000,
<https://www.rfc-editor.org/info/rfc2986>.
[RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen,
"Internet X.509 Public Key Infrastructure Certificate
Management Protocol (CMP)", RFC 4210,
DOI 10.17487/RFC4210, September 2005,
<https://www.rfc-editor.org/info/rfc4210>.
[RFC4211] Schaad, J., "Internet X.509 Public Key Infrastructure
Certificate Request Message Format (CRMF)", RFC 4211,
DOI 10.17487/RFC4211, September 2005,
<https://www.rfc-editor.org/info/rfc4211>.
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[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>.
[RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
"Elliptic Curve Cryptography Subject Public Key
Information", RFC 5480, DOI 10.17487/RFC5480, March 2009,
<https://www.rfc-editor.org/info/rfc5480>.
[RFC5639] Lochter, M. and J. Merkle, "Elliptic Curve Cryptography
(ECC) Brainpool Standard Curves and Curve Generation",
RFC 5639, DOI 10.17487/RFC5639, March 2010,
<https://www.rfc-editor.org/info/rfc5639>.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<https://www.rfc-editor.org/info/rfc5652>.
[RFC5758] Dang, Q., Santesson, S., Moriarty, K., Brown, D., and T.
Polk, "Internet X.509 Public Key Infrastructure:
Additional Algorithms and Identifiers for DSA and ECDSA",
RFC 5758, DOI 10.17487/RFC5758, January 2010,
<https://www.rfc-editor.org/info/rfc5758>.
[RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958,
DOI 10.17487/RFC5958, August 2010,
<https://www.rfc-editor.org/info/rfc5958>.
[RFC6090] McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic
Curve Cryptography Algorithms", RFC 6090,
DOI 10.17487/RFC6090, February 2011,
<https://www.rfc-editor.org/info/rfc6090>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[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>.
[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>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8410] Josefsson, S. and J. Schaad, "Algorithm Identifiers for
Ed25519, Ed448, X25519, and X448 for Use in the Internet
X.509 Public Key Infrastructure", RFC 8410,
DOI 10.17487/RFC8410, August 2018,
<https://www.rfc-editor.org/info/rfc8410>.
[RFC8411] Schaad, J. and R. Andrews, "IANA Registration for the
Cryptographic Algorithm Object Identifier Range",
RFC 8411, DOI 10.17487/RFC8411, August 2018,
<https://www.rfc-editor.org/info/rfc8411>.
[X.690] ITU-T, "Information technology - ASN.1 encoding Rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ISO/IEC 8825-1:2015, November 2015.
12.2. Informative References
[ANSSI2024]
French Cybersecurity Agency (ANSSI), Federal Office for
Information Security (BSI), Netherlands National
Communications Security Agency (NLNCSA), and Swedish
National Communications Security Authority, Swedish Armed
Forces, "Position Paper on Quantum Key Distribution",
n.d., <https://cyber.gouv.fr/sites/default/files/document/
Quantum_Key_Distribution_Position_Paper.pdf>.
[Bindel2017]
Bindel, N., Herath, U., McKague, M., and D. Stebila,
"Transitioning to a quantum-resistant public key
infrastructure", 2017, <https://link.springer.com/
chapter/10.1007/978-3-319-59879-6_22>.
[BSI2021] Federal Office for Information Security (BSI), "Quantum-
safe cryptography - fundamentals, current developments and
recommendations", October 2021,
<https://www.bsi.bund.de/SharedDocs/Downloads/EN/BSI/
Publications/Brochure/quantum-safe-cryptography.pdf>.
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[I-D.ietf-lamps-cms-ml-dsa]
S, B., R, A., and D. Van Geest, "Use of the ML-DSA
Signature Algorithm in the Cryptographic Message Syntax
(CMS)", Work in Progress, Internet-Draft, draft-ietf-
lamps-cms-ml-dsa-02, 17 January 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
cms-ml-dsa-02>.
[I-D.ietf-lamps-dilithium-certificates]
Massimo, J., Kampanakis, P., Turner, S., and B.
Westerbaan, "Internet X.509 Public Key Infrastructure:
Algorithm Identifiers for ML-DSA", Work in Progress,
Internet-Draft, draft-ietf-lamps-dilithium-certificates-
04, 22 July 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-lamps-dilithium-certificates-04>.
[I-D.ietf-pquip-hybrid-signature-spectrums]
Bindel, N., Hale, B., Connolly, D., and F. D, "Hybrid
signature spectrums", Work in Progress, Internet-Draft,
draft-ietf-pquip-hybrid-signature-spectrums-00, 24 May
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
pquip-hybrid-signature-spectrums-00>.
[I-D.ietf-pquip-pqt-hybrid-terminology]
D, F., P, M., and B. Hale, "Terminology for Post-Quantum
Traditional Hybrid Schemes", Work in Progress, Internet-
Draft, draft-ietf-pquip-pqt-hybrid-terminology-04, 10
September 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-pquip-pqt-hybrid-terminology-04>.
[I-D.pala-klaussner-composite-kofn]
Pala, M. and J. Klaußner, "K-threshold Composite
Signatures for the Internet PKI", Work in Progress,
Internet-Draft, draft-pala-klaussner-composite-kofn-00, 15
November 2022, <https://datatracker.ietf.org/doc/html/
draft-pala-klaussner-composite-kofn-00>.
[RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 3279, DOI 10.17487/RFC3279, April
2002, <https://www.rfc-editor.org/info/rfc3279>.
[RFC5914] Housley, R., Ashmore, S., and C. Wallace, "Trust Anchor
Format", RFC 5914, DOI 10.17487/RFC5914, June 2010,
<https://www.rfc-editor.org/info/rfc5914>.
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[RFC7292] Moriarty, K., Ed., Nystrom, M., Parkinson, S., Rusch, A.,
and M. Scott, "PKCS #12: Personal Information Exchange
Syntax v1.1", RFC 7292, DOI 10.17487/RFC7292, July 2014,
<https://www.rfc-editor.org/info/rfc7292>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/info/rfc7296>.
[RFC7299] Housley, R., "Object Identifier Registry for the PKIX
Working Group", RFC 7299, DOI 10.17487/RFC7299, July 2014,
<https://www.rfc-editor.org/info/rfc7299>.
[RFC8017] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
"PKCS #1: RSA Cryptography Specifications Version 2.2",
RFC 8017, DOI 10.17487/RFC8017, November 2016,
<https://www.rfc-editor.org/info/rfc8017>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8551] Schaad, J., Ramsdell, B., and S. Turner, "Secure/
Multipurpose Internet Mail Extensions (S/MIME) Version 4.0
Message Specification", RFC 8551, DOI 10.17487/RFC8551,
April 2019, <https://www.rfc-editor.org/info/rfc8551>.
Appendix A. Samples
A.1. Message Format Examples
A.1.1. Example of MLDSA44-ECDSA-P256 with Context:
M' = Prefix || Domain || len(ctx) || ctx || M
M = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }
ctx = new byte[] { 8, 13, 6, 12, 5, 16, 25, 23 }
Message encoded:
43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:06:0B:60:86:48:01:86:FA:6B:50:08:01:3F:08:08:0D:06:0C:05:10:19:17:00:01:02:03:04:05:06:07:08:09
Prefix: 43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:
Domain: 06:0B:60:86:48:01:86:FA:6B:50:08:01:3F:
len(ctx): 08:
ctx: 08:0D:06:0C:05:10:19:17:
M: 00:01:02:03:04:05:06:07:08:09
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A.1.2. Example of MLDSA44-ECDSA-P256 without a Context
M' = Prefix || Domain || len(ctx) || ctx || M
M = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }
ctx = not used
Message Encoded:
43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:06:0B:60:86:48:01:86:FA:6B:50:08:01:3F:00:00:01:02:03:04:05:06:07:08:09
Prefix: 43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:
Domain: :06:0B:60:86:48:01:86:FA:6B:50:08:01:3F:
len(ctx): 00:
ctx: empty
M: 00:01:02:03:04:05:06:07:08:09
A.1.3. Example of HashMLDSA44-ECDSA-P256-SHA256 with Context
M' = Prefix || Domain || len(ctx) || ctx || HashOID || PH(M)
M = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }
ctx = new byte[] { 8, 13, 6, 12, 5, 16, 25, 23 }
Encoded Message:
43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:06:0B:60:86:48:01:86:FA:6B:50:08:01:53:08:08:0D:06:0C:05:10:19:17:06:09:60:86:48:01:65:03:04:02:01:1F:82:5A:A2:F0:02:0E:F7:CF:91:DF:A3:0D:A4:66:8D:79:1C:5D:48:24:FC:8E:41:35:4B:89:EC:05:79:5A:B3
Prefix: 43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:
Domain: :06:0B:60:86:48:01:86:FA:6B:50:08:01:53:
len(ctx): 08:
ctx: 08:0D:06:0C:05:10:19:17:
HashOID: 06:09:60:86:48:01:65:03:04:02:01:
PH(M): 1F:82:5A:A2:F0:02:0E:F7:CF:91:DF:A3:0D:A4:66:8D:79:1C:5D:48:24:FC:8E:41:35:4B:89:EC:05:79:5A:B3
A.1.4. Example of HashMLDSA44-ECDSA-P256-SHA256 without Context
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M' = Prefix || Domain || len(ctx) || ctx || HashOID || PH(M)
M = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }
ctx = not used
Encoded Message:
43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:06:0B:60:86:48:01:86:FA:6B:50:08:01:53:00:06:09:60:86:48:01:65:03:04:02:01:1F:82:5A:A2:F0:02:0E:F7:CF:91:DF:A3:0D:A4:66:8D:79:1C:5D:48:24:FC:8E:41:35:4B:89:EC:05:79:5A:B3
Prefix: 43:6F:6D:70:6F:73:69:74:65:41:6C:67:6F:72:69:74:68:6D:53:69:67:6E:61:74:75:72:65:73:32:30:32:35:
Domain: :06:0B:60:86:48:01:86:FA:6B:50:08:01:53
len(ctx): 00:
ctx: empty
HashOID: 06:09:60:86:48:01:65:03:04:02:01:
PH(M): 1F:82:5A:A2:F0:02:0E:F7:CF:91:DF:A3:0D:A4:66:8D:79:1C:5D:48:24:FC:8E:41:35:4B:89:EC:05:79:5A:B3
A.2. Composite Signature Examples
TODO - Need Samples
Appendix B. Component Algorithm Reference
This section provides references to the full specification of the
algorithms used in the composite constructions.
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+=========================+=========================+=============+
| Component Signature | OID |Specification|
| Algorithm ID | | |
+=========================+=========================+=============+
| id-ML-DSA-44 | 2.16.840.1.101.3.4.3.17 |[FIPS.204] |
+-------------------------+-------------------------+-------------+
| id-ML-DSA-65 | 2.16.840.1.101.3.4.3.18 |[FIPS.204] |
+-------------------------+-------------------------+-------------+
| id-ML-DSA-87 | 2.16.840.1.101.3.4.3.19 |[FIPS.204] |
+-------------------------+-------------------------+-------------+
| id-Ed25519 | 1.3.101.112 |[RFC8410] |
+-------------------------+-------------------------+-------------+
| id-Ed448 | 1.3.101.113 |[RFC8410] |
+-------------------------+-------------------------+-------------+
| ecdsa-with-SHA256 | 1.2.840.10045.4.3.2 |[RFC5758] |
+-------------------------+-------------------------+-------------+
| ecdsa-with-SHA512 | 1.2.840.10045.4.3.4 |[RFC5758] |
+-------------------------+-------------------------+-------------+
| sha256WithRSAEncryption | 1.2.840.113549.1.1.11 |[RFC8017] |
+-------------------------+-------------------------+-------------+
| sha512WithRSAEncryption | 1.2.840.113549.1.1.13 |[RFC8017] |
+-------------------------+-------------------------+-------------+
| id-RSASSA-PSS | 1.2.840.113549.1.1.10 |[RFC8017] |
+-------------------------+-------------------------+-------------+
Table 9: Component Signature Algorithms used in Composite
Constructions
+==================+=======================+===============+
| Elliptic CurveID | OID | Specification |
+==================+=======================+===============+
| secp256r1 | 1.2.840.10045.3.1.7 | [RFC6090] |
+------------------+-----------------------+---------------+
| secp384r1 | 1.3.132.0.34 | [RFC6090] |
+------------------+-----------------------+---------------+
| brainpoolP256r1 | 1.3.36.3.3.2.8.1.1.7 | [RFC5639] |
+------------------+-----------------------+---------------+
| brainpoolP384r1 | 1.3.36.3.3.2.8.1.1.11 | [RFC5639] |
+------------------+-----------------------+---------------+
Table 10: Elliptic Curves used in Composite Constructions
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+===========+=========================+===============+
| HashID | OID | Specification |
+===========+=========================+===============+
| id-sha256 | 2.16.840.1.101.3.4.2.1 | [RFC6234] |
+-----------+-------------------------+---------------+
| id-sha512 | 2.16.840.1..101.3.4.2.3 | [RFC6234] |
+-----------+-------------------------+---------------+
Table 11: Hash algorithms used in Composite
Constructions
Appendix C. Component AlgorithmIdentifiers for Public Keys and
Signatures
To ease implementing Composite Signatures this section specifies the
Algorithms Identifiers for each component algorithm. They are
provided as ASN.1 value notation and copy and paste DER encoding to
avoid any ambiguity. Developers may use this information to
reconstruct non hybrid public keys and signatures from each component
that can be fed to crypto APIs to create or verify a single component
signature.
For newer Algorithms like Ed25519 or ML-DSA the AlgorithmIdentifiers
are the same for Public Key and Signature. Older Algorithms have
different AlgorithmIdentifiers for keys and signatures and are
specified separately here for each component.
*ML-DSA-44 -- AlgorithmIdentifier of Public Key and Signature*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ML-DSA-44 -- (2 16 840 1 101 3 4 3 17)
}
DER:
30 0B 06 09 60 86 48 01 65 03 04 03 11
*ML-DSA-65 -- AlgorithmIdentifier of Public Key and Signature*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ML-DSA-65 -- (2 16 840 1 101 3 4 3 18)
}
DER:
30 0B 06 09 60 86 48 01 65 03 04 03 12
*ML-DSA-87 -- AlgorithmIdentifier of Public Key and Signature*
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ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ML-DSA-87 -- (2 16 840 1 101 3 4 3 19)
}
DER:
30 0B 06 09 60 86 48 01 65 03 04 03 13
*RSASSA-PSS 2048 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-RSASSA-PSS -- (1.2.840.113549.1.1.10)
}
DER:
30 0B 06 09 2A 86 48 86 F7 0D 01 01 0A
*RSASSA-PSS 2048 -- AlgorithmIdentifier of Signature*
ASN.1:
signatureAlgorithm AlgorithmIdentifier ::= {
algorithm id-RSASSA-PSS, -- (1.2.840.113549.1.1.10)
parameters ANY ::= {
AlgorithmIdentifier ::= {
algorithm id-sha256, -- (2.16.840.1.101.3.4.2.1)
parameters NULL
},
AlgorithmIdentifier ::= {
algorithm id-mgf1, -- (1.2.840.113549.1.1.8)
parameters AlgorithmIdentifier ::= {
algorithm id-sha256, -- (2.16.840.1.101.3.4.2.1)
parameters NULL
}
},
saltLength 32
}
}
DER:
30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 A0 0F 30 0D 06 09 60 86
48 01 65 03 04 02 01 05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 01
08 30 0D 06 09 60 86 48 01 65 03 04 02 01 05 00 A2 03 02 01 20
*RSASSA-PSS 3072 & 4096 -- AlgorithmIdentifier of Public Key*
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ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-RSASSA-PSS -- (1.2.840.113549.1.1.10)
}
DER:
30 0B 06 09 2A 86 48 86 F7 0D 01 01 0A
*RSASSA-PSS 3072 & 4096 -- AlgorithmIdentifier of Signature*
ASN.1:
signatureAlgorithm AlgorithmIdentifier ::= {
algorithm id-RSASSA-PSS, -- (1.2.840.113549.1.1.10)
parameters ANY ::= {
AlgorithmIdentifier ::= {
algorithm id-sha512, -- (2.16.840.1.101.3.4.2.3)
parameters NULL
},
AlgorithmIdentifier ::= {
algorithm id-mgf1, -- (1.2.840.113549.1.1.8)
parameters AlgorithmIdentifier ::= {
algorithm id-sha512, -- (2.16.840.1.101.3.4.2.3)
parameters NULL
}
},
saltLength 64
}
}
DER:
30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 A0 0F 30 0D 06 09 60 86
48 01 65 03 04 02 03 05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 01
08 30 0D 06 09 60 86 48 01 65 03 04 02 03 05 00 A2 03 02 01 40
*RSASSA-PKCS1-v1_5 2048 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm rsaEncryption, -- (1.2.840.113549.1.1.1)
parameters NULL
}
DER:
30 0D 06 09 2A 86 48 86 F7 0D 01 01 01 05 00
*RSASSA-PKCS1-v1_5 2048 -- AlgorithmIdentifier of Signature*
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ASN.1:
signatureAlgorithm AlgorithmIdentifier ::= {
algorithm sha256WithRSAEncryption, -- (1.2.840.113549.1.1.11)
parameters NULL
}
DER:
30 0D 06 09 2A 86 48 86 F7 0D 01 01 0D 05 00
*RSASSA-PKCS1-v1_5 3072 & 4096 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm rsaEncryption, -- (1.2.840.113549.1.1.1)
parameters NULL
}
DER:
30 0D 06 09 2A 86 48 86 F7 0D 01 01 01 05 00
*RSASSA-PKCS1-v1_5 3072 & 4096 -- AlgorithmIdentifier of Signature*
ASN.1:
signatureAlgorithm AlgorithmIdentifier ::= {
algorithm sha512WithRSAEncryption, -- (1.2.840.113549.1.1.13)
parameters NULL
}
DER:
30 0D 06 09 2A 86 48 86 F7 0D 01 01 0D 05 00
*ECDSA NIST 256 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ecPublicKey -- (1.2.840.10045.2.1)
parameters ANY ::= {
AlgorithmIdentifier ::= {
algorithm secp256r1 -- (1.2.840.10045.3.1.7)
}
}
}
DER:
30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 48 CE 3D 03 01 07
*ECDSA NIST 256 -- AlgorithmIdentifier of Signature*
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ASN.1:
signature AlgorithmIdentifier ::= {
algorithm ecdsa-with-SHA256 -- (1.2.840.10045.4.3.2)
}
DER:
30 0A 06 08 2A 86 48 CE 3D 04 03 02
*ECDSA NIST-384 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ecPublicKey -- (1.2.840.10045.2.1)
parameters ANY ::= {
AlgorithmIdentifier ::= {
algorithm secp384r1 -- (1.3.132.0.34)
}
}
}
DER:
30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 04 00 22
*ECDSA NIST-384 -- AlgorithmIdentifier of Signature*
ASN.1:
signature AlgorithmIdentifier ::= {
algorithm ecdsa-with-SHA384 -- (1.2.840.10045.4.3.3)
}
DER:
30 0A 06 08 2A 86 48 CE 3D 04 03 03
*ECDSA Brainpool-256 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ecPublicKey -- (1.2.840.10045.2.1)
parameters ANY ::= {
AlgorithmIdentifier ::= {
algorithm brainpoolP256r1 -- (1.3.36.3.3.2.8.1.1.7)
}
}
}
DER:
30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 03 03 02 08 01 01 07
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*ECDSA Brainpool-256 -- AlgorithmIdentifier of Signature*
ASN.1:
signature AlgorithmIdentifier ::= {
algorithm ecdsa-with-SHA256 -- (1.2.840.10045.4.3.2)
}
DER:
30 0A 06 08 2A 86 48 CE 3D 04 03 02
*ECDSA Brainpool-384 -- AlgorithmIdentifier of Public Key*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-ecPublicKey -- (1.2.840.10045.2.1)
parameters ANY ::= {
AlgorithmIdentifier ::= {
algorithm brainpoolP384r1 -- (1.3.36.3.3.2.8.1.1.11)
}
}
}
DER:
30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 03 03 02 08 01 01 0B
*ECDSA Brainpool-384 -- AlgorithmIdentifier of Signature*
ASN.1:
signature AlgorithmIdentifier ::= {
algorithm ecdsa-with-SHA384 -- (1.2.840.10045.4.3.3)
}
DER:
30 0A 06 08 2A 86 48 CE 3D 04 03 03
*Ed25519 -- AlgorithmIdentifier of Public Key and Signature*
ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-Ed25519 -- (1.3.101.112)
}
DER:
30 05 06 03 2B 65 70
*Ed448 -- AlgorithmIdentifier of Public Key and Signature*
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ASN.1:
algorithm AlgorithmIdentifier ::= {
algorithm id-Ed448 -- (1.3.101.113)
}
DER:
30 05 06 03 2B 65 71
Appendix D. Implementation Considerations
D.1. FIPS certification
One of the primary design goals of this specification is for the
overall composite algorithm to be able to be considered FIPS-approved
even when one of the component algorithms is not.
Implementors seeking FIPS certification of a composite Signature
algorithm where only one of the component algorithms has been FIPS-
validated or FIPS-approved should credit the FIPS-validated component
algorithm with full security strength, the non-FIPS-validated
component algorithm with zero security, and the overall composite
should be considered at least as strong and thus FIPS-approved.
The authors wish to note that this gives composite algorithms great
future utility both for future cryptographic migrations as well as
bridging across jurisdictions, for example defining composite
algorithms which combine FIPS cryptography with cryptography from a
different national standards body.
D.2. Backwards Compatibility
The term "backwards compatibility" is used here to mean something
more specific; that existing systems as they are deployed today can
interoperate with the upgraded systems of the future. This draft
explicitly does not provide backwards compatibility, only upgraded
systems will understand the OIDs defined in this document.
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If backwards compatibility is required, then additional mechanisms
will be needed. Migration and interoperability concerns need to be
thought about in the context of various types of protocols that make
use of X.509 and PKIX with relation to digital signature objects,
from online negotiated protocols such as TLS 1.3 [RFC8446] and IKEv2
[RFC7296], to non-negotiated asynchronous protocols such as S/MIME
signed email [RFC8551], document signing such as in the context of
the European eIDAS regulations [eIDAS2014], and publicly trusted code
signing [codeSigningBRsv2.8], as well as myriad other standardized
and proprietary protocols and applications that leverage CMS
[RFC5652] signed structures. Composite simplifies the protocol
design work because it can be implemented as a signature algorithm
that fits into existing systems.
D.2.1. Hybrid Extensions (Keys and Signatures)
The use of Composite Crypto provides the possibility to process
multiple algorithms without changing the logic of applications but
updating the cryptographic libraries: one-time change across the
whole system. However, when it is not possible to upgrade the crypto
engines/libraries, it is possible to leverage X.509 extensions to
encode the additional keys and signatures. When the custom
extensions are not marked critical, although this approach provides
the most backward-compatible approach where clients can simply ignore
the post-quantum (or extra) keys and signatures, it also requires all
applications to be updated for correctly processing multiple
algorithms together.
Appendix E. Intellectual Property Considerations
The following IPR Disclosure relates to this draft:
https://datatracker.ietf.org/ipr/3588/
Appendix F. Contributors and Acknowledgements
This document incorporates contributions and comments from a large
group of experts. The Editors would especially like to acknowledge
the expertise and tireless dedication of the following people, who
attended many long meetings and generated millions of bytes of
electronic mail and VOIP traffic over the past few years in pursuit
of this document:
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Daniel Van Geest (CryptoNext), Dr. Britta Hale (Naval Postgraduade
School), Tim Hollebeek (Digicert), Panos Kampanakis (Cisco Systems),
Richard Kisley (IBM), Serge Mister (Entrust), Piotr Popis, François
Rousseau, Falko Strenzke, Felipe Ventura (Entrust), Alexander Ralien
(Siemens), José Ignacio Escribano, Jan Oupický, 陳志華 (Abel C. H.
Chen, Chunghwa Telecom), 林邦曄 (Austin Lin, Chunghwa Telecom) and
Mojtaba Bisheh-Niasar
We especially want to recognize the contributions of Dr. Britta Hale
who has helped immensely with strengthening the signature combiner
construction, and with analyzing the scheme with respect to EUF-CMA
and Non-Separability properties.
We are grateful to all who have given feedback over the years,
formally or informally, on mailing lists or in person, including any
contributors who may have been inadvertently omitted from this list.
This document borrows text from similar documents, including those
referenced below. Thanks go to the authors of those documents.
"Copying always makes things easier and less error prone" -
[RFC8411].
F.1. Making contributions
Additional contributions to this draft are welcome. Please see the
working copy of this draft at, as well as open issues at:
https://github.com/lamps-wg/draft-composite-sigs
Authors' Addresses
Mike Ounsworth
Entrust Limited
2500 Solandt Road – Suite 100
Ottawa, Ontario K2K 3G5
Canada
Email: mike.ounsworth@entrust.com
John Gray
Entrust Limited
2500 Solandt Road – Suite 100
Ottawa, Ontario K2K 3G5
Canada
Email: john.gray@entrust.com
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Massimiliano Pala
OpenCA Labs
New York City, New York,
United States of America
Email: director@openca.org
Jan Klaussner
Bundesdruckerei GmbH
Kommandantenstr. 18
10969 Berlin
Germany
Email: jan.klaussner@bdr.de
Scott Fluhrer
Cisco Systems
Email: sfluhrer@cisco.com
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