On Thu, Jun 19, 2025 at 1:52 AM Yaroslav Rosomakho <[email protected]>
wrote:

>
>> S 5.1.1.
>>    When parsing DualSignatureSchemeList, implementations MUST NOT make
>>    assumptions about which sub-list a given algorithm will appear in.
>>    For example, an implementation MUST NOT assume that PQ algorithms
>>    will appear in the first list and PQ in the second.  As a test, if a
>>    TLS handshake containing a DualSignatureSchemeList succeeds, then an
>>    equivalent TLS handshake containing an equivalent
>>    DualSignatureSchemeList but with the first and second lists swapped
>>    MUST also succeed.  However, it is not required that these two test
>>    cases result in the same selected signature algorithm and
>>    certificate.  See Appendix C for a suggested configuration mechanism
>>    for selecting a preferred pair of algorithms.
>>
>> Would it be legal to supply two lists that have the same
>> PQ-status? E.g.,
>>
>>    first_signature_algorithms = [ECDSA-P256]
>>    second_signature_algorithms = [Ed25519]
>>
>>
> Yes, the same PQ-status of elements in both lists is legal according to
> current design. Some may want to allow SLH-DSA or composites
> roots/intermediates in both chains.
>

Now I'm confused. Are you saying you can have the *same values* in both
lists. E.g.,

first_signature_algorithms = [ML-DSA, SLH-DSA]
second_signature_algorithms = [ECDSA-P256, ML-DSA]

But then you can't sign with [ML-DSA, ML-DSA]?

-Ekr
_______________________________________________
TLS mailing list -- [email protected]
To unsubscribe send an email to [email protected]

Reply via email to