[Pkg-rust-maintainers] Bug#1137357: gpg-from-sq: provide a way to provide (or default to) deterministic signatures

[Clemens Lang]

Hi,

> We'd need Sequoia to provide some way to provide deterministic
> signatures for at least v4 signatures, and probably v6 signatures as
> well. I realize that v6 does not intend to allow this, but it is
> functionally required for testsuites as well as some cases with
> reproducible builds[0].


I’m not sure that’s doable. It might be for RSA signatures (if they use RSASSA-PKCS1-v1_5), but even RSASSA-PSS signatures are non-deterministic already and depend on that non-determinism for their security properties.

The same applies for ECDSA signatures by default (there is a deterministic variant in RFC 6979, but RFC 9580 doesn’t mention that RFC, so I’m guessing OpenPGP doesn’t support that).

ML-DSA signatures are have a random component by nature.

Long-term, it seems like the better solution to not assume that the used signature scheme is deterministic, and change the tests to not expect a fixed hash.


Note: I’m not involved with Debian maintenance of this package, just here to provide context.


-- 
Clemens Lang
RHEL Crypto Team
Red Hat