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sphincs / sphincsplus

The SPHINCS+ reference code, accompanying the submission to NIST's Post-Quantum Cryptography project
https://sphincs.org
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Decode FORS indices similarly to WOTS #51

Open bwesterb opened 1 year ago

bwesterb commented 1 year ago

As proposed by NIST's David Cooper:

https://groups.google.com/a/list.nist.gov/g/pqc-forum/c/88tuvtb7nN4/m/DA1QCoJWBAAJ

sfluhrer commented 1 year ago

Oops, David Cooper is right; this does flip the bit order for each leaf. What we want is:

indices[i] ^= ((m[offset >> 3] >> (~offset & 0x7)) & 0x1) << (SPX_FORS_HEIGHT-1-j);

bwesterb commented 1 year ago

Indeed, whoops. Generating new test vectors now ...

bwesterb commented 1 year ago

Done.

mberry commented 1 year ago

Is there a timeline for this getting merged? It's a breaking change so perhaps should come with some forewarning?

bwesterb commented 1 year ago

Is there a timeline for this getting merged? It's a breaking change so perhaps should come with some forewarning?

SPHINCS+ (or SLH-DSA as it will be called by NIST) is not finalised, and could very well see even more changes. If you want to adopt early, you should fix on a specific commit (and keep track for bug fixes.) I'm sorry, this is annoying for early adopters, but that's the risk of adopting early.

mberry commented 1 year ago

It's all good, was simply wondering about how the rollout would happen.

Codewise the change is trivial, it is more the versioning and nomenclature around this change.

bwesterb commented 11 months ago

Rebased on master.

bwesterb commented 6 months ago

Rebased to include fix of #59. /cc @kste