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cloudflare / circl

CIRCL: Cloudflare Interoperable Reusable Cryptographic Library
http://blog.cloudflare.com/introducing-circl
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kem/hybrid: Remove restriction on seed sizes #342

Closed bwesterb closed 2 years ago

bwesterb commented 2 years ago

None of the implemented KEMs aim above 256 bits of security and so SHAKE256 (easily) suffices to stretch one seed into two.

bwesterb commented 2 years ago

I thought about adding a ClaimedSecurityt() function to the kem.Scheme interface and checking that those are below 256 when used in the hybrid construction, but I thought that'd be overdoing it.

bwesterb commented 2 years ago

Another solution I thought about is to simply change our schemes to use ≤32 byte seeds, but that might break existing users and would require an extra function to reproduce the test vectors that come with the implementations.