cloudflare / circl

CIRCL: Cloudflare Interoperable Reusable Cryptographic Library
http://blog.cloudflare.com/introducing-circl
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kyber: remove division by q in ciphertext compression #468

Closed bwesterb closed 6 months ago

bwesterb commented 6 months ago

On some platforms, division by q leaks some information on the ciphertext by its timing. If a keypair is reused, and an attacker has access to a decapsulation oracle, this reveals information on the private key. This is known as "kyberslash2".

Note that this does not affect to the typical ephemeral usage in TLS.