Assigner | mitre |
Reserved | 2024-06-10 |
Published | 2024-06-10 |
Updated | 2024-07-19 |
Description
The Kyber reference implementation before 9b8d306, when compiled by LLVM Clang through 18.x with some common optimization options, has a timing side channel that allows attackers to recover an ML-KEM 512 secret key in minutes. This occurs because poly_frommsg in poly.c does not prevent Clang from emitting a vulnerable secret-dependent branch.
References
https://github.com/antoonpurnal/clangover
https://github.com/pq-crystals/kyber/commit/9b8d30698a3e7449aeb34e62339d4176f11e3c6c
https://news.ycombinator.com/item?id=40577486
https://twitter.com/purnaltoon/status/1797644696568959476