liboqs secret-dependent branching in HQC reference implementation when compiled with Clang 17-20

Vulnerability Description

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Multiple secret-dependent branches have been identified in the reference implementation of the HQC key encapsulation mechanism when it is compiled with Clang for optimization levels above -O0 (-O1, -O2, etc). A proof-of-concept local attack exploits this secret-dependent information to recover the entire secret key. This vulnerability is fixed in 0.14.0.

References

• https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-qq3m-rq9v-jfgm
• https://github.com/open-quantum-safe/liboqs/commit/4215362acbf69b88fe1777c4c052f154e29f9897