CVE-2024-50382: Observable Discrepancy

Botan before 3.6.0, when certain LLVM versions are used, has compiler-induced secret-dependent control flow in lib/utils/ghash/ghash.cpp in GHASH in AES-GCM. There is a branch instead of an XOR with carry. This was observed for Clang in LLVM 15 on RISC-V...