Looks good to me. __CLOBBER_CC is needed as PA-RISC has carry/borrow bits in status register for add/sub instructions.

No, hardware barrier is not needed here. Compiler barrier is used here to prevent optimization removing mask generation and usage in following constant-time code.

Fix for i386 assembly pushed to master and 1.10 branch.

It looks that this is a bit more problematic case than I thought. Now building i386 with "-O2 -fsanitize=undefined" flags fails. I need to think little bit more how to handle this.

Attached patch should workaround the issue:

Yes, int8_t/int16_t/int32_t/uint8_t/uint16_t/uint32_t should not be used. There is size-specific integer types defined in src/types.h which can be used instead (byte/u16/u32). This header does not yet have signed integer types, but those can be added (for example, s8/s16/s32).

• There's many functions that use buffers on stack. Do those contain secrets? Should those buffers be wiped before returning from function (with wipememory())? For example, "mlkem_check_secret_key" has two buffers "shared_secret_1" and "shared_secret_2" which are not wiped.
• mlkem.c: mlkem_check_secret_key: "memcmp" is used to compare shared secrets. Should this use constant time comparison instead?
• mlkem-common.c: _gcry_mlkem_mlkem_shake256_rkprf:
  • _gcry_md_hash_buffers_extract can be used here instead of _gcry_md_open&write&extract&close.
• mlkem-symmetric.c: _gcry_mlkem_shake256_prf:
  • _gcry_md_hash_buffers_extract can be used here instead of _gcry_md_open&write&extract&close. Temporary buffer usage can be avoided by passing input buffers through two IOV to _gcry_md_hash_buffers_extract.

Few comments on the patches.

Just started wondering how much of this slow down is because of MingW libc not having very well optimized memcpy/memmove/memchr/strlen/etc. Is there profiling tools like 'perf' on Linux that could be used for Windows builds?

Problem with SHA-256 on x86-64 is that it took long time for Intel to introduce SHA acceleration (SHA1 & SHA256) to their main CPU products.

Here's fix for mode specific setkey clearing error code:

About error code. You need to use gcry_err_code(error_code) to get the GPG_ERR_WEAK_KEY value.

I'll add documentation about GCRYCTL_SET_ALLOW_WEAK_KEY which was missing from be original commit.

tests/basic now actually fail because setkey not returning GPG_ERR_WEAK_KEY for weak keys with GCRYCTL_SET_ALLOW_WEAK_KEY.

That's right. With GCRYCTL_SET_ALLOW_WEAK_KEY, setkey still returns GPG_ERR_WEAK_KEY when weak key is detected. However, cipher handle can still be used as if setkey succeeded.

Here's mirroring script that is in place currently:

#!/bin/bash -e