Jussi's comments on Phabricator regarding kyber and kmac patches

[falko-strenzke]

From https://dev.gnupg.org/T6637#177086

Few comments on the patches.

• [x] #25 0002-fix-mlkem-memory-leaks.patch907 BDownload
• [x] There's few files missing license text at beginning of file (cipher/consttime.*, tests/test-utils.h).
• [x] // C++ style comment lines are used in few places. These need to be changed to C comments / ... /
  • [X] kyber branch
  • [x] kmac branch
• cipher/consttime.c:
  • [x] #26
  • [x] WONTFIX #27
• [x] cipher/mlkem-cbd.c:
  • [x] "load32_littleendian": there is "buf_get_le32" in bufhelp.h for reading 32-bit in little-endian order.
• [x] postponed #28
• benchmarking: postponed (test work package)
• [x] #37
• [x] #38
• [X] mlkem.c: mlkem_check_secret_key: "memcmp" is used to compare shared secrets. Should this use constant time comparison instead?
• [x] https://github.com/pqc-thunderbird/libgcrypt/issues/40