[core] add comment to ck_memeq_const_time()

add comment to ck_memeq_const_time() with some implementation details
Glenn Strauss 2021-10-16 02:05:19 -04:00
parent cf5644e0c2
commit 69c2b2b207
1 changed files with 5 additions and 0 deletions

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@ -270,6 +270,11 @@ ck_memeq_const_time (const void *a, const size_t alen, const void *b, const size
/* rounds to next multiple of 64 to avoid potentially leaking exact
* string lengths when subject to high precision timing attacks
/* Note: implementation detail
* each string is expected to have a valid char one byte after len,
* i.e. a[alen] and b[blen], and which must match if the strings match.
* (In most use cases, this char is end of string '\0').
/* Note: some libs provide similar funcs but might not obscure length, e.g.
* OpenSSL:
* int CRYPTO_memcmp(const void * in_a, const void * in_b, size_t len)