timingsafe_memcmp3
Timing-safe byte sequence comparisons
Part of timingsafe_bcmp(3).
Usage
#include <string.h>
int
timingsafe_bcmp(const void *b1, const void *b2, size_t len);
int
timingsafe_memcmp(const void *b1, const void *b2, size_t len);
Overview
The timingsafe_bcmp() and timingsafe_memcmp() functions lexicographically compare the first len bytes (each interpreted as an unsigned char) pointed to by b1 and b2.
Additionally, their running times are independent of the byte sequences compared, making them safe to use for comparing secret values such as cryptographic MACs. In contrast, bcmp(3) and memcmp(3) may short-circuit after finding the first differing byte.
Return values
The timingsafe_bcmp() function returns 0 or not zero if the byte sequence pointed to by b1 compares equal to or not equal to (respectively) the byte sequence pointed to by b2.
The timingsafe_memcmp() function returns a negative value, 0, or positive value if the byte sequence pointed to by b1 compares less than, equal to, or greater than (respectively) the byte sequence pointed to by b2.
Releases
24 releases since FreeBSD 11.1-RELEASE; the text changed 11 times.