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TIMINGSAFE_BCMP(3)	 BSD Library Functions Manual	    TIMINGSAFE_BCMP(3)

NAME
     timingsafe_bcmp, timingsafe_memcmp	-- timing-safe byte sequence compar-
     isons

SYNOPSIS
     #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);

DESCRIPTION
     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.

SEE ALSO
     bcmp(3), memcmp(3)

STANDARDS
     The timingsafe_bcmp() and timingsafe_memcmp() functions are FreeBSD ex-
     tensions.

HISTORY
     The timingsafe_bcmp() function first appeared in OpenBSD 4.9.

     The timingsafe_memcmp() function first appeared in	OpenBSD	5.6.

     Both functions first appeared in FreeBSD 12.0.

BSD				August 15, 2016				   BSD

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | STANDARDS | HISTORY

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