NAME¶
RAND_bytes, RAND_pseudo_bytes - generate random data
SYNOPSIS¶
#include <openssl/rand.h>
int RAND_bytes(unsigned char *buf, int num);
int RAND_pseudo_bytes(unsigned char *buf, int num);
DESCRIPTION¶
RAND_bytes() puts
num cryptographically strong pseudo-random bytes
into
buf. An error occurs if the PRNG has not been seeded with enough
randomness to ensure an unpredictable byte sequence.
RAND_pseudo_bytes() puts
num pseudo-random bytes into
buf.
Pseudo-random byte sequences generated by
RAND_pseudo_bytes() will be
unique if they are of sufficient length, but are not necessarily
unpredictable. They can be used for non-cryptographic purposes and for certain
purposes in cryptographic protocols, but usually not for key generation etc.
The contents of
buf is mixed into the entropy pool before retrieving the
new pseudo-random bytes unless disabled at compile time (see FAQ).
RETURN VALUES¶
RAND_bytes() returns 1 on success, 0 otherwise. The error code can be
obtained by
ERR_get_error(3).
RAND_pseudo_bytes() returns 1 if
the bytes generated are cryptographically strong, 0 otherwise. Both functions
return -1 if they are not supported by the current RAND method.
SEE ALSO¶
rand(3),
ERR_get_error(3),
RAND_add(3)
HISTORY¶
RAND_bytes() is available in all versions of SSLeay and OpenSSL. It has a
return value since OpenSSL 0.9.5.
RAND_pseudo_bytes() was added in
OpenSSL 0.9.5.