RAND_bytes(3SSL) OpenSSL RAND_bytes(3SSL)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 ALSOrand(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.
1.0.0e 2007-09-24 RAND_bytes(3SSL)