RAND_bytes(3) OpenSSL RAND_bytes(3)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);
DESCRIPTIONRAND_bytes() puts num cryptographically strong pseudo-random bytes into
buf. An error occurs if the PRNG has not been seeded with enough ran‐
domness to ensure an unpredictable byte sequence.
RAND_pseudo_bytes() puts num pseudo-random bytes into buf. Pseudo-ran‐
dom 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 pur‐
poses 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 VALUESRAND_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 func‐
tions return -1 if they are not supported by the current RAND method.
SEE ALSOrand(3), ERR_get_error(3), RAND_add(3)HISTORYRAND_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.
1.0.0h 2007-09-24 RAND_bytes(3)