RAND_bytes, RAND_pseudo_bytes - generate random data
#include <openssl/rand.h>
int RAND_bytes(unsigned char *buf, int num);
int RAND_pseudo_bytes(unsigned char *buf, int num);
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).
RAND_bytes() returns 1 on success, 0 otherwise. The error code can be
obtained by ERR_get_error. 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.
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.