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.