trusty (3) RAND_bytes.3ssl.gz

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.