/usr/man/cat.3/RAND_bytes.3.Z

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 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 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 func-
       tions 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.

1.0.2t                            2019-09-10                     RAND_bytes(3)
See also RAND_pseudo_bytes(3)