/usr/man/cat.3/RAND_bytes.3(/usr/man/cat.3/RAND_bytes.3)

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);

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.

1.0.2t               Last change: 2019-09-10                    1

See also RAND_pseudo_bytes(3)