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

The RAND_bytes() function 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. 

The RAND_pseudo_bytes() function puts num pseudo-random bytes into buf. Pseudo-random byte sequences generated by the RAND_pseudo_bytes() function 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. 

RETURN VALUES

The RAND_bytes() functon returns 1 on success, 0 otherwise. The error code can be obtained by using ERR_get_error(). The RAND_pseudo_bytes() function 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. 

HISTORY

The RAND_bytes() function is available in all versions of SSLeay and OpenSSL.  It has a return value since OpenSSL 0.9.5. The RAND_pseudo_bytes() function was added in OpenSSL 0.9.5. 

SEE ALSO

Functions: rand_ssl(3), err(3), RAND_add(3)