RAND_bytes(3) - NetBSD Manual Pages

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RAND_bytes(3)                       OpenSSL                      RAND_bytes(3)




NAME

       RAND_bytes, RAND_pseudo_bytes - generate random data


LIBRARY

       libcrypto, -lcrypto


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

       openssl_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.



1.0.2k                            2009-07-19                     RAND_bytes(3)