BN_rand(3)                  OpenSSL                  BN_rand(3)





NAME
       BN_rand, BN_pseudo_rand - generate pseudo-random number

SYNOPSIS
        #include <openssl/bn.h>

        int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);

        int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);

        int BN_rand_range(BIGNUM *rnd, BIGNUM *range);

        int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);

DESCRIPTION
       BN_rand() generates a cryptographically strong pseudo-
       random number of bits bits in length and stores it in
       rnd. If top is -1, the most significant bit of the ran-
       dom number can be zero. If top is 0, it is set to 1, and
       if top is 1, the two most significant bits of the number
       will be set to 1, so that the product of two such random
       numbers will always have 2*bits length.  If bottom is
       true, the number will be odd.

       BN_pseudo_rand() does the same, but pseudo-random num-
       bers generated by this function are not necessarily
       unpredictable. They can be used for non-cryptographic
       purposes and for certain purposes in cryptographic pro-
       tocols, but usually not for key generation etc.

       BN_rand_range() generates a cryptographically strong
       pseudo-random number rnd in the range 0 <lt>= rnd <
       range.  BN_pseudo_rand_range() does the same, but is
       based on BN_pseudo_rand(), and hence numbers generated
       by it are not necessarily unpredictable.

       The PRNG must be seeded prior to calling BN_rand() or
       BN_rand_range().

RETURN VALUES
       The functions return 1 on success, 0 on error.  The
       error codes can be obtained by ERR_get_error(3).

SEE ALSO
       bn(3), ERR_get_error(3), rand(3), RAND_add(3),
       RAND_bytes(3)

HISTORY
       BN_rand() is available in all versions of SSLeay and
       OpenSSL.  BN_pseudo_rand() was added in OpenSSL 0.9.5.
       The top == -1 case and the function BN_rand_range() were
       added in OpenSSL 0.9.6a.  BN_pseudo_rand_range() was
       added in OpenSSL 0.9.6c.



0.9.7c                     2002-09-25                BN_rand(3)
