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);
DESCRIPTIONBN_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 random 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 numbers generated by
this function 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.
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 ALSObn(3), ERR_get_error(3), rand(3), RAND_add(3), RAND_bytes(3)HISTORYBN_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.
0.9.8k 2002-09-25 BN_rand(3)