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Under GNU General Public License
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BN_rand(3) OpenSSL BN_rand(3)
NAME
BN_rand, BN_pseudo_rand, BN_rand_range, BN_pseudo_rand_range - 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 in length and
stores it in rnd. If bits is less than zero, or too small to accomodate the requirements
specified by the top and bottom parameters, an error is returned. 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. The value of bits must be zero or greater. If bits is 1 then top cannot also
be 1.
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 <= 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.
1.0.2k 2017-01-26 BN_rand(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/2.4.6 (CentOS)
Under GNU General Public License
2025-06-23 22:12 @127.0.0.1 CrawledBy Wget/1.21.2