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.
25/Sep/2002 0.9.6j BN_rand(3)
