=pod
=head1 NAME
BN_rand, BN_pseudo_rand, BN_rand_range, BN_pseudo_rand_range - generate pseudo-random number
=head1 SYNOPSIS
#include
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);
=head1 DESCRIPTION
BN_rand() generates a cryptographically strong pseudo-random number of
B in length and stores it in B.
If B is less than zero, or too small to
accomodate the requirements specified by the B and B
parameters, an error is returned.
If B is -1, the
most significant bit of the random number can be zero. If B is 0,
it is set to 1, and if B 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*B length. If B is true, the
number will be odd. The value of B must be zero or greater. If B is
1 then B 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 B in the range 0 E= B E B.
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().
=head1 RETURN VALUES
The functions return 1 on success, 0 on error.
The error codes can be obtained by L.
=head1 SEE ALSO
L, L, L,
L, L
=head1 HISTORY
BN_rand() is available in all versions of SSLeay and OpenSSL.
BN_pseudo_rand() was added in OpenSSL 0.9.5. The B == -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.
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