BN_rand.pod revision 225736
138889Sjdp=pod 238889Sjdp 338889Sjdp=head1 NAME 438889Sjdp 538889SjdpBN_rand, BN_pseudo_rand - generate pseudo-random number 660484Sobrien 760484Sobrien=head1 SYNOPSIS 860484Sobrien 938889Sjdp #include <openssl/bn.h> 1038889Sjdp 1138889Sjdp int BN_rand(BIGNUM *rnd, int bits, int top, int bottom); 1238889Sjdp 1338889Sjdp int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom); 1438889Sjdp 1538889Sjdp int BN_rand_range(BIGNUM *rnd, BIGNUM *range); 1638889Sjdp 1738889Sjdp int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range); 1838889Sjdp 1960484Sobrien=head1 DESCRIPTION 2060484Sobrien 2160484SobrienBN_rand() generates a cryptographically strong pseudo-random number of 2238889SjdpB<bits> bits in length and stores it in B<rnd>. If B<top> is -1, the 2338889Sjdpmost significant bit of the random number can be zero. If B<top> is 0, 2438889Sjdpit is set to 1, and if B<top> is 1, the two most significant bits of 2560484Sobrienthe number will be set to 1, so that the product of two such random 2660484Sobriennumbers will always have 2*B<bits> length. If B<bottom> is true, the 2760484Sobriennumber will be odd. 2860484Sobrien 2960484SobrienBN_pseudo_rand() does the same, but pseudo-random numbers generated by 3060484Sobrienthis function are not necessarily unpredictable. They can be used for 3138889Sjdpnon-cryptographic purposes and for certain purposes in cryptographic 3238889Sjdpprotocols, but usually not for key generation etc. 3338889Sjdp 3438889SjdpBN_rand_range() generates a cryptographically strong pseudo-random 3538889Sjdpnumber B<rnd> in the range 0 <lt>= B<rnd> E<lt> B<range>. 3638889SjdpBN_pseudo_rand_range() does the same, but is based on BN_pseudo_rand(), 3738889Sjdpand hence numbers generated by it are not necessarily unpredictable. 3838889Sjdp 3938889SjdpThe PRNG must be seeded prior to calling BN_rand() or BN_rand_range(). 4060484Sobrien 4160484Sobrien=head1 RETURN VALUES 4260484Sobrien 4338889SjdpThe functions return 1 on success, 0 on error. 4438889SjdpThe error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. 4538889Sjdp 4660484Sobrien=head1 SEE ALSO 4760484Sobrien 4838889SjdpL<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<rand(3)|rand(3)>, 4960484SobrienL<RAND_add(3)|RAND_add(3)>, L<RAND_bytes(3)|RAND_bytes(3)> 5060484Sobrien 5138889Sjdp=head1 HISTORY 5260484Sobrien 5360484SobrienBN_rand() is available in all versions of SSLeay and OpenSSL. 5438889SjdpBN_pseudo_rand() was added in OpenSSL 0.9.5. The B<top> == -1 case 5560484Sobrienand the function BN_rand_range() were added in OpenSSL 0.9.6a. 5660484SobrienBN_pseudo_rand_range() was added in OpenSSL 0.9.6c. 5738889Sjdp 5860484Sobrien=cut 5960484Sobrien