BN_rand.pod revision 89837
1295367Sdes=pod 292559Sdes 357429Smarkm=head1 NAME 457429Smarkm 557429SmarkmBN_rand, BN_pseudo_rand - generate pseudo-random number 657429Smarkm 757429Smarkm=head1 SYNOPSIS 860576Skris 965674Skris #include <openssl/bn.h> 1065674Skris 1165674Skris int BN_rand(BIGNUM *rnd, int bits, int top, int bottom); 1265674Skris 1365674Skris int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom); 1457429Smarkm 1557429Smarkm int BN_rand_range(BIGNUM *rnd, BIGNUM *range); 1657429Smarkm 1757429Smarkm int BN_pseudo_rand_range(BIGNUM *rnd, int bits, int top, int bottom); 1857429Smarkm 1957429Smarkm=head1 DESCRIPTION 2057429Smarkm 2157429SmarkmBN_rand() generates a cryptographically strong pseudo-random number of 2257429SmarkmB<bits> bits in length and stores it in B<rnd>. If B<top> is -1, the 2357429Smarkmmost significant bit of the random number can be zero. If B<top> is 0, 2457429Smarkmit is set to 1, and if B<top> is 1, the two most significant bits of 2565674Skristhe number will be set to 1, so that the product of two such random 2676262Sgreennumbers will always have 2*B<bits> length. If B<bottom> is true, the 27204917Sdesnumber will be odd. 28137019Sdes 29162856SdesBN_pseudo_rand() does the same, but pseudo-random numbers generated by 30226046Sdesthis function are not necessarily unpredictable. They can be used for 31248619Sdesnon-cryptographic purposes and for certain purposes in cryptographic 3257429Smarkmprotocols, but usually not for key generation etc. 3376262Sgreen 3476262SgreenBN_rand_range() generates a cryptographically strong pseudo-random 3576262Sgreennumber B<rnd> in the range 0 <lt>= B<rnd> E<lt> B<range>. 3676262SgreenBN_pseudo_rand_range() does the same, but is based on BN_pseudo_rand(), 3776262Sgreenand hence numbers generated by it are not necessarily unpredictable. 3876262Sgreen 3976262SgreenThe PRNG must be seeded prior to calling BN_rand() or BN_rand_range(). 40226046Sdes 41226046Sdes=head1 RETURN VALUES 42226046Sdes 43240075SdesThe functions return 1 on success, 0 on error. 44226046SdesThe error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. 45248619Sdes 46248619Sdes=head1 SEE ALSO 47248619Sdes 48248619SdesL<bn(3)|bn(3)>, L<err(3)|err(3)>, L<rand(3)|rand(3)>, 49248619SdesL<RAND_add(3)|RAND_add(3)>, L<RAND_bytes(3)|RAND_bytes(3)> 50248619Sdes 51137019Sdes=head1 HISTORY 52181111Sdes 5376262SgreenBN_rand() is available in all versions of SSLeay and OpenSSL. 54181111SdesBN_pseudo_rand() was added in OpenSSL 0.9.5. The B<top> == -1 case 55181111Sdesand the function BN_rand_range() were added in OpenSSL 0.9.6a. 56181111SdesBN_pseudo_rand_range() was added in OpenSSL 0.9.6c. 5757429Smarkm 58192595Sdes=cut 59192595Sdes