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Diffstat (limited to 'openssl/doc/crypto/BN_rand.pod')
-rw-r--r-- | openssl/doc/crypto/BN_rand.pod | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/openssl/doc/crypto/BN_rand.pod b/openssl/doc/crypto/BN_rand.pod new file mode 100644 index 000000000..81f93c2eb --- /dev/null +++ b/openssl/doc/crypto/BN_rand.pod @@ -0,0 +1,58 @@ +=pod + +=head1 NAME + +BN_rand, BN_pseudo_rand - generate pseudo-random number + +=head1 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); + +=head1 DESCRIPTION + +BN_rand() generates a cryptographically strong pseudo-random number of +B<bits> bits in length and stores it in B<rnd>. If B<top> is -1, the +most significant bit of the random number can be zero. If B<top> is 0, +it is set to 1, and if B<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*B<bits> length. If B<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 B<rnd> in the range 0 <lt>= B<rnd> E<lt> B<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(). + +=head1 RETURN VALUES + +The functions return 1 on success, 0 on error. +The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. + +=head1 SEE ALSO + +L<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<rand(3)|rand(3)>, +L<RAND_add(3)|RAND_add(3)>, L<RAND_bytes(3)|RAND_bytes(3)> + +=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<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. + +=cut |