5 BN_rand, BN_pseudo_rand - generate pseudo-random number
9 #include <openssl/bn.h>
11 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
13 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
15 int BN_rand_range(BIGNUM *rnd, BIGNUM *min, BIGNUM *max);
19 BN_rand() generates a cryptographically strong pseudo-random number of
20 B<bits> bits in length and stores it in B<rnd>. If B<top> is true, the
21 two most significant bits of the number will be set to 1, so that the
22 product of two such random numbers will always have 2*B<bits> length.
23 If B<bottom> is true, the number will be odd.
25 BN_pseudo_rand() does the same, but pseudo-random numbers generated by
26 this function are not necessarily unpredictable. They can be used for
27 non-cryptographic purposes and for certain purposes in cryptographic
28 protocols, but usually not for key generation etc.
30 BN_rand_range() generates a cryptographically strong pseudo-random
31 number B<rnd> in the range B<min> E<lt>= B<rnd> E<lt> B<max>. B<min>
32 may be NULL, in that case 0 E<lt>= B<rnd> E<lt> B<max>.
34 The PRNG must be seeded prior to calling BN_rand() or BN_rand_range().
38 The functions return 1 on success, 0 on error.
39 The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
43 L<bn(3)|bn(3)>, L<err(3)|err(3)>, L<rand(3)|rand(3)>,
44 L<RAND_add(3)|RAND_add(3)>, L<RAND_bytes(3)|RAND_bytes(3)>
48 BN_rand() is available in all versions of SSLeay and OpenSSL.
49 BN_pseudo_rand() was added in OpenSSL 0.9.5, and BN_rand_range()