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Commit | Line | Data |
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dd8dec69 UM |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
aafbe1cc | 5 | BN_rand, BN_pseudo_rand, BN_rand_range, BN_pseudo_rand_range - generate pseudo-random number |
dd8dec69 UM |
6 | |
7 | =head1 SYNOPSIS | |
8 | ||
9 | #include <openssl/bn.h> | |
10 | ||
11 | int BN_rand(BIGNUM *rnd, int bits, int top, int bottom); | |
12 | ||
4d524e10 | 13 | int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom); |
38e33cef | 14 | |
e3068929 | 15 | int BN_rand_range(BIGNUM *rnd, BIGNUM *range); |
57e7d3ce | 16 | |
b49053ca | 17 | int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range); |
983495c4 | 18 | |
dd8dec69 UM |
19 | =head1 DESCRIPTION |
20 | ||
21 | BN_rand() generates a cryptographically strong pseudo-random number of | |
f67cbb74 | 22 | B<bits> in length and stores it in B<rnd>. |
01c09f9f RS |
23 | If B<bits> is less than zero, or too small to |
24 | accomodate the requirements specified by the B<top> and B<bottom> | |
25 | parameters, an error is returned. | |
f67cbb74 RS |
26 | The B<top> parameters specifies |
27 | requirements on the most significant bit of the generated number. | |
28 | If it is B<BN_RAND_TOP_ANY>, there is no constraint. | |
29 | If it is B<BN_RAND_TOP_ONE>, the top bit must be one. | |
30 | If it is B<BN_RAND_TOP_TWO>, the two most significant bits of | |
335c4f09 | 31 | the number will be set to 1, so that the product of two such random |
f67cbb74 RS |
32 | numbers will always have 2*B<bits> length. |
33 | If B<bottom> is B<BN_RAND_BOTTOM_ODD>, the number will be odd; if it | |
34 | is B<BN_RAND_BOTTOM_ANY> it can be odd or even. | |
35 | If B<bits> is 1 then B<top> cannot also be B<BN_RAND_FLG_TOPTWO>. | |
dd8dec69 | 36 | |
38e33cef UM |
37 | BN_pseudo_rand() does the same, but pseudo-random numbers generated by |
38 | this function are not necessarily unpredictable. They can be used for | |
39 | non-cryptographic purposes and for certain purposes in cryptographic | |
40 | protocols, but usually not for key generation etc. | |
41 | ||
57e7d3ce | 42 | BN_rand_range() generates a cryptographically strong pseudo-random |
31d6c0b2 | 43 | number B<rnd> in the range 0 E<lt>= B<rnd> E<lt> B<range>. |
983495c4 BM |
44 | BN_pseudo_rand_range() does the same, but is based on BN_pseudo_rand(), |
45 | and hence numbers generated by it are not necessarily unpredictable. | |
57e7d3ce UM |
46 | |
47 | The PRNG must be seeded prior to calling BN_rand() or BN_rand_range(). | |
dd8dec69 UM |
48 | |
49 | =head1 RETURN VALUES | |
50 | ||
57e7d3ce | 51 | The functions return 1 on success, 0 on error. |
9b86974e | 52 | The error codes can be obtained by L<ERR_get_error(3)>. |
dd8dec69 UM |
53 | |
54 | =head1 SEE ALSO | |
55 | ||
9e183d22 | 56 | L<ERR_get_error(3)>, L<RAND_add(3)>, L<RAND_bytes(3)> |
dd8dec69 | 57 | |
e2f92610 RS |
58 | =head1 COPYRIGHT |
59 | ||
9e183d22 | 60 | Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 RS |
61 | |
62 | Licensed under the OpenSSL license (the "License"). You may not use | |
63 | this file except in compliance with the License. You can obtain a copy | |
64 | in the file LICENSE in the source distribution or at | |
65 | L<https://www.openssl.org/source/license.html>. | |
66 | ||
67 | =cut |