| yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame^] | 1 | =pod |
| 2 | |
| 3 | =head1 NAME |
| 4 | |
| 5 | BN_rand, BN_priv_rand, BN_pseudo_rand, |
| 6 | BN_rand_range, BN_priv_rand_range, BN_pseudo_rand_range |
| 7 | - generate pseudo-random number |
| 8 | |
| 9 | =head1 SYNOPSIS |
| 10 | |
| 11 | #include <openssl/bn.h> |
| 12 | |
| 13 | int BN_rand(BIGNUM *rnd, int bits, int top, int bottom); |
| 14 | |
| 15 | int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom); |
| 16 | |
| 17 | int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom); |
| 18 | |
| 19 | int BN_rand_range(BIGNUM *rnd, BIGNUM *range); |
| 20 | |
| 21 | int BN_priv_rand_range(BIGNUM *rnd, BIGNUM *range); |
| 22 | |
| 23 | int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range); |
| 24 | |
| 25 | =head1 DESCRIPTION |
| 26 | |
| 27 | BN_rand() generates a cryptographically strong pseudo-random number of |
| 28 | B<bits> in length and stores it in B<rnd>. |
| 29 | If B<bits> is less than zero, or too small to |
| 30 | accommodate the requirements specified by the B<top> and B<bottom> |
| 31 | parameters, an error is returned. |
| 32 | The B<top> parameters specifies |
| 33 | requirements on the most significant bit of the generated number. |
| 34 | If it is B<BN_RAND_TOP_ANY>, there is no constraint. |
| 35 | If it is B<BN_RAND_TOP_ONE>, the top bit must be one. |
| 36 | If it is B<BN_RAND_TOP_TWO>, the two most significant bits of |
| 37 | the number will be set to 1, so that the product of two such random |
| 38 | numbers will always have 2*B<bits> length. |
| 39 | If B<bottom> is B<BN_RAND_BOTTOM_ODD>, the number will be odd; if it |
| 40 | is B<BN_RAND_BOTTOM_ANY> it can be odd or even. |
| 41 | If B<bits> is 1 then B<top> cannot also be B<BN_RAND_TOP_TWO>. |
| 42 | |
| 43 | BN_rand_range() generates a cryptographically strong pseudo-random |
| 44 | number B<rnd> in the range 0 E<lt>= B<rnd> E<lt> B<range>. |
| 45 | |
| 46 | BN_priv_rand() and BN_priv_rand_range() have the same semantics as |
| 47 | BN_rand() and BN_rand_range() respectively. They are intended to be |
| 48 | used for generating values that should remain private, and mirror the |
| 49 | same difference between L<RAND_bytes(3)> and L<RAND_priv_bytes(3)>. |
| 50 | |
| 51 | =head1 NOTES |
| 52 | |
| 53 | Always check the error return value of these functions and do not take |
| 54 | randomness for granted: an error occurs if the CSPRNG has not been |
| 55 | seeded with enough randomness to ensure an unpredictable byte sequence. |
| 56 | |
| 57 | =head1 RETURN VALUES |
| 58 | |
| 59 | The functions return 1 on success, 0 on error. |
| 60 | The error codes can be obtained by L<ERR_get_error(3)>. |
| 61 | |
| 62 | =head1 SEE ALSO |
| 63 | |
| 64 | L<ERR_get_error(3)>, |
| 65 | L<RAND_add(3)>, |
| 66 | L<RAND_bytes(3)>, |
| 67 | L<RAND_priv_bytes(3)>, |
| 68 | L<RAND(7)>, |
| 69 | L<RAND_DRBG(7)> |
| 70 | |
| 71 | =head1 HISTORY |
| 72 | |
| 73 | =over 2 |
| 74 | |
| 75 | =item * |
| 76 | |
| 77 | Starting with OpenSSL release 1.1.0, BN_pseudo_rand() has been identical |
| 78 | to BN_rand() and BN_pseudo_rand_range() has been identical to |
| 79 | BN_rand_range(). |
| 80 | The "pseudo" functions should not be used and may be deprecated in |
| 81 | a future release. |
| 82 | |
| 83 | =item * |
| 84 | |
| 85 | The |
| 86 | BN_priv_rand() and BN_priv_rand_range() functions were added in OpenSSL 1.1.1. |
| 87 | |
| 88 | =back |
| 89 | |
| 90 | =head1 COPYRIGHT |
| 91 | |
| 92 | Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. |
| 93 | |
| 94 | Licensed under the OpenSSL license (the "License"). You may not use |
| 95 | this file except in compliance with the License. You can obtain a copy |
| 96 | in the file LICENSE in the source distribution or at |
| 97 | L<https://www.openssl.org/source/license.html>. |
| 98 | |
| 99 | =cut |