1=pod 2 3=head1 NAME 4 5BN_rand_ex, BN_rand, BN_priv_rand_ex, BN_priv_rand, BN_pseudo_rand, 6BN_rand_range_ex, BN_rand_range, BN_priv_rand_range_ex, BN_priv_rand_range, 7BN_pseudo_rand_range 8- generate pseudo-random number 9 10=head1 SYNOPSIS 11 12 #include <openssl/bn.h> 13 14 int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, 15 unsigned int strength, BN_CTX *ctx); 16 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom); 17 18 int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, 19 unsigned int strength, BN_CTX *ctx); 20 int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom); 21 22 int BN_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength, 23 BN_CTX *ctx); 24 int BN_rand_range(BIGNUM *rnd, const BIGNUM *range); 25 26 int BN_priv_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength, 27 BN_CTX *ctx); 28 int BN_priv_rand_range(BIGNUM *rnd, const BIGNUM *range); 29 30The following functions have been deprecated since OpenSSL 3.0, and can be 31hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 32see L<openssl_user_macros(7)>: 33 34 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom); 35 int BN_pseudo_rand_range(BIGNUM *rnd, const BIGNUM *range); 36 37=head1 DESCRIPTION 38 39BN_rand_ex() generates a cryptographically strong pseudo-random 40number of I<bits> in length and security strength at least I<strength> bits 41using the random number generator for the library context associated with 42I<ctx>. The function stores the generated data in I<rnd>. The parameter I<ctx> 43may be NULL in which case the default library context is used. 44If I<bits> is less than zero, or too small to 45accommodate the requirements specified by the I<top> and I<bottom> 46parameters, an error is returned. 47The I<top> parameters specifies 48requirements on the most significant bit of the generated number. 49If it is B<BN_RAND_TOP_ANY>, there is no constraint. 50If it is B<BN_RAND_TOP_ONE>, the top bit must be one. 51If it is B<BN_RAND_TOP_TWO>, the two most significant bits of 52the number will be set to 1, so that the product of two such random 53numbers will always have 2*I<bits> length. 54If I<bottom> is B<BN_RAND_BOTTOM_ODD>, the number will be odd; if it 55is B<BN_RAND_BOTTOM_ANY> it can be odd or even. 56If I<bits> is 1 then I<top> cannot also be B<BN_RAND_TOP_TWO>. 57 58BN_rand() is the same as BN_rand_ex() except that the default library context 59is always used. 60 61BN_rand_range_ex() generates a cryptographically strong pseudo-random 62number I<rnd>, of security strength at least I<strength> bits, 63in the range 0 E<lt>= I<rnd> E<lt> I<range> using the random number 64generator for the library context associated with I<ctx>. The parameter I<ctx> 65may be NULL in which case the default library context is used. 66 67BN_rand_range() is the same as BN_rand_range_ex() except that the default 68library context is always used. 69 70BN_priv_rand_ex(), BN_priv_rand(), BN_priv_rand_rand_ex() and 71BN_priv_rand_range() have the same semantics as BN_rand_ex(), BN_rand(), 72BN_rand_range_ex() and BN_rand_range() respectively. They are intended to be 73used for generating values that should remain private, and mirror the 74same difference between L<RAND_bytes(3)> and L<RAND_priv_bytes(3)>. 75 76=head1 NOTES 77 78Always check the error return value of these functions and do not take 79randomness for granted: an error occurs if the CSPRNG has not been 80seeded with enough randomness to ensure an unpredictable byte sequence. 81 82=head1 RETURN VALUES 83 84The functions return 1 on success, 0 on error. 85The error codes can be obtained by L<ERR_get_error(3)>. 86 87=head1 SEE ALSO 88 89L<ERR_get_error(3)>, 90L<RAND_add(3)>, 91L<RAND_bytes(3)>, 92L<RAND_priv_bytes(3)>, 93L<RAND(7)>, 94L<EVP_RAND(7)> 95 96=head1 HISTORY 97 98=over 2 99 100=item * 101 102Starting with OpenSSL release 1.1.0, BN_pseudo_rand() has been identical 103to BN_rand() and BN_pseudo_rand_range() has been identical to 104BN_rand_range(). 105The BN_pseudo_rand() and BN_pseudo_rand_range() functions were 106deprecated in OpenSSL 3.0. 107 108=item * 109 110The BN_priv_rand() and BN_priv_rand_range() functions were added in 111OpenSSL 1.1.1. 112 113=item * 114 115The BN_rand_ex(), BN_priv_rand_ex(), BN_rand_range_ex() and 116BN_priv_rand_range_ex() functions were added in OpenSSL 3.0. 117 118=back 119 120=head1 COPYRIGHT 121 122Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved. 123 124Licensed under the Apache License 2.0 (the "License"). You may not use 125this file except in compliance with the License. You can obtain a copy 126in the file LICENSE in the source distribution or at 127L<https://www.openssl.org/source/license.html>. 128 129=cut 130
