1=pod 2 3=head1 NAME 4 5BN_copy, BN_dup, BN_with_flags - copy BIGNUMs 6 7=head1 SYNOPSIS 8 9 #include <openssl/bn.h> 10 11 BIGNUM *BN_copy(BIGNUM *to, const BIGNUM *from); 12 13 BIGNUM *BN_dup(const BIGNUM *from); 14 15 void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags); 16 17=head1 DESCRIPTION 18 19BN_copy() copies B<from> to B<to>. BN_dup() creates a new B<BIGNUM> 20containing the value B<from>. 21 22BN_with_flags creates a B<temporary> shallow copy of B<b> in B<dest>. It places 23significant restrictions on the copied data. Applications that do no adhere to 24these restrictions may encounter unexpected side effects or crashes. For that 25reason use of this function is discouraged. Any flags provided in B<flags> will 26be set in B<dest> in addition to any flags already set in B<b>. For example this 27might commonly be used to create a temporary copy of a BIGNUM with the 28B<BN_FLG_CONSTTIME> flag set for constant time operations. The temporary copy in 29B<dest> will share some internal state with B<b>. For this reason the following 30restrictions apply to the use of B<dest>: 31 32=over 2 33 34=item * 35 36B<dest> should be a newly allocated BIGNUM obtained via a call to BN_new(). It 37should not have been used for other purposes or initialised in any way. 38 39=item * 40 41B<dest> must only be used in "read-only" operations, i.e. typically those 42functions where the relevant parameter is declared "const". 43 44=item * 45 46B<dest> must be used and freed before any further subsequent use of B<b> 47 48=back 49 50=head1 RETURN VALUES 51 52BN_copy() returns B<to> on success, NULL on error. BN_dup() returns 53the new B<BIGNUM>, and NULL on error. The error codes can be obtained 54by L<ERR_get_error(3)>. 55 56=head1 SEE ALSO 57 58L<ERR_get_error(3)> 59 60=head1 COPYRIGHT 61 62Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. 63 64Licensed under the Apache License 2.0 (the "License"). You may not use 65this file except in compliance with the License. You can obtain a copy 66in the file LICENSE in the source distribution or at 67L<https://www.openssl.org/source/license.html>. 68 69=cut 70
