Updated: 2021/Apr/14


BN_copy(3)                          OpenSSL                         BN_copy(3)



NAME
       BN_copy, BN_dup, BN_with_flags - copy BIGNUMs

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/bn.h>

        BIGNUM *BN_copy(BIGNUM *to, const BIGNUM *from);

        BIGNUM *BN_dup(const BIGNUM *from);

        void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags);

DESCRIPTION
       BN_copy() copies from to to. BN_dup() creates a new BIGNUM containing
       the value from.

       BN_with_flags creates a temporary shallow copy of b in dest. It places
       significant restrictions on the copied data. Applications that do no
       adhere to these restrictions may encounter unexpected side effects or
       crashes. For that reason use of this function is discouraged. Any flags
       provided in flags will be set in dest in addition to any flags already
       set in b. For example this might commonly be used to create a temporary
       copy of a BIGNUM with the BN_FLG_CONSTTIME flag set for constant time
       operations. The temporary copy in dest will share some internal state
       with b. For this reason the following restrictions apply to the use of
       dest:

       ⊕ dest should be a newly allocated BIGNUM obtained via a call to
         BN_new(). It should not have been used for other purposes or
         initialised in any way.

       ⊕ dest must only be used in "read-only" operations, i.e. typically
         those functions where the relevant parameter is declared "const".

       ⊕ dest must be used and freed before any further subsequent use of b

RETURN VALUES
       BN_copy() returns to on success, NULL on error. BN_dup() returns the
       new BIGNUM, and NULL on error. The error codes can be obtained by
       ERR_get_error(3).

SEE ALSO
       ERR_get_error(3)

COPYRIGHT
       Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.



1.1.1i                            2018-09-23                        BN_copy(3)