NAME

       BN_copy, BN_dup, BN_with_flags - copy BIGNUMs

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 Apache License 2.0 (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>.

3.0.13                                             2025-02-05                                      BN_COPY(3SSL)