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2f61bc2ea3
Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/3117)
70 lines
2.0 KiB
Plaintext
70 lines
2.0 KiB
Plaintext
=pod
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=head1 NAME
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BN_copy, BN_dup, BN_with_flags - copy BIGNUMs
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=head1 SYNOPSIS
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#include <openssl/bn.h>
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BIGNUM *BN_copy(BIGNUM *to, const BIGNUM *from);
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BIGNUM *BN_dup(const BIGNUM *from);
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void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags);
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=head1 DESCRIPTION
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BN_copy() copies B<from> to B<to>. BN_dup() creates a new B<BIGNUM>
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containing the value B<from>.
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BN_with_flags creates a B<temporary> shallow copy of B<b> in B<dest>. It places
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significant restrictions on the copied data. Applications that do no adhere to
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these restrictions may encounter unexpected side effects or crashes. For that
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reason use of this function is discouraged. Any flags provided in B<flags> will
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be set in B<dest> in addition to any flags already set in B<b>. For example this
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might commonly be used to create a temporary copy of a BIGNUM with the
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B<BN_FLG_CONSTTIME> flag set for constant time operations. The temporary copy in
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B<dest> will share some internal state with B<b>. For this reason the following
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restrictions apply to the use of B<dest>:
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=over 2
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=item *
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B<dest> should be a newly allocated BIGNUM obtained via a call to BN_new(). It
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should not have been used for other purposes or initialised in any way.
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=item *
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B<dest> must only be used in "read-only" operations, i.e. typically those
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functions where the relevant parameter is declared "const".
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=item *
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B<dest> must be used and freed before any further subsequent use of B<b>
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=back
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=head1 RETURN VALUES
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BN_copy() returns B<to> on success, NULL on error. BN_dup() returns
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the new B<BIGNUM>, and NULL on error. The error codes can be obtained
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by L<ERR_get_error(3)>.
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=head1 SEE ALSO
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L<ERR_get_error(3)>
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=head1 COPYRIGHT
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Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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