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.\" $OpenBSD: BN_zero.3,v 1.6 2016/12/10 21:13:25 schwarze Exp $
.\" OpenSSL a528d4f0 Oct 27 13:40:11 2015 -0400
.\"
.\" This file was written by Ulf Moeller <ulf@openssl.org>.
.\" Copyright (c) 2000, 2001, 2002 The OpenSSL Project. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in
.\" the documentation and/or other materials provided with the
.\" distribution.
.\"
.\" 3. All advertising materials mentioning features or use of this
.\" software must display the following acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
.\"
.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
.\" endorse or promote products derived from this software without
.\" prior written permission. For written permission, please contact
.\" openssl-core@openssl.org.
.\"
.\" 5. Products derived from this software may not be called "OpenSSL"
.\" nor may "OpenSSL" appear in their names without prior written
.\" permission of the OpenSSL Project.
.\"
.\" 6. Redistributions of any form whatsoever must retain the following
.\" acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
.\" OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd $Mdocdate: December 10 2016 $
.Dt BN_ZERO 3
.Os
.Sh NAME
.Nm BN_zero ,
.Nm BN_one ,
.Nm BN_value_one ,
.Nm BN_set_word ,
.Nm BN_get_word
.Nd BIGNUM assignment operations
.Sh SYNOPSIS
.In openssl/bn.h
.Ft int
.Fo BN_zero
.Fa "BIGNUM *a"
.Fc
.Ft int
.Fo BN_one
.Fa "BIGNUM *a"
.Fc
.Ft const BIGNUM *
.Fo BN_value_one
.Fa void
.Fc
.Ft int
.Fo BN_set_word
.Fa "BIGNUM *a"
.Fa "unsigned long w"
.Fc
.Ft unsigned long
.Fo BN_get_word
.Fa "BIGNUM *a"
.Fc
.Sh DESCRIPTION
.Fn BN_zero ,
.Fn BN_one ,
and
.Fn BN_set_word
set
.Fa a
to the values 0, 1 and
.Fa w
respectively.
.Fn BN_zero
and
.Fn BN_one
are macros.
.Pp
.Fn BN_value_one
returns a
.Vt BIGNUM
constant of value 1.
This constant is useful for use in comparisons and assignment.
.Pp
.Fn BN_get_word
returns
.Fa a
if it can be represented as an
.Vt unsigned long .
.Sh RETURN VALUES
.Fn BN_get_word
returns the value
.Fa a ,
or 0xffffffffL if
.Fa a
cannot be represented as an
.Vt unsigned long .
.Pp
.Fn BN_zero ,
.Fn BN_one ,
and
.Fn BN_set_word
return 1 on success, 0 otherwise.
.Fn BN_value_one
returns the constant.
.Sh SEE ALSO
.Xr BN_bn2bin 3 ,
.Xr BN_new 3 ,
.Xr BN_set_bit 3 ,
.Xr BN_set_negative 3
.Sh HISTORY
.Fn BN_zero ,
.Fn BN_one ,
and
.Fn BN_set_word
are available in all versions of SSLeay and OpenSSL.
.Fn BN_value_one
and
.Fn BN_get_word
were added in SSLeay 0.8.
.Pp
.Fn BN_value_one
was changed to return a true
.Vt const BIGNUM *
in OpenSSL 0.9.7.
.Sh BUGS
Someone might change the constant.
.Pp
If a
.Vt BIGNUM
is equal to 0xffffffffL; it can be represented as an
.Vt unsigned long
but this value is also returned on error.
|
