.\" $OpenBSD: BN_zero.3,v 1.12 2022/11/22 19:02:07 schwarze Exp $ .\" full merge up to: OpenSSL a528d4f0 Oct 27 13:40:11 2015 -0400 .\" selective merge up to: OpenSSL b713c4ff Jan 22 14:41:09 2018 -0500 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2021, 2022 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. 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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, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: November 22 2022 $ .Dt BN_ZERO 3 .Os .Sh NAME .Nm BN_zero_ex , .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 void .Fo BN_zero_ex .Fa "BIGNUM *a" .Fc .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 "BN_ULONG w" .Fc .Ft BN_ULONG .Fo BN_get_word .Fa "const BIGNUM *a" .Fc .Sh DESCRIPTION .Vt BN_ULONG is a macro that expands to an unsigned integral type optimized for the most efficient implementation on the local platform. It is .Vt unsigned long Pq = Vt uint64_t on .Dv _LP64 platforms and .Vt unsigned int Pq = Vt uint32_t elsewhere. .Pp .Fn BN_zero_ex , .Fn BN_one , and .Fn BN_set_word set .Fa a to the values 0, 1 and .Fa w respectively. .Fn BN_zero is a deprecated version of .Fn BN_zero_ex that may attempt to allocate memory; consequently, and in contrast to .Fn BN_zero_ex , it may fail. .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 comparisons and assignments. .Sh RETURN VALUES .Fn BN_get_word returns the value .Fa a , or a number with all bits set if .Fa a cannot be represented as a .Vt BN_ULONG . .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 , .Fn BN_value_one , and .Fn BN_set_word first appeared in SSLeay 0.5.1. .Fn BN_get_word first appeared in SSLeay 0.6.0. These functions have been available since .Ox 2.4 . .Pp .Fn BN_zero_ex first appeared in OpenSSL 0.9.8 and has been available since .Ox 4.5 . .Sh BUGS Someone might change the constant. .Pp If the value of a .Vt BIGNUM is equal to a .Vt BN_ULONG with all bits set, the return value of .Fn BN_get_word collides with return value used to indicate errors. .Pp .Vt BN_ULONG should probably be a typedef rather than a macro.