Updated: 2021/Apr/14


BN_zero(3)                          OpenSSL                         BN_zero(3)



NAME
       BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM
       assignment operations

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/bn.h>

        void BN_zero(BIGNUM *a);
        int BN_one(BIGNUM *a);

        const BIGNUM *BN_value_one(void);

        int BN_set_word(BIGNUM *a, BN_ULONG w);
        unsigned BN_ULONG BN_get_word(BIGNUM *a);

DESCRIPTION
       BN_ULONG is a macro that will be an unsigned integral type optimized
       for the most efficient implementation on the local platform.

       BN_zero(), BN_one() and BN_set_word() set a to the values 0, 1 and w
       respectively.  BN_zero() and BN_one() are macros.

       BN_value_one() returns a BIGNUM constant of value 1. This constant is
       useful for use in comparisons and assignment.

       BN_get_word() returns a, if it can be represented as a BN_ULONG.

RETURN VALUES
       BN_get_word() returns the value a, or all-bits-set if a cannot be
       represented as a single integer.

       BN_one() and BN_set_word() return 1 on success, 0 otherwise.
       BN_value_one() returns the constant.  BN_zero() never fails and returns
       no value.

BUGS
       If a BIGNUM is equal to the value of all-bits-set, it will collide with
       the error condition returned by BN_get_word() which uses that as an
       error value.

       BN_ULONG should probably be a typedef.

SEE ALSO
       BN_bn2bin(3)

HISTORY
       In OpenSSL 0.9.8, BN_zero() was changed to not return a value; previous
       versions returned an int.

COPYRIGHT
       Copyright 2000-2018 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_zero(3)