BN_zero

- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- BUGS
- SEE ALSO
- HISTORY
- COPYRIGHT

# NAME

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

# 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.