openssl1.0/doc/crypto/BN_zero.pod
2019-08-09 10:00:55 +02:00

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=pod
=head1 NAME
BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM assignment
operations
=head1 SYNOPSIS
#include <openssl/bn.h>
int BN_zero(BIGNUM *a);
int BN_one(BIGNUM *a);
const BIGNUM *BN_value_one(void);
int BN_set_word(BIGNUM *a, BN_ULONG w);
BN_ULONG BN_get_word(BIGNUM *a);
=head1 DESCRIPTION
B<BN_ULONG> is a macro that will be an unsigned integral type optimied
for the most efficient implementation on the local platform.
BN_zero(), BN_one() and BN_set_word() set B<a> to the values 0, 1 and
B<w> respectively. BN_zero() and BN_one() are macros.
BN_value_one() returns a B<BIGNUM> constant of value 1. This constant
is useful for use in comparisons and assignment.
BN_get_word() returns B<a>, if it can be represented as a B<BN_ULONG>.
=head1 RETURN VALUES
BN_get_word() returns the value B<a>, or all-bits-set if B<a> cannot
be represented as a B<BN_ULONG>.
BN_zero(), BN_one() and BN_set_word() return 1 on success, 0 otherwise.
BN_value_one() returns the constant.
=head1 BUGS
If a B<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.
B<BN_ULONG> should probably be a typedef.
=head1 SEE ALSO
L<bn(3)|bn(3)>, L<BN_bn2bin(3)|BN_bn2bin(3)>
=head1 HISTORY
BN_zero(), BN_one() and BN_set_word() are available in all versions of
SSLeay and OpenSSL. BN_value_one() and BN_get_word() were added in
SSLeay 0.8.
BN_value_one() was changed to return a true const BIGNUM * in OpenSSL
0.9.7.
=cut