xref: /openssl/doc/man3/BN_mod_inverse.pod (revision af0025fc)
1=pod
2
3=head1 NAME
4
5BN_mod_inverse - compute inverse modulo n
6
7=head1 SYNOPSIS
8
9 #include <openssl/bn.h>
10
11 BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
12                        BN_CTX *ctx);
13
14=head1 DESCRIPTION
15
16BN_mod_inverse() computes the inverse of B<a> modulo B<n>
17places the result in B<r> (C<(a*r)%n==1>). If B<r> is NULL,
18a new B<BIGNUM> is created.
19
20B<ctx> is a previously allocated B<BN_CTX> used for temporary
21variables. B<r> may be the same B<BIGNUM> as B<a>.
22
23=head1 NOTES
24
25It is an error to use the same B<BIGNUM> as B<n>.
26
27=head1 RETURN VALUES
28
29BN_mod_inverse() returns the B<BIGNUM> containing the inverse, and
30NULL on error. The error codes can be obtained by L<ERR_get_error(3)>.
31
32=head1 SEE ALSO
33
34L<ERR_get_error(3)>, L<BN_add(3)>
35
36=head1 COPYRIGHT
37
38Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
39
40Licensed under the Apache License 2.0 (the "License").  You may not use
41this file except in compliance with the License.  You can obtain a copy
42in the file LICENSE in the source distribution or at
43L<https://www.openssl.org/source/license.html>.
44
45=cut
46