| =pod | 
 |  | 
 | =head1 NAME | 
 |  | 
 | BN_mod_inverse - compute inverse modulo n | 
 |  | 
 | =head1 SYNOPSIS | 
 |  | 
 |  #include <openssl/bn.h> | 
 |  | 
 |  BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n, | 
 |                         BN_CTX *ctx); | 
 |  | 
 | =head1 DESCRIPTION | 
 |  | 
 | BN_mod_inverse() computes the inverse of B<a> modulo B<n> | 
 | places the result in B<r> (C<(a*r)%n==1>). If B<r> is NULL, | 
 | a new B<BIGNUM> is created. | 
 |  | 
 | B<ctx> is a previously allocated B<BN_CTX> used for temporary | 
 | variables. B<r> may be the same B<BIGNUM> as B<a> or B<n>. | 
 |  | 
 | =head1 RETURN VALUES | 
 |  | 
 | BN_mod_inverse() returns the B<BIGNUM> containing the inverse, and | 
 | NULL on error. The error codes can be obtained by L<ERR_get_error(3)>. | 
 |  | 
 | =head1 SEE ALSO | 
 |  | 
 | L<ERR_get_error(3)>, L<BN_add(3)> | 
 |  | 
 | =head1 COPYRIGHT | 
 |  | 
 | Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. | 
 |  | 
 | Licensed under the Apache License 2.0 (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 | 
 | L<https://www.openssl.org/source/license.html>. | 
 |  | 
 | =cut |