BN_mod_inverse - compute inverse modulo n

#include <openssl/bn.h>

BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
                       BN_CTX *ctx);

BN_mod_inverse() computes the inverse of a modulo n places the result in r ("(a*r)%n==1"). If r is NULL, a new BIGNUM is created.

ctx is a previously allocated BN_CTX used for temporary variables. r may be the same BIGNUM as a or n.

BN_mod_inverse() returns the BIGNUM containing the inverse, and NULL on error. The error codes can be obtained by ERR_get_error(3).

ERR_get_error(3), BN_add(3)

Copyright 2000-2017 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

2021-03-25 1.1.1k