freebsd man page for bn_mod_inverse

BN_mod_inverse(3SSL)						      OpenSSL						      BN_mod_inverse(3SSL)

NAME
       BN_mod_inverse - compute inverse modulo n

SYNOPSIS
	#include <openssl/bn.h>

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

DESCRIPTION
       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.

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

SEE ALSO
       bn(3), ERR_get_error(3), BN_add(3)

HISTORY
       BN_mod_inverse() is available in all versions of SSLeay and OpenSSL.

1.0.1e								    2013-02-11						      BN_mod_inverse(3SSL)