1 /* $NetBSD: bn_mp_invmod.c,v 1.1.1.2 2014/04/24 12:45:31 pettai Exp $ */
2
3 #include <tommath.h>
4 #ifdef BN_MP_INVMOD_C
5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20 /* hac 14.61, pp608 */
mp_invmod(mp_int * a,mp_int * b,mp_int * c)21 int mp_invmod (mp_int * a, mp_int * b, mp_int * c)
22 {
23 /* b cannot be negative */
24 if (b->sign == MP_NEG || mp_iszero(b) == 1) {
25 return MP_VAL;
26 }
27
28 #ifdef BN_FAST_MP_INVMOD_C
29 /* if the modulus is odd we can use a faster routine instead */
30 if (mp_isodd (b) == 1) {
31 return fast_mp_invmod (a, b, c);
32 }
33 #endif
34
35 #ifdef BN_MP_INVMOD_SLOW_C
36 return mp_invmod_slow(a, b, c);
37 #else
38 return MP_VAL;
39 #endif
40 }
41 #endif
42
43 /* Source: /cvs/libtom/libtommath/bn_mp_invmod.c,v */
44 /* Revision: 1.4 */
45 /* Date: 2006/12/28 01:25:13 */
46