3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
12 * The library is free for all purposes without any express
15 * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
18 /* hac 14.61, pp608 */
19 int mp_invmod (mp_int * a, mp_int * b, mp_int * c)
21 /* b cannot be negative */
22 if (b->sign == MP_NEG || mp_iszero(b) == 1) {
26 #ifdef BN_FAST_MP_INVMOD_C
27 /* if the modulus is odd we can use a faster routine instead */
28 if (mp_isodd (b) == 1) {
29 return fast_mp_invmod (a, b, c);
33 #ifdef BN_MP_INVMOD_SLOW_C
34 return mp_invmod_slow(a, b, c);