| #include <tommath.h> |
| #ifdef BN_MP_INVMOD_C |
| /* LibTomMath, multiple-precision integer library -- Tom St Denis |
| * |
| * LibTomMath is a library that provides multiple-precision |
| * integer arithmetic as well as number theoretic functionality. |
| * |
| * The library was designed directly after the MPI library by |
| * Michael Fromberger but has been written from scratch with |
| * additional optimizations in place. |
| * |
| * The library is free for all purposes without any express |
| * guarantee it works. |
| * |
| * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org |
| */ |
| |
| /* hac 14.61, pp608 */ |
| int mp_invmod (mp_int * a, mp_int * b, mp_int * c) |
| { |
| /* b cannot be negative */ |
| if (b->sign == MP_NEG || mp_iszero(b) == 1) { |
| return MP_VAL; |
| } |
| |
| #ifdef BN_FAST_MP_INVMOD_C |
| /* if the modulus is odd we can use a faster routine instead */ |
| if (mp_isodd (b) == 1) { |
| return fast_mp_invmod (a, b, c); |
| } |
| #endif |
| |
| #ifdef BN_MP_INVMOD_SLOW_C |
| return mp_invmod_slow(a, b, c); |
| #endif |
| |
| return MP_VAL; |
| } |
| #endif |
