|
142
|
1 #include <tommath.h> |
|
|
2 #ifdef BN_MP_INVMOD_C |
|
2
|
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
|
|
4 * |
|
|
5 * LibTomMath is a library that provides multiple-precision |
|
|
6 * integer arithmetic as well as number theoretic functionality. |
|
|
7 * |
|
|
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. |
|
|
11 * |
|
|
12 * The library is free for all purposes without any express |
|
|
13 * guarantee it works. |
|
|
14 * |
|
|
15 * Tom St Denis, [email protected], http://math.libtomcrypt.org |
|
|
16 */ |
|
|
17 |
|
|
18 /* hac 14.61, pp608 */ |
|
|
19 int mp_invmod (mp_int * a, mp_int * b, mp_int * c) |
|
|
20 { |
|
|
21 /* b cannot be negative */ |
|
|
22 if (b->sign == MP_NEG || mp_iszero(b) == 1) { |
|
|
23 return MP_VAL; |
|
|
24 } |
|
|
25 |
|
142
|
26 #ifdef BN_FAST_MP_INVMOD_C |
|
2
|
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); |
|
|
30 } |
|
142
|
31 #endif |
|
2
|
32 |
|
142
|
33 #ifdef BN_MP_INVMOD_SLOW_C |
|
|
34 return mp_invmod_slow(a, b, c); |
|
|
35 #endif |
|
2
|
36 |
|
142
|
37 return MP_VAL; |
|
2
|
38 } |
|
142
|
39 #endif |
