Mercurial > dropbear
comparison libtommath/bn_mp_invmod.c @ 284:eed26cff980b
propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Wed, 08 Mar 2006 13:23:49 +0000 |
| parents | |
| children | 5ff8218bcee9 |
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| 283:bd240aa12ba7 | 284:eed26cff980b |
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| 1 #include <tommath.h> | |
| 2 #ifdef BN_MP_INVMOD_C | |
| 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 | |
| 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); | |
| 30 } | |
| 31 #endif | |
| 32 | |
| 33 #ifdef BN_MP_INVMOD_SLOW_C | |
| 34 return mp_invmod_slow(a, b, c); | |
| 35 #endif | |
| 36 | |
| 37 return MP_VAL; | |
| 38 } | |
| 39 #endif |