tommath/bn_mp_invmod.c

41 lines
1.0 KiB
C
Raw Normal View History

#include "tommath_private.h"
2004-10-29 18:07:18 -04:00
#ifdef BN_MP_INVMOD_C
2003-02-28 11:08:34 -05:00
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
2003-08-04 21:24:44 -04:00
* LibTomMath is a library that provides multiple-precision
2003-02-28 11:08:34 -05:00
* integer arithmetic as well as number theoretic functionality.
*
2003-08-04 21:24:44 -04:00
* The library was designed directly after the MPI library by
2003-02-28 11:08:34 -05:00
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
2018-12-29 11:56:20 -05:00
* SPDX-License-Identifier: Unlicense
2003-02-28 11:08:34 -05:00
*/
2003-07-02 11:39:39 -04:00
/* hac 14.61, pp608 */
2017-09-20 10:59:43 -04:00
int mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
2003-02-28 11:08:34 -05:00
{
/* b cannot be negative and has to be >1 */
2017-10-15 10:11:09 -04:00
if ((b->sign == MP_NEG) || (mp_cmp_d(b, 1uL) != MP_GT)) {
2017-08-30 13:11:35 -04:00
return MP_VAL;
}
2003-02-28 11:08:34 -05:00
2004-10-29 18:07:18 -04:00
#ifdef BN_FAST_MP_INVMOD_C
2017-08-30 13:11:35 -04:00
/* if the modulus is odd we can use a faster routine instead */
if ((mp_isodd(b) == MP_YES)) {
2017-08-30 13:11:35 -04:00
return fast_mp_invmod(a, b, c);
}
2004-10-29 18:07:18 -04:00
#endif
2003-02-28 11:08:34 -05:00
2004-10-29 18:07:18 -04:00
#ifdef BN_MP_INVMOD_SLOW_C
2017-08-30 13:11:35 -04:00
return mp_invmod_slow(a, b, c);
#else
2017-08-30 13:11:35 -04:00
return MP_VAL;
#endif
2003-02-28 11:08:34 -05:00
}
2004-10-29 18:07:18 -04:00
#endif
2005-08-01 12:37:28 -04:00
2017-08-28 10:27:26 -04:00
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */