44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
#include <tommath_private.h>
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#ifdef BN_MP_INVMOD_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tstdenis82@gmail.com, http://libtom.org
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*/
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/* hac 14.61, pp608 */
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int mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
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{
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/* b cannot be negative */
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if ((b->sign == MP_NEG) || (mp_iszero(b) == MP_YES)) {
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return MP_VAL;
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}
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#ifdef BN_FAST_MP_INVMOD_C
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/* if the modulus is odd we can use a faster routine instead */
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if ((mp_isodd(b) == MP_YES) && (mp_cmp_d(b, 1) != MP_EQ)) {
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return fast_mp_invmod(a, b, c);
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}
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#endif
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#ifdef BN_MP_INVMOD_SLOW_C
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return mp_invmod_slow(a, b, c);
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#else
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return MP_VAL;
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#endif
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}
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#endif
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/* ref: $Format:%D$ */
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/* git commit: $Format:%H$ */
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/* commit time: $Format:%ai$ */
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