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Diffstat (limited to 'libtommath/bn_mp_submod.c')
-rw-r--r-- | libtommath/bn_mp_submod.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/libtommath/bn_mp_submod.c b/libtommath/bn_mp_submod.c new file mode 100644 index 0000000..7461678 --- /dev/null +++ b/libtommath/bn_mp_submod.c @@ -0,0 +1,38 @@ +#include <tommath.h> +#ifdef BN_MP_SUBMOD_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@gmail.com, http://math.libtomcrypt.com + */ + +/* d = a - b (mod c) */ +int +mp_submod (mp_int * a, mp_int * b, mp_int * c, mp_int * d) +{ + int res; + mp_int t; + + + if ((res = mp_init (&t)) != MP_OKAY) { + return res; + } + + if ((res = mp_sub (a, b, &t)) != MP_OKAY) { + mp_clear (&t); + return res; + } + res = mp_mod (&t, c, d); + mp_clear (&t); + return res; +} +#endif |