mp_exptmod_fast about libtommath

[czurnieden]

Without the normalization and redmode != 0 the rest would not work and an error is thrown.

[dmitry-lipetsk]

I offer to write

/*LINE 147*/
  if (redmode == 0) {
#ifdef BN_MP_MONTGOMERY_CALC_NORMALIZATION_C
     /* now we need R mod m */
     if ((err = mp_montgomery_calc_normalization (&res, P)) != MP_OKAY) {
       goto LBL_RES;
     }

     /* now set M[1] to G * R mod m */
     if ((err = mp_mulmod (G, &res, P, &M[1])) != MP_OKAY) {
       goto LBL_RES;
     }
#else 
     err = MP_VAL;
     goto LBL_RES;
#endif
  }