/* -*-c-*-
*
- * $Id: mpmont-exp.c,v 1.2 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
*
* Modular exponentiation with Montgomery reduction
*
MP_COPY(a);
MP_SHRINK(e);
- if (e->f & MP_NEG) {
- a = mpmont_reduce(mm, a, a);
- a = mp_modinv(a, a, mm->m);
- a = mpmont_mul(mm, a, a, mm->r2);
- }
- if (MP_LEN(e) == 0)
+ if (MP_ZEROP(e))
;
- else if (MP_LEN(e) < EXP_THRESH)
- EXP_SIMPLE(x, a, e);
- else
- EXP_WINDOW(x, a, e);
+ else {
+ if (MP_NEGP(e)) {
+ a = mpmont_reduce(mm, a, a);
+ a = mp_modinv(a, a, mm->m);
+ a = mpmont_mul(mm, a, a, mm->r2);
+ }
+ if (MP_LEN(e) < EXP_THRESH)
+ EXP_SIMPLE(x, a, e);
+ else
+ EXP_WINDOW(x, a, e);
+ }
mp_drop(d);
mp_drop(spare);
mp_drop(a);