/* -*-c-*-
*
- * $Id: mpmont.c,v 1.3 1999/11/21 11:35:10 mdw Exp $
+ * $Id: mpmont.c,v 1.4 1999/11/21 12:27:06 mdw Exp $
*
* Montgomery reduction
*
/*----- Revision history --------------------------------------------------*
*
* $Log: mpmont.c,v $
+ * Revision 1.4 1999/11/21 12:27:06 mdw
+ * Remove a division from the Montgomery setup by calculating
+ * %$R^2 \bmod m$% first and then %$R \bmod m$% by Montgomery reduction of
+ * %$R^2$%.
+ *
* Revision 1.3 1999/11/21 11:35:10 mdw
* Performance improvement: use @mp_sqr@ and @mpmont_reduce@ instead of
* @mpmont_mul@ for squaring in exponentiation.
{
size_t l = MP_LEN(m);
- mp *r = mp_create(l + 1);
+ mp *r = mp_create(2 * l + 1);
mm->shift = l * MPW_BITS;
MPX_ZERO(r->v, r->vl - 1);
r->vl[-1] = 1;
- mm->r = mm->r2 = MP_NEW;
- mp_div(0, &mm->r, r, m);
- r = mp_sqr(r, mm->r);
+ mm->r2 = MP_NEW;
mp_div(0, &mm->r2, r, m);
+ mm->r = mpmont_reduce(mm, MP_NEW, mm->r2);
MP_DROP(r);
}
}