/* -*-c-*-
*
- * $Id: mpmont-mexp.c,v 1.6 2001/06/16 13:00:20 mdw Exp $
+ * $Id$
*
* Multiple simultaneous exponentiations
*
* MA 02111-1307, USA.
*/
-/*----- Revision history --------------------------------------------------*
- *
- * $Log: mpmont-mexp.c,v $
- * Revision 1.6 2001/06/16 13:00:20 mdw
- * Use the generic exponentiation functions.
- *
- * Revision 1.5 2000/10/08 12:11:22 mdw
- * Use @MP_EQ@ instead of @MP_CMP@.
- *
- * Revision 1.4 2000/06/17 11:45:09 mdw
- * Major memory management overhaul. Added arena support. Use the secure
- * arena for secret integers. Replace and improve the MP management macros
- * (e.g., replace MP_MODIFY by MP_DEST).
- *
- * Revision 1.3 1999/12/10 23:18:39 mdw
- * Change interface for suggested destinations.
- *
- * Revision 1.2 1999/11/21 11:35:10 mdw
- * Performance improvement: use @mp_sqr@ and @mpmont_reduce@ instead of
- * @mpmont_mul@ for squaring in exponentiation.
- *
- * Revision 1.1 1999/11/19 13:19:29 mdw
- * Simultaneous exponentiation support.
- *
- */
-
/*----- Header files ------------------------------------------------------*/
#include "mp.h"
*
* Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
* @mp *d@ = fake destination
- * @mp_expfactor *f@ = pointer to array of factors
+ * @const mp_expfactor *f@ = pointer to array of factors
* @size_t n@ = number of factors supplied
*
* Returns: If the bases are %$g_0, g_1, \ldots, g_{n-1}$% and the
* except that the %$g_i$% and result are in Montgomery form.
*/
-mp *mpmont_mexpr(mpmont *mm, mp *d, mp_expfactor *f, size_t n)
+static mp *mexpr(mpmont *mm, mp *d, mp_expfactor *f, size_t n)
{
- mp *a = mp_copy(mm->r);
- mp *spare;
+ mp *a = MP_COPY(mm->r);
+ mp *spare = MP_NEW;
size_t i;
- spare = MP_NEW;
for (i = 0; i < n; i++) {
- if (f[i].exp->f & MP_BURN) {
+ mp *t;
+ if (f[i].exp->f & MP_BURN)
spare = MP_NEWSEC;
- break;
+ if (MP_NEGP(f[i].exp)) {
+ t = mpmont_reduce(mm, f[i].base, f[i].base);
+ t = mp_modinv(t, t, mm->m);
+ f[i].base = mpmont_mul(mm, t, t, mm->r2);
}
}
-
EXP_SIMUL(a, f, n);
mp_drop(d);
mp_drop(spare);
+ for (i = 0; i < n; i++)
+ MP_DROP(f[i].base);
+ xfree(f);
return (a);
}
+mp *mpmont_mexpr(mpmont *mm, mp *d, const mp_expfactor *f, size_t n)
+{
+ mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor));
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ ff[i].base = MP_COPY(f[i].base);
+ ff[i].exp = f[i].exp;
+ }
+ return (mexpr(mm, d, ff, n));
+}
+
/* --- @mpmont_mexp@ --- *
*
* Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
* @mp *d@ = fake destination
- * @mp_expfactor *f@ = pointer to array of factors
+ * @const mp_expfactor *f@ = pointer to array of factors
* @size_t n@ = number of factors supplied
*
* Returns: Product of bases raised to exponents, all mod @m@.
* Use: Convenient interface over @mpmont_mexpr@.
*/
-mp *mpmont_mexp(mpmont *mm, mp *d, mp_expfactor *f, size_t n)
+mp *mpmont_mexp(mpmont *mm, mp *d, const mp_expfactor *f, size_t n)
{
- mp_expfactor *v = xmalloc(sizeof(*v) * n);
+ mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor));
size_t i;
for (i = 0; i < n; i++) {
- v[i].base = mpmont_mul(mm, MP_NEW, f[i].base, mm->r2);
- v[i].exp = f[i].exp;
+ ff[i].base = mpmont_mul(mm, MP_NEW, f[i].base, mm->r2);
+ ff[i].exp = f[i].exp;
}
- d = mpmont_mexpr(mm, d, v, n);
- for (i = 0; i < n; i++)
- MP_DROP(v[i].base);
- xfree(v);
- d = mpmont_reduce(mm, d, d);
- return (d);
+ d = mexpr(mm, d, ff, n);
+ return (mpmont_reduce(mm, d, d));
}
/*----- Test rig ----------------------------------------------------------*/