/* -*-c-*-
*
- * $Id: mpmont.c,v 1.5 1999/11/22 13:58:40 mdw Exp $
+ * $Id: mpmont.c,v 1.6 1999/12/10 23:18:39 mdw Exp $
*
* Montgomery reduction
*
/*----- Revision history --------------------------------------------------*
*
* $Log: mpmont.c,v $
+ * Revision 1.6 1999/12/10 23:18:39 mdw
+ * Change interface for suggested destinations.
+ *
* Revision 1.5 1999/11/22 13:58:40 mdw
* Add an option to disable Montgomery reduction, so that performance
* comparisons can be done.
* Returns: ---
*
* Use: Initializes a Montgomery reduction context ready for use.
+ * The argument @m@ must be a positive odd integer.
*/
#ifdef MPMONT_DISABLE
void mpmont_create(mpmont *mm, mp *m)
{
+ /* --- Validate the arguments --- */
+
+ assert(((void)"Montgomery modulus must be positive",
+ (m->f & MP_NEG) == 0));
+ assert(((void)"Montgomery modulus must be odd", m->v[0] & 1));
+
/* --- Take a copy of the modulus --- */
mp_shrink(m);
{
mpw av[2] = { 0, 1 };
mp a, b;
- mp *i;
+ mp *i = MP_NEW;
mpw mi;
mp_build(&a, av, av + 2);
*
* Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
* @mp *d@ = destination
- * @const mp *a@ = source, assumed positive
+ * @mp *a@ = source, assumed positive
*
* Returns: Result, %$a R^{-1} \bmod m$%.
*/
#ifdef MPMONT_DISABLE
-mp *mpmont_reduce(mpmont *mm, mp *d, const mp *a)
+mp *mpmont_reduce(mpmont *mm, mp *d, mp *a)
{
mp_div(0, &d, a, mm->m);
return (d);
#else
-mp *mpmont_reduce(mpmont *mm, mp *d, const mp *a)
+mp *mpmont_reduce(mpmont *mm, mp *d, mp *a)
{
mpw *dv, *dvl;
- const mpw *mv, *mvl;
+ mpw *mv, *mvl;
size_t n;
/* --- Initial conditioning of the arguments --- */
*
* Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
* @mp *d@ = destination
- * @const mp *a, *b@ = sources, assumed positive
+ * @mp *a, *b@ = sources, assumed positive
*
* Returns: Result, %$a b R^{-1} \bmod m$%.
*/
#ifdef MPMONT_DISABLE
-mp *mpmont_mul(mpmont *mm, mp *d, const mp *a, const mp *b)
+mp *mpmont_mul(mpmont *mm, mp *d, mp *a, mp *b)
{
d = mp_mul(d, a, b);
mp_div(0, &d, d, mm->m);
#else
-mp *mpmont_mul(mpmont *mm, mp *d, const mp *a, const mp *b)
+mp *mpmont_mul(mpmont *mm, mp *d, mp *a, mp *b)
{
- mpw *dv, *dvl;
- const mpw *av, *avl;
- const mpw *bv, *bvl;
- const mpw *mv, *mvl;
- mpw y;
- size_t n, i;
-
- /* --- Initial conditioning of the arguments --- */
+ if (MP_LEN(a) > KARATSUBA_CUTOFF && MP_LEN(b) > KARATSUBA_CUTOFF) {
+ d = mp_mul(d, a, b);
+ d = mpmont_reduce(mm, d, d);
+ } else {
+ mpw *dv, *dvl;
+ mpw *av, *avl;
+ mpw *bv, *bvl;
+ mpw *mv, *mvl;
+ mpw y;
+ size_t n, i;
+
+ /* --- Initial conditioning of the arguments --- */
+
+ if (MP_LEN(a) > MP_LEN(b)) {
+ mp *t = a; a = b; b = t;
+ }
+ n = MP_LEN(mm->m);
- if (MP_LEN(a) > MP_LEN(b)) {
- const mp *t = a; a = b; b = t;
- }
- n = MP_LEN(mm->m);
-
- MP_MODIFY(d, 2 * n + 1);
- dv = d->v; dvl = d->vl;
- MPX_ZERO(dv, dvl);
- av = a->v; avl = a->vl;
- bv = b->v; bvl = b->vl;
- mv = mm->m->v; mvl = mm->m->vl;
- y = *bv;
+ a = MP_COPY(a);
+ b = MP_COPY(b);
+ MP_MODIFY(d, 2 * n + 1);
+ dv = d->v; dvl = d->vl;
+ MPX_ZERO(dv, dvl);
+ av = a->v; avl = a->vl;
+ bv = b->v; bvl = b->vl;
+ mv = mm->m->v; mvl = mm->m->vl;
+ y = *bv;
+
+ /* --- Montgomery multiplication phase --- */
+
+ i = 0;
+ while (i < n && av < avl) {
+ mpw x = *av++;
+ mpw u = MPW((*dv + x * y) * mm->mi);
+ MPX_UMLAN(dv, dvl, bv, bvl, x);
+ MPX_UMLAN(dv, dvl, mv, mvl, u);
+ dv++;
+ i++;
+ }
- /* --- Montgomery multiplication phase --- */
+ /* --- Simpler Montgomery reduction phase --- */
- i = 0;
- while (i < n && av < avl) {
- mpw x = *av++;
- mpw u = MPW((*dv + x * y) * mm->mi);
- MPX_UMLAN(dv, dvl, bv, bvl, x);
- MPX_UMLAN(dv, dvl, mv, mvl, u);
- dv++;
- i++;
- }
+ while (i < n) {
+ mpw u = MPW(*dv * mm->mi);
+ MPX_UMLAN(dv, dvl, mv, mvl, u);
+ dv++;
+ i++;
+ }
- /* --- Simpler Montgomery reduction phase --- */
+ /* --- Done --- */
- while (i < n) {
- mpw u = MPW(*dv * mm->mi);
- MPX_UMLAN(dv, dvl, mv, mvl, u);
- dv++;
- i++;
+ memmove(d->v, dv, MPWS(dvl - dv));
+ d->vl -= dv - d->v;
+ MP_SHRINK(d);
+ d->f = (a->f | b->f) & MP_BURN;
+ if (MP_CMP(d, >=, mm->m))
+ d = mp_sub(d, d, mm->m);
+ MP_DROP(a);
+ MP_DROP(b);
}
- /* --- Done --- */
-
- memmove(d->v, dv, MPWS(dvl - dv));
- d->vl -= dv - d->v;
- MP_SHRINK(d);
- d->f = (a->f | b->f) & MP_BURN;
- if (MP_CMP(d, >=, mm->m))
- d = mp_sub(d, d, mm->m);
return (d);
}
/* --- @mpmont_expr@ --- *
*
* Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
- * @const mp *a@ = base
- * @const mp *e@ = exponent
+ * @mp *d@ = fake destination
+ * @mp *a@ = base
+ * @mp *e@ = exponent
*
* Returns: Result, %$a^e R \bmod m$%.
*/
-mp *mpmont_expr(mpmont *mm, const mp *a, const mp *e)
+mp *mpmont_expr(mpmont *mm, mp *d, mp *a, mp *e)
{
mpscan sc;
mp *ar = mpmont_mul(mm, MP_NEW, a, mm->r2);
- mp *d = MP_COPY(mm->r);
+ mp *x = MP_COPY(mm->r);
mp *spare = MP_NEW;
mp_scan(&sc, e);
spare = ar; ar = dd;
sq--;
}
- dd = mpmont_mul(mm, spare, d, ar);
- spare = d; d = dd;
+ dd = mpmont_mul(mm, spare, x, ar);
+ spare = x; x = dd;
}
sq++;
if (!MP_STEP(&sc))
MP_DROP(ar);
if (spare != MP_NEW)
MP_DROP(spare);
- return (d);
+ if (d != MP_NEW)
+ MP_DROP(d);
+ return (x);
}
/* --- @mpmont_exp@ --- *
*
* Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
- * @const mp *a@ = base
- * @const mp *e@ = exponent
+ * @mp *d@ = fake destination
+ * @mp *a@ = base
+ * @mp *e@ = exponent
*
* Returns: Result, %$a^e \bmod m$%.
*/
-mp *mpmont_exp(mpmont *mm, const mp *a, const mp *e)
+mp *mpmont_exp(mpmont *mm, mp *d, mp *a, mp *e)
{
- mp *d = mpmont_expr(mm, a, e);
+ d = mpmont_expr(mm, d, a, e);
d = mpmont_reduce(mm, d, d);
return (d);
}
MP_DROP(r);
MP_DROP(r2);
mpmont_destroy(&mm);
+ assert(mparena_count(MPARENA_GLOBAL) == 0);
return (ok);
}
MP_DROP(b);
MP_DROP(r);
mpmont_destroy(&mm);
+ assert(mparena_count(MPARENA_GLOBAL) == 0);
return ok;
}
mpmont mm;
mpmont_create(&mm, m);
- mr = mpmont_exp(&mm, a, b);
+ mr = mpmont_exp(&mm, MP_NEW, a, b);
if (MP_CMP(mr, !=, r)) {
fputs("\n*** montgomery modexp failed", stderr);
MP_DROP(r);
MP_DROP(mr);
mpmont_destroy(&mm);
+ assert(mparena_count(MPARENA_GLOBAL) == 0);
return ok;
}
static test_chunk tests[] = {
- { "create", tcreate, { &type_mp, &type_mp, &type_mp, &type_mp } },
- { "mul", tmul, { &type_mp, &type_mp, &type_mp, &type_mp } },
- { "exp", texp, { &type_mp, &type_mp, &type_mp, &type_mp } },
+ { "create", tcreate, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
+ { "mul", tmul, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
+ { "exp", texp, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
{ 0, 0, { 0 } },
};
projects / u / mdw / catacomb / blobdiff