X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/math/mpmont-mexp.c

diff --git a/math/mpmont-mexp.c b/math/mpmont-mexp.c
new file mode 100644
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+++ b/math/mpmont-mexp.c
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+/* -*-c-*-
+ *
+ * Multiple simultaneous exponentiations
+ *
+ * (c) 1999 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Catacomb is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include "mp.h"
+#include "mpmont.h"
+
+#define EXP_WINSZ 3
+#include "mpmont-exp.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @mpmont_mexpr@ --- *
+ *
+ * Arguments:	@mpmont *mm@ = pointer to Montgomery reduction context
+ *		@mp *d@ = fake destination
+ *		@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
+ *		exponents are %$e_0, e_1, \ldots, e_{n-1}$% then the result
+ *		is:
+ *
+ *		%$g_0^{e_0} g_1^{e_1} \ldots g_{n-1}^{e_{n-1}} \bmod m$%
+ *
+ *		except that the %$g_i$% and result are in Montgomery form.
+ */
+
+static mp *mexpr(mpmont *mm, mp *d, mp_expfactor *f, size_t n)
+{
+  mp *a = MP_COPY(mm->r);
+  mp *spare = MP_NEW;
+  size_t i;
+
+  for (i = 0; i < n; i++) {
+    mp *t;
+    if (f[i].exp->f & MP_BURN)
+      spare = MP_NEWSEC;
+    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
+ *		@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, 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 = mpmont_mul(mm, MP_NEW, f[i].base, mm->r2);
+    ff[i].exp = f[i].exp;
+  }
+  d = mexpr(mm, d, ff, n);
+  return (mpmont_reduce(mm, d, d));
+}
+
+/*----- Test rig ----------------------------------------------------------*/
+
+#ifdef TEST_RIG
+
+#include <mLib/testrig.h>
+
+static int verify(size_t n, dstr *v)
+{
+  mp *m = *(mp **)v[0].buf;
+  mp_expfactor *f = xmalloc(n * sizeof(*f));
+  mp *r, *rr;
+  size_t i, j;
+  mpmont mm;
+  int ok = 1;
+
+  j = 1;
+  for (i = 0; i < n; i++) {
+    f[i].base = *(mp **)v[j++].buf;
+    f[i].exp = *(mp **)v[j++].buf;
+  }
+
+  rr = *(mp **)v[j].buf;
+  mpmont_create(&mm, m);
+  r = mpmont_mexp(&mm, MP_NEW, f, n);
+  if (!MP_EQ(r, rr)) {
+    fputs("\n*** mexp failed\n", stderr);
+    fputs("m = ", stderr); mp_writefile(m, stderr, 10);
+    for (i = 0; i < n; i++) {
+      fprintf(stderr, "\ng_%u = ", i);
+      mp_writefile(f[i].base, stderr, 10);
+      fprintf(stderr, "\ne_%u = ", i);
+      mp_writefile(f[i].exp, stderr, 10);
+    }
+    fputs("\nr = ", stderr); mp_writefile(r, stderr, 10);
+    fputs("\nR = ", stderr); mp_writefile(rr, stderr, 10);
+    fputc('\n', stderr);
+    ok = 0;
+  }
+
+  for (i = 0; i < n; i++) {
+    MP_DROP(f[i].base);
+    MP_DROP(f[i].exp);
+  }
+  MP_DROP(m);
+  MP_DROP(r);
+  MP_DROP(rr);
+  mpmont_destroy(&mm);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
+  return (ok);
+}
+
+static int t1(dstr *v) { return verify(1, v); }
+static int t2(dstr *v) { return verify(2, v); }
+static int t3(dstr *v) { return verify(3, v); }
+static int t4(dstr *v) { return verify(4, v); }
+static int t5(dstr *v) { return verify(5, v); }
+
+static test_chunk tests[] = {
+  { "mexp-1", t1, { &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, 0 } },
+  { "mexp-2", t2, { &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, 0 } },
+  { "mexp-3", t3, { &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, 0 } },
+  { "mexp-4", t4, { &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, 0 } },
+  { "mexp-5", t5, { &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, &type_mp,
+		    &type_mp, 0 } },
+  { 0, 0, { 0 } }
+};
+
+int main(int argc, char *argv[])
+{
+  sub_init();
+  test_run(argc, argv, tests, SRCDIR "/t/mpmont");
+  return (0);
+}
+
+#endif
+
+/*----- That's all, folks -------------------------------------------------*/