X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/4cc02d06a57cc386ba445d34d9b83329bb29f89c..d34decd2b2b88240cf4ca68a2a5feb7bf36de6e7:/mpmont-mexp.c

diff --git a/mpmont-mexp.c b/mpmont-mexp.c
index 4180fbc..0e5da91 100644
--- a/mpmont-mexp.c
+++ b/mpmont-mexp.c
@@ -1,8 +1,8 @@
 /* -*-c-*-
  *
- * $Id: mpmont-mexp.c,v 1.1 1999/11/19 13:19:29 mdw Exp $
+ * $Id: mpmont-mexp.c,v 1.4 2000/06/17 11:45:09 mdw Exp $
  *
- * Multiplle simultaneous exponentiations
+ * Multiple simultaneous exponentiations
  *
  * (c) 1999 Straylight/Edgeware
  */
@@ -30,6 +30,18 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpmont-mexp.c,v $
+ * 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.
  *
@@ -45,6 +57,7 @@
 /* --- @mpmont_mexpr@ --- *
  *
  * Arguments:	@mpmont *mm@ = pointer to Montgomery reduction context
+ *		@mp *d@ = fake destination
  *		@mpmont_factor *f@ = pointer to array of factors
  *		@size_t n@ = number of factors supplied
  *
@@ -60,7 +73,7 @@ typedef struct scan {
   mpw w;
 } scan;
 
-mp *mpmont_mexpr(mpmont *mm, mpmont_factor *f, size_t n)
+mp *mpmont_mexpr(mpmont *mm, mp *d, mpmont_factor *f, size_t n)
 {
   size_t vn = 1 << n;
   mp **v = xmalloc(vn * sizeof(mp *));
@@ -113,6 +126,9 @@ mp *mpmont_mexpr(mpmont *mm, mpmont_factor *f, size_t n)
    *
    * I must scan the exponents from left to right, which is a shame.  It
    * means that I can't use the standard @mpscan@ stuff, in particular.
+   *
+   * If any of the exponents are considered secret then make the accumulator
+   * automatically set the secret bit.
    */
 
   {
@@ -124,6 +140,8 @@ mp *mpmont_mexpr(mpmont *mm, mpmont_factor *f, size_t n)
       s[i].len = MP_LEN(f[i].exp);
       if (s[i].len > o)
 	o = s[i].len;
+      if (f[i].exp->f & MP_BURN)
+	spare = MP_NEWSEC;
     }
     b = 0;
   }
@@ -157,7 +175,8 @@ mp *mpmont_mexpr(mpmont *mm, mpmont_factor *f, size_t n)
     /* --- Accumulate the result --- */
 
     if (spare) {
-      dd = mpmont_mul(mm, spare, a, a);
+      dd = mp_sqr(spare, a);
+      dd = mpmont_reduce(mm, dd, dd);
       spare = a;
       a = dd;
     }
@@ -181,12 +200,16 @@ mp *mpmont_mexpr(mpmont *mm, mpmont_factor *f, size_t n)
     free(s);
   }
 
+  if (d != MP_NEW)
+    MP_DROP(d);
+
   return (a);
 }
 
 /* --- @mpmont_mexp@ --- *
  *
  * Arguments:	@mpmont *mm@ = pointer to Montgomery reduction context
+ *		@mp *d@ = fake destination
  *		@mpmont_factor *f@ = pointer to array of factors
  *		@size_t n@ = number of factors supplied
  *
@@ -195,9 +218,9 @@ mp *mpmont_mexpr(mpmont *mm, mpmont_factor *f, size_t n)
  * Use:		Convenient interface over @mpmont_mexpr@.
  */
 
-mp *mpmont_mexp(mpmont *mm, mpmont_factor *f, size_t n)
+mp *mpmont_mexp(mpmont *mm, mp *d, mpmont_factor *f, size_t n)
 {
-  mp *d = mpmont_mexpr(mm, f, n);
+  d = mpmont_mexpr(mm, d, f, n);
   d = mpmont_reduce(mm, d, d);
   return (d);
 }
@@ -225,7 +248,7 @@ static int verify(size_t n, dstr *v)
 
   rr = *(mp **)v[j].buf;
   mpmont_create(&mm, m);
-  r = mpmont_mexp(&mm, f, n);
+  r = mpmont_mexp(&mm, MP_NEW, f, n);
   if (MP_CMP(r, !=, rr)) {
     fputs("\n*** mexp failed\n", stderr);
     fputs("m = ", stderr); mp_writefile(m, stderr, 10);
@@ -249,6 +272,7 @@ static int verify(size_t n, dstr *v)
   MP_DROP(r);
   MP_DROP(rr);
   mpmont_destroy(&mm);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
   return (ok);
 }