ct.c, ct.h: New constant-time operations.

[u/mdw/catacomb] / mpbarrett.h

diff --git a/mpbarrett.h b/mpbarrett.h
index aa1971e..71d9ba7 100644 (file)
--- a/mpbarrett.h
+++ b/mpbarrett.h
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: mpbarrett.h,v 1.2 2000/10/08 12:03:44 mdw Exp $
+ * $Id$
  *
  * Barrett modular reduction
  *
  * (c) 1999 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,29 +15,18 @@
  * 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.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: mpbarrett.h,v $
- * Revision 1.2  2000/10/08 12:03:44  mdw
- * (mpbarrett_reduce): Cope with negative numbers.
- *
- * Revision 1.1  1999/12/10 23:22:00  mdw
- * Barrett reduction support: works with even moduli.
- *
- */
-
 /*----- Notes on Barrett reduction ----------------------------------------*
  *
  * Barrett reduction is a technique for computing modular residues.  Unlike
@@ -83,13 +72,12 @@ typedef struct mpbarrett {
  * Arguments:  @mpbarrett *mb@ = pointer to Barrett reduction context
  *             @mp *m@ = modulus to work to
  *
- *
- * Returns:    ---
+ * Returns:    Zero on success, nonzero on error.
  *
  * Use:                Initializes a Barrett reduction context ready for use.
  */
 
-extern void mpbarrett_create(mpbarrett */*mb*/, mp */*m*/);
+extern int mpbarrett_create(mpbarrett */*mb*/, mp */*m*/);
 
 /* --- @mpbarrett_destroy@ --- *
  *
@@ -120,15 +108,32 @@ extern mp *mpbarrett_reduce(mpbarrett */*mb*/, mp */*d*/, mp */*m*/);
 /* --- @mpbarrett_exp@ --- *
  *
  * Arguments:  @mpbarrett *mb@ = pointer to Barrett reduction context
- *              @mp *d@ = fake destination
- *              @mp *a@ = base
- *              @mp *e@ = exponent
+ *             @mp *d@ = fake destination
+ *             @mp *a@ = base
+ *             @mp *e@ = exponent
  *
- * Returns:     Result, %$a^e \bmod m$%.
+ * Returns:    Result, %$a^e \bmod m$%.
  */
 
 extern mp *mpbarrett_exp(mpbarrett */*mb*/, mp */*d*/, mp */*a*/, mp */*e*/);
 
+/* --- @mpbarrett_mexp@ --- *
+ *
+ * Arguments:  @mpbarrett *mb@ = pointer to Barrett 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:
+ *
+ *             %$g_0^{e_0} g_1^{e_1} \ldots g_{n-1}^{e_{n-1}} \bmod m$%
+ */
+
+extern mp *mpbarrett_mexp(mpbarrett */*mb*/, mp */*d*/,
+                         const mp_expfactor */*f*/, size_t /*n*/);
+
 /*----- That's all, folks -------------------------------------------------*/
 
 #ifdef __cplusplus