Add cyclic group abstraction, with test code. Separate off exponentation

[u/mdw/catacomb] / mpbarrett.h

diff --git a/mpbarrett.h b/mpbarrett.h
index d9c02ad..3168205 100644 (file)
--- a/mpbarrett.h
+++ b/mpbarrett.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpbarrett.h,v 1.1 1999/12/10 23:22:00 mdw Exp $
+ * $Id: mpbarrett.h,v 1.4 2004/04/01 12:50:09 mdw Exp $
  *
  * Barrett modular reduction
  *
@@ -30,6 +30,19 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpbarrett.h,v $
+ * Revision 1.4  2004/04/01 12:50:09  mdw
+ * Add cyclic group abstraction, with test code.  Separate off exponentation
+ * functions for better static linking.  Fix a buttload of bugs on the way.
+ * Generally ensure that negative exponents do inversion correctly.  Add
+ * table of standard prime-field subgroups.  (Binary field subgroups are
+ * currently unimplemented but easy to add if anyone ever finds a good one.)
+ *
+ * Revision 1.3  2001/06/16 12:58:47  mdw
+ * Added simultaneous exponentiation with Barrett reduction.
+ *
+ * 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.
  *
@@ -109,8 +122,7 @@ extern void mpbarrett_destroy(mpbarrett */*mb*/);
  * Returns:    The residue of @m@ modulo the number in the reduction
  *             context.
  *
- * Use:                Performs an efficient modular reduction.  The argument is
- *             assumed to be positive.
+ * Use:                Performs an efficient modular reduction.
  */
 
 extern mp *mpbarrett_reduce(mpbarrett */*mb*/, mp */*d*/, mp */*m*/);
@@ -127,6 +139,23 @@ extern mp *mpbarrett_reduce(mpbarrett */*mb*/, mp */*d*/, mp */*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