X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/4edc47b89bc56cd4041fdb0f4e8e892acd589ed8..18b3351a3791f19a63c0af05640719db8eb5d184:/field.h

diff --git a/field.h b/field.h
index 3a46ac9..6085716 100644
--- a/field.h
+++ b/field.h
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: field.h,v 1.10 2004/04/01 21:28:41 mdw Exp $
+ * $Id$
  *
  * Definitions for field arithmetic
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,65 +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: field.h,v $
- * Revision 1.10  2004/04/01 21:28:41  mdw
- * Normal basis support (translates to poly basis internally).  Rewrite
- * EC and prime group table generators in awk, so that they can reuse data
- * for repeated constants.
- *
- * Revision 1.9  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 1.8  2004/03/27 17:54:11  mdw
- * Standard curves and curve checking.
- *
- * Revision 1.7  2004/03/27 00:04:46  mdw
- * Implement efficient reduction for pleasant-looking primes.
- *
- * Revision 1.6  2004/03/23 15:19:32  mdw
- * Test elliptic curves more thoroughly.
- *
- * Revision 1.5  2004/03/23 12:08:26  mdw
- * Random field-element selection.
- *
- * Revision 1.4  2004/03/21 22:52:06  mdw
- * Merge and close elliptic curve branch.
- *
- * Revision 1.3.4.2  2004/03/21 22:39:46  mdw
- * Elliptic curves on binary fields work.
- *
- * Revision 1.3.4.1  2004/03/20 00:13:31  mdw
- * Projective coordinates for prime curves
- *
- * Revision 1.3  2002/01/13 13:48:44  mdw
- * Further progress.
- *
- * Revision 1.2  2001/05/07 17:30:13  mdw
- * Add an internal-representation no-op function.
- *
- * Revision 1.1  2001/04/29 18:12:33  mdw
- * Prototype version.
- *
- */
-
 #ifndef CATACOMB_FIELD_H
 #define CATACOMB_FIELD_H
 
@@ -103,6 +56,7 @@ typedef struct field {
   mp *m;				/* Modulus (prime and binary) */
   unsigned long nbits;			/* Length of field element in bits */
   size_t noctets;			/* Length of element in octets */
+  mp *q;				/* Number of elements in field */
 } field;
 
 enum {
@@ -217,6 +171,25 @@ extern int field_samep(field */*f*/, field */*g*/);
 
 extern int field_stdsamep(field */*f*/, field */*g*/);
 
+/*----- Arithmetic --------------------------------------------------------*/
+
+/* --- @field_exp@ --- *
+ *
+ * Arguments:	@field *f@ = pointer to field
+ *		@mp *d@ = fake destination
+ *		@mp *a@ = base
+ *		@mp *e@ = exponent
+ *
+ * Returns:	Result, %$a^e$%.
+ *
+ * Use:		Exponentiation in a finite field.  Note that all quantities
+ *		are in internal format.  This is a generic implementation
+ *		suitable for use with all fields and is not intended to be
+ *		optimal.
+ */
+
+extern mp *field_exp(field */*f*/, mp */*d*/, mp */*a*/, mp */*e*/);
+
 /*----- Creating fields ---------------------------------------------------*/
 
 /* --- @field_prime@ --- *
@@ -235,7 +208,7 @@ extern field *field_prime(mp */*p*/);
  *
  * Arguments:	@mp *p@ = the characteristic of the field
  *
- * Returns:	A pointer to the field.
+ * Returns:	A pointer to the field, or null.
  *
  * Use:		Creates a field structure for a prime field of size %$p$%,
  *		using efficient reduction for nice primes.
@@ -280,7 +253,7 @@ extern field *field_binnorm(mp */*p*/, mp */*beta*/);
  *		  * `prime', `niceprime', `binpoly', or `binnorm'
  *		  * an optional `:'
  *		  * the field modulus
- *	          * for `binnorm', an optional `,' and the beta value
+ *		  * for `binnorm', an optional `,' and the beta value
  */
 
 extern field *field_parse(qd_parse */*qd*/);