X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/432c4e184d44704511a5991b80224a87cb1d4613..7280f7f44cfae62f6d34761ac88aa19da7da5dd8:/field.h

diff --git a/field.h b/field.h
index 7af9b4f..6085716 100644
--- a/field.h
+++ b/field.h
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: field.h,v 1.8 2004/03/27 17:54:11 mdw Exp $
+ * $Id$
  *
  * Definitions for field arithmetic
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,53 +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 1.8  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
 
@@ -91,6 +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 {
@@ -109,6 +75,7 @@ typedef struct field_ops {
 
   void (*destroy)(field */*f*/);
   mp *(*rand)(field */*f*/, mp */*d*/, grand */*r*/);
+  int (*samep)(field */*f*/, field */*g*/);
 
   mp *(*in)(field */*f*/, mp */*d*/, mp */*x*/);
   mp *(*out)(field */*f*/, mp */*d*/, mp */*x*/);
@@ -141,6 +108,7 @@ typedef struct field_ops {
 
 #define F_DESTROY(f)		(f)->ops->destroy((f))
 #define F_RAND(f, d, r)		(f)->ops->rand((f), (d), (r))
+#define F_SAMEP(f, g)		(f)->ops->samep((f), (g))
 
 #define F_IN(f, d, x)		(f)->ops->in((f), (d), (x))
 #define F_OUT(f, d, x)		(f)->ops->out((f), (d), (x))
@@ -178,6 +146,50 @@ typedef struct field_ops {
 
 extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 
+/* --- @field_samep@ --- *
+ *
+ * Arguments:	@field *f, *g@ = two fields
+ *
+ * Returns:	Nonzero if the fields are identical (not just isomorphic).
+ *
+ * Use:		Checks for sameness of fields.  This function does the full
+ *		check, not just the field-type-specific check done by the
+ *		@sampep@ field operation.
+ */
+
+extern int field_samep(field */*f*/, field */*g*/);
+
+/* --- @field_stdsamep@ --- *
+ *
+ * Arguments:	@field *f, *g@ = two fields
+ *
+ * Returns:	Nonzero if the fields are identical (not just isomorphic).
+ *
+ * Use:		Standard sameness check, based on equality of the @m@
+ *		member.
+ */
+
+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@ --- *
@@ -196,7 +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.
@@ -216,6 +228,20 @@ extern field *field_niceprime(mp */*p*/);
 
 extern field *field_binpoly(mp */*p*/);
 
+/* --- @field_binnorm@ --- *
+ *
+ * Arguments:	@mp *p@ = the reduction polynomial
+ *		@mp *beta@ = representation of normal point
+ *
+ * Returns:	A pointer to the field.
+ *
+ * Use:		Creates a field structure for a binary field mod @p@ which
+ *		uses a normal basis representation externally.  Computations
+ *		are still done on a polynomial-basis representation.
+ */
+
+extern field *field_binnorm(mp */*p*/, mp */*beta*/);
+
 /* --- @field_parse@ --- *
  *
  * Arguments:	@qd_parse *qd@ = parser context
@@ -224,9 +250,10 @@ extern field *field_binpoly(mp */*p*/);
  *
  * Use:		Parses a field description, which has the form
  *
- *		  * `prime', `niceprime' or `binpoly'
+ *		  * `prime', `niceprime', `binpoly', or `binnorm'
  *		  * an optional `:'
  *		  * the field modulus
+ *		  * for `binnorm', an optional `,' and the beta value
  */
 
 extern field *field_parse(qd_parse */*qd*/);