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

[u/mdw/catacomb] / field.h

diff --git a/field.h b/field.h
index db27e63..bf0428a 100644 (file)
--- a/field.h
+++ b/field.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: field.h,v 1.6 2004/03/23 15:19:32 mdw Exp $
+ * $Id: field.h,v 1.9 2004/04/01 12:50:09 mdw Exp $
  *
  * Definitions for field arithmetic
  *
@@ -30,6 +30,19 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: field.h,v $
+ * 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.
  *
@@ -73,11 +86,18 @@
 #  include "mp.h"
 #endif
 
+#ifndef CATACOMB_QDPARSE_H
+#  include "qdparse.h"
+#endif
+
 /*----- Data structures ---------------------------------------------------*/
 
 typedef struct field {
   const struct field_ops *ops;         /* Field operations */
   mp *zero, *one;                      /* Identities in the field */
+  mp *m;                               /* Modulus (prime and binary) */
+  unsigned long nbits;                 /* Length of field element in bits */
+  size_t noctets;                      /* Length of element in octets */
 } field;
 
 enum {
@@ -96,6 +116,7 @@ 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*/);
@@ -128,6 +149,7 @@ 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))
@@ -165,6 +187,31 @@ 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*/);
+
 /*----- Creating fields ---------------------------------------------------*/
 
 /* --- @field_prime@ --- *
@@ -179,6 +226,18 @@ extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 
 extern field *field_prime(mp */*p*/);
 
+/* --- @field_niceprime@ --- *
+ *
+ * Arguments:  @mp *p@ = the characteristic of the field
+ *
+ * Returns:    A pointer to the field.
+ *
+ * Use:                Creates a field structure for a prime field of size %$p$%,
+ *             using efficient reduction for nice primes.
+ */
+
+extern field *field_niceprime(mp */*p*/);
+
 /* --- @field_binpoly@ --- *
  *
  * Arguments:  @mp *p@ = an irreducible polynomial over %$\gf{2}$%
@@ -191,6 +250,21 @@ extern field *field_prime(mp */*p*/);
 
 extern field *field_binpoly(mp */*p*/);
 
+/* --- @field_parse@ --- *
+ *
+ * Arguments:  @qd_parse *qd@ = parser context
+ *
+ * Returns:    Field pointer if OK, or null.
+ *
+ * Use:                Parses a field description, which has the form
+ *
+ *               * `prime', `niceprime' or `binpoly'
+ *               * an optional `:'
+ *               * the field modulus
+ */
+
+extern field *field_parse(qd_parse */*qd*/);
+
 /*----- That's all, folks -------------------------------------------------*/
 
 #ifdef __cplusplus