X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/34e4f738bcba58e6d8c4cabbb0b3232a65b42a9d..c65df27983057ec76ed0e72bb370f9a5ae7dad28:/f-binpoly.c

diff --git a/f-binpoly.c b/f-binpoly.c
index aeec0cf..4282ad4 100644
--- a/f-binpoly.c
+++ b/f-binpoly.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: f-binpoly.c,v 1.6 2004/04/01 12:50:09 mdw Exp $
+ * $Id: f-binpoly.c,v 1.9 2004/04/08 01:36:15 mdw Exp $
  *
  * Binary fields with polynomial basis representation
  *
@@ -27,33 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: f-binpoly.c,v $
- * Revision 1.6  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 1.5  2004/03/27 17:54:11  mdw
- * Standard curves and curve checking.
- *
- * Revision 1.4  2004/03/23 15:19:32  mdw
- * Test elliptic curves more thoroughly.
- *
- * Revision 1.3  2004/03/23 12:08:26  mdw
- * Random field-element selection.
- *
- * Revision 1.2  2004/03/21 22:52:06  mdw
- * Merge and close elliptic curve branch.
- *
- * Revision 1.1.2.1  2004/03/21 22:39:46  mdw
- * Elliptic curves on binary fields work.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <mLib/sub.h>
@@ -62,82 +35,52 @@
 #include "gf.h"
 #include "gfreduce.h"
 #include "mprand.h"
+#include "gfn.h"
 
-/*----- Data structures ---------------------------------------------------*/
+/*----- Polynomial basis --------------------------------------------------*/
 
 typedef struct fctx {
   field f;
   gfreduce r;
 } fctx;
 
-/*----- Main code ---------------------------------------------------------*/
-
 /* --- Field operations --- */
 
 static void fdestroy(field *ff)
-{
-  fctx *f = (fctx *)ff;
-  gfreduce_destroy(&f->r);
-  DESTROY(f);
-}
+  { fctx *f = (fctx *)ff; gfreduce_destroy(&f->r); DESTROY(f); }
 
 static mp *frand(field *f, mp *d, grand *r)
-{
-  return (mprand(d, f->nbits, r, 0));
-}
+  { return (mprand(d, f->nbits, r, 0)); }
 
-static int fzerop(field *ff, mp *x)
-{
-  return (!MP_LEN(x));
-}
+static int fzerop(field *ff, mp *x) { return (!MP_LEN(x)); }
 
-static mp *fadd(field *ff, mp *d, mp *x, mp *y)
-{
-  return (gf_add(d, x, y));
-}
+static mp *fadd(field *ff, mp *d, mp *x, mp *y) { return (gf_add(d, x, y)); }
 
-static mp *fmul(field *ff, mp *d, mp *x, mp *y)
-{
-  fctx *f = (fctx *)ff;
-  d = gf_mul(d, x, y);
+static mp *fmul(field *ff, mp *d, mp *x, mp *y) {
+  fctx *f = (fctx *)ff; d = gf_mul(d, x, y);
   return (gfreduce_do(&f->r, d, d));
 }
 
-static mp *fsqr(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  d = gf_sqr(d, x);
+static mp *fsqr(field *ff, mp *d, mp *x) {
+  fctx *f = (fctx *)ff; d = gf_sqr(d, x);
   return (gfreduce_do(&f->r, d, d));
 }
 
 static mp *finv(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  gf_gcd(0, 0, &d, f->r.p, x);
-  return (d);
-}
+  { fctx *f = (fctx *)ff; d = gf_modinv(d, x, f->r.p); return (d); }
 
 static mp *freduce(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  return (gfreduce_do(&f->r, d, x));
-}
+  { fctx *f = (fctx *)ff; return (gfreduce_do(&f->r, d, x)); }
 
 static mp *fsqrt(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  return (gfreduce_sqrt(&f->r, d, x));
-}
+  { fctx *f = (fctx *)ff; return (gfreduce_sqrt(&f->r, d, x)); }
 
 static mp *fquadsolve(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  return (gfreduce_quadsolve(&f->r, d, x));
-}
+  { fctx *f = (fctx *)ff; return (gfreduce_quadsolve(&f->r, d, x)); }
 
 /* --- Field operations table --- */
 
-static field_ops fops = {
+static const field_ops fops = {
   FTY_BINARY, "binpoly",
   fdestroy, frand, field_stdsamep,
   freduce, field_id,
@@ -168,4 +111,67 @@ field *field_binpoly(mp *p)
   return (&f->f);
 }
 
+/*----- Normal basis ------------------------------------------------------*/
+
+typedef struct fnctx {
+  fctx f;
+  gfn ntop, pton;
+} fnctx;
+
+/* --- Field operations --- */
+
+static void fndestroy(field *ff) {
+  fnctx *f = (fnctx *)ff; gfreduce_destroy(&f->f.r);
+  gfn_destroy(&f->ntop); gfn_destroy(&f->pton);
+  DESTROY(f);
+}
+
+static int fnsamep(field *ff, field *gg) {
+  fnctx *f = (fnctx *)ff, *g = (fnctx *)gg;
+  return (MP_EQ(f->ntop.r[0], g->ntop.r[0]) && field_stdsamep(ff, gg));
+}
+
+static mp *fnin(field *ff, mp *d, mp *x)
+  { fnctx *f = (fnctx *)ff; return (gfn_transform(&f->ntop, d, x)); }
+
+static mp *fnout(field *ff, mp *d, mp *x)
+  { fnctx *f = (fnctx *)ff; return (gfn_transform(&f->pton, d, x)); }
+
+/* --- Field operations table --- */
+
+static const field_ops fnops = {
+  FTY_BINARY, "binnorm",
+  fndestroy, frand, fnsamep,
+  fnin, fnout,
+  fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt,
+  fquadsolve,
+  0, 0, 0, 0
+};
+
+/* --- @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.
+ */
+
+field *field_binnorm(mp *p, mp *beta)
+{
+  fnctx *f = CREATE(fnctx);
+  f->f.f.ops = &fnops;
+  f->f.f.zero = MP_ZERO;
+  f->f.f.one = MP_ONE;
+  f->f.f.nbits = mp_bits(p) - 1;
+  f->f.f.noctets = (f->f.f.nbits + 7) >> 3;
+  gfreduce_create(&f->f.r, p);
+  f->f.f.m = f->f.r.p;
+  gfn_create(p, beta, &f->ntop, &f->pton);
+  return (&f->f.f);
+}
+
 /*----- That's all, folks -------------------------------------------------*/