Field exponentiation. Add field size to field structure. Make check

failure nonfatal in point decompression utility.

diff --git a/f-binpoly.c b/f-binpoly.c
index 23d9984..2d2221c 100644 (file)
--- a/f-binpoly.c
+++ b/f-binpoly.c
@@ -41,7 +41,7 @@
 
 static void fdestroy(field *ff) {
   fctx_binpoly *f = (fctx_binpoly *)ff;
-  gfreduce_destroy(&f->r);
+  gfreduce_destroy(&f->r); MP_DROP(f->f.q);
   DESTROY(f);
 }
 
@@ -114,6 +114,7 @@ field *field_binpoly(mp *p)
   f->f.noctets = (f->f.nbits + 7) >> 3;
   gfreduce_create(&f->r, p);
   f->f.m = f->r.p;
+  f->f.q = mp_lsl(MP_NEW, MP_ONE, f->f.nbits);
   return (&f->f);
 }
 
@@ -123,7 +124,7 @@ field *field_binpoly(mp *p)
 
 static void fndestroy(field *ff) {
   fctx_binnorm *f = (fctx_binnorm *)ff; gfreduce_destroy(&f->f.r);
-  gfn_destroy(&f->ntop); gfn_destroy(&f->pton);
+  gfn_destroy(&f->ntop); gfn_destroy(&f->pton); MP_DROP(f->f.f.q);
   DESTROY(f);
 }
 
@@ -175,6 +176,7 @@ field *field_binnorm(mp *p, mp *beta)
   f->f.f.noctets = (f->f.f.nbits + 7) >> 3;
   gfreduce_create(&f->f.r, p);
   f->f.f.m = f->f.r.p;
+  f->f.f.q = mp_lsl(MP_NEW, MP_ONE, f->f.f.nbits);
   gfn_create(p, beta, &f->ntop, &f->pton);
   return (&f->f.f);
 }

diff --git a/f-prime.c b/f-prime.c
index 9b1ceb6..b1c4367 100644 (file)
--- a/f-prime.c
+++ b/f-prime.c
@@ -170,6 +170,7 @@ field *field_prime(mp *p)
   f->f.m = f->mm.m;
   f->f.nbits = mp_bits(p);
   f->f.noctets = (f->f.nbits + 7) >> 3;
+  f->f.q = f->mm.m;
   return (&f->f);
 }
 

diff --git a/field-exp.c b/field-exp.c
new file mode 100644 (file)
index 0000000..fe3e8ce
--- /dev/null
+++ b/field-exp.c
@@ -0,0 +1,73 @@
+/* -*-c-*-
+ *
+ * $Id$
+ *
+ * Exponentiation in finite fields
+ *
+ * (c) 2004 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------* 
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * 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.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include "field.h"
+#include "field-exp.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @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.
+ */
+
+mp *field_exp(field *f, mp *d, mp *a, mp *e)
+{
+  mp *x = MP_COPY(f->one);
+  mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW;
+
+  MP_COPY(a);
+  MP_SHRINK(e);
+  if (MP_ZEROP(e))
+    ;
+  else {
+    if (MP_NEGP(e))
+      a = F_INV(f, a, a);
+    if (MP_LEN(e) < EXP_THRESH)
+      EXP_SIMPLE(x, a, e);
+    else
+      EXP_WINDOW(x, a, e);
+  }
+  mp_drop(d);
+  mp_drop(spare);
+  mp_drop(a);
+  return (x);
+}
+
+/*----- That's all, folks -------------------------------------------------*/

diff --git a/field-exp.h b/field-exp.h
new file mode 100644 (file)
index 0000000..5a32356
--- /dev/null
+++ b/field-exp.h
@@ -0,0 +1,59 @@
+/* -*-c-*-
+ *
+ * $Id$
+ *
+ * Exponentiation in finite fields
+ *
+ * (c) 2004 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------* 
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * 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.
+ */
+
+#ifndef CATACOMB_FIELD_EXP_H
+#define CATACOMB_FIELD_EXP_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Exponentiation definitions ----------------------------------------*/
+
+#define EXP_TYPE mp *
+
+#define EXP_COPY(d, x) d = MP_COPY(x)
+#define EXP_DROP(x) MP_DROP(x)
+
+#define EXP_MUL(a, x) a = F_MUL(f, a, a, x)
+#define EXP_SQR(a) a = F_SQR(f, a, a)
+#define EXP_FIX(x)
+
+#define EXP_SETMUL(d, x, y) d = F_MUL(f, MP_NEW, x, y)
+#define EXP_SETSQR(d, x) d = F_SQR(f, MP_NEW, x)
+
+#include "exp.h"
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif

diff --git a/field.h b/field.h
index 5790284..4164bce 100644 (file)
--- a/field.h
+++ b/field.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: field.h,v 1.11 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
  *
  * Definitions for field arithmetic
  *
@@ -56,6 +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 {
@@ -170,6 +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@ --- *

diff --git a/utils/ecptdecompress.c b/utils/ecptdecompress.c
index 09e1f88..e438696 100644 (file)
--- a/utils/ecptdecompress.c
+++ b/utils/ecptdecompress.c
@@ -126,10 +126,8 @@ int main(int argc, char *argv[])
     mp_drop(y); mp_drop(yy);
   }
 
-  if ((err = ec_checkinfo(&ei, &rand_global)) != 0) {
+  if ((err = ec_checkinfo(&ei, &rand_global)) != 0)
     fprintf(stderr, "bad curve: %s\n", err);
-    exit(0);
-  }
   puthex("p", ei.c->f->m, 0);
   if (strcmp(F_NAME(ei.c->f), "binnorm") == 0) {
     fctx_binnorm *fc = (fctx_binnorm *)ei.c->f;