X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/1ba83484ee5bb486da9aa958576de4bc29ef0c1d..34e4f738bcba58e6d8c4cabbb0b3232a65b42a9d:/ec-info.c

diff --git a/ec-info.c b/ec-info.c
index 8270c2e..a99cba5 100644
--- a/ec-info.c
+++ b/ec-info.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: ec-info.c,v 1.1 2004/03/27 17:54:11 mdw Exp $
+ * $Id: ec-info.c,v 1.2 2004/04/01 12:50:09 mdw Exp $
  *
  * Elliptic curve information management
  *
@@ -30,6 +30,13 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: ec-info.c,v $
+ * Revision 1.2  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 1.1  2004/03/27 17:54:11  mdw
  * Standard curves and curve checking.
  *
@@ -167,6 +174,42 @@ fail:
   return (0);
 }
 
+/* --- @getinfo@ --- *
+ *
+ * Arguments:	@ec_info *ei@ = where to write the information
+ *		@ecdata *ed@ = raw data
+ *
+ * Returns:	---
+ *
+ * Use:		Loads elliptic curve information about one of the standard
+ *		curves.
+ */
+
+static void getinfo(ec_info *ei, ecdata *ed)
+{
+  field *f;
+
+  switch (ed->ftag) {
+    case FTAG_PRIME:
+      f = field_prime(&ed->p);
+      ei->c = ec_primeproj(f, &ed->a, &ed->b);
+      break;
+    case FTAG_NICEPRIME:
+      f = field_niceprime(&ed->p);
+      ei->c = ec_primeproj(f, &ed->a, &ed->b);
+      break;
+    case FTAG_BINPOLY:
+      f = field_binpoly(&ed->p);
+      ei->c = ec_binproj(f, &ed->a, &ed->b);
+      break;
+    default:
+      abort();
+  }
+
+  EC_CREATE(&ei->g); ei->g.x = &ed->gx; ei->g.y = &ed->gy; ei->g.z = 0;
+  ei->r = &ed->r; ei->h = &ed->h;
+}
+
 /* --- @ec_infoparse@ --- *
  *
  * Arguments:	@qd_parse *qd@ = parser context
@@ -176,7 +219,8 @@ fail:
  * Returns:	Zero on success, nonzero on failure.
  *
  * Use:		Parses an elliptic curve information string, and stores the
- *		information in @ei@.  This has the form
+ *		information in @ei@.  This is either the name of a standard
+ *		curve, or it has the form
  *
  *		  * elliptic curve description
  *		  * optional `/'
@@ -192,14 +236,22 @@ int ec_infoparse(qd_parse *qd, ec_info *ei)
   ec_curve *c = 0;
   field *f;
   ec g = EC_INIT;
+  const ecentry *ee;
   mp *r = MP_NEW, *h = MP_NEW;
 
+  for (ee = ectab; ee->name; ee++) {
+    if (qd_enum(qd, ee->name) >= 0) {
+      getinfo(ei, ee->data);
+      goto found;
+    }
+  }
   if ((c = ec_curveparse(qd)) == 0) goto fail;
   qd_delim(qd, '/'); if (!ec_ptparse(qd, &g)) goto fail;
   qd_delim(qd, ':'); if ((r = qd_getmp(qd)) == 0) goto fail;
   qd_delim(qd, '*'); if ((h = qd_getmp(qd)) == 0) goto fail;
-
   ei->c = c; ei->g = g; ei->r = r; ei->h = h;
+
+found:
   return (0);
 
 fail:
@@ -210,64 +262,6 @@ fail:
   return (-1);
 }
 
-/* --- @getinfo@ --- *
- *
- * Arguments:	@ec_info *ei@ = where to write the information
- *		@const ecdata *ed@ = raw data
- *
- * Returns:	---
- *
- * Use:		Loads elliptic curve information about one of the standard
- *		curves.
- */
-
-static mp *getmp(const mpw *v, size_t n)
-{
-  mp *x = mp_new(n, 0);
-  memcpy(x->v, v, MPWS(n));
-  return (x);
-}
-
-static void getinfo(ec_info *ei, const ecdata *ed)
-{
-  field *f;
-  mp *p = 0, *a = 0, *b = 0;
-
-  switch (ed->ftag) {
-    case FTAG_PRIME:
-      p = getmp(ed->p, ed->psz);
-      f = field_prime(p);
-      a = getmp(ed->a, ed->asz); b = getmp(ed->b, ed->bsz);
-      ei->c = ec_primeproj(f, a, b);
-      break;
-    case FTAG_NICEPRIME:
-      p = getmp(ed->p, ed->psz);
-      f = field_niceprime(p);
-      a = getmp(ed->a, ed->asz); b = getmp(ed->b, ed->bsz);
-      ei->c = ec_primeproj(f, a, b);
-      break;
-    case FTAG_BINPOLY:
-      p = getmp(ed->p, ed->psz);
-      f = field_binpoly(p);
-      a = getmp(ed->a, ed->asz); b = getmp(ed->b, ed->bsz);
-      ei->c = ec_binproj(f, a, b);
-      break;
-    default:
-      abort();
-  }
-
-  EC_CREATE(&ei->g);
-  ei->g.x = getmp(ed->gx, ed->gxsz);
-  ei->g.y = getmp(ed->gy, ed->gysz);
-  ei->g.z = 0;
-  ei->r = getmp(ed->r, ed->rsz);
-  ei->h = getmp(ed->h, ed->hsz);
-
-  MP_DROP(p);
-  MP_DROP(a);
-  MP_DROP(b);
-}
-
 /* --- @ec_getinfo@ --- *
  *
  * Arguments:	@ec_info *ei@ = where to write the information
@@ -282,19 +276,11 @@ static void getinfo(ec_info *ei, const ecdata *ed)
 const char *ec_getinfo(ec_info *ei, const char *p)
 {
   qd_parse qd;
-  const ecentry *ee;
 
   qd.p = p;
   qd.e = 0;
-  for (ee = ectab; ee->name; ee++) {
-    if (qd_enum(&qd, ee->name) >= 0) {
-      getinfo(ei, ee->data);
-      goto found;
-    }
-  }
   if (ec_infoparse(&qd, ei))
     return (qd.e);
-found:
   if (!qd_eofp(&qd)) {
     ec_freeinfo(ei);
     return ("junk found at end of string");
@@ -302,6 +288,22 @@ found:
   return (0);
 }
 
+/* --- @ec_sameinfop@ --- *
+ *
+ * Arguments:	@ec_info *ei, *ej@ = two elliptic curve parameter sets
+ *
+ * Returns:	Nonzero if the curves are identical (not just isomorphic).
+ *
+ * Use:		Checks for sameness of curve parameters.
+ */
+
+int ec_sameinfop(ec_info *ei, ec_info *ej)
+{
+  return (ec_samep(ei->c, ej->c) &&
+	  MP_EQ(ei->r, ej->r) && MP_EQ(ei->h, ej->h) &&
+	  EC_EQ(&ei->g, &ej->g));
+}
+
 /* --- @ec_freeinfo@ --- *
  *
  * Arguments:	@ec_info *ei@ = elliptic curve information block to free
@@ -330,28 +332,6 @@ void ec_freeinfo(ec_info *ei)
  * Use:		Checks an elliptic curve according to the rules in SEC1.
  */
 
-static int primep(mp *p, grand *gr)
-{
-  int i = rabin_iters(mp_bits(p));
-  rabin r;
-  mp *x = MP_NEW;
-
-  switch (pfilt_smallfactor(p)) {
-    case PGEN_DONE: return (1);
-    case PGEN_FAIL: return (0);
-  }
-  rabin_create(&r, p);
-  while (i) {
-    x = mprand_range(x, p, gr, 0);
-    if (rabin_rtest(&r, x) == PGEN_FAIL)
-      break;
-    i--;
-  }
-  MP_DROP(x);
-  rabin_destroy(&r);
-  return (!i);
-}
-
 static int primeeltp(mp *x, field *f)
 {
   return (!MP_ISNEG(x) && MP_CMP(x, <, f->m));
@@ -368,7 +348,7 @@ static const char *primecheck(const ec_info *ei, grand *gr)
 
   /* --- Check %$p$% is an odd prime --- */
 
-  if (!primep(f->m, gr)) return ("p not prime");
+  if (!pgen_primep(f->m, gr)) return ("p not prime");
 
   /* --- Check %$a$%, %$b$%, %$G_x$% and %$G_y$% are in %$[0, p)$% --- */
 
@@ -399,7 +379,7 @@ static const char *primecheck(const ec_info *ei, grand *gr)
 
   /* --- Check %$r$% is prime --- */
 
-  if (!primep(ei->r, gr)) return ("generator order not prime");
+  if (!pgen_primep(ei->r, gr)) return ("generator order not prime");
 
   /* --- Check %$0 < h \le 4$% --- */
 
@@ -486,7 +466,7 @@ static const char *bincheck(const ec_info *ei, grand *gr)
 
   /* --- Check %$r$% is prime --- */
 
-  if (!primep(ei->r, gr)) return ("generator order not prime");
+  if (!pgen_primep(ei->r, gr)) return ("generator order not prime");
 
   /* --- Check %$0 < h \le 4$% --- */