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

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+/* -*-c-*-
+ *
+ * $Id: g-ec.c,v 1.1 2004/04/01 12:50:09 mdw Exp $
+ *
+ * Abstraction for elliptic curve groups
+ *
+ * (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.
+ */
+
+/*----- Revision history --------------------------------------------------* 
+ *
+ * $Log: g-ec.c,v $
+ * Revision 1.1  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.)
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <ctype.h>
+
+#include <mLib/sub.h>
+
+#define ge ec
+#include "group.h"
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct gctx {
+  group g;
+  ec id, gen;
+  ec_info ei;
+} gctx;
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- Group operations --- */
+
+static void gdestroygroup(group *gg) {
+  gctx *g = (gctx *)gg;
+  EC_DESTROY(&g->gen);
+  ec_freeinfo(&g->ei);
+  DESTROY(g);
+}
+
+static ec *gcreate(group *gg)
+  { ec *x = CREATE(ec); EC_CREATE(x); return (x); }
+
+static void gcopy(group *gg, ec *d, ec *x) { EC_COPY(d, x); }
+
+static void gburn(group *gg, ec *x) { if (x->x) (x->x)->f |= MP_BURN; }
+
+static void gdestroy(group *gg, ec *x) { EC_DESTROY(x); DESTROY(x); }
+
+static int gsamep(group *gg, group *hh) {
+  gctx *g = (gctx *)gg, *h = (gctx *)hh;
+  return (ec_sameinfop(&g->ei, &h->ei));
+}
+
+static int geq(group *gg, ec *x, ec *y) {
+  gctx *g = (gctx *)gg; EC_FIX(g->ei.c, x, x); EC_FIX(g->ei.c, y, y);
+  return (EC_EQ(x, y));
+}
+
+static int gidentp(group *gg, ec *x) { return (EC_ATINF(x)); }
+
+static const char *gcheck(group *gg, grand *gr)
+  { gctx *g = (gctx *)gg; return (ec_checkinfo(&g->ei, gr)); }
+
+static void gmul(group *gg, ec *d, ec *x, ec *y)
+  { gctx *g = (gctx *)gg; EC_ADD(g->ei.c, d, x, y); }
+
+static void gsqr(group *gg, ec *d, ec *x)
+  { gctx *g = (gctx *)gg; EC_DBL(g->ei.c, d, x); }
+
+static void ginv(group *gg, ec *d, ec *x)
+  { gctx *g = (gctx *)gg; EC_NEG(g->ei.c, d, x); }
+
+static void gdiv(group *gg, ec *d, ec *x, ec *y)
+  { gctx *g = (gctx *)gg; EC_SUB(g->ei.c, d, x, y); }
+
+static void gexp(group *gg, ec *d, ec *x, mp *n)
+  { gctx *g = (gctx *)gg; ec_imul(g->ei.c, d, x, n); }
+
+static void gmexp(group *gg, ec *d, const group_expfactor *f, size_t n) {
+  gctx *g = (gctx *)gg; size_t i;
+  ec_mulfactor *ff = xmalloc(n * sizeof(ec_mulfactor)); 
+  for (i = 0; i < n; i++) { ff[i].base = *f[i].base; ff[i].exp = f[i].exp; }
+  ec_immul(g->ei.c, d, ff, n); xfree(ff);
+}
+
+static int gread(group *gg, ec *d, const mptext_ops *ops, void *p) {
+  gctx *g = (gctx *)gg;
+  ec t = EC_INIT;
+  int rc = -1;
+  int ch;
+
+  ch = ops->get(p);
+  if (tolower(ch) == 'i') {
+    if (tolower(ops->get(p)) != 'n' || tolower(ops->get(p)) != 'f')
+      return (-1);
+    EC_SETINF(d);
+    return (0);
+  }
+  ops->unget(ch, p);
+  if ((t.x = mp_read(MP_NEW, 0, ops, p)) == 0) goto done;
+  do ch = ops->get(p); while (ch == ',' || isspace(ch)); ops->unget(ch, p);
+  if ((t.y = mp_read(MP_NEW, 0, ops, p)) == 0) goto done;
+  EC_IN(g->ei.c, &t, &t);
+  if (EC_CHECK(g->ei.c, &t)) goto done;
+  EC_COPY(d, &t); rc = 0;
+  EC_DESTROY(&t);
+done:
+  return (rc);
+}
+
+static int gwrite(group *gg, ec *x, const mptext_ops *ops, void *p) {
+  gctx *g = (gctx *)gg; int rc = -1; ec t = EC_INIT; EC_OUT(g->ei.c, &t, x);
+  if (EC_ATINF(&t)) rc = ops->put("inf", 3, p);
+  else if (!ops->put("0x", 2, p) && !mp_write(t.x, 16, ops, p) &&
+	   !ops->put(", 0x", 4, p) && !mp_write(t.y, 16, ops, p)) rc = 0;
+  EC_DESTROY(&t); return (rc);
+}
+
+static mp *gtoint(group *gg, mp *d, ec *x) {
+  gctx *g = (gctx *)gg; ec t = EC_INIT; mp *i; if (EC_ATINF(x)) i = 0;
+  else { EC_OUT(g->ei.c, &t, x); i = MP_COPY(t.x); EC_DESTROY(&t); }
+  mp_drop(d); return (i);
+}
+
+static int gfromint(group *gg, ec *d, mp *x) {
+  gctx *g = (gctx *)gg; ec t = EC_INIT;
+  if (!ec_find(g->ei.c, &t, x)) return (-1);
+  EC_IN(g->ei.c, d, &t); EC_DESTROY(&t); return (0);
+}
+
+static int gtoec(group *gg, ec *d, ec *x)
+  { gctx *g = (gctx *)gg; EC_OUT(g->ei.c, d, x); return (0); }
+
+static int gfromec(group *gg, ec *d, ec *x) {
+  gctx *g = (gctx *)gg; ec t = EC_INIT; int rc; EC_IN(g->ei.c, &t, x);
+  rc = EC_CHECK(g->ei.c, &t); if (!rc) EC_COPY(d, &t); EC_DESTROY(&t);
+  return (rc);
+}
+  
+static int gtobuf(group *gg, buf *b, ec *x) {
+  gctx *g = (gctx *)gg; ec t = EC_INIT; int rc;
+  EC_OUT(g->ei.c, &t, x); rc = buf_putec(b, &t); EC_DESTROY(&t); return (rc);
+}
+
+static int gfrombuf(group *gg, buf *b, ec *d) {
+  gctx *g = (gctx *)gg; ec t = EC_INIT; int rc;
+  if (buf_getec(b, &t)) return (-1);
+  EC_IN(g->ei.c, &t, &t); rc = EC_CHECK(g->ei.c, &t);
+  if (!rc) EC_COPY(d, &t); EC_DESTROY(&t); return (rc);
+}
+
+/* --- @group_ec@ --- *
+ *
+ * Arguments:	@const ec_info *ei@ = elliptic curve parameters
+ *
+ * Returns:	A pointer to the group.
+ *
+ * Use:		Constructs an abstract group interface for an elliptic curve
+ *		group.  Group elements are @ec@ structures.  The contents of
+ *		the @ec_info@ structure becomes the property of the @group@
+ *		object; you can (and should) free the structure itself, but
+ *		calling @ec_freeinfo@ on it is not allowed.
+ */
+
+static const group_ops gops = {
+  GTY_EC,
+  gdestroygroup, gcreate, gcopy, gburn, gdestroy,
+  gsamep, geq, gidentp,
+  gcheck,
+  gmul, gsqr, ginv, gdiv, gexp, gmexp,
+  gread, gwrite,
+  gtoint, gfromint, gtoec, gfromec, gtobuf, gfrombuf
+};
+
+group *group_ec(const ec_info *ei)
+{
+  gctx *g = CREATE(gctx);
+
+  g->g.ops = &gops;
+  g->g.nbits = ei->c->f->nbits * 2;
+  g->g.noctets = ei->c->f->noctets * 2;
+  g->ei = *ei;
+  EC_CREATE(&g->id);
+  g->g.i = &g->id;
+  EC_CREATE(&g->gen);
+  EC_IN(g->ei.c, &g->gen, &ei->g);
+  g->g.r = ei->r;
+  g->g.h = ei->h;
+  return (&g->g);
+}
+
+/*----- That's all, folks -------------------------------------------------*/