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

[u/mdw/catacomb] / key-binary.c

diff --git a/key-binary.c b/key-binary.c
index c05adee..82a1ecb 100644 (file)
--- a/key-binary.c
+++ b/key-binary.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: key-binary.c,v 1.4 2004/03/28 01:58:47 mdw Exp $
+ * $Id: key-binary.c,v 1.5 2004/04/01 12:50:09 mdw Exp $
  *
  * Key binary encoding
  *
@@ -30,6 +30,13 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: key-binary.c,v $
+ * Revision 1.5  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 1.4  2004/03/28 01:58:47  mdw
  * Generate, store and retreive elliptic curve keys.
  *
@@ -122,12 +129,13 @@ int key_decode(const void *p, size_t sz, key_data *k)
 
     case KENC_EC: {
       size_t xsz, ysz;
+      EC_CREATE(&k->u.e);
+      if (!sz) break;
       if (sz < 2) return (-1);
       xsz = LOAD16(q + 4);
       if (sz < xsz + 4) return (-1);
       ysz = LOAD16(q + 6 + xsz);
       if (sz < xsz + ysz + 4) return (-1);
-      EC_CREATE(&k->u.e);
       k->u.e.x = mp_loadb(MP_NEW, q + 6, xsz);
       k->u.e.y = mp_loadb(MP_NEW, q + 6 + xsz, ysz);
     } break;
@@ -256,17 +264,26 @@ int key_encode(key_data *k, dstr *d, const key_filter *kf)
 
     case KENC_EC: {
       char *p;
-      size_t xsz = mp_octets(k->u.e.x), ysz = mp_octets(k->u.e.y);
-      size_t sz = xsz + ysz + 4;
+      size_t xsz, ysz;
+      size_t sz;
 
+      if (EC_ATINF(&k->u.e))
+       sz = 0;
+      else {
+       xsz = mp_octets(k->u.e.x);
+       ysz = mp_octets(k->u.e.y);
+       sz = xsz + ysz + 4;
+      }
       DENSURE(d, (sz + 7) & ~3);
       p = d->buf + d->len;
       STORE16(p, k->e);
       STORE16(p + 2, sz);
-      STORE16(p + 4, xsz);
-      mp_storeb(k->u.e.x, p + 6, xsz);
-      STORE16(p + 6 + xsz, ysz);
-      mp_storeb(k->u.e.y, p + 8 + xsz, ysz);
+      if (!EC_ATINF(&k->u.e)) {
+       STORE16(p + 4, xsz);
+       mp_storeb(k->u.e.x, p + 6, xsz);
+       STORE16(p + 6 + xsz, ysz);
+       mp_storeb(k->u.e.y, p + 8 + xsz, ysz);
+      }
       d->len += sz + 4;
       rc = 1;
     } break;