X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/a27430a2fc1347926142db0f1a24fe6ecaee9163..f52f2db067dc1388b16ab00ddb53e26a381a6e3e:/idea.c

diff --git a/idea.c b/idea.c
index cde3af4..c0f7fe7 100644
--- a/idea.c
+++ b/idea.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: idea.c,v 1.3 2000/07/02 18:24:39 mdw Exp $
+ * $Id: idea.c,v 1.5 2004/04/08 01:36:15 mdw Exp $
  *
  * Implementation of the IDEA cipher
  *
  * (c) 1999 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,33 +15,18 @@
  * 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: idea.c,v $
- * Revision 1.3  2000/07/02 18:24:39  mdw
- * Use a new multiplication function from an Ascom white paper to resist
- * timing attacks.
- *
- * Revision 1.2  2000/06/17 11:24:08  mdw
- * New key size interface.
- *
- * Revision 1.1  1999/09/03 08:41:12  mdw
- * Initial import.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <assert.h>
@@ -75,13 +60,16 @@ static uint16 inv(uint16 n)
 {
   uint32 m = 0x10001;
   uint32 a = 1, b = 0;
+  uint32 nn = n;
 
+  if (!nn)
+    nn = 0x10000;
   for (;;) {
     uint32 q, r, t;
-    if (!(r = m % n))
+    if (!(r = m % nn))
       break;
-    q = m / n;
-    m = n; n = r;
+    q = m / nn;
+    m = nn; nn = r;
     t = a; a = b - q * a; b = t;
   }
   if (a > MASK16)
@@ -255,8 +243,8 @@ void idea_init(idea_ctx *k, const void *buf, size_t sz)
   ROUND(_k, _a, _b, _c, _d);						\
   ROUND(_k, _a, _c, _b, _d);						\
   MIX  (_k, _a, _c, _b, _d);						\
-  c = (U16(_a) << 16) | U16(_c);					\
-  d = (U16(_b) << 16) | U16(_d);					\
+  c = ((uint32)U16(_a) << 16) | (uint32)U16(_c);			\
+  d = ((uint32)U16(_b) << 16) | (uint32)U16(_d);			\
 } while (0)
 
 #define DBLK(k, a, b) EBLK((k), (a), (b))