Fix bug in decryption key scheduling.

diff --git a/idea.c b/idea.c
index cde3af4..c0a1d07 100644 (file)
--- a/idea.c
+++ b/idea.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: idea.c,v 1.3 2000/07/02 18:24:39 mdw Exp $
+ * $Id: idea.c,v 1.4 2000/07/15 17:47:58 mdw Exp $
  *
  * Implementation of the IDEA cipher
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: idea.c,v $
+ * Revision 1.4  2000/07/15 17:47:58  mdw
+ * Fix bug in decryption key scheduling.
+ *
  * Revision 1.3  2000/07/02 18:24:39  mdw
  * Use a new multiplication function from an Ascom white paper to resist
  * timing attacks.
@@ -75,13 +78,16 @@ 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 +261,8 @@ 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))