Allow the number of rounds to be configured. This isn't exported

[u/mdw/catacomb] / xtea.c

diff --git a/xtea.c b/xtea.c
index 1d65c4d..32702fe 100644 (file)
--- a/xtea.c
+++ b/xtea.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: xtea.c,v 1.1 2000/07/15 13:44:31 mdw Exp $
+ * $Id: xtea.c,v 1.2 2000/07/29 09:56:47 mdw Exp $
  *
  * The Extended Tiny Encryption Algorithm
  *
@@ -30,6 +30,10 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: xtea.c,v $
+ * Revision 1.2  2000/07/29 09:56:47  mdw
+ * Allow the number of rounds to be configured.  This isn't exported
+ * through the gcipher interface, but it may be useful anyway.
+ *
  * Revision 1.1  2000/07/15 13:44:31  mdw
  * New ciphers.
  *
@@ -76,8 +80,9 @@ void xtea_init(xtea_ctx *k, const void *buf, size_t sz)
     p = kb;
   }
 
-  k->k[0] = LOAD32(p +  0);   k->k[1] = LOAD32(p +  4);
-  k->k[2] = LOAD32(p +  8);   k->k[3] = LOAD32(p + 12);
+  k->k[0] = LOAD32(p +  0); k->k[1] = LOAD32(p +  4);
+  k->k[2] = LOAD32(p +  8); k->k[3] = LOAD32(p + 12);
+  k->r = 32;
 
   if (p == kb)
     BURN(kb);
@@ -102,7 +107,7 @@ void xtea_eblk(const xtea_ctx *k, const uint32 *s, uint32 *d)
   uint32 n = 0;
   unsigned i;
 
-  for (i = 0; i < 32; i++) {
+  for (i = 0; i < k->r; i++) {
     y = U32(y + ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3])));
     n += DELTA;
     z = U32(z + ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3])));
@@ -113,10 +118,10 @@ void xtea_eblk(const xtea_ctx *k, const uint32 *s, uint32 *d)
 void xtea_dblk(const xtea_ctx *k, const uint32 *s, uint32 *d)
 {
   uint32 y = s[0], z = s[1];
-  uint32 n = DELTA << 5;
+  uint32 n = DELTA * k->r;
   unsigned i;
 
-  for (i = 0; i < 32; i++) {
+  for (i = 0; i < k->r; i++) {
     z = U32(z - ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3])));
     n -= DELTA;
     y = U32(y - ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3])));