New key size interface. Add notes about the cipher.

diff --git a/rc5.h b/rc5.h
index 877b849..04bcf32 100644 (file)
--- a/rc5.h
+++ b/rc5.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: rc5.h,v 1.2 1999/12/10 23:29:48 mdw Exp $
+ * $Id: rc5.h,v 1.3 2000/06/17 11:55:50 mdw Exp $
  *
  * The RC5-32/12 block cipher
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: rc5.h,v $
+ * Revision 1.3  2000/06/17 11:55:50  mdw
+ * New key size interface.  Add notes about the cipher.
+ *
  * Revision 1.2  1999/12/10 23:29:48  mdw
  * Change header file guard names.
  *
@@ -38,6 +41,16 @@
  *
  */
 
+/*----- Notes on the RC5 block cipher -------------------------------------*
+ *
+ * RC5 was designed by Ron Rivest as a test vehicle for the use of data-
+ * dependent rotations in cryptographic transformations.  The algorithm is
+ * covered by a patent held by RSA Security Inc. (US Patent# 5,724,428).
+ * It's vulnerable to some clever differential attacks, which can break it in
+ * about %$2^{44}$% chosen plaintexts.  I don't recommend the use of this
+ * cipher.
+ */
+
 #ifndef CATACOMB_RC5_H
 #define CATACOMB_RC5_H
 
@@ -52,10 +65,12 @@
 /*----- Magic numbers -----------------------------------------------------*/
 
 #define RC5_ROUNDS 12
-#define RC5_KEYSZ 0
+#define RC5_KEYSZ 10
 #define RC5_BLKSZ 8
 #define RC5_CLASS (N, L, 64)
 
+extern const octet rc5_keysz[];
+
 /*----- Data structures ---------------------------------------------------*/
 
 typedef struct rc5_ctx {