+/*----- 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.
+ */
+