In this article we assess the cost of DES key search using hardware methods and examine the effectiveness of some proposed methods for thwarting attacks on [?] _______________________ Michael J. Wiener, Entrust Technologies, 750 Heron Road, Suite E08, Ottawa, Ontario, Canada K1V 1A7 Michael J. Wiener, Entrust Technologies, 750 Heron Road, Suite E08, Ottawa, Ontario, Canada K1V 1A7