Raphael Chung-Wei Phan Soichi Furuya Sliding Properties of the DES Key Schedule and Potential Extensions to the Slide Attacks. 138-148 2002 conf/icisc/2002 ICISC http://link.springer.de/link/service/series/0558/bibs/2587/25870138.htm db/conf/icisc/icisc2002.html#PhanF02