Dirk Westhoff Markus Schneider II Claus Unger Firoz Kaderali Protecting a Mobile Agent's Route against Collusions. 215-225 http://link.springer.de/link/service/series/0558/bibs/1758/17580215.htm 1999 conf/sacrypt/1999 Selected Areas in Cryptography db/conf/sacrypt/sacrypt1999.html#WesthoffSUK99