Sabine Leveiller Joseph Boutros Philippe Guillot Gilles Zémor Cryptanalysis of Nonlinear Filter Generators with {0, 1}-Metric Viterbi Decoding. 50 2001 conf/icisc/2001 ICISC http://link.springer.de/link/service/series/0558/bibs/2288/22880050.htm db/conf/icisc/icisc2001.html#LeveillerBGZ01