Shahram Khazaei Willi Meier New Directions in Cryptanalysis of Self-Synchronizing Stream Ciphers. 15-26 2008 INDOCRYPT http://dx.doi.org/10.1007/978-3-540-89754-5_2 conf/indocrypt/2008 db/conf/indocrypt/indocrypt2008.html#KhazaeiM08