Distinguishing Attacks on the Stream Cipher Py

The stream cipher Py designed by Biham and Seberry is a submission to the ECRYPT stream cipher competition. The cipher is based on two large arrays (one is 256 bytes and the other is 1040 bytes) and it is designed for high speed software applications (Py is more than 2.5 times faster than the RC4 on Pentium III). The paper shows a statistical bias in the distribution of its output-words at the 1st and 3rd rounds. Exploiting this weakness, a distinguisher with advantage greater than 50% is constructed that requires 284.7 randomly chosen key/IV's and the first 24 output bytes for each key. The running time and the data required by the distinguisher are tini

• Type: Conference
• Year: 2006
• Where: FSE
• Authors: Souradyuti Paul, Bart Preneel, Gautham Sekar
• Keywords: Cryptology, FSE 2006, Running Time, Stream Cipher, Stream Cipher Py