An Improved Correlation Attack Against Irregular Clocked and Filtered Keystream Generators

Abstract. In this paper we propose a new key recovery attack on irregular clocked keystream generators where the stream is filtered by a nonlinear Boolean function. We show that the attack is much more efficient than expected from previous analytic methods, and we believe it improves all previous attacks on the cipher model.

• Type: Conference
• Year: 2004
• Where: CRYPTO
• Authors: Håvard Molland, Tor Helleseth
• Keywords: CRYPTO 2004, Irregular Clocked Keystream, Key Recovery Attack, Nonlinear Boolean Function