Algebraic Countermeasure to Enhance the Improved Summation Generator with 2 Bit Memory
Recently proposed algebraic attack has been shown to be very effective on several stream ciphers. In this paper, the authors have investigated the resistance of PingPong family of stream ciphers against algebraic attacks. This stream cipher was proposed in 2008 to enhance the security of the improved summation generator against the algebraic attack. In particular, they focus on the PingPong-128 stream cipher's resistance against algebraic attack in this paper. In their analysis, it is found that an algebraic attack on PingPong family of stream ciphers require much more operations compare to the exhaustive key search on the internal state of the LFSRs.