New Methods for Cryptanalysis of Stream Ciphers
Håvard Molland · 2005
In this paper we present a new and improved correlation attack based on maximum likelihood (ML) decoding. Previously the code rate used for decoding has typically been around r = 1/2. Our algorithm has low computational complexity and is able to use code rates around r = 1/2. This way we get much more information about the key bits. Furthermore, the run time for a successful attack is reduced significantly and we need fewer keystream bits.