Improved Message Passing Techniques in Fast Correlation Attacks on Stream Ciphers
The fast correlation attack is a general cryptanalytic attack directed at stream ciphers and is related to the decoding of low-density parity-check (LDPC) codes. In this paper, we improve the message passing algorithm by exploiting the fact that the sum of an arbitrary number of initial state variables, called a fixed point, can be written as the sum of only a few other variables. This will result