Study Of Fast Correlation Attacks On Stream Ciphers

Security analysis of the key stream generators is always at the central of the research on stream ciphers. This thesis mainly analyzes the fast correlation attacks on stream ciphers.After systematically studying and analyzing some typical algorithms of the fast correlation attacks on stream ciphers, aiming at the shortcomings of serial algorithm, the proposed technique is based on parallel computing. This kind of attack divides the initial state of linear feedback shift register into several parts, uses multiprocessor to recover all parts of the initial state synchronously. Comparing with previous results, this kind of attack can provide a better tradeoff between key stream length, success probability and attack complexity.Inspired by fast correlation attacks on stream ciphers, we analyze a stream cipher-like construction for a public-key cryptosystem whose security relies on two problems: finding a low-weight multiple of a given polynomial and a Hidden Correlation problem. This kind of cryptosystem has low-cost hardware implementation, but the decryption is non-deterministic. The decryption algorithm of this kind of cryptosystem still needs to be researched.