Research On The Security Of Word-Oriented Stream Cipher

Stream cipher is a very important symmetric cryptosystem. The facts that stream ciphers can be implemented in hardware very efficiently and are tolerant to bit-errors, etc., are desirable properties in the practical use such as the mobile/wireless communication. Traditionally stream cipher design has focused on bit based linear feedback shift registers (LFSRs). However due to their bit-oriented nature their software implementations are very slow. To address this drawback recently many word oriented stream ciphers have been proposed. This results in the research on their security in this paper.The design structures, period, randomness and methods of attacks of word-oriented stream ciphers are discussed in this paper. To explain it more clearly, we have surveyed all of these word-oriented algorithms submitted to ECRYPT Stream Cipher Project. Our study shows that both advantages and disadvantages exist in the current trend of stream cipher design.Statistical analysis of stream ciphers are easier and faster compared to the theoretical analysis, and usually the internal structure of the ciphers is not taken into account in the statistical testing. However, enough importance has not been given to this method among eSTREAM candidates. Moreover, there is no statistical testing method especially for the word-oriented stream...