Design And Analysis Of Modern Stream Cipher

ESTREAM is a four-year information security research project launched by Europe in 2004. The goal of this project is to establish a new fast and safe sequence cipher standard of Europe, by publicly calling for the design and analysis of sequence cipher algorithms throughout the world. ESTREAM institution has received 35 algorithms all over the world. Now the second round evaluation of 35 algorithms has ended.Tracking closely the ESTREAM project, we do some researches on the new design ideas and methods of modern sequence ciphers. We divide the submitted sequence cipher algorithms into four main types according to the devices properties and design ideas of the algorithms: sequence ciphers based on LFSR, sequence ciphers based on NLFSR, sequences ciphers based on the design idea of RC4 , and sequence ciphers based on the block ciphers. For each type of sequence cipher, we study their properties of design and analysis combining with two or three standard algorithms. Our works reflect the new design idea and methods of the design and analysis of modern sequence ciphers.LEX is a software-oriented submitted algorithm based on Advanced Encryption Standard. It has already entered the third round of assessment. We analyze its design principle and attack algorithm. We presents a variety of the slide attack which is called interruption slide attack, and use it to attack the variety of the second version of LEX. Our research results show that the 96-bit key can be recovered throught 500 AES encryption iterations and about 2⁶¹ IVs. At last, we give some improvement suggestion of the variety of LEX algorithm.