Dynamic Peer Group Key Agreement And Encryption Algorithm Safer + + Security Analysis

Cryptology mainly discusses the techniques related to the design and analysis of crypto schemes (algorithms and protocols). The design techniques are used to obtain secure and practical crypto schemes to guarantee information security. However, the cryptanalysis techniques are utilized to find the weaknesses, which would impair the security of these schemes, and to transform the analytic results into new design criteria in the future.This thesis involves two parts: firstly, an efficient authenticated key agreement protocol for dynamic peer groups is designed. Secondly, we give the cryptanalysis of the block cipher Safer++/128, which is the candidate for European pre-standardization project NESSIE.* Key Agreement for Dynamic Peer GroupsThe security of cryptosystem (i.e. confidentiality, identification, data integrity, non-repudiation and availability) completely depends on the security of keys in terms of Kerckhoff's assumption [1], Therefore key management techniques (including key establishment, key distribution, storage, backup and archiving etc) play a fundamental role in cryptography. As a crucial part, key establishment attracts many cryptographers' attention.Key establishment, which is a type of protocols that share a secret key among the legitimate participants, involves 2-party key establishment and group key establishment respectively. In 1976, Dime and Hellman presented the first 2-party key agreement protocol and motivated the researches in this field. Up to now, the techniques about 2-party key establishment are quite mature. Unfortunately, while the applications of group communication are growing more and more widely, the techniques about group key establishment are still comparably unexplored.Key establishment for group communication is not a simple extension of key...