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The existing block encryption algorithms have been designed for the encryption key value to be unchanged and applied to the round functions of each block, and enciphered. Therefore, it has such a weak point that the plain text or encryption key could be easily exposed by differential cryptanalysis or linear cryptanalysis, both are the most powerful methods for decoding block encryption of a round--repeating structure. In order to cope with this weak point, an encryption algorithm using a more efficient key should be designed.In this paper, a block encryption algorithm which is designed for each encryption key value to be applied to each round block with a different value is proposed. This algorithm needs a short processing time in encryption and decryption, has a high intensity, can apply to electronic commerce and various applications of data protection.

The latency occurring from the load fluctuation in a real-time network games may be overcome by using an initial delay scheme on the client, and then play the game, it means that stability can be maintained, and the shortcomings of packet losses and errors on UDP communications are alleviated. In this paper, we suggest a retransmission algorithm using an N-Based game command history that supports End-to-End protocol, and retransmits data without alteration of existing protocols, and also supports video games based on multi-platform in wired-wireless network environments, and it can possibly work under multi-user games. As demonstrated in the simulations, we confirm that the suggested system is more stable than existing systems.

It is not easy to analyze and code programs in Java because those programs in the object oriented language hide much information, including in particular the execution process of the programs. Classfile, however, contains useful information that can trace the execution process. The authors implement a static Java classfile analyzer that can show the relationships among classes; caller/callee relationships, inheritance hierarchies, and detailed information within classes. Our analyzer can also display decompiled source programs from the given class files. It can help users to understand Java programs better, and help Java programs to be designed and developed in an efficient manner.