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Abstract:This paper elaborates on the application of Hellman's cryptanalytic timememory trade-off approach in the RFID systems. First, the original method is briefly explained. Then, the situations and conditions that make the application of Hellman's idea possible in the RFID environment are discussed and analyzed. The effects of application of the time-memory trade-off method are illustrated for two RFID techniques: Ohkubo, Suzuki and Kinoshita's protocol, and constant-time identification protocol. For both of them the performance analysis is performed before and after application of the time-memory tradeoff approach. Finally, the similarities and differences in modifications of the original method and its consequences in these two cases are pointed out.

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Abstract. The paper introduces an abstraction in form of general conditions for cryptanalytic managing of the information about the current state of the RC4 stream cipher. The general conditions based strategy is used to favor more promising values that should be assigned to unknown entries in the RC4 table. The estimated complexity of the cryptanalytic attack is lower than the best published result although the RC4 remains a quite secure cipher in practice.