Cipher

About: Cipher is a research topic. Over the lifetime, 9409 publications have been published within this topic receiving 110309 citations. The topic is also known as: cypher & cryptographic algorithm.

Genetic algorithms in cryptography

Abstract: Genetic algorithms (GAs) are a class of optimization algorithms. GAs attempt to solve problems through modeling a simplified version of genetic processes. There are many problems for which a GA approach is useful. It is, however, undetermined if cryptanalysis is such a problem. Therefore, this work explores the use of GAs in cryptography. Both traditional crypt analysis and GA-based methods are implemented in software. The results are then com pared using the metrics of elapsed time and percentage of successful decryptions. A de termination is made for each cipher under consideration as to the validity of the GA-based approaches found in the literature. In general, these GA-based approaches are typical of the field. Of the genetic algorithm attacks found in the literature, totaling twelve, seven were re-implemented. Of these seven, only three achieved any success. The successful attacks were those on the transposition and permutation ciphers by Matthews [20], Clark [4], and Griindlingh and Van Vuuren [13], respectively. These attacks were further investigated in an attempt to improve or extend their success. Unfortunately, this attempt was unsuccessful, as was the attempt to apply the Clark [4] attack to the monoalphabetic substitution cipher and achieve the same or indeed any level of success. Overall, the standard fitness equation genetic algorithm approach, and the scoreboard variant thereof, are not worth the extra effort involved. Traditional cryptanalysis methods are more successful, and easier to implement. While a traditional method takes more time, a faster unsuccessful attack is worthless. The failure of the genetic algorithm approach indicates that supplementary research into traditional cryptanalysis methods may be more useful and valuable than additional modification ofGA-based approaches.

Denial featured cryptography

Abstract: Daniel (alternatively written as DNL) is a cryptographic paradigm, featuring ease of matching: many plaintexts of choice to any give cipher (the deniability property). Consequently, the cipher itself cannot betray the specific plaintext that generated it, as it is “lost” in the large list of candidate plaintexts, all of which are decryption-generated from the ciphertext.

Personal information control and processing

Abstract: The present invention provides a personal information controlling system that limits use of personal information stored in a storage device. An example of a system comprises: controlling means for controlling a privacy policy for each piece of personal information in connection with a specified available period in which a user of the personal information is allowed to use the personal information, the privacy policy being information specifying the available period; key acquiring means for acquiring a cipher key for a cipher that can be deciphered by an administrator of the privacy policy and that cannot be deciphered by the user of the personal information; and ciphering means for using the cipher key acquired by the key acquiring means to cipher the personal information so that the user cannot use the personal information if the available period specified by the privacy policy has expired.

Group cipher communication method and group cipher communication system

Abstract: Method and system which permit, among a plurality of terminals, group cipher communication from a desired terminal to a number of desired terminals while ensuring safety of security. A plurality of secret values called master keys which are common to a predetermined subset of IC cards are stored in an IC card. A terminal initially starting communication generates a destination indicator to transmit it to other terminals, selects one of a plurality of master keys stored in an IC card on the basis of the destination indicator, generates a group key by using the selected master key, and performs encipherment and decipherment of a communication message by using the generated group key to carry out broadcast. A terminal standing for a destination receives the destination indicator, selects one of a plurality of master keys on the basis of the destination indicator, generates the group key on the basis of the selected master key and performs encipherment and decipherment of the communication message by using the generated group key.

Automatic Search of Meet-in-the-Middle and Impossible Differential Attacks

Abstract: Tracking bits through block ciphers and optimizing attacks at hand is one of the tedious task symmetric cryptanalysts have to deal with. It would be nice if a program will automatically handle them at least for well-known attack techniques, so that cryptanalysts will only focus on finding new attacks. However, current automatic tools cannot be used as is, either because they are tailored for specific ciphers or because they only recover a specific part of the attacks and cryptographers are still needed to finalize the analysis. In this paper we describe a generic algorithm exhausting the best meet-in-the-middle and impossible differential attacks on a very large class of block ciphers from byte to bit-oriented, SPN, Feistel and Lai-Massey block ciphers. Contrary to previous tools that target to find the best differential / linear paths in the cipher and leave the cryptanalysts to find the attack using these paths, we automatically find the best attacks by considering the cipher and the key schedule algorithms. The building blocks of our algorithm led to two algorithms designed to find the best simple meet-in-the-middle attacks and the best impossible truncated differential attacks respectively. We recover and improve many attacks on AES, mCRYPTON, SIMON, IDEA, KTANTAN, PRINCE and ZORRO. We show that this tool can be used by designers to improve their analysis.