in this paper, we show how to obtain suitable differential charactristics for block ciphers with neural networks. we represent the operations of a block cipher, regarding their differential characteristics, through a directed weighted graph. in this way, the problem of finding the best differential characteristic for a block cipher reduces to the problem of finding the minimum-weight multi-path...

An earlier paper by the same author suggested combining a block cipher and a stream cipher to get a strong hybrid cipher. This paper proposes a specific cipher based on those ideas, using the HC-128 stream cipher and a tweakable block cipher based on Serpent. Table of

Serpent is an SP Network block cipher submitted to the AES competition and chosen as one of its five finalists. The security of Serpent is widely acknowledged, especially as the best known attack so far is a differential-linear attack on only 11 rounds out of the 32 rounds of the cipher. In this paper we introduce a more accurate analysis of the differentiallinear attack on 11-round Serpent. Th...

The results of fast implementations of all five AES final candidates using Virtex Xilinx Field Programmable Gate Arrays are presented and analyzed. Performance of several alternative hardware architectures is discussed and compared. One architecture optimum from the point of view of the throughput to area ratio is selected for each of the two major types of block cipher modes. For feedback ciph...

In this paper, we propose a genetic algorithm, called GenSPN, for finding highly probable differential characteristics of substitution permutation networks (SPNs). A special fitness function and a heuristic mutation operator have been used to improve the overall performance of the algorithm. We report our results of applying GenSPN for finding highly probable differential characteristics of Ser...

Serpent is a 128-bit block cipher designed by Ross Anderson, Eli Biham and Lars Knudsen as a candidate for the Advanced Encryption Standard (AES). It was a finalist in the AES competition. The winner, Rijndael, got 86 votes at the last AES conference while Serpent got 59 votes [1]. The designers of Serpent claim that Serpent is more secure than Rijndael.In this paper we have observed that the n...

Serpent is a 128-bit SP-Network block cipher consisting of 32 rounds with variable key length (up to 256 bits long). It was selected as one of the 5 AES finalists. The best known attack so far is a linear attack on an 11-round reduced variant. In this paper we apply the enhanced differential-linear cryptanalysis to Serpent. The resulting attack is the best known attack on 11-round Serpent. It r...

Serpent is a 128-bit block cipher designed by Ross Anderson, Eli Biham and Lars Knudsen as a candidate for the Advanced Encryption Standard, a competition sponsored by the National Institute of Standards and Technology to define a successor to DES. Serpent is designed to be faster than DES and more secure than triple-DES. It is in the public domain and there are no restrictions on its use: the ...

Sosemanuk is a new synchronous software-oriented stream cipher, corresponding to Profile 1 of the ECRYPT call for stream cipher primitives. Its key length is variable between 128 and 256 bits. It accommodates a 128-bit initial value. Any key length is claimed to achieve 128-bit security. The Sosemanuk cipher uses both some basic design principles from the stream cipher SNOW 2.0 and some transfo...