Topic
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.
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24 Mar 1999TL;DR: This paper provides a formal treatment for differential, linear and truncated differential cryptanalysis, and applies it to CS-Cipher in order to prove that there exists no good characteristic for these attacks.
Abstract: CS-Cipher is a block cipher which has been proposed at FSE 1998. It is a Markov cipher in which diffusion is performed by multipermutations. In this paper we first provide a formal treatment for differential, linear and truncated differential cryptanalysis, and we apply it to CS-Cipher in order to prove that there exists no good characteristic for these attacks. This holds under the approximation that all round keys of CS-Cipher are uniformly distributed and independent. For this we introduce some new technique for counting active Sboxes in computational networks by the Floyd-Warshall algorithm.
33 citations
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TL;DR: The margin of safety for two-key triple DES is slim, and efforts to replace it, at least with its three-key variant, and preferably with a more modern cipher such as AES should be pursued with some urgency.
Abstract: This paper reconsiders the security offered by two-key triple DES, an encryption technique that remains widely used despite recently being de-standardised by NIST. A generalization of the 1990 van Oorschot–Wiener attack is described, constituting the first advance in cryptanalysis of two-key triple DES since 1990. We give further attack enhancements that together imply that the widely used estimate that two-key triple DES provides 80 bits of security can no longer be regarded as conservative; the widely stated assertion that the scheme is secure as long as the key is changed regularly is also challenged. The main conclusion is that, whilst not completely broken, the margin of safety for two-key triple DES is slim, and efforts to replace it, at least with its three-key variant, and preferably with a more modern cipher such as AES, should be pursued with some urgency.
33 citations
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TL;DR: The results indicate that RNNs can learn algorithmic representations of black box polyalphabetic ciphers and that these representations are useful for cryptanalysis.
Abstract: Recurrent neural networks (RNNs) represent the state of the art in translation, image captioning, and speech recognition. They are also capable of learning algorithmic tasks such as long addition, copying, and sorting from a set of training examples. We demonstrate that RNNs can learn decryption algorithms -- the mappings from plaintext to ciphertext -- for three polyalphabetic ciphers (Vigenere, Autokey, and Enigma). Most notably, we demonstrate that an RNN with a 3000-unit Long Short-Term Memory (LSTM) cell can learn the decryption function of the Enigma machine. We argue that our model learns efficient internal representations of these ciphers 1) by exploring activations of individual memory neurons and 2) by comparing memory usage across the three ciphers. To be clear, our work is not aimed at 'cracking' the Enigma cipher. However, we do show that our model can perform elementary cryptanalysis by running known-plaintext attacks on the Vigenere and Autokey ciphers. Our results indicate that RNNs can learn algorithmic representations of black box polyalphabetic ciphers and that these representations are useful for cryptanalysis.
33 citations
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TL;DR: A sequential addition operation is introduced before the bit-level permutation for the purpose of reducing the permutation redundancy and a plaintext-related permutation mechanism is implemented in the lookup table construction to enhance the security of the proposed cryptosystem.
Abstract: Recently, bit-level permutation strategy in chaotic image cryptosystem has been studied extensively due to its pixel value mixing effect. However, the efficiency of such a cryptosystem suffers from its high computational complexity, since more chaotic state variables are required to shuffle the bits rather than pixels. Besides, there exists computational redundancy when ciphering some special images using conventional approaches. To promote the efficiency, a novel bit-level chaotic image cipher based on lookup table is proposed in this paper. Accordingly, a sequential addition operation is introduced before the bit-level permutation for the purpose of reducing the permutation redundancy. Moreover, the diffusion in a cross-reverse manner is also contributed to the speed acceleration. On the other hand, a plaintext-related permutation mechanism is implemented in the lookup table construction to enhance the security of the proposed cryptosystem. Simulation results and analyses show that the proposed scheme is efficient while maintaining high security performance.
33 citations
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IBM1
TL;DR: In this paper, the authors designed compact and high-speed implementations of the KASUMI block cipher and compared several prototypes to existing designs in ASICs and FPGAs.
Abstract: The KASUMI block cipher and the confidentiality (f8) and integrity (f9) algorithms using KASUMI in feed back cipher modes have been standardized by the 3GPP. We designed compact and high-speed implementations and then compared several prototypes to existing designs in ASICs and FPGAs. Making good use of the nested structure of KASUMI, a lot of function blocks are shared and reused. The data paths of the f8 and f9 algorithms are merged using only one 64-bit selector. An extremely small size of 3.07 Kgates with a 288 Mbps throughput is obtained for a KASUMI core using a 0.13-µm CMOS standard cell library. Even simultaneously supporting both the f8 and f9 algorithms, the same throughput is achieved with 4.89 Kgates. The fastest design supporting the two algorithms achieves 1.6 Gbps with 8.27 Kgates.
33 citations