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.

Automatic Search for Differential Trails in ARX Ciphers

Abstract: We propose a tool for automatic search for differential trails in ARX ciphers. By introducing the concept of a partial difference distribution table (pDDT) we extend Matsui’s algorithm, originally proposed for DES-like ciphers, to the class of ARX ciphers. To the best of our knowledge this is the first application of Matsui’s algorithm to ciphers that do not have S-boxes. The tool is applied to the block ciphers TEA, XTEA, SPECK and RAIDEN. For RAIDEN we find an iterative characteristic on all 32 rounds that can be used to break the full cipher using standard differential cryptanalysis. This is the first cryptanalysis of the cipher in a non-related key setting. Differential trails on 9, 10 and 13 rounds are found for SPECK32, SPECK48 and SPECK64 respectively. The 13 round trail covers half of the total number of rounds. These are the first public results on the security analysis of SPECK. For TEA multiple full (i.e. not truncated) differential trails are reported for the first time, while for XTEA we confirm the previous best known trail reported by Hong et al.,. We also show closed formulas for computing the exact additive differential probabilities of the left and right shift operations.

Implementing Grover oracles for quantum key search on AES and LowMC.

Abstract: Grover’s search algorithm gives a quantum attack against block ciphers by searching for a key that matches a small number of plaintext-ciphertext pairs. This attack uses \(O(\sqrt{N})\) calls to the cipher to search a key space of size N. Previous work in the specific case of AES derived the full gate cost by analyzing quantum circuits for the cipher, but focused on minimizing the number of qubits.

Rasta: A Cipher with Low ANDdepth and Few ANDs per Bit

Abstract: Recent developments in multi party computation (MPC) and fully homomorphic encryption (FHE) promoted the design and analysis of symmetric cryptographic schemes that minimize multiplications in one way or another. In this paper, we propose with Rastaa design strategy for symmetric encryption that has ANDdepth d and at the same time only needs d ANDs per encrypted bit. Even for very low values of d between 2 and 6 we can give strong evidence that attacks may not exist. This contributes to a better understanding of the limits of what concrete symmetric-key constructions can theoretically achieve with respect to AND-related metrics, and is to the best of our knowledge the first attempt that minimizes both metrics simultaneously. Furthermore, we can give evidence that for choices of d between 4 and 6 the resulting implementation properties may well be competitive by testing our construction in the use-case of removing the large ciphertext-expansion when using the BGV scheme.

Substitution deciphering based on HMMs with applications to compressed document processing

Abstract: It has been shown that simple substitution ciphers can be solved using statistical methods such as probabilistic relaxation. However, the utility of such solutions has been limited by their inability to cope with noise encountered in practical applications. We propose a new solution to substitution deciphering based on hidden Markov models. We show that our algorithm is more accurate than relaxation and much more robust in the presence of noise, making it useful for applications in compressed document processing. Recovering character interpretations from the sequence of cluster identifiers in a symbolically compressed document can be treated as a cipher problem. Although a significant amount of noise is present in the cluster sequence, enough information can be recovered with a robust deciphering algorithm to accomplish certain document analysis tasks. The feasibility of this approach is demonstrated in a multilingual document duplicate detection system.

System and method of authenticating individuals

Abstract: A method of dynamic password authentication used in an authentication system, in which a password generator applies a segmentation on its dynamic variable, according to predetermined segment length and positions, to produce a segment initial value and an offset for the dynamic variable. An encryption process applied on secret cryptographic key, segment initial value and offset results in the production of first dynamic cipher. Another encryption process applied on secret cryptographic key, dynamic variable etc results in the production of second dynamic cipher. Then first dynamic cipher and second dynamic cipher are combined to result in the production of a dynamic password. When a password undergoes verification executed by verifier, the verifier applies appropriate inverse processing. The present method can serve to enable the generator generated dynamic password to transmit synchronous information implicitly to verifier, which improves security in generation of a dynamic password and efficiency in password verification. Therefore reduction in costs of generator manufacture may be resulted.