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.

2Gbit/s Hardware Realizations of RIJNDAEL and SERPENT: A Comparative Analysis

Abstract: We present and evaluate efficient VLSI implementations of both Rijndael and Serpent. The two cipher algorithms have been implemented by two comparable design teams within the same timeframe using the same fabrication process and EDA tools. We are thus in a position to compare to what degree the Rijndael and Serpent ciphers are suitable for dedicated hardware architectures. Both ASICs support encryption as well as decryption in ECB mode and include on-chip subkey generation. The two designs have been fabricated in a 0.6µm 3LM CMOS technology. Measurement results verified an encryption and decryption throughput of 2.26Gbit/s and 1.96Gbit/s for Rijndael and Serpent respectively. Circuit complexity is in the order of 300k transistors in either case.

Proposal for DICOM Multiframe Medical Image Integrity and Authenticity

Abstract: This paper presents a novel algorithm to successfully achieve viable integrity and authenticity addition and verification of n-frame DICOM medical images using cryptographic mechanisms. The aim of this work is the enhancement of DICOM security measures, especially for multiframe images. Current approaches have limitations that should be properly addressed for improved security. The algorithm proposed in this work uses data encryption to provide integrity and authenticity, along with digital signature. Relevant header data and digital signature are used as inputs to cipher the image. Therefore, one can only retrieve the original data if and only if the images and the inputs are correct. The encryption process itself is a cascading scheme, where a frame is ciphered with data related to the previous frames, generating also additional data on image integrity and authenticity. Decryption is similar to encryption, featuring also the standard security verification of the image. The implementation was done in JAVA, and a performance evaluation was carried out comparing the speed of the algorithm with other existing approaches. The evaluation showed a good performance of the algorithm, which is an encouraging result to use it in a real environment.

Invariant Subspace Attack Against Midori64 and The Resistance Criteria for S-box Designs

Abstract: We present an invariant subspace attack on the block cipher Midori64, proposed at Asiacrypt 2015. Our analysis shows that Midori64 has a class of 2 32 weak keys. Under any such key, the cipher can be distinguished with only a single chosen query, and the key can be recovered in 2 16 time with two chosen queries. As both the distinguisher and the key recovery have very low complexities, we confirm our analysis by implementing the attacks. Some tweaks of round constants make Midori64 more resistant to the attacks, but some lead to even larger weak-key classes. To eliminate the dependency on the round constants, we investigate alternative S-boxes for Midori64 that provide certain level of security against the found invariant subspace attacks, regardless of the choice of the round constants. Our search for S-boxes is enhanced with a dedicated tool which evaluates the depth of any given 4-bit S-box that satisfies certain design criteria. The tool may be of independent interest to future S-box designs.

Ic card using device, ic card, and storage medium

Abstract: PROBLEM TO BE SOLVED: To improve the safety by obstructing the leak of a key by analyzing an IC card device. SOLUTION: When PIN(personal identification number) data are inputted, an application software part 70 generates a temporary common key K used for cipher communication when the function of an IC card 20 is used and transfers the temporary common key K and inputted PIN data to the IC card 20. Thus, the cipher key which is temporarily effective is used only when the application software part 70 and IC card 20 are connected which hold no cipher key normally.

Unconditional Security in Cryptography

Abstract: The fact that most presently- used cryptosystems cannot be rigorously proven secure and hence permanently face the risk of being broken motivates the search for schemes with unconditional security. The corresponding proofs however must be based on information theory rather than complexity theory. One reason for this is the lack of known lower bounds on the running time of algorithms solving certain computational problems such as the discrete-logarithm problem or the integer-factoring problem. At the beginning of an information-theoretic analysis of cryptosystems stands Shannon's definition of perfect secrecy, unquestionably the strongest possible security definition, and his wellknown inequality giving a lower bound on the key length of every perfectly secret cipher, thus suggesting that such a high level of confidentiality cannot be realized in any practical scheme. This pessimism has later been qualified by several authors who showed that unconditional security can be achieved in many special but realistic scenarios. Some of these approaches are described in this introductory overview article.