Efficient Differential Fault Analysis for AES

This paper proposes improved post analysis methods for Differential Fault Analysis (DFA) against AES. In detail, we propose three techniques to improve the attack efficiency as 1) combining previous DFA methods, 2) performing a divide-and-conquer attack by considering the AES key-schedule structure, and 3) taking the linearity of the MixColumns operation into account. As a result, the expectation of the analysis time in the previous work can be reduced to about one sixteenth. Notice that these improvements are based on the detailed analysis of the previous DFA methods and the calculation time and memory cost in practical implementations. Moreover, the proposed techniques can be widely applied to DFA attacks under different assumptions

Wave-Shaped Round Functions and Primitive Groups

Round functions used as building blocks for iterated block ciphers, both in the case of Substitution-Permutation Networks and Feistel Networks, are often obtained as the composition of different layers which provide confusion and diffusion, and key additions. The bijectivity of any encryption function, crucial in order to make the decryption possible, is guaranteed by the use of invertible layers or by the Feistel structure. In this work a new family of ciphers, called wave ciphers, is introduced. In wave ciphers, round functions feature wave functions, which are vectorial Boolean functions obtained as the composition of non-invertible layers, where the confusion layer enlarges the message which returns to its original size after the diffusion layer is applied. This is motivated by the fact that relaxing the requirement that all the layers are invertible allows to consider more functions which are optimal with regard to non-linearity. In particular it allows to consider injective APN S-boxes. In order to guarantee efficient decryption we propose to use wave functions in Feistel Networks. With regard to security, the immunity from some group-theoretical attacks is investigated. In particular, it is shown how to avoid that the group generated by the round functions acts imprimitively, which represent a serious flaw for the cipher

KLEIN: A New Family of Lightweight Block Ciphers

Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact

LEE: Light‐Weight Energy‐Efficient encryption algorithm for sensor networks

Data confidentiality in wireless sensor networks is mainly achieved by RC5 and Skipjack encryption algorithms. However, both algorithms have their weaknesses, for example RC5 supports variable-bit rotations, which are computationally expensive operations and Skipjack uses a key length of 80-bits, which is subject to brute force attack. In this paper we introduce a light-weight energy- fficient encryption-algorithm (LEE) for tiny embedded devices, such as sensor network nodes. We present experimental results of LEE under real sensor nodes operating in TinyOS. We also discuss the secrecy of our algorithm by presenting a security analysis of various tests and cryptanalytic attacks

Differential cryptanalysis of substitution permutation networks and Rijndael-like ciphers

A block cipher, in general, consist of several repetitions of a round transformation. A round transformation is a weak block cipher which consists of a nonlinear substitution transformation, a linear diffusion transformation and a key mixing. Differential cryptanalysis is a well known chosen plaintext attack on block ciphers. In this project, differential cryptanalysis is performed on two kinds of block ciphers: Substitution Permutation Networks(SPN) and Rijndael-like Ciphers. In order to strengthen a block cipher against differential attack, care should be taken in the design of both substitution and diffusion components and in the choice of number of rounds. In this context, most of the researches has been focused on the design of substitution component. In this project, differential cryptanalysis is carried out on several SPNs to find the role of permutation. Differential analysis on Rijndael-like ciphers is done to find the strength of the cipher as a whole. Tools are developed to configure and to perform differential analysis on these ciphers. In the context of SPN, the importance of permutation, the effect of bad permutation, no permutation and sequentially chosen plaintext pairs are discussed. The diffusion strength of SPN and Rijndael-like ciphers are discussed and compared