Survey and Benchmark of Block Ciphers for Wireless Sensor Networks

Cryptographic algorithms play an important role in the security architecture of wireless sensor networks (WSNs). Choosing the most storage- and energy-efficient block cipher is essential, due to the facts that these networks are meant to operate without human intervention for a long period of time with little energy supply, and that available storage is scarce on these sensor nodes. However, to our knowledge, no systematic work has been done in this area so far.We construct an evaluation framework in which we first identify the candidates of block ciphers suitable for WSNs, based on existing literature and authoritative recommendations. For evaluating and assessing these candidates, we not only consider the security properties but also the storage- and energy-efficiency of the candidates. Finally, based on the evaluation results, we select the most suitable ciphers for WSNs, namely Skipjack, MISTY1, and Rijndael, depending on the combination of available memory and required security (energy efficiency being implicit). In terms of operation mode, we recommend Output Feedback Mode for pairwise links but Cipher Block Chaining for group communications

Boomerang Connectivity Table:A New Cryptanalysis Tool

A boomerang attack is a cryptanalysis framework that regards a block cipher $E$ as the composition of two sub-ciphers $E_1\circ E_0$ and builds a particular characteristic for $E$ with probability $p^2q^2$ by combining differential characteristics for $E_0$ and $E_1$ with probability $p$ and $q$, respectively. Crucially the validity of this figure is under the assumption that the characteristics for $E_0$ and $E_1$ can be chosen independently. Indeed, Murphy has shown that independently chosen characteristics may turn out to be incompatible. On the other hand, several researchers observed that the probability can be improved to $p$ or $q$ around the boundary between $E_0$ and $E_1$ by considering a positive dependency of the two characteristics, e.g.~the ladder switch and S-box switch by Biryukov and Khovratovich. This phenomenon was later formalised by Dunkelman et al.~as a sandwich attack that regards $E$ as $E_1\circ E_m \circ E_0$, where $E_m$ satisfies some differential propagation among four texts with probability $r$, and the entire probability is $p^2q^2r$. In this paper, we revisit the issue of dependency of two characteristics in $E_m$, and propose a new tool called Boomerang Connectivity Table (BCT), which evaluates $r$ in a systematic and easy-to-understand way when $E_m$ is composed of a single S-box layer. With the BCT, previous observations on the S-box including the incompatibility, the ladder switch and the S-box switch are represented in a unified manner. Moreover, the BCT can detect a new switching effect, which shows that the probability around the boundary may be even higher than $p$ or $q$. To illustrate the power of the BCT-based analysis, we improve boomerang attacks against Deoxys-BC, and disclose the mechanism behind an unsolved probability amplification for generating a quartet in SKINNY. Lastly, we discuss the issue of searching for S-boxes having good BCT and extending the analysis to modular addition

A Salad of Block Ciphers

This book is a survey on the state of the art in block cipher design and analysis. It is work in progress, and it has been for the good part of the last three years -- sadly, for various reasons no significant change has been made during the last twelve months. However, it is also in a self-contained, useable, and relatively polished state, and for this reason I have decided to release this \textit{snapshot} onto the public as a service to the cryptographic community, both in order to obtain feedback, and also as a means to give something back to the community from which I have learned much. At some point I will produce a final version -- whatever being a ``final version\u27\u27 means in the constantly evolving field of block cipher design -- and I will publish it. In the meantime I hope the material contained here will be useful to other people

Основные принципы проектирования, оценка стойкости и перспективы использования в Украине алгоритма шифрования AES

Представлені основні принципи проектування алгоритму шифрування AES, оцінка їх обгрунтованості та прозорості. Зроблений огляд найбільш ефективних методів криптоаналізу FIPS-197. Розглянуті проблемні питання безпеки, котрі у перспективі можуть бути використані для реалізації ефективної аналітичної атаки на шифр. Наведені дані про продуктивність програмних і апаратних реалізацій AES.Designing principles of AES, their validity and clearness are given. The review of the most effective cryptanalytical attacks of Rijndael is given. Potential weaknesses in security of FIPS-197 leading to possible implementation of effective analytical attacks on the cipher in the future are considered. Performance of software and hardware implementation of FIPS-197 is given

Cryptanalytic Attacks on IDEA Block Cipher

International data encryption algorithm (IDEA) is a secret key or symmetric key block cipher. The purpose of IDEA was to replace data encryption standard (DES) cipher, which became practically insecure due to its small key size of 56 bits and increase in computational power of systems. IDEA cipher mainly to provide data confidentiality in variety of applications such as commercial and financial application e.g. pretty good privacy (PGP) protocol. Till 2015, no successful linear or algebraic weaknesses IDEA of have been reported. In this paper, author explained IDEA cipher, its application in PGP and did a systematic survey of various attacks attempted on IDEA cipher. The best cryptanalysis result which applied to all keys could break IDEA up to 6 rounds out of 8.5 rounds of the full IDEA cipher1. But the attack requires 264 known plaintexts and 2126.8 operations for reduced round version. This attack is practically not feasible due to above mention mammoth data and time requirements. So IDEA cipher is still completely secure for practical usage. PGP v2.0 uses IDEA cipher in place of BassOmatic which was found to be insecure for providing data confidentiality

Advanced Differential Cryptanalysis of Reduced-Round SIMON64/128 Using Large-Round Statistical Distinguishers

Lightweight cryptography is a rapidly evolving area of research and it has great impact especially on the new computing environment called the Internet of Things (IoT) or the Smart Object networks (Holler et al., 2014), where lots of constrained devices are connected on the Internet and exchange information on a daily basis. Every year there are many new submissions of cryptographic primitives which are optimized towards both software and hardware implementation so that they can operate in devices which have limited resources of hardware and are subject to both power and energy consumption constraints. In 2013, two families of ultra-lightweight block ciphers were proposed, SIMON and SPECK, which come in a variety of block and key sizes and were designed to be optimized in hardware and software implementation respectively (Beaulieu et al., 2013). In this paper, we study the security of the 64-bit SIMON with 128-bit key against advanced forms of differential cryptanalysis using truncated differentials (Knudsen, 1995; Courtois et al., 2014a). We follow similar method as the one proposed in SECRYPT 2013 (Courtois and Mourouzis, 2013) in order to heuristically discover sets of differences that propagate with sufficiently good probability and allow us to combine them efficiently in order to construct large-round statistical distinguishers. We present a 22-round distinguisher which we use it in a depth-first key search approach to develop an attack against 24 and 26 rounds with complexity 2^{124.5} and 2^{126} SIMON encryptions respectively. Our methodology provides a framework for extending distinguishers to attacks to a larger number of rounds assuming truncated differential properties of relatively high probability were discovered

Searching for Subspace Trails and Truncated Differentials

Grassi et al. [Gra+16] introduced subspace trail cryptanalysis as a generalization of invariant subspaces and used it to give the first five round distinguisher for Aes. While it is a generic method, up to now it was only applied to the Aes and Prince. One problem for a broad adoption of the attack is a missing generic analysis algorithm. In this work we provide efficient and generic algorithms that allow to compute the provably best subspace trails for any substitution permutation cipher

The (related-key) impossible boomerang attack and its application to the AES block cipher

The Advanced Encryption Standard (AES) is a 128-bit block cipher with a user key of 128, 192 or 256 bits, released by NIST in 2001 as the next-generation data encryption standard for use in the USA. It was adopted as an ISO international standard in 2005. Impossible differential cryptanalysis and the boomerang attack are powerful variants of differential cryptanalysis for analysing the security of a block cipher. In this paper, building on the notions of impossible differential cryptanalysis and the boomerang attack, we propose a new cryptanalytic technique, which we call the impossible boomerang attack, and then describe an extension of this attack which applies in a related-key attack scenario. Finally, we apply the impossible boomerang attack to break 6-round AES with 128 key bits and 7-round AES with 192/256 key bits, and using two related keys we apply the related-key impossible boomerang attack to break 8-round AES with 192 key bits and 9-round AES with 256 key bits. In the two-key related-key attack scenario, our results, which were the first to achieve this amount of attacked rounds, match the best currently known results for AES with 192/256 key bits in terms of the numbers of attacked rounds. The (related-key) impossible boomerang attack is a general cryptanalytic technique, and can potentially be used to cryptanalyse other block ciphers