1,653 research outputs found
Further Improving Differential-Linear Attacks: Applications to Chaskey and Serpent
Differential-linear attacks are a cryptanalysis family that has recently benefited from various technical improvements, mainly in the context of ARX constructions. In this paper we push further this refinement, proposing several new improvements. In particular, we develop a better understanding of the related correlations, improve upon the statistics by using the LLR, and finally use ideas from conditional differentials for finding many right pairs. We illustrate the usefulness of these ideas by presenting the first 7.5-round attack on Chaskey. Finally, we present a new competitive attack on 12 rounds of Serpent, and as such the first cryptanalytic progress on Serpent in 10 years
A note on some algebraic trapdoors for block ciphers
We provide sufficient conditions to guarantee that a translation based cipher
is not vulnerable with respect to the partition-based trapdoor. This trapdoor
has been introduced, recently, by Bannier et al. (2016) and it generalizes that
introduced by Paterson in 1999. Moreover, we discuss the fact that studying the
group generated by the round functions of a block cipher may not be sufficient
to guarantee security against these trapdoors for the cipher.Comment: to be published on Advances in Mathematics of Communication
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
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
A Security Analysis of IoT Encryption: Side-channel Cube Attack on Simeck32/64
Simeck, a lightweight block cipher has been proposed to be one of the
encryption that can be employed in the Internet of Things (IoT) applications.
Therefore, this paper presents the security of the Simeck32/64 block cipher
against side-channel cube attack. We exhibit our attack against Simeck32/64
using the Hamming weight leakage assumption to extract linearly independent
equations in key bits. We have been able to find 32 linearly independent
equations in 32 key variables by only considering the second bit from the LSB
of the Hamming weight leakage of the internal state on the fourth round of the
cipher. This enables our attack to improve previous attacks on Simeck32/64
within side-channel attack model with better time and data complexity of 2^35
and 2^11.29 respectively.Comment: 12 pages, 6 figures, 4 tables, International Journal of Computer
Networks & Communication
- …