49 research outputs found
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
Design and Analysis of Cryptographic Hash Functions
Wydział Matematyki i InformatykiKryptograficzne funkcje haszujące stanowią element składowy wielu algorytmów kryptograficznych. Przykładowymi zastosowaniami kryptograficznych funkcji haszujących są podpisy
cyfrowe oraz kody uwierzytelniania wiadomości. Ich własności kryptograficzne mają znaczący wpływ na poziom bezpieczeństwa systemów kryptograficznych wykorzystujących haszowanie.
W dysertacji analizowane są
kryptograficzne funkcje haszujące oraz omówione główne zasady tworzenia
bezpiecznych kryptograficznych funkcji haszujących. Analizujemy bezpieczeństwo dedykowanych funkcji haszujących (BMW, Shabal, SIMD, BLAKE2, Skein) oraz funkcji haszujących zbudowanych z szyfrów blokowych (Crypton, Hierocrypt-3, IDEA, SAFER++, Square). Głównymi metodami kryptoanalizy użytymi są skrócona analiza różnicowa, analiza rotacyjna i przesuwna. Uzyskane wyniki pokazują słabości analizowanych konstrukcji.Cryptographic Hash Functions (CHFs) are building blocks of many cryptographic algorithms. For instance, they are indispensable tools for efficient digital signature and authentication tags. Their security properties have tremendous impact on the security level of systems, which use cryptographic hashing.
This thesis analyzes CHFs and studies the design principles for construction of secure and efficient CHFs. The dissertation investigates security of both dedicated hash functions (BMW, Shabal, SIMD, BLAKE2, Skein) and hash functions based on block ciphers (Crypton, Hierocrypt-3, IDEA, SAFER++, Square). The main cryptographic tools applied are truncated differentials, rotational and
shift analysis. The findings show weaknesses in the designs
Cryptanalysis of Block Ciphers Using Almost-Impossible Differentials
In this paper, inspired from the notion of impossible differentials, we present a model to use differentials that are less probable than a random permutation. We introduce such a distinguisher for 2 rounds of Crypton, and present an attack on 6 rounds of this predecessor AES candidate. As a special case of this idea, we embed parts of the additional rounds around the impossible differential into the distinguisher to make a probabilistic distinguisher with more rounds. We show that with this change, the data complexity is increased but the time complexity may be reduced or increased. Then we discuss that this change in the impossible differential cryptanalysis is commodious and rational when the data complexity is low and time complexity is marginal
Improved Meet-in-the-Middle Attacks on Round-Reduced Crypton-256
The meet-in-the-middle (MITM) attack has prove to be efficient in analyzing the AES block cipher.
Its efficiency has been increasing with the introduction of various techniques such as differential enumeration, key-dependent sieve, super-box etc.
The recent MITM attack given by Li and Jin has successfully mounted to 10-round AES-256.
Crypton is an AES-like block cipher.
In this paper, we apply the MITM method to the cryptanalysis of Crypton-256.
Following Li and Jin\u27s idea, we give the first 6-round distinguisher for Crypton.
Based on the distinguisher as well as the properties of Crypton\u27s simple key schedule, we successfully launch MITM attacks on Crypton-256 reduced to 9 and 10 rounds.
For 9-round Crypton-256, our MITM attack can recover the 256-bit key with a time complexity , a memory complexity .
For the 10-round version, we give two MITM attacks.
The basic attack requires a time complexity and memory complexity .
The time/memory complexity of the advanced MITM attack on 10-round Crypton is .
Our MITM attacks share the same data complexity and their error rates are negligible
Tuple Cryptanalysis: Slicing and Fusing Multisets
International audienceIn this paper, we revisit the notions of Square, saturation, integrals, multisets, bit patterns and tuples, and propose a new Slice & Fuse paradigm to better exploit multiset type properties of block ciphers, as well as relations between multisets and constituent bitslice tuples. With this refined analysis, we are able to improve the best bounds proposed in such contexts against the following block ciphers: Threefish, Prince, Present and Rectangle
Некоторые условия применимости интегрального метода к четырем раундам AES-подобных алгоритмов
Получен ряд необходимых и одно достаточное условие того, что к блочным алгоритмам, построенным аналогично алгоритму AES (например, SQUARE, Rijndael, Crypton) с уменьшенным до четырёх числом раундов может быть применён интегральный метод криптоанализа. Приведены данные экспериментов о применении интегрального метода к алгоритму Rijndael
Integral Distinguishers for Reduced-round Stribog
In January 2013, the Stribog hash function officially replaced GOST R 34.11-94 as the new Russian cryptographic hash standard GOST R 34.11-2012. Stribog is an AES-based primitive and is considered as an asymmetric reply to the new SHA-3 selected by NIST. In this paper we investigate the structural integral properties of reduced version of the Stribog compression function and its internal permutation. Specifically, we present a forward and backward higher order integrals that can be used to distinguish 4 and 3.5 rounds, respectively. Moreover, using the start from the middle approach, we combine the two proposed integrals to get 6.5-round and 7.5-round distinguishers for the internal permutation and 6-round and 7-round distinguishers for the compression function
Construction of Lightweight S-Boxes using Feistel and MISTY structures (Full Version)
The aim of this work is to find large S-Boxes, typically operating on 8
bits, having both good cryptographic properties and a low implementation
cost. Such S-Boxes are suitable building-blocks in many lightweight
block ciphers since they may achieve a better security level than
designs based directly on smaller S-Boxes. We focus on S-Boxes
corresponding to three rounds of a balanced Feistel and of a balanced
MISTY structure, and generalize the recent results by Li and Wang on the
best differential uniformity and linearity offered by such a
construction. Most notably, we prove that Feistel networks supersede
MISTY networks for the construction of 8-bit permutations. Based on
these results, we also provide a particular instantiation of an 8-bit
permutation with better properties than the S-Boxes used in several
ciphers, including Robin, Fantomas or CRYPTON