Security Analysis Techniques Using Differential Relationships For Block Ciphers

The uses of block cipher has become crucial in nowadays’ computing era as well as the information security. Information must be available only for authenticated and authorized users.However,flaws and weaknesses in the cryptosystem can breach the security of stored and transmitted information.A weak key in the key schedule is well-known issues which may affect several round keys have same bits in common.Besides,information leaked from the implementation also affects the security of block ciphers.Based on the flaws and leakage,the adversary is able to assess the differential relationships in block cipher using differential cryptanalysis technique. Firstly,the existing differential cryptanalysis techniques have been evaluated.Secondly,based on the gaps that have to be filled in the existing differential cryptanalysis techniques,new frameworks of differential cryptanalysis techniques have been proposed and designed by using Pearson correlation coefficient,Hamming-weight leakage assumption and reference point.The Pearson correlation coefficient is used to determine the repeated differential properties in the key schedules.Meanwhile, reference point and Hamming-weight leakage assumption are used to assess the security of the implementation of block ciphers against side-channel cube attack and differential fault analysis.Thirdly,all proposed frameworks have been assessed.The results show that the repeated differential properties are found for AES, PRESENT and Simeck key schedules.However,AES key schedule is definitely ideal to be adopted in the design for the future cryptographic algorithm.In addition,the newly designed frameworks for side-channel differential analysis techniques have been able to reduce the attack complexities for Simeck32/64,KATAN32 and KTANTAN32 compared to previous work.In conclusion,the proposed frameworks are effective in analyzing the security of block ciphers using differential cryptanalysis techniques

Systematization of a 256-bit lightweight block cipher Marvin

In a world heavily loaded by information, there is a great need for keeping specific information secure from adversaries. The rapid growth in the research field of lightweight cryptography can be seen from the list of the number of lightweight stream as well as block ciphers that has been proposed in the recent years. This paper focuses only on the subject of lightweight block ciphers. In this paper, we have proposed a new 256 bit lightweight block cipher named as Marvin, that belongs to the family of Extended LS designs.Comment: 12 pages,6 figure

Blok şifrelerin olası olmayan diferansiyel kriptanalizi

TÜBİTAK EEEAG Proje01.10.201

Plaintext Recovery in DES-like Cryptosystems Based on S-boxes with Embedded Parity Check

We describe an approach for recovering the plaintext in block ciphers having a design structure similar to the Data Encryption Standard but with improperly constructed S-boxes. The experiments with a backtracking search algorithm performing this kind of attack against modified DES/Triple-DES in ECB mode show that the unknown plaintext can be recovered with a small amount of uncertainty and this algorithm is highly efficient both in time and memory costs for plaintext sources with relatively low entropy. Our investigations demonstrate once again that modifications resulting to S-boxes which still satisfy some design criteria may lead to very weak ciphers. ACM Computing Classification System (1998): E.3, I.2.7, I.2.8.This work was presented in part at the 1-st International Conference Bulgarian Cryptography Days 2012, Sofia, Bulgaria, 20–21 September 2012

Evaluating Coppersmith’s Criteria by way of SAT Solving

S-boxes are the non-linear part of DES cryptosystem. Along the years it has became clear that any kind of edit to the structure of DES S-boxes increases the probability of success of breaking the algorithm, which was very carefully designed. The reason why the S-boxes were built in this way was clarified by Coppersmith, years after the publication of the encryption algorithm. The aim of this thesis is to investigate on Coppersmith’s DES S-boxes design criteria and to evaluate them by way of SAT Solving, in order to analyze the performance of SAT-Solvers for different versions of DES algorithm, in which S-boxes respect only a sample of Coppersmith’s design criteria. This aim is achieved thanks to the implementation of a Python tool: DESBoxGen. The main challenge in the design of DESBoxGen is the one of finding a way to efficiently generating S-boxes satisfying certain criteria

Differential cryptanalysis of new Qamal encryption algorithm

Currently, the Republic of Kazakhstan is developing a new standard for symmetric data encryption. One of the candidates for the role of the standard is the Qamal encryption algorithm developed by the Institute of Information and Computer Technologies (Almaty, Republic of Kazakhstan). The article describes the algorithm. Differential properties of the main operations that make up the Qamal cypher are considered in the questions of stability. We have shown that for a version with a 128-bit data block and the same secret key size for three rounds of encryption it is difficult to find the right pairs of texts with a probability of 2–120, which makes differential cryptanalysis not applicable to the Qamal cyphe