Блочний шифр на основі псевдонедетермінованої послідовності криптопримітивів

Запропоновано новий підхід до реалізації блочного шифру, який базується на використанні псевдонедетермінованих послідовностей криптопримітивів та розбитті повідомлення на блоки різної довжини на кожному з раундів перетворення

Анализ алгоритмов симетричного блочного шифрования

Проведено аналіз алгоритмів симетричного блокового шифрування з точки зору способу реалізації перетворення вхідних даних у шифротекст. Сформульовано рекомендації для вибору перетворень, що забезпечать підвищення швидкості шифрування.Проведен анализ алгоритмов симметричного блочного шифрования с точки зрения способа реализации преобразования входных данных в шифротекст. Сформулированы рекомендации для выбора преобразований что обеспечат повешение скорости шифрования.We analyzed the symmetric block cipher algorithms, depending on the method of converting input data into ciphertext. We proposed recommendations for selection of transformations that will provide increasing speed of encryption

The cross-correlation measure for families of binary sequences

Large families of binary sequences of the same length are considered and a new measure, the cross-correlation measure of order $k$ is introduced to study the connection between the sequences belonging to the family. It is shown that this new measure is related to certain other important properties of families of binary sequences. Then the size of the cross-correlation measure is studied. Finally, the cross-correlation measures of two important families of pseudorandom binary sequences are estimated

Hardware Bit-Mixers

A new concept, the Bit-Mixer is introduced. It is a function of fixed, possibly different size of input and output, which computes statistically uncorrelated output from correlated input values, and its behavior is altered by parameters, called keys. Several constructions are presented, with very fast, power efficient implementations in electronic hardware, having very little side channel leakage. In information security bit-mixers have many applications, mostly when their output is hidden from an adversary. They include key generators, parallel stream ciphers, hash functions, data dependent authentication codes, and many mor

Random generation of Boolean functions with high degree of correlation immunity, Journal of Telecommunications and Information Technology, 2006, nr 3

In recent years a cryptographic community is paying a lot of attention to the constructions of so called resilient functions for use mainly in stream cipher systems. Very little work however has been devoted to random generation of such functions. This paper tries to fill that gap and presents an algorithm that can generate at random highly nonlinear resilient functions. Generated functions are analyzed and compared to the results obtained from the best know constructions and some upper bounds on nonlinearity and resiliency. It is shown that randomly generated functions achieve in most cases results equal to the best known designs, while in other cases fall just behind such constructs. It is argued that the algorithm can perhaps be used to prove the existence of some resilient functions for which no mathematical prove has been given so far

A study of differences between bent functions constructed using Rothaus method and randomly generated bent functions, Journal of Telecommunications and Information Technology, 2003, nr 4

Bent functions, having the highest possible nonlinearity, are among the best candidates for construction of S-boxes. One problem with bent functions is the fact that they are hard to find among randomly generated set of Boolean functions already for 6 argument functions. There exist some algorithms that allow for easy generation of bent functions. The major drawback of these algorithms is the fact that they rely on deterministic dependencies and are only able to generate bent functions belonging to one specific class. In our paper we present an efficient generator of random bent functions of more than 4 arguments. Resulting functions are not bounded by constraints described above. The generator operates in algebraic normal form domain (ANF). We also present our result on comparing the performance of S-boxes build using our bent function generator versus a standard method of bent function construction. We also give some directions for further research

On the cross-combined measure of families of binary lattices and sequences

The cross-combined measure (which is a natural extension of cross-correlation measure) is introduced and important constructions of large families of binary lattices with optimal or nearly optimal cross-combined measures are presented. These results are also strongly related to the one-dimensional case: An easy method is showed obtaining strong constructions of families of binary sequences with nearly optimal cross-correlation measures based on the previous constructions of families of lattices. The important feature of this result is that so far there exists only one type of constructions of very large families of binary sequences with small cross-correlation measure, and this only type of constructions was based on one-variable irreducible polynomials. Since it is very complicated to construct one-variable irreducible polynomials over $\mathbb F_p$, it became necessary to show other types of constructions where the generation of sequences is much faster. Using binary lattices based on two-variable irreducible polynomials this problem can be avoided. (Since, contrary to one-variable polynomials, using Sch\"oneman-Eisenstein criteria it is possible to generate two-variable irreducible polynomials over $\mathbb F_p$ fast.

The QARMA Block Cipher Family. Almost MDS Matrices Over Rings With Zero Divisors, Nearly Symmetric Even-Mansour Constructions With Non-Involutory Central Rounds, and Search Heuristics for Low-Latency S-Boxes

This paper introduces QARMA, a new family of lightweight tweakable block ciphers targeted at applications such as memory encryption, the generation of very short tags for hardware-assisted prevention of software exploitation, and the construction of keyed hash functions. QARMA is inspired by reflection ciphers such as PRINCE, to which it adds a tweaking input, and MANTIS. However, QARMA differs from previous reflector constructions in that it is a three-round Even-Mansour scheme instead of a FX-construction, and its middle permutation is non-involutory and keyed. We introduce and analyse a family of Almost MDS matrices defined over a ring with zero divisors that allows us to encode rotations in its operation while maintaining the minimal latency associated to {0, 1}-matrices. The purpose of all these design choices is to harden the cipher against various classes of attacks. We also describe new S-Box search heuristics aimed at minimising the critical path. QARMA exists in 64- and 128-bit block sizes, where block and tweak size are equal, and keys are twice as long as the blocks. We argue that QARMA provides sufficient security margins within the constraints determined by the mentioned applications, while still achieving best-in-class latency. Implementation results on a state-of-the art manufacturing process are reported. Finally, we propose a technique to extend the length of the tweak by using, for instance, a universal hash function, which can also be used to strengthen the security of QARMA

Journal of Telecommunications and Information Technology, 2003, nr 4

kwartalni