Bicliques for preimages: Attacks on Skein-512 and the SHA-2 family
We present a new concept of biclique as a tool for preimage attacks, which employs many powerful techniques from differential cryptanalysis of block ciphers and hash functions. The new tool has proved to be widely applicable by inspiring many authors to publish new results of the full versions of AES, KASUMI, IDEA, and Square. In this paper, we show how our concept leads to the first cryptanalysis of the round-reduced Skein hash function, and describe an attack on the SHA-2 hash function with more rounds than before.
Modes for parallelization of the process of calculating the hash code and data transfer based on l-ary trees are described. A comparative analysis of their implementations written in the Python programming language is carried out and some functional features are described. Promising directions in the field of synthesis of the tree modes of hash functions are proposed.
We present optimization guidelines and implementations of cryptographic hash functions GOST R 34.11-94 and GOST R 34.11-2012. Results for x86_64 CPUs and NVIDIA CUDA-capable GPUs are provided for our and several other well-known implementations. It is shown that the new standard may be twice as fast as the old one on modern CPUs, but it may be slower on embedded devices and GPUs. The results given for our implementation are the fastest among all the tested implementations on both platforms.
Classical approaches to the construction of hash function modes, based on the using of iterative procedures, do not allow efficient processing of large amounts of data and can’t be adapted to parallel computing architectures. It applies to both the Russian cryptographic standard GOST R 34.11-2012, which determines the algorithm and procedure for calculating the hash function, as well as many other foreign standards (for example, SHA-3). The absence of standards for parallelized modes for the hash functions of GOST R 34.11-2012 creates an urgent need for the development of the domestic standard of the parallelized mode of hash code.
This article is devoted to the research and development of new modes of hash code generation that allow efficient parallelization of the computation process and provide cryptographic resistance satisfying modern requirements. This work continues the research carried out by the authors, and offers a fundamentally new tree mode of hash code generation ("FT-mode"), based on l-ary hash trees and allowed to use any compression mapping for a mechanism of forming tree nodes. The resistance of the mode is completely determined by the resistance of the corresponding compressive mapping. In particular, the FT-mode allows using block ciphers and substitution transformations to form nodes of a hash tree along with compression functions and hash functions. In addition, the FT-mode excludes the main functional disadvantages of the known tree modes of hash code generation that affect their operational, technical and cryptographic quality.Within the framework of the present research a number of characteristics of FT-mode are calculated, and a comparative analysis of the time and computational complexity of implementations of FT-mode and some foreign tree hash modes is carried out. The corresponding results showed that the developed mode is not inferior to any of the considered modes.
This proceedings publication is a compilation of selected contributions from the “Third International Conference on the Dynamics of Information Systems” which took place at the University of Florida, Gainesville, February 16–18, 2011. The purpose of this conference was to bring together scientists and engineers from industry, government, and academia in order to exchange new discoveries and results in a broad range of topics relevant to the theory and practice of dynamics of information systems. Dynamics of Information Systems: Mathematical Foundation presents state-of-the art research and is intended for graduate students and researchers interested in some of the most recent discoveries in information theory and dynamical systems. Scientists in other disciplines may also benefit from the applications of new developments to their own area of study.
One of the most important indicators of company's success is the increase of its value. The article investigates traditional methods of company's value assessment and the evidence that the application of these methods is incorrect in the new stage of economy. So it is necessary to create a new method of valuation based on the new main sources of company's success that is its intellectual capital.