Stanislav Smyshlyaev

Security bounds for the Magma cipher CTR encryption mode with the CryptoPro Key Meshing (CPKM) re-keying method are obtained for the standard security model and side channel information model. A modified re-keying method better than CPKM is proposed. Operational features of the Kuznyechik cipher CTR encryption mode for several re-keying methods are discussed.

This document describes the Security Evaluated Standardized Password-Authenticated Key Exchange (SESPAKE) protocol. The SESPAKE protocol provides password-authenticated key exchange for usage in systems for protection of sensitive information. The security proofs of the protocol were made for situations involving an active adversary in the channel, including man-in-the-middle (MitM) attacks and attacks based on the impersonation of one of the subjects.

We consider a family of protocols permitting the parties sharing a weak key (a password) to generate a strong common key using the unprotected channel. It is supposed that to check the password correctness the adversary should interact with legitimate participants. A review of the known vulnerabilities of the protocols of the family considered is given. This review is used to explain the main principles of the SESPAKE protocol construction.

For a number of commonly accepted models of eavesdropper the cryptographic properties of the algorithms accompanying the standards GOST R 34.11-2012 and GOST R 34.10-2012 are justified, namely, the algorithm generating the message autentication codes, algorithms generating pseudorandom sequences and key exchange algorithm. The conclusions on the security of these algorithms are based on the properties of the GOST R 34.11-2012 algorithm and on the classical complexity-theoretical problems… Показать еще

For a number of commonly accepted models of eavesdropper the cryptographic properties of the algorithms accompanying the standards GOST R 34.11-2012 and GOST R 34.10-2012 are justified, namely, the algorithm generating the message autentication codes, algorithms generating pseudorandom sequences and key exchange algorithm. The conclusions on the security of these algorithms are based on the properties of the GOST R 34.11-2012 algorithm and on the classical complexity-theoretical problems (decisional and computational Diffie – Hellman problems). Свернуть

The purpose of this document is to make the specifications of the cryptographic algorithms defined by the Russian national standards GOST R 34.10-2012 and GOST R 34.11-2012 available to the Internet community for their implementation in the cryptographic protocols based on the accompanying algorithms.

These specifications define the pseudorandom functions, the key agreement algorithm based on the Diffie-Hellman algorithm and a hash function, the parameters of elliptic curves, the key… Показать еще

The purpose of this document is to make the specifications of the cryptographic algorithms defined by the Russian national standards GOST R 34.10-2012 and GOST R 34.11-2012 available to the Internet community for their implementation in the cryptographic protocols based on the accompanying algorithms.

These specifications define the pseudorandom functions, the key agreement algorithm based on the Diffie-Hellman algorithm and a hash function, the parameters of elliptic curves, the key derivation functions, and the key export functions. Свернуть

We consider certain performance issues related to one block cipher scheme that is based on LSX transformations. A number of software implementation tweaks that manage to improve total speed characteristics are presented, helping to understand general performance properties of the proposed scheme.

The property of perfect balancedness of k-valued functions is of primary importance for cryptographic properties of stream ciphers constructed with such functions. The problem of description of the set of perfectly balanced k-valued functions for which the property of perfect balancedness is preserved for any choice of tapping sequence is considered. For the case of 2-valued (Boolean) functions this problem was raised in 1996 by Golić and later addressed and fully solved in 2009 by the author.… Показать еще

The property of perfect balancedness of k-valued functions is of primary importance for cryptographic properties of stream ciphers constructed with such functions. The problem of description of the set of perfectly balanced k-valued functions for which the property of perfect balancedness is preserved for any choice of tapping sequence is considered. For the case of 2-valued (Boolean) functions this problem was raised in 1996 by Golić and later addressed and fully solved in 2009 by the author. Recently we obtained some results for the case of k-valued functions. A classification of the known results on this subject (both obtained earlier and new) is provided, open problems and questions are formulated.
Свернуть

Problems of k-valued logic generalisations of the Golic conjecture are considered. In the case of prime k, a number of results on correctness of the k-valued analogue of the Golic conjecture are obtained in many subcases. We also present a full proof of incorrectness of the k-valued analogue of the Golic conjecture in the case of composite k.

This book offers a systematic presentation of cryptographic and code-theoretic aspects of the theory of Boolean functions. Both classical and recent results are thoroughly presented. Prerequisites for the book include basic knowledge of linear algebra, group theory, theory of finite fields, combinatorics, and probability. The book can be used by research mathematicians and graduate students interested in discrete mathematics, coding theory, and cryptography.