The Kupyna hash function was selected as the new Ukrainian standard DSTU 7564:2014 in 2015. It is designed to replace the old Independent States (CIS) standard GOST 34.311-95. The Kupyna hash function is an AES-based primitive, which uses Merkle-Damg̊ard compression function based on Even-Mansour design. In this paper, we show the first cryptanalytic attacks on the round-reduced Kupyna hash func...

We use ideas from game theory to transform two families of authentication protocols so that even if an intruder attacks a protocol, its payoff will still be lower than when it does not. This is particularly useful in resisting or discouraging a powerful and rational intruder (as present in military applications) who makes many attempts to break a protocol because (1) even if the intruder fails,...

Since the security analysis against stream ciphers becomes more difficult nowadays, it is urgent and significant to propose new generic methods. In this work, we introduce guess-and-determine techniques to two traditional analysis methods and make the new approaches methodological for generalization. We show the power of the new methods by analyzing two stream ciphers: Grain-v1 and ACORN. Grain...

Design of secure light-weight stream ciphers is an important area in cryptographic hardware & embedded systems and a very recent design by Armknecht and Mikhalev (FSE 2015) has received serious attention that uses shorter internal state and still claims to resist the time-memory-data-tradeoff (TMDTO) attacks. An instantiation of this design paradigm is the stream cipher named Sprout with 80-bit...

Generic distinguishers against Feistel Network with up to 5 rounds exist in the regular setting and up to 6 rounds in a multi-key setting. We present new cryptanalyses against Feistel Networks with 5, 6 and 7 rounds which are not simply distinguishers but actually recover completely the unknown Feistel functions. When an exclusive-or is used to combine the output of the round function with the ...