Cryptography Research Group


The group leader started to deal with data security and cryptography 30 years ago. In these diverse disciplines we have achieved remarkable results at international level in the following topics.

Anonymity and its applications (Attila PETHŐ, Andrea HUSZTI, Zita KOVÁCS)

There are many applications where a user does not want to reveal his or her identity. A typical example is secret voting where it must be ensured that only eligible voters have the right to vote and at the same time they cannot be identified. Similar problems arise in case of e-exam schemes, when the examinee and the examiner mutually unknown to each other. In recent years, we have developed several algorithms and protocols to solve these problems and improve their security.

Provable security analysis of cryptographic algorithms and protocols (Andrea HUSZTI, László ASZALÓS, Zita KOVÁCS)

Unfortunately, there are more and more cryptographic schemes used in practice that are believed to be secure for long time and turns out to be broken. Applying provable security methods we can verify whether a cryptographic protocol possesses a security requirement. We apply technologies based on computational and formal methods as well.

Mathematical constructions for hash functions and random number generators (Attila PETHŐ, Tamás HERENDI)

The currently used hash functions are designed with emphasis placed on speed. Recently, attacks pointed out that the speed should not be the main design principle. Thus, it is important to develop sufficiently effective hash functions which can be analyzed with mathematical methods. The random number generators are another essential component of the cryptographic algorithms. We have developed a method that characterizes the generator of the uniformly distributed bitstrings with large period length. Last years an FPGA implementation is prepared, which is significantly faster than implementations on conventional machines.

Cryptosystems based on automata compositions (Géza HORVÁTH, Zita KOVÁCS, Dömösi Pál)

We have introduced the concept of two-phase and sequentially working automata compositions, which are feasible for cryptographic applications. We have designed several symmetric block ciphers. In these novel cyphers, component automata communicate to each other to achieve their main goal. Moreover, Dömösi’s encryption scheme, which is based on automata-theory, has been improved. Since it is not a conventional encrytion, we invented new attacks. We applied Viterbi algorithm in the hidden Markov model, and we also defined a statistical attack.

Updated: 2018.03.09.

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