Technical Reports

A List by Author: Petr ©véda


Attackers in Wireless Sensor Networks Will Be Neither Random nor Jumping -- Secrecy Amplification Case, Extended Version

by Radim O¹»ádal, Petr ©véda, Václav Matyá¹, September 2016, 20 pages.

FIMU-RS-2016-04. Available as Postscript, PDF.


Partially compromised network is a pragmatic assumption in many real-life scenarios. Secrecy amplification protocols provide a significant increase in the number of secure communication links by re-establishing new keys via different communication paths. Our paper shows that so far research in the area of secrecy amplification protocols for wireless sensor networks has been based on rather simplified foundations with respect to attacker models. The attacker does not behave randomly and different attacker capabilities and behaviour have to be considered. We provide means to experimental work with parametrisable attacker capabilities and behaviour in realistic simulations, and evaluate the impact of the realistic attacker properties on the performance of major amplification protocols. We also show which secrecy amplification protocols perform best in different attacker settings and help to select a protocol that exhibits good results in a prevalent number of inspected scenarios. This is the extended version of our paper that is to be presented at 15th International Conference on Cryptology and Network Security (CANS 16) in Milan, Italy, November 14-16, 2016.

Trustworthiness of Signed Data

by Petr ©véda, September 2002, 13 pages.

FIMU-RS-2002-06. Available as Postscript, PDF.


Use of digital signatures is not as straightforward as one would like to see it. We have to be aware of the fact that computers sign all electronic documents on behalf of humans and only few computers can be considered as fully trustworthy. Visual representation of file formats can be dramatically changed by settings of a viewer or a text processor. Users cannot be absolutely sure that they sign only the data visible on their computer screen. Proprietary signature solutions are not fully compatible as there are no standards.

The report reviews the problem of the document content interpretation. Introductory section reviews problems related to the use of digital signatures in practice. The second section briefly summarizes necessary cryptographic assumptions and gives an overview of signature functional properties. The third section discusses questions and possible ways of an interpretation of documents content. The fourth section suggests design principles for trustworthy electronic document structure.

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