In this paper we give necessary design principles to be used, when constructing secure Feistel ciphers. We introduce a new concept, practical security against linear and differential attacks on Feistel ciphers. We give examples of such Feistel ciphers (practically) resistant to differential attacks, linear attacks and other attacks.

Finding a pattern which separates two sets is a critical task in discovery. Given two sets of strings, consider the problem to find a subsequence that is common to one set but never appears in the other set. The problem is known to be NP-complete. Episode pattern is a generalized concept of subsequence pattern where the length of substring containing the subsequence is bounded. We generalize th...

Formal methods are considered to be highly expensive. Therefore, they are currently applied almost only in high risk software development. In this paper, we show that formal techniques can be also efficiently used in standard large-scale applications. We focus on the generation of specifications which state the termination condition of for loops in Java code (expressed as so called Java Modelin...

In this paper we give necessary design principles to be used, when constructing secure Feistel ciphers. We introduce a new concept, practical security against linear and di erential attacks on Feistel ciphers. We give examples of such Feistel ciphers (practically) resistant to di erential attacks, linear attacks and other attacks.

With the emergence of technologies designed to support social activities online, it is beneficial to explore their potential in novel application areas. These studies, in the research tradition of Bowers et al. (1996), can be used to evaluate and develop technologies while providing the opportunity to study the social practices that develop around their use. We examine the use of online seminar...

Virtual synchrony is an important abstraction that is proven to be extremely useful when implemented over asynchronous, typically large, message-passing distributed systems. Fault tolerant design is a key criterion for the success of such implementations. This is because large distributed systems can be highly available as long as they do not depend on the full operational status of every syste...