Stream ciphers are often used in applications where high speed and low delay are a requirement. The Solitaire stream cipher was developed by B. Schneier as a paper-and-pencil cipher. Solitaire gets its security from the inherent randomness in a shuffled deck of cards. In this paper we investigate semigroups and groups properties of the Solitaire stream cipher and its regular modiÞcations.

Well-designed initialisation and keystream generation processes for stream ciphers should ensure that each key-IV pair generates a distinct keystream. In this paper, we analyse some ciphers where this does not happen due to state convergence occurring either during initialisation, keystream generation or both. We show how state convergence occurs in each case and identify two mechanisms which c...

Streams are infinite sequences over a given data type. A stream specification is a set of equations intended to define a stream. We propose a transformation from such a stream specification to a term rewriting system (TRS) in such a way that termination of the resulting TRS implies that the stream specification is well-defined, that is, admits a unique solution. As a consequence, proving well-d...

A new version of the stream cipher Grain-128 is proposed. The new version, Grain-128a, is strengthened against all known attacks and observations on the original Grain-128, and has built-in support for authentication. The changes are modest, keeping the basic structure of Grain-128. This gives a high confidence in Grain-128a and allows for easy updating of existing implementations.

We present a design approach for hardware-oriented selfsynchronizing stream ciphers and illustrate it with a concrete design called Moustique. The latter is intended as a research cipher: it proves that the design approach can lead to concrete results and will serve as a target for cryptanalysis where new attacks may lead to improvements in the design approach such as new criteria for the ciphe...

In 2000, the stream cipher SNOW was proposed. A few attacks followed, indicating certain weaknesses in the design. In this paper we propose a new version of SNOW, called SNOW 2.0. The new version of the cipher does not only appear to be more secure, but its implementation is also a bit faster in software.

This document contains test vectors for the stream cipher RC4.