Slovak University of Technology in Bratislava
Faculty of electrical engineering and information technology
Degree Course: INFORMATICS
Author: Marek Greško
Thesis: Keystream generator based on cyclotomy
Supervisor: RNDr. Hana Lichardová, PhD.
December 2000

The main purpose of this project is to implement and analyse a keystream generator based on cyclotomy.

We describe the most significant theoretical facts about cyclotomic generators of order 2 and order 4. Then we design and implement a cyclotomic generator of order 2 and order 4. We also include an analyser of generated sequences. This analyser is based on P-C attack.

Moreover, we analyse generated sequences on randomness. The following empirical tests have been implemented: the serial test, the gap test, the poker test, the coupon collector's test, the maximum of t test, the permutation test and partially the spectral test. Also tests specified by the FIPS PUB 140-1 and the Maurer's Universal test have been implemented.

Our results show that pseudorandom sequences generated by such generator generally do not pass all used statistical tests.

Due to these results the usability of such sequences in cryptography is not so clear although they satisfy many other cryptographic properties.