Abstract:

Most of the stream ciphers proposed so far are based on 
Linear Feedback Shift Registers (LFSR's). They are ideally suited to 
hardware implementations, but less efficient in software, and their 
linearity makes it possible to apply correlation and algebraic attacks

to many of the resultant ciphers. In this talk I'll describe a 
different type of a sequence generator which is exceptionally 
efficient in software, is based on non-linear and non-algebraic 
machine operations, and has many provable desirable properties. After 
introducing the basic techniques used to build and analyse such 
generators, I'll describe several concrete constructions and analyse 
the best known attacks on the resultant stream ciphers.

Joint work with Alexander Klimov.