Finite Automaton Public Key Cryptosystems

Abstract

Since the introduction of the concept of public key cryptosystems by Diffie and Hellman^[32], many concrete cryptosystems had been proposed and found applications in the area of information security; almost all are block. In this chapter, we present a sequential one, the so-called finite automaton public key cryptosystem; it can be used for encryption as well as for implementing digital signatures. The public key is a compound finite automaton of n + 1(≥ 2) finite automata and states, the private key is the n + 1 weak inverse finite automata of them and states; no feasible inversion algorithm for the compound finite automaton is known unless its decomposition is known. Chapter 3 gives implicitly a feasible method to construct the 2n + 2 finite automata. We restrict the 2n + 2 finite automata to memory finite automata in the first five sections; in the last section, we use pseudo-memory finite automata to construct generalized cryptosystems.

Security of finite automaton public key cryptosystems is discussed in Sects. 9.4 and 9.5, which is heavily dependent on Chap. 4 and Sect. 2.3.