A String-Based Public Key Cryptosystem

Traditional methods in public key cryptography are based on number theory, and suffer from problems such as dealing with very large numbers, making key creation cumbersome. Here, we propose a new public key cryptosystem based on strings only, which avoids the difficulties of the traditional number theory approach. The security mechanism for public and secret keys generation is ensured by a recursive encoding mechanism embedded in a quasi-commutative-random function, resulted from the composition of a quasi-commutative function with a pseudo-random function. In this revised version of the paper we show that the eavesdropper's problem of the proposed cryptosystem has a solution, and we give the details of the solution.