Abstract: Secure, complex and high speed cryptosystem is essential for transmission of information. Attackers can be avoided in application specific hardware. In this study, security is enhanced by Pell equation and chaotic key based algorithm. Chaotic key based algorithm has been widely used for encryption now days. The proposed algorithm is for encryption and decryption of text. VLSI architecture of cryptosystem is proposed for hardware implementation to increase the speed of computation and complexity. Separate hardware increases security and consumes less power.