A New Key Exchange Scheme Based on Chebyshev Polynomials

Kocarev gave the first cryptosystems based on the semi-group property of Chebyshev polynomials, which seemed excellent but actually insecure. Due to the inherent periodicity of trigonometric function, an attack can easily get plaintext given ciphertext. In this paper, we extend Chebyshev polynomials from real number to finite fields to avoid the attack and present the corresponding key exchange scheme, which is secure and practical.