Abstract: DifficHcllman key exchange algorithm, which is used in regular scenes based on the discrete logarithm problem, demands that both of two communication parties struck up a lively conversation long-term dependable fellowship. A much more secure polymorphic key exchange algorithm was proposed based on the DifficHellman key exchange algorithm The identity information of two parties can be appended to the agreement. Both communication parties use their PRNGs to finish the polymorphic virtual S-box together. The polymorphic S-box can become a broad agreement in irregular scenes.

Key words: Polymorphic cipher, Polymorphic virtual S-box, Polymorphic key exchange algorithm, Bit independence criterion