The Design And Implementation Of An Identity Authentication System Against Dictionary Attack Based On Password

The computer network is an open system, and because of its openness, there exist quite a few security vulnerabilities and threats and different kinds of resources are easy to be accessed illegally. Therefore, identity authentication for visitors is more and more important and become one of the most significant techniques in network security field.Identity authentication based on password is widely used in the user authentication key negotiation procedure because it allows users to choose their own passwords without any accessories for generating or store them. But simple passwords are also ease to be attacked in various ways, such as Sniffer, Record/Replay and dictionary attack. So it is necessary and important to design a system of identity authentication with high security.This paper deeply researches on EKE protocol and CAPTCHA on the base of the knowledge of Data Encryption and Information Security. EKE is a kind of key exchange protocol based on week password and can resist offline dictionary attacks by use of symmetric key encryption and public key encryption. CAPTCHA is Completely Automated Public Turing Test to Tell Computes and Humans Aparts. By keeping testing, it can complete two functions: one is most users can pass the test, the other is current computers can not. Therefore, CAPTCHA can resist online dictionary attacks.Our work is designing an identity authentication system by use of EKE protocol and CAPTCHA; which can resist online and offline dictionary attacks. And the generation of big prime number and the googol computation are also solved in this system.