A RSA Key Security Gradating Algorithm Based on Threshold Attack Time

In this paper, we pioneer a key security level gradation scheme which is proved to efficient to counteract Iterative-Encrypting-Attack against RSA. And we make it clear that the bug which hides after the traditional key generation algorithm is exploited by Iterative-EncryptingAttack and weakens RSA security, and that the case can be improved if the traditional key generation algorithm is modified delicately. After analyzing the preliminaries and practical steps of Iterative-Encrypting-Attack in detail, we propose the concept of security grade of key-pair and depict the hierarchy of grades systematically, and bring forward an algorithm that grades security grade of key pairs. Furthermore, we introduce the concept of attack cost into the gradation prototype, then program for grading algorithm and set in motion a series of experiments for surveying the relationship between attack-cost and key-security-grade. At last, by the attained result from experimental statistics, we point it out that if key-pair is properly chosen RSA system can acquire a satisfying immunity from IterativeEncrypting-Attack.