Supervising secret-key agreements in a level-based hierarchy

A key agreement protocol is utilized in a network system such that two users are able to establish a commonly shared secret key. Entities within the same security level can communicate securely with each other by using the session key. In this paper, we will propose an approach to solve the problem of supervising secure communication in a level-based hierarchy. In the proposed scheme, any two users with the same security level can efficiently establish a session key and both of them can apply it to encrypt (or decrypt) the communication messages. Accordingly, a user with higher security level can conveniently derive the session key and supervise the communication. The security of the proposed scheme is based on Diffie-Hellman's key agreement and RSA's scheme. To reveal the session key, a malicious user has to solve the factorization and the discrete logarithm problems.