Anonymous message communications with user hierarchy in a multicast system

摘要

In this paper, an anonymous communication protocol is proposed. The proposed scheme is then further expanded to support the user hierarchy. Higher security class users have the right to monitor a private communication involving lower security class users in the hierarchy. In our scheme, the identities of the sender and the destinations can be concealed. Every participant of the multicast connection can determine whether it is on the list of recipients of a packet, but can not derive any further information about who else is also able to receive that packet. The main mechanism we adopted in our scheme is kind of knapsack-like system in which we define the volume-increasing knapsack to encrypt a bit vector, and reveal the specified bit in the decryption manner. In our scheme, less multiplication and addition operations on modular computation are required to conceal the addresses, as long as all the encryption keys are set up in a table in advance. As a result we obtain better benefits in the encryption/decryption operations when compared to the exponential operations in general crypto manner. Consequently, the anonymous message communications with an addressed packet are efficiently implemented in our proposed scheme.