Proxy Key Re-encapsulation Mechanism for Group Communications

Many practical applications use hybrid encryption mechanism to deal with large plaintext messages or real-time communication since the performance of the public key encryption scheme is poor. The key encapsulation is a crucial part in hybrid encryption mechanism, which allows a sender to generate a random session key and distribute it to recipient. In this paper we present a proxy key re-encapsulation scheme for group communication. The proxy in our scheme is allowed to transform the encapsulated message corresponding to group A’s public key into one that can be decapsulated by the member in group B. It can be used in cases when a group users need to perform sensitive operation without holding the necessary secret key.