Auditable hierarchy-private public-key encryption

Abstract

A member of an intelligence agency needs to receive messages secretly from outside. Except for authorized officers of the agency, no one knows how the members are organized, even a receiver only knows the organization of his/her subordinates. However, existing primitives cannot implement this typical scenario. In this paper, we propose a primitive, referred to as auditable hierarchy-private public-key encryption (AHPE), to address the problem. The system has several important properties: the organization of the members in the agency is hidden from the outside world, but the members can still communicate with the outside secretly; if there exists a suspicious behaviour in one of the members, managers in the system can still discover him/her. Finally, analyses show that the proposed AHPE scheme is efficient and practical.