Conference key distribution system with user anonymity based on algebraic approach

Most previously proposed conference key distribution systems (CKDSs) have been performed through modular exponentiation, which makes them inefficient in practical usage, especially in the case that the attending principals of the conference have less computing power. Extended from the Diffie-Hellman key distributed system (KDS), we propose an efficient CKDS with user anonymity based on the algebraic approach. The main feature of the proposed CKDS is that, except for the chairperson, all the attending principals of the conference are anonymous to each other, and even the unattending principals do not know who the attending ones are. With proper precomputation of the common secret keys shared between each pair of principals (each requires one modular exponentiation), the proposed CKDS can be performed efficiently, because only one-way hash functions and simple algebraic operations are required. The authors also show that, based on the Diffie-Hellman (DH) and the one-way hash (OWH) assumptions, the proposed CKDS is secure against impersonation and conspiracy attacks