A conference key establishment protocol allows a group of conferees to agree on a secret key shared among them for secure group communication. This paper proposes a three-level conference key establishment protocol based on the Universal Mobile Telecommunications System (UMTS) framework to establish a group-level key

home location register (HLR) level keys

and visitor location register (VLR) level keys simultaneously for a group of conferees. The group-level key is used to secure the communications for all conferees

the HLR-level key is for those within the same HLR domain

and the VLR-level key is for those within the same VLR domain. The group-level key can be used for securing inter-domain group-oriented applications such as commercial remote conferencing systems. The HLR- and VLR-level keys can be used for securing intra-domain subgroup applications (e.g.

location-based or context-aware services) and dynamic key updating. Since our proposed protocol exploits existing UMTS security functions and the exclusive-or operation

it is compatible with UMTS architecture. This means that it is fast and easy to implement on the existing UMTS architecture. Furthermore

the proposed protocol has low computational complexities and can provide cost effectiveness

load-amortization

scalability

user authentication

key establishment

key confirmation

key updating

and lawful interception.