The Fairy-Ring Dance: Password Authenticated Key Exchange in a Group

In this paper, we study Password Authenticated Key Exchange (PAKE) in a group. First, we present a generic “fairy-ring dance” construction that transforms any secure two-party PAKE scheme to a group PAKE protocol while preserving the round efficiency in the optimal way. Based on this generic construction, we present two concrete instantiations based on using SPEKE and J-PAKE as the underlying PAKE primitives respectively. The first protocol, called SPEKE+, accomplishes authenticated key exchange in a group with explicit key confirmation in just two rounds. This is more round-efficient than any existing group PAKE protocols in the literature. The second protocol, called J-PAKE+, requires one more round than SPEKE+, but is computationally faster. Finally, we present full implementations of SPEKE+ and J-PAKE+ with detailed performance measurements. Our experiments suggest that both protocols are feasible for practical applications in which the group size may vary from three to se...

• Type: Journal
• Year: 2015
• Where: CCS
• Authors: Feng Hao, Xun Yi, Liqun Chen, Siamak Fayyaz Shahandashti
• Keywords: CCS 2015, Security Privacy