An enhanced of Simple Three-Party Key Exchange Protocol

Three-party password authenticated key exchange (3PAKE) protocol is capable of reducing the number of required keys stored by users in a conference. In 2007, Lu and Cao proposed a simple three-party password authenticated key exchange (S-3PAKE) protocol for assisting users to complete business negotiations and agreements during a communication process without requiring a public server key, and the S-3PAKE protocol can resist all known attacks. However, in 2008, Cuo et al. pointed out the protocol proposed by Lu et al. still cannot resist man-in-the-middle attacks and online dictionary attacks thus further proposed an improved solution as follows. Two parties execute the 2-PAKE protocol to obtain an agreement key first, so that when they execute the 3PAKE protocol, they can authenticate the real identity with each other. An effective three-party password authenticated key exchange (3PAKE) protocol was proposed for authenticating the real identity of both parties without requiring an execution of the 2-PAKE protocol to obtain the agreement key first, but simply adding the real identity of the opposite party in the communication