Multi-party fair ring-exchange scheme based on group signcryption

Electronic Commerce is the Internet-based exchange of tangible merchandize or in-tangible service between two or multi parts, so the fair exchange schemes have been widely used in electronic commerce. However, most studies focused on single exchange scheme and the multi-exchange scheme. A special mode can be isolated from the traditional multi-party exchange: the participants cannot get what they want with only one exchange, but after several indirectly exchanges they can ultimately get the things. So that the exchange model can be abstracted into a ring structure, referred to as the ring-exchange.