By introducing signcryption technology into concurrent signature,a signcryption-based concurrent signature scheme was presented,which was proven to have the existential unforgeability against adaptive chosen messages attacks under the random oracle model,Based on this scheme,a fair exchange protocol was proposed,which could be used to exchange digital goods.This protocol did not need secure communications channel,in which two parties generate symmetrical ambiguous signatures and individual keystones were released by themselves,which ensured the properties of confidentiality,ambiguousness and fairness,which made our protocol could be used in e-commerce payment,e-contract signing,mail authentication,etc.
