Protocol Of Digital Goods Transaction

With the popularization of the computer and Internet, many digital goods enter into our lives. Digital goods have many characteristics such as empty-physical-space, zero-weight, easily duplicated and transmissibility via Internet. Combined with some methods of electronic payment, the whole trade of digital goods can be accomplished through network. It brings many differences between digital goods transaction and traditional commodity transaction via Internet.Simple Public Key Infrastructure — SPKI is a secure mechanism which can be implemented more easily than PKI. It authorizes some actions by certification rather than authentication. With this infrastructure and security policy, a secure distributed system can be established.Electronic transaction protocol is designed for protecting advantage of participants in the E-Commerce, adjusting the interactive flows relationship such as information, capital and goods among actors. There are many directive principles in the electronic transaction protocol designing such as security, anonymity, non-repudiation, atomicity, fairness and efficiency.This paper, which imports SPKI and bases on "SPKI Multiple Channels Electronic Payment System", combining the trait of digital goods transaction, puts forward a secure, fair, easily implemented digital goods transaction — DGT protocol, which integrates goods transaction and electronic payment. DGT protocol, including consumer, merchant and gateway, is made up of transaction, inquiry and clearence sub-protocol. In this article, the requirements of transaction is analyzed, system model and running environment are given, all kinds of protocol aspects such as high level protocol, detail protocol, protocol flow process and wrong- tolerance are expatiated.In the end, the paper analyzes the DGT protocol through security, anonymity, non-repudiation, atomicity and fairness. The DGT protocol improves many limitations such as security, evidence of transaction, complexity of authentication in traditional electronic transaction system.