The proliferated electronic commerce continuously promotes the development of Internet transactions. Information goods, which can be delivered through networks, are more suitable for Internet transactions than physical products. Nevertheless, most electronic payment systems are designed regarding physical goods. Considering the properties of Information goods, this thesis proposes several protocols for trading Information goods over the Internet.The evidences during transactions are essential for the dispute arbitration about fully digitized transactions of Information goods. Accordingly, we design three protocols for setting up non-repudiation mechanisms to afford abundant evidences. In all protocols, each step in every transaction bears effective digital evidences for resolving distinct disputes. The Evidence Reservation Level further reduces overheads of evidence management.Service providers are required to transmit goods and evidences in the first protocol. Without service providers, the second protocol further protects privacy with direct transmission from merchants. The third protocol furnishes evidences with trusted timestamps by Timestamp Authority to avoid disputes on transaction times.Because of the importance of e-commerce security, and therefore continue to develop security technologies and applications, such as encryption, firewalls, digital signatures, digital certificates and secure transaction agreements. The invention and application of security technology enables rapid development of e-commerce. As e-commerce security technology continues to evolve, both in software or hardware, both for the development of e-commerce provides a good security guarantees and development environment. |