Properties of Secure Transaction Protocols

Communication protocols are the computational basis for distributed electronic commerce systems, and thus the properties of these protocols define the forms of commerce possible in electronic systems. Existing protocols used for electronic commerce focus primarily on security properties, including message integrity, privacy and non-repudiation, and on basic transaction properties, usually just atomicity; their structural properties are limited to supporting two-party transactions with fixed semantics. We believe that the properties provided by these protocols limit their use to simple forms of commerce. In this paper we define the properties we believe are necessary for electronic commerce protocols. These include the security properties of existing protocols, and extend the transactional properties to include isolation and causality. Causality is a new property for transactions. It allows the order of the messages in a completed transaction to be independently verified, and thus infer..