E-Commerce Trust Metrics and Models

T he Internet gives vendors an easy way to set up shop for electronic commerce throughout the world. In an extension of mailand phone-order transactions, customers usually pay for e-commerce goods and services through a credit card. The transmission of credit card numbers requires vendor sites to support encryption through the Secure Sockets Layer1 or Transport Layer Security2 protocols. SSL can be enhanced through special payment protocols such as Secure Electronic Transactions3 or Electronic Commerce Modeling Language.4 However, as millions of customers begin to participate in e-commerce, we can expect increased transactions of extremely varied quantity and value; in addition, the goods and services transacted will be subject to very different legal regulation and economic risk. This emerging marketplace will require the ability to make distinctions that the credit-card transaction model does not support. How do we set measurement criteria to make these distinctions? One way is to quantify trust. This fundamental concept in managing commercial risk refers broadly to the assurance that someone or something will act in exactly the way you expect. Research on this problem in e-commerce has focused on authentication—that is, associating a public key with its owner. Reiter and Stubblebine5 derived principles for developing authentication metrics by studying systems that used trust metrics. However, all their models were based on transitive trust along a transaction path of entities that trust the key to different extents. E-commerce, on the other hand, requires mutual trust among a vendor, a customer, and all transaction intermediaries. This article introduces a notion of quantifiable trust and then develops models that can use these metrics to verify e-commerce transactions in ways that might be able to satisfy the requirements of mutual trust. The article uses two examples in illustrating these concepts: one for an e-commerce printing enterprise and the other for Internet stock trading; see the sidebar, “Trust Concept Examples,” for general descriptions.