Example Payment System: CMU's NetBill

• Third party payment system designed for low transaction costs ("micropayment")

• NetBill server maintains accounts for both customers and merchants

• Accounts are linked to conventional financial institutions

• MoneyTool runs on client (external application)

• ProductServer runs on server (launched by CGI script)

• ProductServer and MoneyTool communicate on separate connection

Netbill Protocol

Seven-step process

Client receives goods encrypted before payment is processed

Client receives decryption key after payment is processed

Support for micro-payments, customized pricing, 4-th party approval

More info on NetBill