2009 Reports

An Anonymous Credit Card System

Androulaki, Elli; Bellovin, Steven Michael

Credit cards have many important benefits; however, these same benefits often carry with them many privacy concerns. In particular, the need for users to be able to monitor their own transactions, as well as bank's need to justify its payment requests from cardholders, entitle the latter to maintain a detailed log of all transactions its credit card customers were involved in. A bank can thus build a profile of each cardholder even without the latter's consent. In this technical report, we present a practical and accountable anonymous credit system based on ecash, with a privacy preserving mechanism for error correction and expense-reporting.