Accountability in centralized payment environments

Centralized payment system relies on a single party to deliver messages related to payment transactions from one party to another. Several security issues related to this central party occur in this kind of system, especially trust relationships among engaging parties and party authentication. To deal with these issues, a centralized payment protocol should satisfy accountability. In this paper, we introduce BPAC, a bill payment protocol ensuring accountability. We perform a formal analysis to show that BPAC satisfies the accountability. To analyze BPAC, we propose an accountability logic that is able to reason about accountability of any payment protocols.