Mobile devices might soon be the most popular payment mechanism for electronic payments and, therefore, the perfect candidate for a personal trusted device. An electronic payment system (such as credit card networks) can perform e-payments by extending payment transactions to the handheld device. The need for security services, such as authentication, confidentiality, integrity, and nonrepudiation is paramount because heterogeneous wireless network technologies such as personal area networks, local area networks, and wide area networks have both well-known and yet-undiscovered security weaknesses. A Java-based, secure local macropayment system prototype retrieves electronic checks from a bank and uses them to pay vendors for goods and services, with different interaction levels at the point of sale.