Secure PC-Franking for Everyone

PC franking systems allow customers to download postage value into their PCs and to print postage value onto envelopes or mailing labels by using regular desktop printers connected to their PCs. In emerging standards, such as the IBIP program of the US postal services, the resulting imprints are called indicia, and they are printed as 2-D bar codes that are easy and reliable to scan while passing through the mail delivery system. In contrast to the IBIP program, which requires a tamper responsive postal security device for each customer, we propose a pure software solution for PC franking systems that is more secure for the postal services, gives more privacy to the customers and has the potential of being much cheaper than any IBIP compliant franking system. In contrast to existing PC-franking products that require no hardware postal security device, our solution works off-line. Customers are not required to be online while printing indicia. Our solution operates an existing offline e-cash scheme over certain elliptic curves rather than over finite fields. 1