Abstract: A self-contained payment system uses circulating digital vouchers for the transfer of value. The system creates and transfers digital vouchers. A digital voucher has an identifying element and a dynamic log. The identifying element includes information such as the transferable value, a serial number and a digital signature. The dynamic log records the movement of the voucher through the system and accordingly grows over time. This allows the system operator to not only reconcile the vouchers before redeeming them but also to recreate the history of movement of a voucher should an irregularity like a duplicate voucher be detected. These vouchers are used within a self-contained system including a large number of remote devices which are linked to a central system. The central system can be linked to an external system. The external system, as well as the remote devices, are connected to the central system by any one or a combination of networks.