One of the various aspects of the invention is related to suggesting various techniques for improving the tamper-resistibility of hardware. The tamper-resistant hardware may be advantageously used in a transaction system that provides the off-line transaction protocol. Amongst these techniques for improving the tamper-resistibility are trusted bootstrapping by means of secure software entity modules, a new use of hardware providing a Physical Unclonable Function, and the use of a configuration fingerprint of a FPGA used within the tamper-resistant hardware.