Electronic cash register systems in Germany must be equipped with tamper protection, the so-called technical security device (TSE). The basis for this is the “Verordnung zur Bestimmung der technischen Anforderungen an elektronische Aufzeichnungs- und Sicherungssysteme im Geschäftsverkehr” – in short: Kassensicherungsverordnung (KassenSichV). The core of the TSE is the digital signature of the individual cash register receipts. A check value for each transaction ensures the integrity of the data, and subsequent tampering can be easily detected. The TSE must be certified by the German Federal Office for Information Security (BSI).