INSIKA: Cryptographic Tamper-proofing of Electronic Cash Registers

The tax laws of most countries stipulate that digital records of sales transactions have to be complete and unchangeable. The taxpayers themselves are required to supply a proof for this. Application of the INSIKA concept guarantees the legal and auditable recording of the data. From 2008 to 2012, the Physikalisch-Technische Bundesanstalt (German National Metrology Institute) together with industrial partners developed and tested INSIKA („INtegrierte SIcherheitslösung für messwertverarbeitende KAssensysteme“ meaning “integrated security solution for cash registers processing metered values”) based on a concept of the German fiscal authorities.

The INSIKA method can be used without patents, license costs and similar expenses or restrictions. INSIKA can be integrated easily into cash registers, taximeters and similar systems. It does not impede product improvements which makes it innovation-friendly. It is particularly important that there are no design requirements for systems that are using INSIKA and thus no tedious and expensive certification procedures. However, INSIKA can only be applied reasonably when there is a legal basis, allowing and guaranteeing its acceptance by the fiscal authorities.