The field of lightweight cryptography has developed significantly over the last years. But while many impressive implementation results have been published, the figures that are quoted are often for the core computation. This means that when it comes to a real implementation there can be significant, hidden overheads. In this paper we consider the case of cryptoGPS and we show that the full Implementation - which has been implemented and fabricated in ASIC - still stays within the typical limits cited as the requirement for on-the-tag cryptography.