I have a question about TIDs and EPCs. From what I understand, a TID is, more or less, the serial number of a card being read. Other than that, is the TID of any value? Do the machines that read cards rely on this number at all, or is it mostly the data in the EPC?
An Electronic Product Code (EPC) is a number written to a passive UHF RFID transponder by a product's manufacturer. It contains a GS1 company identifier, a product identifier and a unique serial number. In most cases, companies using RFID read EPC numbers to identify products, as well as their product category and manufacturer.
A transponder ID (TID) is a unique number written to a transponder's microchip by the microchip's manufacturer. This number cannot be changed. The TID is not usually read by an RFID reader, but it is possible to create a system that authenticates the tag by cross-checking the TID and EPC.
Let's say, for example, that a sophisticated organized crime group were to counterfeit high-end handbags. The criminals could buy passive UHF RFID transponders and write EPCs similar to or the same as those found on legitimate bags. An unsuspecting shop owner might read the EPCs, recognize that they were similar those on other handbags being sold and mistakenly think the bags were legitimate. However, by using a system that reads TIDs and cross-references them with EPCs, it would be possible to determine that a manufacturer had never used transponders with the specific TIDs found on the counterfeit goods. It's a bit like checking someone's Social Security Number and date of birth to ensure they both match what is on record.
—Mark Roberti, Founder and Editor, RFID Journal
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