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Identifying RFID's Biggest Threats

If end users employ proprietary tag ID schemes—as some are starting to do—the full benefits of RFID adoption may never be realized.
By Patrick King
Reading a Tag
Now let's imagine you begin a conversation. The first exchange is always "hello," followed by a decision (do I continue talking to this person, or do I move on?). In the world of RFID, after the initial "hello," the decision could be "thanks and goodbye", or it could be "tell me more." For the past 25 years LF, HF and early UHF tags all worked exactly in this way. The reader would transit a signal that signified "hello" (a request that the tag transmit its TID), followed by "tell me more" (a request for additional information, programmed in a section outside the TID, often referred to as user memory, or just memory), and/or "thanks and goodbye." For example, ISO-18000-6b UHF RFID tags carried 2 kilobits bits of data capability, of which the TID accounted for less than 100 bits. Once the interrogator captured the TID and was locked into a conversation with a particular tag, it could then choose to read all or part of the remaining tag memory. LF, HF and UHF all worked this way until the dawn of the ISO 18000-6C or EPC Gen 2 standards.

Prior to the creation of the EPC Gen 2 standard, and for almost 60 years thereafter, RFID began with "hello" in the form of an exchange between the reader and the chips' TID. British and American World War II-era warplanes had TIDs and were recognized by Allied forces. When your dog has an LF glass tag injected under the skin, the animal can then be identified by the tag's TID. When you use your smart-card HF passport, the initial read is between the interrogator and the TID. And when the Automotive Industry Action Group (AIAG) first demonstrated UHF applications (in its development of the B11 Item-Level RFID standard) at GM's plant in Detroit, the reader identified tires by interrogating the TID. In the case of the passport, the chip is encoded with additional information that may be interrogated, if required. In the case of the GM tire, the chip also contained additional information chip, but was accessed only after the TID was identified.

What Changed With Gen 2
Part of the genius of EPC Gen 2 is that, upon being initially interrogated by a reader, the tag transmits an Electronic Product Code—a UII that identifies the product the tag to which it is attached—instead of transmitting a TID number assigned by the chip manufacturer (which just identified the tag). The "genius" is that it achieves two benefits over past designs: First, it assures that the initial read provides actual item identification, and second, it enables the UII to provide the key to a long list of business and consumer benefits, accessed via the Internet or some other network. The creation of EPC Gen 2 was the first time in RFID history that the TID was not read as the initial action between the reader and the chip. What's more, the first supply of Gen 2 chips did not even contain a TID. This has been corrected, and the standards now support that a unique serial number can be written—and locked—to the TID in Gen 2 chips, thereby providing assurance that the tag's data has not been duplicated into another tag (unique data = UII + TID).

The Problems With EPC Gen 2
There are now two major threats to EPC Gen 2's approach: The first is the use of proprietary item numbers instead of the numbering system specified by the EPC Gen 2 standard that enables the UII to serve as the birth record for both a tag and the item to which it is attached; the second involves violating the concept that the UII must be monomorphic.

The UII must be the birth record for the item to which the tag is being attached, and not an arbitrary number assigned after the item's manufacture. Within EPCglobal, the Gen 2 standards provide clear solutions when programming the UII memory bank (MB01). In simple terms, this memory bank is programmed with a code that first identifies the company making the item, then the item's product number and, finally, its unique serial number. When all three come together, a globally unique serialized item number—the EPC—is created. In the ideal scenario, this number could be rapidly searched for on the Web, even during RFID scanning, in order to provide additional information regarding this particular item. Non-EPC applications are somewhat more flexible in how they can program data into MB01.

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