RFID Fingerprints To Fight Tag Cloning

Bourdain writes with news out of the University of Arkansas, where researchers are looking for ways to combat counterfeit RFID tags. Passive tags typically wait for a reader to transmit a signal of the appropriate strength and frequency before sending their own transmission. The scientists found that the amount of power required to trigger this varies quite a bit from one tag to the next, especially when many different frequencies are sampled. This and other physical characteristics give the tag its own "fingerprint" that is independent of the signal information stored in its memory, which the researchers say will facilitate the detection of cloned tags.

Comments

Security enhancement at best

[Anonymous Coward]

If you can read the fingerprint, so can anyone...

So what's to stop a dedicated attacker from reading the fingerprint when they read the tag contents, and then devising a method to duplicate all the data?

An active tag might even be programmed to emulate the fingerprint characteristics.

Re:Security enhancement at best

[cortesoft]

I don't know if it will be that easy. These fingerprints seem to be based on the fact that all RFID chips have flaws, and they are all flawed in different ways.... including the device that is trying to act as the clone of the RFID. What this means is that this clone RFID has to be able to mimic EXACTLY the flaws of the real thing without giving itself away by its OWN flaws. Without knowing more details about the flaws they are trying to measure, it is hard to say whether that would be possible. If the flaws are easily mimicked in the sense that you can create a clone whose own defects are not detected because they are all superseded by the original's flaws, it may work. If they vary so much that every clone will have some flaw that is severe enough to shine through, it would be impossible.

Re:What's the point?

[cortesoft]

Crypto wouldn't work... the cloner doesn't have to break the encryption to copy the chip.

Imagine in this way.... you have an encrypted hard drive, and someone wants to pass off their hard drive as yours. They don't have to break the encryption... they can copy the drive byte for byte, and hand it to the person who if verifying that is the original. The person checking the data is the one who does the decrypting.

Solving the wrong problem

[lhunath]

RFID tags are not security devices, they are hyped barcodes. They do not provide any authentication.

If you're worrying about your RFID tags being cloned for a malicious purpose, you are using them for the wrong thing.

This is nothing new

[ian_mackereth]

This sort of physical characteristic fingerprinting has been done for years on magnetic stripe cards and EEPROM smartcards, so this is nothing new in theory, just in what physical characteristics are being measured.

In mag stripes, the magnetic remanence of the strip is different from card to card, in EEPROM, differences in the voltage levels and speed of reading of the cells are used.

The general principle is that it's no point having unbreakable crypto if the data can simply be copied to a new medium. Consider a card (of whatever type) that stores monetary value for public transport or photocopying or whatever: Put $100 on it and copy the data, not knowing which bits are what. Copy that data onto a heap of cards bought with $5 of credit on them and sell them in the grey market for $50 each and pocket the profit.

With this sort of technique, though, part of that encrypted data is a fingerprint based on the physical characteristics of the original card. The new cards will generate a fingerprint in the reader that doesn't match the original, making the copies invalid.

Sure, if you can crack the encryption, this method is useless, but that's not the point. Crypto can be pretty good and costs more than a cheap reader/writer to break to duplicate cards/RFIDs.