Keeping your pallets secure using unhackable RFID

If it was impossible to hack radiofrequency identification (RFID) chips, thieves would be thwarted in their attempts to pilfer pallets from warehouses by replacing their RFID tags with dummy tags.

This dream is close to reality as Denso-sponsored research at MIT and Texas Instruments is at the prototype stage with the new chips behaving as expected. The chips have been designed to prevent side-channel attacks where the cryptographic key is extracted by analysing patterns of memory access or fluctuations in power usage when a device is performing a cryptographic operation.

One way to thwart side-channel attacks is to regularly change secret keys. In that case, the RFID chip would run a random-number generator that would spit out a new secret key after each transaction. A central server would run the same generator, and every time an RFID scanner queried the tag, it would relay the results to the server, to see if the current key was valid.

Such a system would still, however, be vulnerable to a ‘power glitch’ attack, in which the RFID chip’s power would be repeatedly cut right before it changed its secret key. An attacker could then run the same side-channel attack thousands of times, with the same key. Power-glitch attacks have been used to circumvent limits on the number of incorrect password entries in password-protected devices, but RFID tags are particularly vulnerable to them, since they’re charged by tag readers and have no onboard power supplies.

Two design innovations allow the MIT researchers’ chip to thwart power-glitch attacks: One is an on-chip power supply whose connection to the chip circuitry would be virtually impossible to cut and the other is a set of ‘non-volatile’ memory cells that can store whatever data the chip is working on when it begins to lose power.

For both of these features, the researchers use ferroelectric crystals. Texas Instruments and other chip manufacturers have been using ferroelectric materials to produce non-volatile memory, or computer memory, that retains data when it’s powered off.