“We evaluated all the PUF products and IP on the market but they all fell short,” said Don Loomis, Vice President of the Micros, Security and Software Business Unit at Maxim Integrated.
Many techniques use variations in the substrates of chips, but instead Maxim has used the variation in the threshold voltage of the transistors on the chip. The transistors are mapped into pairs that always produce a 1 or a zero, regardless of process, voltage, temperature and aging. This is then used as a unique random number for encryption with a lifetime of 20 years.
The company is also now looking at techniques to provide secure encryption that quantum computers cannot crack, he says. “Making sure things age well is particularly important,” he said.
The new PUF technique, called ChipDNA, has been used for the first time in the 83¢ DS28E38 DeepCover secure authenticator chip.
When needed, the circuit generates the per-device unique key, which instantly disappears when it is no longer in use. If the device comes under an invasive physical attack, the attack would cause the sensitive electrical characteristics of the circuit to change, further impeding the breach.
This also simplifies or eliminates the need for complicated secure IC key management as the key can be used directly for cryptographic operations including asymmetric (ECCP256) hardware engine, true random number generator (TRNG), decrement-only counter with authenticated read, 2Kb of secured electrically erasable programmable read-only memory (EEPROM), and unique 64-bit ROM identification number
“With the ChipDNA PUF technology, the DS28E38 secure authenticator is highly effective and resistant against physical or black-box reverse engineering attacks,” said Michael Strizich, president of MicroNet Solutions. “Even in a worst-case insider attack, the PUF-generated data is likely to remain protected due to the security features implemented.”
Next: quantum safe