Toshiba Develops Chip Authentication Technology Using Transistor Noise

A new method has been developed by Toshiba to make effective use of random telegraph noise (RTN) created from insulating material faults to put a physical unclonable function (PUF) into effect, an important security technology.

On June 16, at a conference named VLSI Technology Symposium held on semiconductor devices in Kyoto, Japan, it was announced that the method is expected to help in the making of safe and secure cloud services for smart communities.

PUFs help in improving security technologies for encoding and validation by making use of a chip’s “fingerprint”, which is a unique identifier that is the outcome from variations in the devices in an electronic circuit. As the PUFs seek a high degree of unclonability at a low cost, they attract a lot of attention.

There are two types of PUFs, one is memory-based PUFs and the other one is delay-based PUFs. Both the PUFs have been commercialized. While the memory-based PUF systems make use of individual dissimilarity in the loading status of memory cells as soon as they are powered up, the delay-based PUF systems use dissimilarity in wiring delays inside the circuit.

The memory method mostly makes use of variations in the beginning voltage that ascertains the transistor ON/OFF state as the PUF fingerprint. However, the quality of the transistors becomes low with use and the beginning point changes over time, raising questions that at first established IDs will change. There is a urgent need for more consistent and good quality PUF mechanisms that do not change over time.

Toshiba’s answer concentrates on RTN, a factor that lies beneath image deterioration in CMOS image sensors and data reversal in memories and transistors. While RTN can be lessened, its complete removal is very hard.

Detailed examination and analyses of RTN concentrated on the unpredictability of time constants for the shortcomings that helps its “fingerprint” (uniqueness and difficulty of replication) and resistance against electrical stress durability, has caused the first ever application of RTN to a PUF security technology. Toshiba says that the outcome is a novel algorithm and actual measurement proof for an RTN-based PUF that can be made use of over one million times.

Toshiba will work towards the process of putting the proposed technology into effect.


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