Power/Performance Bits: July 13

Graphene PUFs
Researchers at Pennsylvania State University propose using graphene to create physically unclonable functions (PUFs) that are energy efficient, scalable, and secure against AI attacks.

The team first fabricated nearly 2,000 identical graphene transistors. Despite their structural similarity, the transistors’ electrical conductivity varied due to the inherent randomness arising from the production process. It is these manufacturing variations that enable PUFs to create secure keys.

After the graphene transistors were implemented into PUFs, the researchers modeled their characteristics to create a simulation of 64 million graphene-based PUFs. To test the PUFs’ security, the team trained a machine learning model with the simulation data to see if it could use the training to make predictions about the encrypted data and reveal system insecurities.

“Neural networks are very good at developing a model from a huge amount of data, even if humans are unable to,” said Saptarshi Das, assistant professor of engineering science and mechanics at Penn State. “We found that AI could not develop a model, and it was not possible for the encryption process to be learned.”

This resistance to machine learning attacks makes the PUF more secure because potential hackers could not use breached data to reverse engineer a device for future exploitation, Das said. Even if the key could be predicted, the graphene PUF could generate a new key through a reconfiguration process requiring no additional hardware or replacement of components.

“Normally, once a system’s security has been compromised, it is permanently compromised,” said Akhil Dodda, an engineering science and mechanics graduate student at Penn State. “We developed a scheme where such a compromised system could be reconfigured and used again, adding tamper resistance as another security feature.”

The researchers think the graphene-based PUF could be used in a variety of applications, including flexible and printable electronics.

Polypeptide battery
Researchers at Texas A&M University propose a new battery technology platform that utilizes polypeptides, making it completely metal free as well as degradeable in specific circumstances.

“By moving away from lithium and working with these polypeptides, which are components of proteins, it really takes us into this realm of not only avoiding the need for mining precious metals, but opening opportunities to power wearable or implantable electronic devices and also to easily recycle the new batteries,” said Karen Wooley, distinguished professor in the Department of Chemistry and Chair in Chemistry in the College of Science at Texas A&M. “They [polypeptide batteries] are degradable, they are recyclable, they are non-toxic and they are safer across the board.”

The polypeptide organic radical battery is made up of redox-active amino-acid macromolecules that can be degraded on demand in acidic conditions, producing amino acids and other building blocks.

“The big problem with lithium-ion batteries right now is that they’re not recycled to the degree that we are going to need for the future electrified transportation economy,” said Jodie Lutkenhaus, Chair and professor in the Department of Chemical Engineering at Texas A&M. “The rate of recycling lithium-ion batteries right now is in the single digits. There is valuable material in the lithium-ion battery, but it’s very difficult and energy intensive to recover.”

The team is now working with another group to utilize machine learning to optimize the materials and structure of the battery platform.