During the Institute of Electrical and Electronics Engineers (IEEE) International Solid-State Circuits Conference (ISSCC) held on February 18-22 in San Francisco, California, researchers introduced new technologies that they developed to fight hack attacks. Among these innovations, one team came up with a chip-fingerprint self-destruction scheme.
Physically Unclonable Functions
Devices, particularly those part of the Internet of Things (IoT), require keys to protect their data, Internet protocol (IP), and operations. These keys can be provisioned onto the devices by the manufacturers (OEMs) or at an earlier stage by a chip vendor. When the chip vendors provide pre-provisioned chips, they increase the value of the product they sell to the OEMs. If OEMs choose to do provisioning themselves, they can buy chips that cost less.
Regardless of which of the two parties is accountable for provisioning the cryptographic keys, it is not a trivial task. Injecting secret keys into chips requires a trusted factory, which will add cost and complexity to the manufacturing process and limit flexibility. This complexity can be avoided by having the keys created internally inside the chip, either by using an internal random number generator (RNG) or a physically unclonable function (PUF).
Physically unclonable functions refer to innovative physical security primitives that create unclonable and inherent instance-specific measurements of physical objects. They serve as the inanimate equivalent of biometrics for human beings. They can securely generate and store secrets, allowing humans to bootstrap the physical implementation of an information security system.
Circuit Suicide
Some of the attacks that are difficult to defend against involve a hacker having physical access to a system's circuit board and putting a probe at various points. A probe attack happening in the right place does not only steal critical information and monitor traffic but also takes over a whole system.
At the University of Vermont, experts developed a new mechanism involving a physically unclonable function that can destroy itself. The techniques can serve as a security measure and hinder counterfeits.
Led by Eric Hunt-Schroeder, the research team collaborated with Marvell Technology to work with physically unclonable functions. This is a technique in hardware security that utilizes unique characteristics in individual transistors, allowing the creation of code that acts like a unique digital fingerprint.
When compromised, the system can boost the operating voltage across circuits to trigger electromigration, which involves blowing metal atoms out of place to create open circuits and voids. A similar technique can increase the operating voltage from less than one volt to around 2.5 V. This accelerates time-dependent dielectric breakdown to develop short circuits. This mechanism can be translated into circuit death.
Hunt-Schroeder inspired him to create the self-destructing mechanism after discovering that researchers could use a scanning electron microscope to clone physically unclonable functions based on static random access memory.
The method can also prevent counterfeit chips from being widely distributed. Hunt-Schroeder noted that when a company is done with a chip, it can ensure it is destroyed in a way that makes it useless.
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