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How embedded systems are protected by Physically Unclonable Function Technology

Abstract

Hardware-based security provides robust protection against cyberattacks, and physically unclonable function (PUF) technology can further enhance that level of protection when used by chips that implement cryptographic functionality. This application note discusses a new PUF semiconductor solution that employs the random analog characteristics of MOSFET transistors, the essential foundation of CMOS ICs. In the chip level, the PUF solution is made of a range of analog circuit elements, featuring inherent randomness in I-V characteristics and sized based on the number of bits necessary to attain the cryptographic requirements of the chip. When needed, the PUF is operated to derive a per-chip random, unique, and repeatable binary value that is only accessible by chip crypto blocks. Once it is no longer needed, the PUF-derived key value is instantaneously erased and does not appear in digital form. This PUF solution has revealed high reliability and appropriate crypto quality -both criteria that enable a PUF output for use as a cryptographic key value.

Introduction

Cryptography provides flexible and efficient tools to counter an array of potential security threats that embedded electronic systems face. There are a number of software and hardware processes for implementing crypto solutions. It's generally understood that the hardware-based solution (i.e., a dedicated security IC) is the most effective formulation for the root of trust and the way to supply the countermeasures and protection that prevent numerous types of common attacks.

Valuable assets associated with embedded systems face relentless threats. For example, such systems encounter intrusions for example theft of ip, introduction of malware to disrupt or destroy equipment, unauthorized access to sensitive communication, and tampering with data produced from IoT endpoints. Security ICs and also the cryptographic solutions available can address these threats. However, the safety ICs themselves may become the target of attack by an adversary trying to circumvent or break the security.

Attacks on Security ICs

Assuming a burglar IC-based protection solution, there are two general categories of attack scenarios: non-invasive