ZEBRA: Zero Trust Architecture Employing Blockchain Technology and ROPUF for AMI Security

Smart grid (SG) has evolved as a recent topic of discussion and research globally, due to the integration of communication and internet in its network. It facilitates the bidirectional flow of information and power making it vulnerable to attacks including denial of service, fault injection, man-in-the-middle, etc. An integral part of the SG, is the advanced metering infrastructure (AMI), which in turn embodies within itself a critical component of SG such as smart meter (SM), utility company (UC), etc. The AMI also exchanging data and electricity within itself, is a gold mine for adversaries. In addition, the smart meter, being a hardware entity, is susceptible to hardware oriented attacks. In this work, a novel authentication scheme, ZEBRA, for the AMI is proposed. ZEBRA utilizes a combination of Ring Oscillator Physical Unclonable Functions (ROPUFs) for authentication and blockchain for traceability in a Zero Trust Architecture (ZTA) to enhance the security of the AMI. The architecture entails a design that allows for the smart meters in the AMI network to be retrofitted with the new hardware and does not require any use of onboard memory. The authentication scheme, itself, is built to function using the Hamming code parity bits of the ROPUF's response, rather than the direct responses from the ROPUFs. This ensures a higher degree of difficulty towards a malicious actor attempting to hack the device. By combining ROPUFs and blockchain technology for ZTA a maximum security, real-time AMI authentication scheme is realized. The investigation aimed at satisfying the tenets of ZTA laid down by National Institute of Standard and Technology. ROPUF and blockchain have been used individually and together to realize these tenets for sucessful implementation of ZEBRA.