Secure and Reliable Key Agreement with Physical Unclonable Functions
This work addresses secure key agreement for hardware security applications, presenting incremental improvements in transform-coding and error-correction for PUF-based systems.
The paper tackled the problem of securely binding secret keys to physical unclonable functions (PUFs) by comparing transforms to decorrelate outputs and applying scalar quantizers, resulting in improved uniqueness, reliability, and secret-key length with better rates than existing methods.
Different transforms used in binding a secret key to correlated physical-identifier outputs are compared. Decorrelation efficiency is the metric used to determine transforms that give highly-uncorrelated outputs. Scalar quantizers are applied to transform outputs to extract uniformly distributed bit sequences to which secret keys are bound. A set of transforms that perform well in terms of the decorrelation efficiency is applied to ring oscillator (RO) outputs to improve the uniqueness and reliability of extracted bit sequences, to reduce the hardware area and information leakage about the key and RO outputs, and to maximize the secret-key length. Low-complexity error-correction codes are proposed to illustrate two complete key-binding systems with perfect secrecy, and better secret-key and privacy-leakage rates than existing methods. A reference hardware implementation is also provided to demonstrate that the transform-coding approach occupies a small hardware area.