Response-Based Cryptographic Methods with Ternary Physical Unclonable Functions

Abstract

Physical Unclonable Functions (PUFs) are used as hardware fingerprints for access control, and authentication in mobile and wireless networks and Internet of Things. However, it is challenging to use PUFs to extract cryptographic keys, because a single bit mismatch in the keys is not acceptable to most encryption algorithms. PUFs are aging; they are sensitive to temperature drifts, and other environmental effects. Successful implementation of PUFs, as key generators, requires power hungry error correcting schemes that add latency, and vulnerability to attacks such as differential power analysis. This work proposes methods to generate cryptographic keys directly from the un-corrected responses of the PUFs. The secure server, driving the network, manages the differences between the PUF responses and the original PUF challenges, through matching algorithms, mitigating the need to use heavy error correction schemes. In these methods, both the server and the client devices independently generate the exact same un-corrected responses of the PUF. These responses are therefore suitable for cryptographic protocols such as public key infrastructure or highly secure ledger protecting blockchain technology. The method presented in this paper, which is based on ternary PUFs, was successfully implemented and tested in a PC environment.