Low cost devices such as RFIDs, sensor network nodes, and smartcards are crucial for building the next generation pervasive and ubiquitous networks. The inherent power and footprint limitations of such networks, prevent us from employing standard cryptographic techniques for authentication which were originally designed to secure high end systems with abundant power. Furthermore, the sharp increase in the number, diversity and strength of physical attacks which directly target the implementation may have devastating consequences in a network setting creating a single point of failure. A compromised node may leak a master key, or may give the attacker an opportunity for injecting faulty messages. In this paper we present a lightweight challenge response authentication scheme based on noisy physical unclonable functions (PUF) that allows for extremely efficient implementations. Furthermore, the inherent properties of PUFs provide cryptographically strong tamper resilience. In a network setting this means that a tampered device will no longer authenticate and in a sense will be isolated from the network.

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We propose a light-weight protocol for authentication of lowpower devices. Our construction PUF-HB merges the positive qualities of two families of authentication functions. PUF represents physically unclonable functions and fulfills the purpose of providing low-cost tamperresilient challenge-response authentication. On the other hand, the Hopper Blum (HB) function provides provable cryptographic strength against passive adversaries. By building on an earlier proof of the security of HB + by Katz et al.[1], we rigorously prove the security of the proposed scheme against active adversaries. While the active adversary model does not include man-in-the-middle attacks, we show that a previously successful man-in-the-middle attack proposed for HB + , does not carry to PUF-HB.

Abstract. We introduce a new technique for extracting unique fingerprints from identical CDs. The proposed technique takes advantage of manufacturing variability found in the length of the CD lands and pits. Although the variability measured is on the order of 20 nm, the technique does not require the use of microscopes or any advanced equipment. Instead, we show that the electrical signal produced by the photodetector inside the CD reader is sufficient to measure the desired variability. We investigate the new technique by analyzing data collected from 100 identical CDs and show how to extract a unique fingerprint for each CD. Furthermore, we introduce a technique for utilizing fuzzy extractors over the Lee metric without much change to the standard code offset construction. Finally, we identify specific parameters and a code construction to realize the proposed fuzzy extractor and convert the derived fingerprints into 128-bit cryptographic keys.