Physical Unclonable Functions (PUFs) are innovative circuit primitives that extract secrets from physical characteristics of integrated circuits (ICs). We present PUF designs that exploit inherent delay characteristics of wires and transistors that differ from chip to chip, and describe how PUFs can enable low-cost authentication of individual ICs and generate volatile secret keys for cryptographic operations.

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Physical unclonable functions for device authentication and secret key generation

Physical Unclonable Functions for Device Authentication and Secret Key Generation

In recent years, IP protection of FPGA hardware designs has become a requirement for many IP vendors. In [34], Simpson and Schaumont proposed a fundamentally different approach to IP protection on FPGAs based on the use of Physical Unclonable Functions (PUFs). Their work only assumes the existence of a PUF on the FPGAs without actually proposing a PUF construction. In this paper, we propose new protocols for the IP protection problem on FPGAs and provide the first construction of a PUF intrinsic to current FPGAs based on SRAM memory randomness present on current FPGAs. We analyze SRAM-based PUF statistical properties and investigate the trade offs that can be made when implementing a fuzzy extractor.

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FPGA Intrinsic PUFs and Their Use for IP Protection

Biometric recognition offers a reliable solution to the problem of user authentication in identity management systems. With the widespread deployment of biometric systems in various applications, there are increasing concerns about the security and privacy of biometric technology. Public acceptance of biometrics technology will depend on the ability of system designers to demonstrate that these systems are robust, have low error rates, and are tamper proof. We present a high-level categorization of the various vulnerabilities of a biometric system and discuss countermeasures that have been proposed to address these vulnerabilities. In particular, we focus on biometric template security which is an important issue because, unlike passwords and tokens, compromised biometric templates cannot be revoked and reissued. Protecting the template is a challenging task due to intrauser variability in the acquired biometric traits. We present an overview of various biometric template protection schemes and discuss their advantages and limitations in terms of security, revocability, and impact on matching accuracy. A template protection scheme with provable security and acceptable recognition performance has thus far remained elusive. Development of such a scheme is crucial as biometric systems are beginning to proliferate into the core physical and information infrastructure of our society.

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Biometric template security

Have you ever felt that the very title, Progress in Optics, conjured an image in your mind? Don’t you see a row of handsomely printed books, bearing the editorial stamp of one of the most brilliant members of the optics community, and chronicling the field of optics since the invention of the laser? If so, you are certain to move the bookend to make room for Volume 16, the latest of this series. It contains seven chapters on widely diverging topics, written by well-known authorities in their fields. These are: 1) Laser Selective Photophysics and Photochemistry by V. S. Letokhov, 2) Recent Advances in Phase Profiles (sic) Generation by J. J. Clair and C. I. Abitbol, 3 ) Computer-Generated Holograms: Techniques and Applications by W.-H. Lee, 4) Speckle Interferometry by A. E. Ennos, 5 ) Deformation  Invariant, Space-Variant Optical  Pattern Recognition by D. Casasent and D. Psaltis, 6) Light Emission from High-Current Surface-Spark Discharges by R. E. Beverly, and 7) Semiclassical Radiation  Theory within a  QuantumMechanical Framework by I. R. Senitzkt. The  breadth of topic  matter  spanned  by  these  chapters makes it impossible, for this reviewer at least, to pass judgement on the comprehensiveness, relevance, and completeness of every chapter. With an editorial board as prominent as that of Progress in Optics, however, it seems hardly likely that such comments should be necessary. It should certainly be possible to take the authority of each author as credible. The only remaining judgment to be  made on these chapters is their readability. In short, what are they like to read? The first sentence of the first chapter greets the eye with an obvious typographical error: “The creation of coherent laser light source, that have tunable radiation, opened the . . . .” Two pages later we find: “When two types of atoms or molecules of different isotopic composition ( A and B ) have even one spectral line that does not overlap with others, it is pos-

Progress in optics

We propose a generic information-theoretic distinguisher for differential side-channel analysis. Our model of side-channel leakage is a refinement of the one given by Standaert et al.An embedded device containing a secret key is modeled as a black box with a leakage function whose output is captured by an adversary through the noisy measurement of a physical observable. Although quite general, the model and the distinguisher are practical and allow us to develop a new differential side-channel attack. More precisely, we build a distinguisher that uses the value of the Mutual Information between the observed measurements and a hypothetical leakage to rank key guesses. The attack is effective without any knowledge about the particular dependencies between measurements and leakage as well as between leakage and processed data, which makes it a universal tool. Our approach is confirmed by results of power analysis experiments. We demonstrate that the model and the attack work effectively in an attack scenario against DPA-resistant logic.

Mutual Information Analysis

The Butterfly PUF: Protecting IP on every FPGA.

IP protection of hardware designs is the most important requirement for many FPGA IP vendors. To this end, various solutions have been proposed by FPGA manufacturers based on the idea of bitstream encryption. An alternative solution was advocated in (E. Simpson and P. Schaumont, 2006). Simpson and Schaumont proposed a new approach based on physical unclonable functions (PUFs) for IP protection on FPGAs. PUFs are a unique class of physical systems that extract secrets from complex physical characteristics of the integrated circuits which along with the properties of unclonability provide a highly secure means of generating volatile secret keys for cryptographic operations. However, the first practical PUF on an FPGA was proposed only later in (J. Guajardo et al., 2007) based on the startup values of embedded SRAM memories which are intrinsic in some of the current FPGAs. The disadvantage of these intrinsic SRAM PUFs is that not all FPGAs support uninitialized SRAM memory. In this paper, we propose a new PUF structure called the butterfly PUF that can be used on all types of FPGAs. We also present experimental results showing their identification and key generation capabilities.

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Extended abstract: The butterfly PUF protecting IP on every FPGA

In cryptography it is assumed that adversaries only have black box access to the secret keys of honest parties. In real life, however, the black box approach is not sufficient because attackers have access to many physical means that enable them to derive information on the secret keys. In order to limit the attacker’s ability to read out secret information, the concept of Algorithmic Tamper Proof (ATP) security is needed as put forth by Gennaro, Lysyanskaya, Malkin, Micali and Rabin. An essential component to achieve ATP security is read-proof hardware. In this paper, we develop an implementation of read-proof hardware that is resistant against invasive attacks. The construction is based on a hardware and a cryptographic part. The hardware consists of a protective coating that contains a lot of randomness. By performing measurements on the coating a fingerprint is derived. The cryptographic part consists of a Fuzzy Extractor that turns this fingerprint into a secure key. Hence no key is present in the non-volatile memory of the device. It is only constructed at the time when needed, and deleted afterwards. A practical implementation of the hardware and the cryptographic part is given. Finally, experimental evidence is given that an invasive attack on an IC equipped with this coating, reveals only a small amount of information on the key.

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Pim Tuyls

Papers

FPGA Intrinsic PUFs and Their Use for IP Protection

Mutual Information Analysis

The Butterfly PUF: Protecting IP on every FPGA.

Extended abstract: The butterfly PUF protecting IP on every FPGA

Read-proof hardware from protective coatings