Generic Security Proof of Quantum Key Exchange using Squeezed States

Recently, a Quantum Key Exchange protocol that uses squeezed states was presented by Gottesman and Preskill. In this paper we give a generic security proof for this protocol. The method used for this generic security proof is based on recent work by Christiandl, Renner and Ekert.Comment: 5 pages, 7 figures, accepted at IEEE ISIT 200

An efficient fuzzy extractor for limited noise

A fuzzy extractor is a security primitive that allows for reproducible extraction of an almost uniform key from a non-uniform noisy source. We analyze a fuzzy extractor scheme that uses universal hash functions for both information reconciliation and privacy amplification. This is a useful scheme when the number of error patterns likely to occur is limited, regardless of the error probabilities. We derive a sharp bound on the uniformity of the extracted key, making use of the concatenation property of universal hash functions and a recent tight formulation of the leftover hash lemma

09282 Executive Summary -- Foundations for Forgery-Resilient Cryptographic Hardware

From 05.07 to 08.07.2009, the Dagstuhl Seminar 09282 ``Foundations for Forgery-Resilient Cryptographic Hardware \u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. This paper provides a summary of the motivation for the seminar and the importance of the research area, a list of the participants and the program of talks given during the seminar

A New Biometric Template Protection using Random Orthonormal Projection and Fuzzy Commitment

Biometric template protection is one of most essential parts in putting a biometric-based authentication system into practice. There have been many researches proposing different solutions to secure biometric templates of users. They can be categorized into two approaches: feature transformation and biometric cryptosystem. However, no one single template protection approach can satisfy all the requirements of a secure biometric-based authentication system. In this work, we will propose a novel hybrid biometric template protection which takes benefits of both approaches while preventing their limitations. The experiments demonstrate that the performance of the system can be maintained with the support of a new random orthonormal project technique, which reduces the computational complexity while preserving the accuracy. Meanwhile, the security of biometric templates is guaranteed by employing fuzzy commitment protocol.Comment: 11 pages, 6 figures, accepted for IMCOM 201

Erasable PUFs: Formal treatment and generic design

Physical Unclonable Functions (PUFs) have not only been suggested as new key storage mechanism, but - in the form of so-called "Strong PUFs"- also as cryptographic primitives in advanced schemes, including key exchange, oblivious transfer, or secure multi-party computation. This notably extends their application spectrum, and has led to a sequence of publications at leading venues such as IEEE S&P, CRYPTO, and EUROCRYPT in the past[3,6,10,11,29, 41]. However, one important unresolved problem is that adversaries can break the security of all these advanced protocols if they gain physical access to the employed Strong PUFs after protocol completion [41]. It has been formally proven[49] that this issue cannot be overcome by techniques on the protocol side alone, but requires resolution on the hardware level - the only fully effective known countermeasure being so-called Erasable PUFs. Building on this work, this paper is the first to describe a generic method how any given silicon Strong PUF with digital CRP-interface can be turned into an Erasable PUFs[36]. We describe how the Strong PUF can be surrounded with a trusted control logic that allows the blocking (or "erasure") of single CRPs. We implement our approach, which we call "GeniePUF", on FPGA, reporting detailed performance data and practicality figures. Furthermore, we develop the first comprehensive definitional framework for Erasable PUFs. Our work so re-establishes the effective usability of Strong PUFs in advanced cryptographic applications, and in the realistic case adversaries get access to the Strong PUF after protocol completion

Efficient binary conversion for Paillier encrypted values

Abstract. We consider the framework of secure n-party computation based on threshold homomorphic cryptosystems as put forth by Cramer, Damg˚ard, and Nielsen at Eurocrypt 2001. When used with Paillier’s cryptosystem, this framework allows for efficient secure evaluation of any arithmetic circuit defined over ZN, where N is the RSA modulus of the underlying Paillier cryptosystem. In this paper, we extend the scope of the framework by considering the problem of converting a given Paillier encryption of a value x ∈ ZN into Paillier encryptions of the bits of x. We present solutions for the general case in which x can be any integer in {0, 1,..., N − 1}, and for the restricted case in which x < N/(n2 κ) for a security parameter κ. In the latter case, we show how to extract the ℓ least significant bits of x (in encrypted form) in time proportional to ℓ, typically saving a factor of (log 2 N)/ℓ compared to the general case. Thus, intermediate computations that rely in an essential way on the binary representations of their input values can be handled without enforcing that the entire computation is done bitwise. Typical examples involve the relational operators such as < and =. As a specific scenario we will consider the setting for (approximate) matching of biometric templates, given as bit strings.

On the Amount of Entropy in PUFs

The aim of this chapter is to provide an information-theoretic framework for the analysis of physical unclonable function (PUF) security. We set up this framework and then apply it to optical PUFs and coating PUFs. From the description of PUFs in Chapter 1 some obvious questions arise in the context of the security primitives discussed in Part I