The innovative HB + protocol of Juels and Weis  extends device authentication to low-cost RFID tags. However, despite the very simple on-tag computation there remain some practical problems with HB + and despite an elegant proof of security against some limited active attacks, there is a simple man-in-the-middle attack due to Gilbert et al. . In this… (More)
Much research has focused on providing RFID tags with lightweight cryptographic functionality. The HB + authentication protocol was recently proposed  and claimed to be secure against both passive and active attacks. In this note we propose a linear-time active attack against HB + .
Radio Frequency IDentifiers (RFID) are low-cost pervasive devices used in various settings for identification purposes: although they have originally been introduced to ease the supply chain management, they are already used in many other applications. Some of these applications need secure identification and ad-hoc authentication protocols have to be… (More)
We introduce a practical synchronous stream cipher with provable security named QUAD. The cipher relies on the iteration of a multivariate quadratic system of m equations in n < m unknowns over a finite field. The security of QUAD is provably reducible to the conjectured intractability of the MQ problem, namely solving a multivariate system of quadratic… (More)
Sosemanuk is a new synchronous software-oriented stream cipher, corresponding to Profile 1 of the ECRYPT call for stream cipher primitives. Its key length is variable between 128 and 256 bits. It accommodates a 128-bit initial value. Any key length is claimed to achieve 128-bit security. The Sosemanuk cipher uses both some basic design principles from the… (More)
Grain  is a lightweight stream cipher proposed by M. Hell, T. Johansson, and W. Meier to the eSTREAM call for stream cipher proposals of the European project ECRYPT . Its 160-bit internal state is divided into a LFSR and an NFSR of length 80 bits each. A filtering boolean function is used to derive each keystream bit from the internal state. By… (More)
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Rainbow is a fast asymmetric multivariate signature algorithm proposed by J. Ding and D. Schmidt in . This paper presents a cryptanalysis of Rainbow which enables an attacker provided with the public key to recover an equivalent representation of the secret key, thus allowing her to efficiently forge a signature of any message. For the set of parameter… (More)