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Seminars given
May 02, 2001 - Anonymity in a non-broadcast environment
by Jean-François Dhem
| Abstract: | For 20 years anonymity has been studied primarily in a broadcast environment. In many practical circumstances one does not have such a setting. We describe the first formal general model covering both broadcast and non-broadcast scenarios. We present several models. The first ones describe anonymity. We address such issues as receiver anonymity and sender anonymity. The second ones focus on total privacy, i.e. anonymity and privacy.
We demonstrate that the methods to achieve anonymity studied so far apply primarily to the broadcast scenario.
This presentation is based on joint work with Prof. Piper (University of London)
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April 17, 2003 - Cryptography in smart cards: current directions to improve hardware performances
by Jean-François Dhem
| Abstract: | Since the Kocher's first publication in 1996, a major concern in the smart card domain lies in security improvements in term of robustness against side channel attacks like (e.g. DPA, SPA, EMA...) or fault attacks. This should nevertheless not occult the hardware functionalities on which the final software cryptographic libraries will run.
Today, various "second generation" modular multiplication cryptographic hardware based on modular reduction algorithms like the one of Montgomery, Barrett, Quisquater or Sedlak cohabit with a (triple)-DES or elliptic curve accelerator. Most of the major smart card founders (e.g. Infineon, STM, Philips, Atmel,...) also propose high-end 32-bit chips. Some of them have
even chosen to no longer include a dedicated cryptographic hardware accelerator but to improve the instruction set to keep good speed performances.
In our presentation, we will quickly recall the various modular reduction algorithms and the way they could be implemented in hardware. We will then try to compare the advantages and disadvantages of the various implementations and the overall performances of them. Not only performances and security constrains are leading the smart card market. In the GSM/3G
market, for example, (very)-low power consumption is a main constraint but with important computing power and important storage capabilities. In the transport market however, the main constrain is their cost. All this leads to various optimizations and several type of cards depending on the market.
This also may imply the use of "lower cost" cryptographic algorithms like elliptic curves on low cost cards. Finally, we will try to depict, in some way, these various constraints on the smart card hardware.
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Publications
Jean-François Dhem, and Jean-Jacques Quisquater. Recent results on modular multiplications for smart cards, Proceedings of CARDIS 1998, Volume 1820 of Lecture Notes in Computer Security, pages 350-366, Springer-Verlag, January 2000 BibTeX
Jean-François Dhem, François Koeune, Philippe-Alexandre Leroux, Patrick Mestré, Jean-Jacques Quisquater, and Jean-Louis Willems. A practical implementation of the timing attack, In Jean-Jacques Quisquater and Bruce Schneier, editor(s), Proceedings of the Third Working Conference on Smart Card Research and Advanced Applications (CARDIS 1998), Volume 1820 of LNCS, Springer-Verlag, January 1998 PDF BibTeX
Jean-François Dhem. Normalisation in diminished-radix modulus transformation, In Electronic Letters, Volume 33-23, pages 1931, November 1997 PDF BibTeX
Jean-François Dhem. Lossless compression algorithms for smart cards: A progress report-13, pages 27-38, January 1997 BibTeX
Jean-François Dhem, Marc Joye, and Jean-Jacques Quisquater. RSA-type signatures in the presence of transient faults, In M. Darnell, editor(s), Cryptography and Coding, Volume 1355 of Lecture Notes in Computer Science, pages 155-160, Springer-Verlag, January 1997 PDF BibTeX
Jean-François Dhem, D. Veithen, and Jean-Jacques Quisquater. SCALPS: Smart Card Applied to Limited Payment Systems, In IEEE Micro, Volume 16-3, pages 42-51, January 1996 BibTeX
Jean-François Dhem, Jean-Jacques Quisquater, and R. Lecat. Progress towards efficient lossless compression algorithms for smart cards, In P. H. Hartel, et al., editor(s), Smart card Research and Advanced Applications -- Cardis '96, pages 73-88, January 1996 BibTeX
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