Publications
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Differential collisions in SHA-0,
F. Chabaud, and A. Joux,
extended abstract published in
CRYPTO'98, H. Krawczyk ed.,
LNCS 1462, pp 56--71, 1998.
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In this paper we present a method for finding collisions in SHA-0
which is related to differential cryptanalysis of block ciphers.
Using this method, we obtain a theoretical attack on the compression
function SHA-0 with complexity 261, which is thus better than
the birthday paradox attack. In the case of SHA-1, this method is
unable to find collisions faster than the birthday paradox. This is a
strong evidence that the transition to version 1 indeed raised the
level of security of SHA.
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Contrôle d'intégrité de la séquence de démarrage d'un ordinateur,
F. Chabaud, and N. Cuillandre,
extended abstract published in
SECI'02, 2002.
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The boot sequence of a computer begins at the power on of the machine
and ends when the operationg system is completely charged.
One can see this boot procedure as a sequence of steps that lead the
computer from a shut down state to a usable state with an active
operating system ready to execute the user applications.
This article presents an integrity control method of the end of the
boot sequence. It has been developed on a mono-processor PC running
Windows 95 and linux but can be generalized to all operating systems
and can be adapted to other hardware.
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Secured and Practical Voting Machines,
E. Bresson, F. Chabaud, X. Chassagneux, and M. Videau,
abstract published in
C&ESAR'08, 2008.
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Voting machines are used in France in political elections since
2004. Other examples, notably in the USA, have raised a lot of concerns
and some criticisms against their use. The purpose of this paper is to
propose new conception rules for voting machines, in order to improve
their security to achieve the sincerity of the ballot, to obtain transparency
of the voting and counting procedures, so as to raise the confidence of
citizens. One way to reach this final goal, is to give to the citizens the
ability to participate into control operations, which is easier to do in
paper voting than in the case of voting machines. |
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Recherche de performance dans l'algorithmique des corps finis. Applications à la cryptographie.,
Thèse de doctorat, École Polytechnique, Oct. 1996.
(in french)
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We present in this thesis
ZEN,
a programming library for computing in
every finite extension over a finite ring. This library gives an easy
and efficient way to implement such computations in C.
We then introduce some applications that were implemented using this
library. These applications are related to the cryptanalysis of some
cryptosystems based on error-correcting codes. Mainly, we present two
algorithms for the general decoding of linear error-correcting codes,
using Hamming's metric on one hand, and Gabidulin's rank metric on the
other one.
We derive a few results
- the true minimum distance of some BCH codes of length 511,
- a bound on the minimum distance of linear codes using Gabidulin's
metric,
- the underestimation of some parameters in an identification scheme
proposed by Véron,
- a realist cryptanalysis of another identification scheme proposed by Chen.
We also note that, to our knowledge, our algorithms seems to be the
best attacks against a large variety of cryptosystems including the
well-known McEliece's, Niederreiter's and Stern's SD cryptosystems.
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A new algorithm for finding minimum-weight words in a linear
code: Application to primitive narrow-sense BCH codes of length 511.,
A. Canteaut, and F. Chabaud
published in
IEEE Trans. Inform. Theory, 44(1):367--378, jan
1998.
Preliminary version:
Rapport de recherche 2685, INRIA, oct 1995.
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An algorithm for
finding small-weight words in large linear codes is developed. We determine
with it the minimum distance of some binary BCH codes of length 511, which
were not known.
Keywords: error-correcting
codes, decoding algorithm, minimum weight, random linear codes, BCH codes
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The cryptographic security of the syndrome decoding problem for rank distance codes,
F. Chabaud, and J. Stern,
extended abstract published in
Advances in Cryptology: ASIACRYPT '96, volume 1163 of LNCS, pages 368--381. Springer-Verlag, 1996.
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An algorithm
that achieves general syndrome decoding of linear rank distance code is
proposed. As a consequence, the cryptographical schemes as proposed by K.
Chen are not secure. We also derive a bound on the minimal rank distance of a
linear code. |
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On
the security of some cryptosystems based on error-correcting codes,
F. Chabaud,
extended abstract published in
A. de Santis, editor, Advances in Cryptology:
Proceedings of EUROCRYPT'94, volume 950 of LNCS, pages
131--139. Springer-Verlag, 1995.
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A certain number
of public-key cryptosystems based on error-correcting codes have been
proposed as an alternative to algorithms based on number theory. In this
paper, we analyze algorithms that can be used to attack such cryptosystems in
a very precise way. |
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Links between differential and linear cryptanalysis,
F. Chabaud, and S. Vaudenay,
extended abstract published in
A. de Santis, editor, Advances in Cryptology:
Proceedings of EUROCRYPT'94, volume 950 of LNCS, pages
356--365. Springer-Verlag, 1995.
Preliminary version:
Report LIENS-94-3
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This paper exhibits new relations between linear and
differential cryptanalysis and presents new classes of functions which are
optimally resistant to these attacks. |
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Asymptotic analysis of probabilistic algorithms for finding
short codewords,
F. Chabaud,
extended abstract published in
In P. Camion, P. Charpin, and S. Harari, editors,
EUROCODE'92, volume 339 of CISM Courses and Lectures, pages
175--183. Springer-Verlag, 1993.
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We present the
asymptotic analysis of two previously known algorithms for finding short
codewords in linear binary codes. The results are confirmed by
implementation, and this allows extrapolation for larger codes. |
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