Thomas Baignères

Now

Since 2010, I am a Cryptography & Security Expert for CryptoExperts in Paris !

Before

I received a Ph.D. in 2008 under the direction of Prof. Serge Vaudenay, head of the Cryptography and Security Laboratory (LASEC) at EPFL, Switzerland. My main research areas cover block ciphers and their cryptanalysis. I then spent some time in Belgium where I worked as a consultant and researcher for Smals.

Contact

Thomas Baignères - CryptoExperts
41 boulevard des Capucines
75002, Paris, France
+33 6 48 44 74 92
first.last @ cryptoexperts.com

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ECRYPT Workshop on Lightweight Cryptography

Posted in November 2011

I am part of the program committee of the 2011 edition of the ECRYPT Workshop on Lightweight Cryptography.

LC 2011 is organized by the UCL Crypto Group and sponsored by the SymLab and VAMPIRE virtual labs of the Network of Excellence in Cryptology - ECRYPT II. It will be held on November 28-29, 2011, in Louvain-la-Neuve in Belgium.

Linear Cryptanalysis of Non Binary Ciphers (with an Application to SAFER)

Joint work with Jacques Stern, Serge Vaudenay
Published in the Proceedings of SAC 2007

In this paper we re-visit distinguishing attacks. We show how to generalize the notion of linear distinguisher to arbitrary sets. Our thesis is that our generalization is the most natural one. We compare it with the one by Granboulan et al. from FSE’06 by showing that we can get sharp estimates of the data complexity and cumulate characteristics in linear hulls. As a proof of concept, we propose a better attack on their toy cipher TOY100 than the one that was originally suggested and we propose the best known plaintext attack on SAFER K/SK so far. This provides new directions to block cipher cryptanalysis even in the binary case. On the constructive side, we introduce DEAN18, a toy cipher which encrypts blocks of 18 decimal digits and we study its security.

PDF PS Slides

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