511 results
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Packings on the Grassmann manifold: an interesting approach for non coherent space-time coding
Speaker : Jean-Claude Belfiore - ENST
The need of high data rates on the radio channel (WiFi and its future for example) explains the increasing number of researchers working on space-time codes. Preparing Wireless IP systems, some companies and some researchers are promoting the use of non coherent space-time codes.<br/> We show that designing a non coherent space-time code is equivalent to finding some good packings on the[…] -
Countermeasures Against Leaked-Emission Analysis for Curve-Based Cryptosystems
Speaker : Roberto Avanzi - Universität Essen
Power Analysis (and, more generally, Leaked-Emission Analysis) is a technique for guessing the flow of cryptographic algorithms implemented on embedded devices, in particular smart cards. If a single input is used, the process is referred to as a Simple Power Analysis (SPA), and if several different inputs are used together with statistical tools, it is called Differential Power Analysis (DPA).[…] -
On homomorpic public-key cryptosystems over groups and rings
Speaker : Ilia Ponomarenko - St. Petersburg
We describe new public-key cryptosystems based on secret group and ring homomorphisms. For the group case, we use a secret embedding of a free group of rank 2 to the 2-dimensional modular group. For the ring case, we use a secret homomorphism induced by a secret group homomorphism of the corresponding multiplicative groups. -
Complexité du calcul de bases de Gröbner pour des systèmes semi-réguliers dans le corps fini GF(2)
Speaker : Magali Bardet - Université Pierre et Marie Curie
Pour de nombreuses applications dans le domaine de la cryptographie (par exemple pour des systèmes de chiffrement où la clef publique est un système polynômial comme HFE, ou des systèmes de registres filtrés), nous sommes amenés à résoudre des systèmes à coefficients dans le corps fini GF(2), pour lesquels les seules solutions intéressantes sont celles dans GF(2). On a donc à résoudre un système[…] -
Divisibilité des nombres de classes
Speaker : Yuri Bilu - Université Bordeaux I
Soient m,n>1 des nombres entiers. Alors pour tout $X$ suffisamment grand, il y a >>X^\mu corps de nombres K de degré n avec m|h(K). Ici \mu = \frac1{2m(n-1)}. Ceci généralise le résultat de R. Murty pour des corps quadratiques (le cas n=2). Un travail commun avec F. Luca. -
Courbes elliptiques et attaques par canaux cachés
Speaker : Marc Joye - Gem+
Provable security becomes more and more popular in the cryptographic community. As exemplified by the NESSIE project, it is now common to see it as an attribute of a cryptosystem. Provable security is at the protocol level; a harder task may be to evaluate the security of a cryptosystem at the implementation level. Rather than considering a cryptosystem as a black-box, we may assume that some[…]