Publications de Pouyan Sepehrdad

On Selection of Samples in Algebraic Attacks and a New Technique to Find Hidden Low Degree Equations

Serge Vaudenay, Pouyan Sepehrdad, Petr Susil

The best way of selecting samples in algebraic attacks against block ciphers is not well explored and understood. We introduce a simple strategy for selecting the plaintexts and demonstrate its strength by breaking reduced-round KATAN, LBLOCK and SIMON. Fo ...

Springer Verlag2016

Efficient Recursive Diffusion Layers for Block Ciphers, and Hash Functions

Pouyan Sepehrdad

Many modern block ciphers use maximum distance separable (MDS) matrices as the main part of their diffusion layers. In this paper, we propose a very efficient new class of diffusion layers constructed from several rounds of Feistel-like structures whose ro ...

Springer2015

On Selection of Samples in Algebraic Attacks and a New Technique to Find Hidden Low Degree Equations

Serge Vaudenay, Pouyan Sepehrdad, Petr Susil

The best way of selecting samples in algebraic attacks against block ciphers is not well explored and understood. We introduce a simple strategy for selecting the plaintexts and demonstrate its strength by breaking reduced-round KATAN32 and LBlock. In both ...

Springer-Verlag Berlin2014

Smashing WEP in A Passive Attack

Serge Vaudenay, Martin Vuagnoux, Pouyan Sepehrdad, Petr Susil

In this paper, we report extremely fast and optimised active and passive attacks against the old IEEE 802.11 wireless communication protocol WEP. This was achieved through a huge amount of theoretical and experimental analysis (capturing WiFi packets), ref ...

2013

Statistical and Algebraic Cryptanalysis of Lightweight and Ultra-Lightweight Symmetric Primitives

Pouyan Sepehrdad

Symmetric cryptographic primitives such as block and stream ciphers are the building blocks in many cryptographic protocols. Having such blocks which provide provable security against various types of attacks is often hard. On the other hand, if possible, ...

EPFL2012

ElimLin Algorithm Revisited

Serge Vaudenay, Pouyan Sepehrdad, Petr Susil

ElimLin is a simple algorithm for solving polynomial systems of multivariate equations over small finite fields. It was initially proposed as a single tool by Courtois to attack DES. It can reveal some hidden linear equations existing in the ideal generate ...

Springer2012

Recursive Diffusion Layers for Block Ciphers and Hash Functions

Pouyan Sepehrdad

Many modern block ciphers use maximum distance separable (MDS) matrices as the main part of their diffusion layers. In this paper, we propose a new class of diffusion layers constructed from several rounds of Feistel-like structures whose round functions a ...

Springer2012

Fast Key Recovery Attack on ARMADILLO1 and Variants

Serge Vaudenay, Pouyan Sepehrdad, Petr Susil

The ARMADILLO cryptographic primitive is a multi-purpose cryptographic primitive for RFID devices proposed at CHES’10. The main purpose of the primitive is to provide a secure authentication in a challenge-response protocol. It has two versions, named ARMA ...

Springer2011

Statistical Attack on RC4: Distinguishing WPA

Serge Vaudenay, Martin Vuagnoux, Pouyan Sepehrdad

In this paper we construct several tools for manipulating pools of biases in the analysis of RC4. Then, we show that optimized strategies can break WEP based on 4000 packets by assuming that the first bytes of plaintext are known for each packet. We descri ...

Springer2011

Discovery and Exploitation of New Biases in RC4

Serge Vaudenay, Martin Vuagnoux, Pouyan Sepehrdad

In this paper, we present several weaknesses in the stream cipher RC4. First, we present a technique to automatically reveal linear correlations in the PRGA of RC4. With this method, 48 new exploitable correlations have been discovered. Then we bind these ...

Springer-Verlag New York, Ms Ingrid Cunningham, 175 Fifth Ave, New York, Ny 10010 Usa2010