Publications de Serge Vaudenay

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This paper presents the first independent and systematic lin- ear, differential and impossible-differential (ID) cryptanalyses of MIBS, a lightweight block cipher aimed at constrained devices such as RFID tags and sensor networks. Our contributions include ...

Decorrelation Theory deals with general adversaries who are mounting iterated attacks, i.e., attacks in which an adversary is allowed to make d queries in each iteration with the aim of distinguishing a random cipher C from the ideal random cipher C^*. A b ...

The aim of the invention is to propose the generation, verification and denial of an undeniable signature which has a size smaller than the currently available undeniable signatures, i.e. less than 80 bits. This aim is achieved by the method to generate an ...

Homomorphic encryption allows to make specific operations on private data which stays encrypted. While applications such as cloud computing require to have a practical solution, the encryption scheme must be secure. In this article, we detail and analyze i ...

We design a consecution of protocols which allows organizations to have secure strong access control of their users to their desktop machines based on biometry. It provides both strong secure authentication and privacy. Moreover, our mechanism allows the s ...

Distance-bounding protocols form a family of challenge-response authentication protocols that have been introduced to thwart relay attacks. They enable a verifier to authenticate and to establish an upper bound on the physical distance to an untrusted prov ...

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 ...

Passports are documents that help immigration officers to identify people. In order to strongly authenticate their data and to automatically identify people, they are now equipped with RFID chips. These contain private information, biometrics, and a digita ...

In previous work, security results of decorrelation theory was based on the infinity-associated matrix norm. This enables to prove that decorrelation provides security against non-adaptive iterated attacks. In this paper we define a new matrix norm dedicated to adaptive chosen plaintext attacks. Similarly, we construct another matrix norm dedicated to chosen plaintext and ciphertext attacks. The formalism from decorrelation enables to manipulate the notion of best advantage for distinguishers so easily that

Most of the known public-key cryptosystems have an overall complexity which is dominated by the key-production algorithm, which requires the generation of prime numbers. This is most inconvenient in settings where the key-generation is not an one-off proce ...

We propose HELEN, a code-based public-key cryptosystem whose security is based on the hardness of the Learning from Parity with Noise problem (LPN) and the decisional minimum distance problem. We show that the resulting cryptosystem achieves indistinguisha ...

Query-response based protocols between a client and a server such as SSL, TLS, SSH are asymmetric in the sense that the querying client and the responding server play different roles, and for which there is a need for two-way linkability between queries an ...

We provide a formal model for identification schemes. Under this model, we give strong definitions for security and privacy. Our model captures the notion of a powerful adversary who can monitor all communications, trace tags within a limited period of tim ...

Secure asynchronous two-party communication applies ratcheting to strengthen privacy, in the presence of internal state exposures. Security with ratcheting is provided in two forms: forward security and post-compromise security. There have been several suc ...

Feistel Networks (FN) are now being used massively to encrypt credit card numbers through format-preserving encryption. In our work, we focus on FN with two branches, entirely unknown round functions, modular additions (or other group operations), and when ...

Relay attacks (and, more generally, man-in-the-middle attacks) are a serious threat against many access control and payment schemes. In this work, we present distance-bounding protocols, how these can deter relay attacks, and the security models formalizing these protocols. We show several pitfalls making existing protocols insecure (or at least, vulnerable, in some cases). Then, we introduce the SKI protocol which enjoys resistance to all popular attack-models and features provable security. As far as we k

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 ...

The fair exchange problem is key to trading electronic items in systems of mutually untrusted parties.We consider modern variants of such systems where each party is equipped with a tamper proof security module. The security modules trust each other but can only communicate by exchanging messages through their host parties. These are untrusted and could intercept and drop those messages. We show that the fair exchange problem at the level of untrusted parties can be reduced to an atomic commit problem at th

In this paper, we describe the design of a new family of block ciphers based on a Lai-Massey scheme, named FOX. The main features of this design, besides a very high security level, are a large implementation flexibility on various platforms as well as high performances. In addition, we propose a new design of strong and efficient key-schedule algorithms. We provide evidence that FOX is immune to linear and differential cryptanalysis, and we discuss its security towards integral cryptanalysis, algebraic att

In many standards, e.g. SSL/TLS, IPSEC, WTLS, messages are first pre-formatted, then encrypted in CBC mode with a block cipher. Decryption needs to check if the format is valid. Validity of the format is easily leaked out from communication protocols because the receiver usually sends an error message when the format is not valid. This is a side channel. In this paper we show that the validity of the format of the decryption is actually a hard core bit predicate. We demonstrate this by implementing an effic

Serge Vaudenay

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Cryptanalysis of reduced-round MIBS Block cipher

Resistance against Adaptive Plaintext-Ciphertext Iterated Distinguishers

Method to generate, verify and deny an undeniable signature

Cryptanalysis of a Homomorphic Encryption Scheme

BioLocker: A Practical Biometric Authentication Mechanism based on 3D Fingervein

On Selecting the Nonce Length in Distance-Bounding Protocols

Discovery and Exploitation of New Biases in RC4

About Machine-Readable Travel Documents

Adaptive-Attack Norm for Decorrelation and Super-Pseudorandomness

Primeless Modular Cryptography (Extended Abstract)

HELEN: A Public-Key Cryptosystem Based on the LPN and the Decisional Minimal Distance Problems

Security-Preserving Asymmetric Protocol Encapsulation

On Privacy Models for RFID

Beyond Security and Efficiency: On-Demand Ratcheting with Security Awareness

Generic Round-Function-Recovery Attacks for Feistel Networks over Small Domains

Towards Secure Distance Bounding

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

Reducing Fair Exchange to Atomic Commit

FOX: a new family of block ciphers

CBC Padding: Security Flaws in SSL, IPSEC, WTLS, ...