*19:17* [Pub][ePrint]
A Comparison of the Homomorphic Encryption Schemes FV and YASHE, by Tancrède Lepoint and Michael Naehrig
We conduct a theoretical and practical comparison of two Ring-LWE-based, scale-invariant, leveled homomorphic encryption schemes -- Fan and Vercauteren\'s adaptation of BGV and the YASHE scheme proposed by Bos, Lauter, Loftus and Naehrig. In particular, we explain how to choose parameters to ensure correctness and security against lattice attacks. Our parameter selection improves the approach of van de Pol and Smart to choose parameters for schemes based on the Ring-LWE problem by using the BKZ-2.0 simulation algorithm.We implemented both schemes in C++, using the arithmetic library FLINT, and compared them in practice to assess their respective strengths and weaknesses. In particular, we performed a homomorphic evaluation of the lightweight block cipher SIMON. Combining block ciphers with homomorphic encryption allows to solve the gargantuan ciphertext expansion in cloud applications.

*14:48* [Job][New]
Postdoc in Cryptology, *Technical University of Denmark, DTU*
Department of Applied Mathematics and Computer Science, Technical University of Denmark, would like to invite applications for a Postdoc position of 18 months, starting 1 April 2014 or soon thereafter. The topic of the project is lightweight cryptology, which regards scenarios involving strongly resource-constrained devices.Candidates for the position should have a solid background in hardware design and automation and be able to work on the physical constraints and optimization of the hardware implementations or, alternatively, we will consider candidates with a strong cryptanalytic and mathematical background who are able to analyse the security of ciphers to be designed.

*14:44* [Job][New]
Post-Doc in Applied Cryptography, *University of Trier, Germany*
The Chair for Information Security and Cryptography at the University of Trier, Germany, offersa full-time position for a postdoctoral researcher

in a project funded by the German Research Foundation (DFG). The goal of the project is to develop methods for the modular analysis of real-world cryptographic protocols, such as TLS, SSH, WPA2, etc., based on the approach of universal composability, and to apply the developed methods to such protocols.

The position is available immediately, with an internationally competitive salary. The starting date is negotiable. Contracts can initially be offered for up to three years, with the perspective of an extension.

There are no teaching obligations.

The successful candidate must have a Master`s degree (or an equivalent degree) in Computer Science, Mathematics, or a related discipline, and have completed, or be near completion of a PhD degree relevant to the research area of the project. You should have a proven high level of analytical capability and mathematical skills. Good English skills are expected; knowledge of German is not required.

Applications will be considered until the position is filled.

*10:17* [Pub][ePrint]
Cryptanalysis of FIDES, by Itai Dinur and Jérémy Jean
FIDES is a lightweight authenticated cipher, presented at CHES 2013.The cipher has two version, providing either 80-bit or 96-bit

security. In this paper, we describe internal state-recovery attacks

on both versions of FIDES, and show that once we recover the internal

state, we can use it to immediately forge any message. Our attacks are

based on a guess-and-determine algorithm, exploiting the slow

diffusion of the internal linear transformation of FIDES. Our most

basic attacks have time complexities of 2^{75} and 2^{90} for FIDES-80

and FIDES-96, respectively, use a very small amount of memory, and

their most distinctive feature is their very low data complexity: the

attacks require at most 24 bytes of an arbitrary plaintext and its

corresponding ciphertext, in order to break the cipher with

probability 1. In addition to the basic attacks, we describe optimized

attacks which exploit additional data in order to reduce the time

complexities to 2^{73} and 2^{88} for FIDES-80 and FIDES-96,

respectively.

*01:17* [Pub][ePrint]
Computing Discrete Logarithms in F_{3^{6*137}} using Magma , by Gora Adj and Alfred Menezes and Thomaz Oliveira and Francisco Rodríguez-Henríquez
We show that a Magma implementation of Joux\'s new L[1/4] algorithmcan be used to compute discrete logarithms in the 1303-bit finite field

F_{3^{6*137}} with very modest computational resources.

Our implementation illustrates the effectiveness of Joux\'s algorithm

for computing discrete logarithms in small-characteristic finite

fields which are not Kummer or twisted-Kummer extensions.