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19 December 2018
Nicolas Sendrier, Valentin Vasseur
In particular, QC-MDPC are among the most promising code-based key encapsulation mechanisms (KEM) that are proposed to the NIST call for standardization of quantum safe cryptography (two proposals, BIKE and QC-MDPC KEM).
The first generation of decoding algorithms suffers from a small, but not negligible, decoding failure rate (DFR in the order of $10^{-7}$ to $10^{-10}$). This allows a key recovery attack presented by Guo, Johansson, and Stankovski (GJS attack) at Asiacrypt 2016 which exploits a small correlation between the faulty message patterns and the secret key of the scheme, and limits the usage of the scheme to KEMs using ephemeral public keys. It does not impact the interactive establishment of secure communications (e.g. TLS), but the use of static public keys for asynchronous applications (e.g. email) is rendered dangerous.
Understanding and improving the decoding of QCMDPC is thus of interest for cryptographic applications. In particular, finding parameters for which the failure rate is provably negligible (typically as low as $2^{-64}$ or $2^{-128}$) would allow static keys and increase the applicability of the mentioned cryptosystems.
We study here a simple variant of bit-flipping decoding, which we call step-by-step decoding. It has a higher DFR but its evolution can be modelled by a Markov chain, within the theoretical framework of Julia Chaulet's PhD thesis. We study two other, more efficient, decoders. One is the textbook algorithm. The other is (close to) the BIKE decoder. For all those algorithms we provide simulation results, and, assuming an evolution similar to the step-by-step decoder, we extrapolate the value of the DFR as a function of the block length. This will give an indication of how much the code parameters must be increased to ensure resistance to the GJS attack.
Derek Zhang, Alex Su, Felix Xu, Jiang Chen
Jean-Christophe Deneuville, Philippe Gaborit
Be'er Sheva, Israel, 27 June - 28 June 2019
Submission deadline: 20 February 2019
Notification: 20 March 2019
Bogota, Colombia, 5 June - 7 June 2019
Submission deadline: 30 March 2019
Notification: 30 April 2019
COSIC, KU Leuven
The goal of the research is to develop new methods for efficient MPC, methods to apply MPC to large numbers of parties, methods to build automated tools to support development of applications based on MPC and FHE, as well as innovative new MPC solutions which solve real world problems.
We are looking for applicants who can work on practice inspired theoretical work in MPC, applicants who can work on implementation research in MPC and FHE, applicants with previous experience in programming language research, as well as applicants working in theoretical aspects of the MPC and FHE.
Strong background in mathematics/computer science and/or cryptography.
PhD applicants we would prefer to have experience in C or C++.
For PostDoc researchers experience in theoretical or practical aspects of secure computation is a must.
Please apply as soon as possible (we will not wait until the closing date to make decisions, but will make them as applications come in).
Closing date for applications: 31 May 2019
Contact: Nigel Smart (nigel.smart (at) kuleuven.be)
More information: https://www.esat.kuleuven.be/cosic/wp-content/uploads/2018/12/PhD-PostDoc-positions-in-secure-computation.pdf
18 December 2018
Antonis Michalas
Gustavo Banegas, Paulo S. L. M. Barreto, Brice Odilon Boidje, Pierre-Louis Cayrel, Gilbert Ndollane Dione, Kris Gaj, Cheikh Thiecoumba Gueye, Richard Haeussler, Jean Belo Klamti, Ousmane N'diaye, Duc
Jihye Kim, Jiwon Lee, Hankyung Ko, Donghwan Oh, Semin Han, Kwonho Jeong, Hyunok Oh
Joonsang Baek, Willy Susilo, Jongkil Kim, Yang-Wai Chow
Julian Renner, Sven Puchinger, Antonia Wachter-Zeh
Steven Galbraith, Lorenz Panny, Benjamin Smith, Frederik Vercauteren
Michael Meyer, Fabio Campos, Steffen Reith
NICOLAS BELLEVILLE, DAMIEN COUROUSSÉ, KARINE HEYDEMANN, HENRI-PIERRE CHARLES
Loïc Masure, Cécile Dumas, Emmanuel Prouff
Lauren De Meyer, Victor Arribas, Svetla Nikova, Ventzislav Nikov, Vincent Rijmen
Christof Beierle, Alex Biryukov, Aleksei Udovenko
The motivation for studying those objects comes from the fact that degree-$d$ zero-sum sets of full rank can be used to build linear mappings that preserve special kinds of \emph{nonlinear invariants}, similar to those obtained from orthogonal matrices and exploited by Todo, Leander and Sasaki for breaking the block ciphers Midori, Scream and iScream.
Gembu Ito, Akinori Hosoyamada, Ryutaroh Matsumoto, Yu Sasaki, Tetsu Iwata
In this paper, based on Simon's algorithm, we first formalize a sufficient condition of a quantum distinguisher against block ciphers so that it works even if there are multiple collisions other than the real period. This distinguisher is similar to the one proposed by Santoli and Schaffner, and it does not recover the period. Instead, we focus on the dimension of the space obtained from Simon's quantum circuit. This eliminates the need to evaluate the probability of collisions, which was needed in the work by Kaplan et al. at CRYPTO 2016. Based on this, we continue the investigation of the security of Feistel ciphers in the quantum setting. We show a quantum CCA distinguisher against the 4-round Feistel cipher. This extends the result of Kuwakado and Morii by one round, and follows the intuition of the result by Luby and Rackoff where the CCA setting can extend the number of rounds by one. We also consider more practical cases where the round functions are composed of a public function and XORing the subkeys. We show the results of both distinguishing and key recovery attacks against these constructions.
Nicolas Aragon, Olivier Blazy, Philippe Gaborit, Adrien Hauteville, Gilles Zémor
17 December 2018
Submissions due Feb 13
The conference will take place in Santa Barbara, USA on August 18-22, 2019.