Wed, 08 Mar 2017
15:00
L5

Long-term security

Johannes Buchmann
(Technische Universitat Darmstadt)
Abstract

The amount of digital data that requires long-term protection 
of integrity, authenticity, and confidentiality protection is steadily 
increasing. Examples are health records and genomic data which may have 
to be kept and protected for 100 years and more. However, current 
security technology does not provide such protection which I consider a 
major challenge. In this talk I report about a storage system that 
achieves the above protection goals in the long-term. It is based on 
information theoretic secure cryptography (both classical and quantum) 
as well as on chains of committments. I discuss its security and present 
a proof-of-concept implementation including an experimental analysis.

Tue, 06 Sep 2016

11:30 - 12:30
L4

A Unified Approach to Bayesian Optimization and Level-Set Estimation

Volkan Cevher
(EPFL)
Abstract

Bayesian optimization (BO) is a powerful tool for sequentially optimizing black-box functions that are expensive to evaluate, and has extensive applications including automatic hyperparameter tuning, environmental monitoring, and robotics. The problem of level-set estimation (LSE) with Gaussian processes is closely related; instead of performing optimization, one seeks to classify the whole domain according to whether the function lies above or below a given threshold, which is also of direct interest in applications.

In this talk, we present a new algorithm, truncated variance reduction (TruVaR) that addresses Bayesian optimization and level-set estimation in a unified fashion. The algorithm greedily shrinks a sum of truncated variances within a set of potential maximizers (BO) or unclassified points (LSE), which is updated based on confidence bounds. TruVaR is effective in several important settings that are typically non-trivial to incorporate into myopic algorithms, including pointwise costs, non-uniform noise, and multi-task settings. We provide a general theoretical guarantee for TruVaR covering these phenomena, and use it to obtain regret bounds for several specific settings. We demonstrate the effectiveness of the algorithm on both synthetic and real-world data sets.

Searches for sterile neutrinos with the IceCube detector
Aartsen, M Abraham, K Ackermann, M Adams, J Aguilar, J Ahlers, M Ahrens, M Altmann, D Andeen, K Anderson, T Ansseau, I Anton, G Archinger, M Argüelles, C Arlen, T Auffenberg, J Axani, S Bai, X Barwick, S Baum, V Bay, R Beatty, J Becker Tjus, J Becker, K BenZvi, S Berghaus, P Berley, D Bernardini, E Bernhard, A Besson, D Binder, G Bindig, D Blaufuss, E Blot, S Boersma, D Bohm, C Börner, M Bos, F Bose, D Böser, S Botner, O Braun, J Brayeur, L Bretz, H Burgman, A Casey, J Casier, M Cheung, E Chirkin, D Christov, A Physical Review Letters volume 117 issue 7 (08 Aug 2016)
Wed, 19 Oct 2016
15:00
L5

Cryptanalysis of the Algebraic Eraser

Simon Blackburn
(Royal Holloway University of London)
Abstract

The Algebraic Eraser is a cryptosystem (more precisely, a class of key
agreement schemes) introduced by Anshel, Anshel, Goldfeld and Lemieux
about 10 years ago. There is a concrete instantiation of the Algebraic
Eraser called the Colored Burau Key Agreement Protocol (CBKAP), which
uses a blend of techniques from permutation groups, matrix groups and
braid groups. SecureRF, the company owning the trademark to the
Algebraic Eraser, is marketing this system for lightweight
environments such as RFID tags and other Internet of Things
applications; they have proposed making this scheme the basis for an
ISO RFID standard.

This talk gives an introduction to the Algebraic Eraser, a brief
history of the attacks on this scheme using ideas from group-theoretic
cryptography, and describes the countermeasures that have been
proposed. I would not recommend the scheme for the proposed
applications: the talk ends with a brief sketch of a recent convincing
cryptanalysis of this scheme due to Ben-Zvi, Blackburn and Tsaban
(which appeared at CRYPTO this summer), and significant attacks
on the protocol in the proposed ISO standard due to Blackburn and
Robshaw (which appeared at ACNS earlier this year).

There is a wide class of problems in mathematics known as inverse problems. Rather than starting with a mathematical model and analysing its properties, mathematicians start with a set of properties and try to obtain mathematical models which display them. For example, in mathematical chemistry researchers try to construct chemical reaction systems that have certain predefined behaviours. From a mathematical point of view, this can be used to create simplified chemical systems that can be used as test problems for different mathematical fields.

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