Estonian Cryptography

Seminars

We do not have a regular seminar series, but please come back here now and then. Also, since it is a generic "Estonian crypto group" page here, we list any seminars that are organized in Estonia.

28.02-05.03.10: EWSCS 2010

06.11.09 Tartu: Sven Heiberg

Sven Heiberg will give a talk in the Research Seminar in Cryptography. The talk will be about electronic voting protocols with emphasis on the practical implementation details and practical factors that determine the actual security of e-voting. Sven Heiberg has been participating in several e-voting projects and thus has extensive experiences.

We recommend that all students in the Research Seminar participate and also we expect all students from the NordSecMob and Cyber Defense Master's programmes.

The talk will take place on Friday at 14:15 in Liivi 2-404.

Seminar webpage: http://courses.cs.ut.ee/2009/security-seminar-fall/

05.10.09 Tartu: Dominik Raub

Dominik Raub, a soon-to-defend PhD student from ETH Zürich is currently visiting the information security and cryptology working group. He will give a talk at Liivi 2-317 (Tartu, the building of the MIT department) at 16:00.

Title: Optimally Hybrid-Secure Multi-Party Computation

slides

Abstract:

In multi-party computation (MPC) the task is to compute a function, or, more generally, evaluate a reactive functionality, among a number of parties, each giving input or receiving output. An MPC is secure if it computes the correct result (correctness), no party learns anything but the result (privacy), even if parties maliciously deviate from their prescribed program or protocol. We generally make the worst case assumption that malicious parties are corrupted and controlled by a central adversary.

Most MPC protocols in the literature are either information-theoretically (IT) secure and tolerate computationally unbounded adversaries or computationally (CO) secure and tolerate computationally bounded adversaries only without loosing security. As shown by Kilian [STOC'00] IT secure general MPC is not attainable if more than half of the participants are corrupted. On the other hand CO secure protocols like the one of Goldreich et al. [STOC'87] can tolerate corrupted majorities, but rely on unproven computational assumptions.

We present hybrid-secure MPC protocols that guarantee different levels of security, depending on the power of the adversary. Our protocol achieves graceful degradation of security guarantees, from IT security and robustness for few corrupted parties and to CO security without robustness and fairness for corrupted majorties. Our construction is secure in the universal composability (UC) framework (with broadcast and CRS), and optimal under the bounds of Ishai et al. [CRYPTO'06], Katz [STOC'07], and Cleve [STOC'86] on trade-offs between robustness and privacy, and on fairness.

We furthermore provide protocols and matching bounds for the settings without a broadcast channel but with a public-key infrastructure (PKI) and for the setting without broadcast channel or PKI.

01-03.10.09 Mäetaguse: Estonian Theory Days

Estonian Theory Days in Mäetaguse had quite many talks in cryptography and related topics, including information security and complexity theory (circuit lower bounds). A short list of interesting talks follows. Please see the homepage of ETD for more talks, abstracts, and also for the slides.

• Alexander Kulikov, Introduction to circuit complexity
• Sergey Nurk, An upper bound for circuit SAT
• Edward Hirsch, Introduction to propositional proof complexity
• Olga Melanich, Constructions of feebly secure cryptographic primitives
• Emilia Käsper, Anonymous routing via crowds: attacks and optimal constructions
• Peeter Laud, Analysis of the Estonian Mobile-ID protocol
• Dominik Raub, Multi-party computation in presence of corrupted majorities
• Helger Lipmaa, Additive combinatorics and discrete logarithm based range protocols
• Bingsheng Zhang, Linear hull and algebraic cryptanalysis of block cipher PRESENT
• Margus Niitsoo, Serial model of attack trees