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2015-06-17
03:17 [Pub][ePrint] Cryptanalysis of Reduced-Round Whirlwind (Full Version), by Bingke Ma and Bao Li and Ronglin Hao and Xiaoqian Li

  The \\texttt{Whirlwind} hash function, which outputs a 512-bit digest, was designed by Barreto $et\\ al.$ and published by \\textit{Design, Codes and Cryptography} in 2010. In this paper, we provide a thorough cryptanalysis on \\texttt{Whirlwind}. Firstly, we focus on security properties at the hash function level by presenting (second) preimage, collision and distinguishing attacks on reduced-round \\texttt{Whirlwind}. In order to launch the preimage attack, we have to slightly tweak the original Meet-in-the-Middle preimage attack framework on \\texttt{AES}-like compression functions by partially fixing the values of the state. Based on this slightly tweaked framework, we are able to construct several new and interesting preimage attacks on reduced-round \\texttt{Whirlpool} and \\texttt{AES} hashing modes as well. Secondly, we investigate security properties of the reduced-round components of \\texttt{Whirlwind}, including semi-free-start and free-start (near) collision attacks on the compression function, and a limited-birthday distinguisher on the inner permutation. As far as we know, our results are currently the best cryptanalysis on \\texttt{Whirlwind}.



00:17 [Pub][ePrint] Efficiency Evaluation of Cryptographic Protocols for Boardroom Voting, by Oksana Kulyk, Stephan Neumann, Jurlind Budurushi, Melanie Volkamer, Rolf Haenni, Reto Koenig, Philemon von Bergen

  Efficiency is the bottleneck of many cryptographic protocols towards their practical application in different contexts. This holds true also in the context of electronic voting, where cryptographic protocols are used to ensure a diversity of security requirements, e.g. secrecy and integrity of cast votes. A new and promising application area of electronic voting is boardroom voting, which in practice takes place very frequently and often on simple issues such as approving or refusing a budget. Hence, it is not a surprise that a number of cryptographic protocols for boardroom voting have been already proposed.

In this work, we introduce a security model adequate for the boardroom voting context. Further, we evaluate the efficiency of four boardroom voting protocols, which to best of our knowledge are the only boardroom voting protocols that satisfy our security model. Finally, we compare the performance of these protocols in different election settings.



00:17 [Pub][ePrint] Concurrent Secure Computation with Optimal Query Complexity, by Ran Canetti and Vipul Goyal and Abhishek Jain

  The multiple ideal query (MIQ) model [Goyal, Jain, and Ostrovsky, Crypto\'10] offers a relaxed notion of security for concurrent secure computation, where the simulator is allowed to query the ideal functionality multiple times per session (as opposed to just once in the standard definition). The model provides a quantitative measure for the degradation in security under concurrent self-composition, where the degradation is measured by the number of ideal queries. However, to date, all known MIQ-secure protocols guarantee only an overall average bound on the number of queries per session throughout the execution, thus allowing the adversary to potentially fully compromise some sessions of its choice. Furthermore, [Goyal and Jain, Eurocrypt\'13] rule out protocols where the simulator makes only an adversary-independent constant number of ideal queries per session.

We show the first MIQ-secure protocol with worst-case per-session guarantee. Specifically, we show a protocol for any functionality that matches the [GJ13] bound: The simulator makes only a constant number of ideal queries in every session. The constant depends on the adversary but is independent of the security parameter.

As an immediate corollary of our main result, we obtain the first password authenticated key exchange (PAKE) protocol for the fully concurrent, multiple password setting in the standard model with no set-up assumptions.



00:17 [Pub][ePrint] Generic Construction of UC-Secure Oblivious Transfer, by Olivier Blazy and Céline Chevalier

  We show how to construct a completely generic UC-secure oblivious transfer scheme from a collision-resistant chameleon hash scheme (CH) and a CCA encryption scheme accepting a smooth projective hash function (SPHF). Our work is based on the work of Abdalla et al. at Asiacrypt 2013, where the authors formalize the notion of SPHF-friendly commitments, i.e. accepting an SPHF on the language of valid commitments (to allow implicit decommitment), and show how to construct from them a UC-secure oblivious transfer in a generic way. But Abdalla et al. only gave a DDH-based construction of SPHF-friendly commitment schemes, furthermore highly relying on pairings. In this work, we show how to generically construct an SPHF-friendly commitment scheme from a collision-resistant CH scheme and an SPHF-friendly CCA encryption scheme. This allows us to propose an instantiation of our schemes based on the DDH, as efficient as that of Abdalla et al., but without requiring any pairing. Interestingly, our generic framework also allows us to propose an instantiation based on the learning with errors (LWE) assumption. For the record, we finally propose a last instantiation based on the decisional composite residuosity (DCR) assumption.



00:17 [Pub][ePrint] SoC it to EM: electromagnetic side-channel attacks on a complex system-on-chip, by J. Longo and E. De Mulder and D. Page and M. Tunstall

  Increased complexity in modern embedded systems has presented various important challenges with regard to side-channel attacks. In particular, it is common to deploy SoC-based target devices with high clock frequencies in security-critical scenarios; understanding how such features align with techniques more often deployed against simpler devices is vital from both destructive (i.e., attack) and constructive (i.e., evaluation and/or countermeasure) perspectives. In this paper, we investigate electromagnetic-based leakage from three different means of executing cryptographic workloads (including the general purpose ARM core, an on-chip co-processor, and the NEON core) on the AM335x SoC. Our conclusion is that addressing challenges of the type above {\\em is} feasible, and that key recovery attacks can be conducted with modest resources.



00:17 [Pub][ePrint] PUA - Privacy and Unforgeability for Aggregation, by Iraklis Leontiadis and Kaoutar Elkhiyaoui and Refik Molvaa and Melek Onen ¨

  xisting work on data collection and analysis for aggregation is mainly

focused on confidentiality issues. That is, the untrusted Aggregator learns only the aggregation result without divulging individual data inputs. In this paper we extend the existing models with stronger security requirements. Apart from the privacy requirements with respect to the individual inputs we ask for unforgeability for the aggregate result. We first define the new security requirements of the model. We also instantiate a protocol for private and unforgeable aggregation for a non-interactive multi-party environment. I.e, multiple unsynchronized users owing to personal sensitive information without interacting with each other contribute their values in a secure way: The Aggregator learns the result of a function without learning individual values and moreover it constructs a proof that is forwarded to a verifier that will let the latter be convinced for the correctness of the computation. The verifier is restricted to not communicate with the users. Our protocol is provably secure in the random oracle model.





2015-06-16
15:55 [Event][New] PKC: Public Key Cryptography

  Submission: 6 October 2015
Notification: 11 December 2015
From March 6 to March 9
Location: Taipei, Taiwan
More Information: http://troll.iis.sinica.edu.tw/pkc16/


15:54 [Event][New] 16th International Conference on Cryptology, Indocrypt (Indocrypt)

  Submission: 13 July 2015
Notification: 7 September 2015
From December 6 to December 10
Location: Bangalore, India
More Information: http://www.indocrypt2015.org/




2015-06-15
23:09 [Job][New] PhD student in Information Security and Cryptography, Chalmers University of Technology, Sweden

  We are looking for an excellent, motivated, self-driven doctoral student to work in the area of information security and cryptography. The position is for five years at the Department of Computer Science and Engineering.

The PhD student will join the Chalmers Systems Security group, working in the area of information and communication security with a focus on security and privacy issues in wearable computing devices. More precisely, the student shall be working on investigating efficient authentication mechanisms for wearable computing devices (RFID tags, sensors connected with mobile phones or other wireless devices) that provide: i) accurate and transparent authentication, ii) rigorous privacy guarantees, even if multiple wearable devices are involved in the authentication. The overall aim of the announced PhD position will be to develop nearly optimal algorithms for achieving security while minimising resource use and guaranteeing privacy-preservation.

More concretely, part of the research will involve the analysis and development of authentication protocols in specific settings. This will include investigating resistance of both existing and novel protocols against different types of attacks, theoretically and experimentally. The project should result in the development of theory and authentication mechanisms for noisy, constrained settings that strike an optimal balance between reliable authentication, privacy-preservation and resource consumption.

The PhD student will be supervised by Prof. Katerina Mitrokotsa. Some previous research related to this research project can be found here: http://www.cse.chalmers.se/~aikmitr/

16:00 [Job][New] Postdoctoral researcher in Quantum Cryptography, University of Amsterdam

  The Institute for Logic, Language & Computation at the University of Amsterdam is looking for a postdoctoral researcher in the area of quantum cryptography, as part of Christian Schaffner’s NWO VIDI Project Cryptography in the Quantum Age.

The aim of the project is to develop new quantum-cryptographic protocols (beyond the task of key distribution) and explore their limitations. An example of an active research is position-based quantum cryptography. Another aspect is to investigate the security of classical cryptographic schemes against quantum adversaries (post-quantum cryptography).

The full-time appointment (38 hours per week) will be on a temporary basis, initially for one year with an extension for a further two years on positive evaluation. Depending on experience, the gross monthly salary will range from €2,476 to €3,908 (scale 10), excl. 8% holiday allowance and 8,3% annual bonus.

Prospective candidates should:

  • hold or be about to obtain a PhD degree in computer science, mathematics or physics;

  • have a proven track record of excellence in cryptography and/or quantum information, as witnessed by a strong publication list in relevant first-tier conference proceedings or journals;

  • have in-depth knowledge of one of the following fields is a plus: parallel repetition, limited-quantum-storage models, continuous variables, quantum security notions;

  • have strong passion for research, a drive to publish and the wish to learn new skills through working with or assisting in guiding PhD and MSc students;

  • have good communication skills in English, both oral and written.



16:00 [Job][New] PhD candidate in Quantum Cryptography, University of Amsterdam

  The Institute for Logic, Language & Computation at the University of Amsterdam is looking for a PhD candidate in the area of quantum cryptography, as part of Christian Schaffner’s NWO VIDI Project Cryptography in the Quantum Age.

The aim of the PhD project is to develop new quantum-cryptographic protocols (beyond the task of key distribution) and explore their limitations. An example of an active research is position-based quantum cryptography. Another aspect is to investigate the security of classical cryptographic schemes against quantum adversaries (post-quantum cryptography).

The full-time appointment at ILLC will be on a temporary basis for a maximum period of four years (18 months plus a further 30 months after a positive evaluation) and should lead to a dissertation (PhD thesis). On the basis of a full-time appointment (38 hours per week), the gross monthly salary amounts to €2,125 during the first year, rising to €2,717 during the fourth year.

Requirements:

  • A Master\'s degree with excellent grades in computer science, mathematics or physics with outstanding results or a comparable degree;

  • candidates with a strong background in cryptography or quantum information are preferred;

  • demonstrated research abilities by completion of an (undergraduate) research project;

  • good academic writing and presentation skills;

  • good social and organisational skills.