International Association for Cryptologic Research

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2014-10-10
06:17 [Pub][ePrint] Tightly-Secure Authenticated Key Exchange, by Christoph Bader and Dennis Hofheinz and Tibor Jager and Eike Kiltz and Yong Li

  We construct the first Authenticated Key Exchange (AKE) protocol whose security does not degrade with an increasing number of users or sessions. We describe a three-message protocol and prove security in an enhanced version of the classical Bellare-Rogaway security model.

Our construction is modular, and can be instantiated efficiently from standard assumptions (such as the SXDH or DLIN assumptions in pairing-friendly groups). For instance, we provide an SXDH-based protocol whose communication complexity is only 14 group elements and 4 exponents (plus some bookkeeping information).

Along the way we develop new, stronger security definitions for digital signatures and key encapsulation mechanisms. For instance, we introduce a security model for digital signatures that provides existential unforgeability under chosen-message attacks in a multi-user setting with adaptive corruptions of secret keys. We show how to construct efficient schemes that satisfy the new definitions with tight security proofs under standard assumptions.



06:17 [Pub][ePrint] Multi-Identity and Multi-Key Leveled FHE from Learning with Errors, by Michael Clear and Ciar\\\'{a}n McGoldrick

  Gentry, Sahai and Waters recently presented the first (leveled) identity-based fully homomorphic (IBFHE) encryption scheme (CRYPTO 2013). Their scheme however only works in the single-identity setting; that is, homomorphic evaluation can only be performed on ciphertexts created with the same identity. In this work, we extend their results to the multi-identity setting and obtain a multi-identity IBFHE scheme that is selectively secure in the random oracle model under the hardness of Learning with Errors (LWE). We also obtain a multi-key fully-homomorphic encryption (FHE) scheme that is secure under LWE in the standard model. This is the first multi-key FHE based on a well-established assumption such as standard LWE. The multi-key FHE of L\\\'{o}pez-Alt, Tromer and Vaikuntanathan (STOC 2012) relied on a non-standard assumption, referred to as the Decisional Small Polynomial Ratio assumption.



06:17 [Pub][ePrint] Verifiable Random Functions from Weaker Assumptions, by Tibor Jager

  Constructing a verifiable random function (VRF) with large input space and full adaptive security from a static complexity assumption, like decisional Diffie-Hellman for instance, has proven to be a challenging task. To date it is not even clear that such a VRF exists. Most known constructions either allow only a small input space of polynomially-bounded size, or do not achieve full adaptive security under a static complexity assumption.

The only known constructions without these restrictions are based on non-static, so-called \"q-type\" assumptions, which are parametrized by an integer q. Since q-type assumptions get stronger with larger q, it is desirable to have q as small as possible. In current constructions q is a polynomial (Hohenberger and Waters, Eurocrypt 2010) or at least linear (Boneh et al., CCS 2010) in the security parameter.

We construct a relatively simple and efficient verifiable random function, based on a q-type assumption where q is only logarithmic in the security parameter. We also describe a verifiable unpredictable function from a similar, but weaker assumption. Both constructions have full adaptive security and large input spaces.



06:17 [Pub][ePrint] Efficient Pairings and ECC for Embedded Systems, by Thomas Unterluggauer and Erich Wenger

  The research on pairing-based cryptography brought forth a wide range of protocols interesting for future embedded applications. One significant obstacle for the widespread deployment of pairing-based cryptography are its tremendous hardware and software requirements. In this paper we present three side-channel protected hardware/software designs for pairing-based cryptography yet small and practically fast: our plain ARM Cortex-M0+-based design computes a pairing in less than one second. The utilization of a multiply-accumulate instruction-set extension or a light-weight drop-in hardware accelerator that is placed between CPU and data memory improves runtime up to six times. With a 10.1 kGE large drop-in module and a 49 kGE large platform, our design is one of the smallest pairing designs available. Its very practical runtime of 162 ms for one pairing on a 254-bit BN curve and its reusability for other elliptic-curve based crypto systems offer a great solution for every microprocessor-based embedded application.





2014-10-09
09:44 [Job][New] Associate professor (lecturer) in Computer Security., University of Birmingham, UK

  This is a permanent research and teaching position in one of UK\'s top research-led universities. The Security and Privacy group undertakes research in all fields related to information and cyber security,

privacy, cryptography, etc.



2014-10-08
23:53 [Event][New] DAC: Design Automation Conference - Hardware Software Security Track

  Submission: 21 November 2014
Notification: 17 February 2015
From June 7 to June 11
Location: San Francisco , USA
More Information: https://dac.com/submission-categories/hardware-and-software-security


23:53 [Event][New] COSADE 2015: 6th Int. Workshop on Constructive Side-Channel Analysis and Secure Design

  Submission: 8 December 2014
Notification: 4 February 2015
From April 13 to April 14
Location: Berlin, Germany
More Information: http://www.cosade.org/


09:23 [Event][New] 5th Bar-Ilan Winter School on Cryptography: Advances in Practical MPC

  From February 15 to February 19
Location: Tel Aviv, Israel
More Information: http://crypto.2bwebsite.co.il/5th-biu-winter-school




2014-10-07
15:25 [Job][New] Two full-time PhD or Postdoc positions in the area of Wireless Sensor Networks (WSN) Security, Universität Mannheim (Germany) and Friedrich-Alexander-Universität Erlangen-Nürnberg (Germany)

  The positions are funded by the German Research Foundation (DFG) in the project WSNSec (Wireless Sensor Network Security). The project is a collaboration between the Universität Mannheim (Germany) and the Friedrich-Alexander Universität Erlangen-Nürnberg (Germany) where the two positions are located, respectively.

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Position 1 at the Working Group for Theoretical Computer Science and IT-Security at Universität Mannheim (Germany) focuses on the theoretical aspects of WSNSec:

- Formalization of attacker models and security goals

- Cryptanalysis of existing cryptographic protocols

- Development of provably secure cryptographic protocols

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Position 2 at the Chair for IT-Security Infrastructures (Informatik 1) at the Friedrich-Alexander-Universität Erlangen-Nürnberg (Germany) focuses on the practical aspects of WSNSec:

- Investigation of security strengths and weaknesses of the real WSNs at both the hardware and the software levels

- Implementation of cryptographic protocols for WSNs in simulation environments and on the real sensor nodes

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13:29 [Job][New] 4 Research Scientists, Temasek Laboratories at Nanyang Technological University, Singapore

  Temasek Laboratories at Nanyang Technological University, Singapore is seeking candidates for 4 research scientist positions (from fresh post-docs to senior research scientists) in the areas of symmetric key cryptography and lightweight cryptography, supported by a government funded project of duration 2 years.

Salaries are globally competitive and are determined according to the successful applicants accomplishments, experience and qualifications. Interested applicants are encouraged to send early their detailed CVs, cover letter and reference letters.

Review process starts immediately and will continue until all positions are filled.

06:17 [Pub][ePrint] Tuning GaussSieve for Speed, by Robert Fitzpatrick and Christian Bischof and Johannes Buchmann and Ozgur Dagdelen and Florian Gopfert and Artur Mariano and Bo-Yin Yang

  The area of lattice-based cryptography is growing ever-more prominent as a paradigm for quantum-resistant cryptography. One of the most important hard problem underpinning the security of lattice- based cryptosystems is the shortest vector problem (SVP). At present, two approaches dominate methods for solving instances of this problem in practice: enumeration and sieving. In 2010, Micciancio and Voulgaris presented a heuristic member of the sieving family, known as GaussSieve, demonstrating it to be comparable to enumeration methods in practice. With contemporary lattice-based cryptographic proposals relying largely on the hardness of solving the shortest and closest vector problems in ideal lattices, examining possible improvements to sieving algorithms becomes highly pertinent since, at present, only sieving algorithms have been successfully adapted to solve such instances more efficiently than in the random lattice case. In this paper, we propose a number of heuristic improvements to GaussSieve, which can also be applied to other sieving algorithms for SVP.