International Association for Cryptologic Research

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2013-09-04
15:17 [Pub][ePrint]

Functional encryption is an important generalization of several types of encryption such as public-key, identity-based, and attribute-based encryption. Numerous different security definitions for functional encryption have been proposed, most of them being rather complex and involving several algorithms. Many of these definitions differ in details such as which algorithm has oracle access to which oracle, while the consequences of specific choices are often unclear. This spans a large space of possible definitions without a consensus on the adequacy of specific points in this space. What a particular definition means and for which applications it is suitable remains unsettled.

To remedy this situation, we propose a novel interpretation of functional encryption, based on the Constructive Cryptography framework, in which a protocol is seen as a construction of an ideal resource with desired properties from a real resource, which is assumed to be available. The resulting ideal resource can then be used as a real resource in other protocols to construct more advanced resources. The real resource we consider here corresponds to a public repository that allows everyone to read its contents. Such repositories are indeed widely available on the internet. Using functional encryption, we construct, as the ideal resource, a repository with fine-grained access control.

Based on this constructive viewpoint, we propose a new security definition, called FA-security, for functional encryption by adequately modifying an established definition, and prove the equivalence to our notion of construction. This gives evidence that FA-security is an appropriate definition. We further consider known impossibility results and examine a weaker security definition. We show that this weaker definition, for which secure schemes exist, is sufficient to construct a repository that restricts the number and order of interactions. This makes explicit how such schemes can be used.

15:17 [Pub][ePrint]

We describe a security-preserving construction of a random permutation of domain size N from a random function, the construction tolerating adversaries asking all N plaintexts, yet employing just \\Theta(lg N) calls, on average, to the one-bit-output random function. The approach is based on card shuffling. The basic idea is to use the \\textit{sometimes-recurse} transformation: lightly shuffle the deck (with some other shuffle), cut the deck, and then recursively shuffle one of the two halves. Our work builds on a recent paper of Ristenpart and Yilek.

15:17 [Pub][ePrint]

In this paper we use differential cryptanalysis to attack the winner of the SHA-3 competition, namely Keccak hash function. Despite more than 6 years of intensive cryptanalysis there have been known only two preimage attacks which reach 3 (or slightly more) rounds. Our 3-round preimage attack improves the complexity of those two existing attacks and it is obtained with a different technique. We also show the partial preimage attack on the 4-round Keccak, exploiting two properties of the linear step of the Keccak-f permutation.

13:32 [Event][New]

From August 17 to August 21
Location: Santa Barbara, USA

2013-09-03
20:48 [Job][New]

The Faculty of Electrical Engineering and Information Technology at the Ruhr-Universität Bochum invites applications for the position of a Junior Professorship for Mobile Security.

The future occupant of the position Mobile Security represents the department in this field in research and teaching. The appointment will be at the rank of an assistant professor.

His/her scientific work should focus on one or more of the following key research areas:

- Security of mobile systems at the hard- or software level

- Security aspects of new application domains (especially cyber-physical systems)

- Reverse engineering of hardware and software systems

- Security aspects of distributed systems

- Secure and dependable software systems

A doctoral degree of outstanding quality and evidence of special aptitude in teaching are just as much required as the willingness to participate in the self-governing bodies of the RUB. Furthermore, we expect the candidate to generally get involved in university processes according to RUB’s mission statement. Beside the specific skills the candidate should have a profound didactical qualification to develop new learning environments such as research oriented teaching.

We expect furthermore readiness to participate in interdisciplinary academic work, willingness and ability to attract external funding, ability to work in teams, and the will to participate in collaborative research.

The Ruhr-Universität Bochum is an equal opportunity employer.

06:30 [Event][New]

Submission: 27 October 2013
From January 20 to January 20
Location: Vienna, Austria

2013-08-30
21:47 [Job][New]

UTRCI seeks candidates with expertise in cyber-physical security, wireless sensor networks and embedded systems to join their Networks & Embedded Systems group in Cork, Ireland. The successful candidates are expected to coordinate and primarily execute R&D activities within international projects on cyber-physical systems security. UTRC is developing capability in cyber-physical security to apply to the full range of UTC (http://www.utc.com) products and programs.

The candidate should have a solid background in vulnerability assessment and thorough knowledge of best practices in countermeasures and design processes for secure systems, for example, encryption, authentication and anomaly detection. A successful candidate would also have a solid background in embedded systems and cyber-physical systems with past experience in applying cyber-physical security concepts to the particular constraints of embedded systems, including scalability of countermeasures. Practical experience in identifying and demonstrating both vulnerabilities and countermeasures is highly desirable for this position.

Candidates should have a proven track record of research (top journals and conferences) in cyber-security or cyber-physical security.

The ideal candidate is a self-starter who works well in an international teaming environment, is extremely well-organized and has excellent interpersonal, leadership and communication skills. Besides technical excellence, an entrepreneurial attitude towards innovation is essential.

The candidate should have a PhD in Computer Science, Electrical and Computer Engineering or related fields, with particular expertise in Cyber-Physical Systems and Wireless Sensor Networks. The candidate should also have a strong international publication record and demonstrated ability to do independent research. Fluency in written and spoken English is required.

21:46 [Job][New]

Hochschule Furtwangen University, Germany, Two Full-time Ph.D. Positions

* The Chair for Security in Distributed Systems, computer science Hochschule Furtwangen, Germany, offers two full-time PhD positions

* The position involves research in the area of IT-security within the BMBF project

ProSeCCo \\\'Promotionsvorhaben zur Erarbeitung von Sicherheitserweiterungen für das

Cloud Computing\\\' in cooperation with the Albert-Ludwig University of Freiburg at the \\\'Institut für Informatik und Gesellschaft (IIG) - Telematik\\\' (Prof. Dr.

Günter Müller) and the university of Karlsruhe (KIT) at the \\\'Institut for Kryptographie und Sicherheit (IKS) (Prof. Dr. Jörn Müller-Quade).

The successful candidate is expected to contribute to research in IT-Security and applied cryptography for Cloud Security.

Besides other cloud security related aspects topics of interest for the two open positions are

- application of homomorphic cryptographic primitives for secure cloud storage,

- monitoring- and attestation mechanisms to control information flow between VMs.

* The position is available from November on and is fully funded. The salary scale for both positions is TV-L E13.

The gross income depends on the candidate\\\'s experience level. At the lowest level it corresponds to approx. 40,000 EUR per year.

* Contracts are initially offered for two years. An extension is possible.

* She or he is given the possiblity to carry out a Ph.D.

* The successful candidate should have a Master\\\'s degree in Computer Science, Mathematics, Information Security, or a related field.

Deep Knowledge in cryptography is not a must but an asset.

* The deadline for applications is September 20, 2013. However, late applications will be considered until the position is filled.

21:43 [Event][New]

Submission: 12 April 2014
From August 22 to August 23
Location: Santa Barbara, California, USA

15:17 [Pub][ePrint]

This note reports major previously unpublished security vulnerabilities in the password-only authenticated three-party key exchange protocol due to Lee and Hwang (Information Sciences, 180, 1702-1714, 2010): (1) the Lee-Hwang protocol is susceptible to a man-in-the-middle attack and thus fails to achieve implicit key authentication; (2) the protocol cannot protect clients\' passwords against an offline dictionary attack; and (3) the indistinguishability-based security of the protocol can be easily broken even in the presence of a passive adversary.

15:17 [Pub][ePrint]

We show that (leveled) fully homomorphic encryption (FHE) can be based on the hardness of $\\otild(n^{1.5+\\epsilon})$-approximation for lattice problems (such as GapSVP) under quantum reductions for any $\\epsilon>0$ (or $\\otild(n^{2+\\epsilon})$-approximation under classical reductions). This matches the best known hardness for regular\'\' (non-homomorphic) lattice based public-key encryption up to the $\\epsilon$ factor. A number of previous methods had hit a roadblock at quasipolynomial approximation. (As usual, a circular security assumption can be used to achieve a non-leveled FHE scheme.)

Our approach consists of three main ideas: Noise-bounded sequential evaluation of

high fan-in operations; Circuit sequentialization using Barrington\'s Theorem; and finally,

successive dimension-modulus reduction.