International Association for Cryptologic Research

# IACR News Central

You can also access the full news archive.

Further sources to find out about changes are CryptoDB, ePrint RSS, ePrint Web, Event calender (iCal).

2012-11-20
13:17 [Pub][ePrint]

Coin-tossing protocols are protocols that generate a random bit with uniform distribution. These protocols are used as a building block in many cryptographic protocols. Cleve [STOC 1986] has shown that if at least half of the parties can be malicious, then, in any r-round coin-tossing protocol, the malicious parties can cause a bias of Omega(1/r) to the bit that the honest parties output. However, for more than two decades the best known protocols had bias t/\\sqrt{r}, where t is the number of corrupted parties. Recently, in a surprising result, Moran, Naor, and Segev [TCC 2009] have shown that there is an r-round two-party coin-tossing protocol with the optimal bias of O(1/r). We extend Moran et al. results to the multiparty model when less than 2/3 of the parties are malicious. The bias of our protocol is proportional to 1/r and depends on the gap between the number of malicious parties and the number of honest parties in the protocol. Specifically, for a constant number of parties or when the number of malicious parties is somewhat larger than half, we present an r-round m-party coin-tossing protocol with optimal bias of O(1/r).

13:17 [Pub][ePrint]

The indifferentiability framework of Maurer, Renner, and Holenstein (MRH) has gained immense popularity in recent years and has proved to be a powerful way to argue security of cryptosystems that enjoy proofs in the random oracle model. Recently, however, Ristenpart, Shacham, and Shrimpton (RSS) showed that the composition theorem of MRH has a more limited scope than originally thought, and that extending its scope required the introduction of reset-indifferentiability, a notion which no practical domain extenders satisfy with respect to random oracles.

In light of the results of RSS, we set out to rigorously tackle the specifics of indifferentiability and reset-indifferentiability by viewing the notions as special cases of a more general definition. Our contributions are twofold. Firstly, we provide the necessary formalism to refine the notion of indifferentiability regarding composition. By formalizing the definition of stage minimal games we expose new notions lying in between regular indifferentiability (MRH) and reset-indifferentiability (RSS).

Secondly, we answer the open problem of RSS by showing that it is impossible to build any domain extender which is reset-indifferentiable from a random oracle. This result formally confirms the intuition that reset-indifferentiability is too strong of a notion to be satisfied by any hash function. As a consequence we look at the weaker notion of single-reset-indifferentiability, yet there as well we demonstrate that there are no meaningful\'\' domain extenders which satisfy this notion. Not all is lost though, as we also view indifferentiability in a more general setting and point out the possibility for different variants of indifferentiability.

13:17 [Pub][ePrint]

Hierarchical Key Assignment Schemes can be used to enforce access control policies by cryptographic means. In this paper, we present a new, enhanced security model for such schemes. We also give simple, efficient, and strongly-secure constructions for Hierarchical Key Assignment Schemes for arbitrary hierarchies using pseudorandom functions and forward-secure pseudorandom generators. We compare instantiations of our constructions with state-of-the-art Hierarchical Key Assignment Schemes, demonstrating that our new schemes possess an attractive trade-off between storage requirements and efficiency of key derivation.

2012-11-19
13:41 [Job][New]

The Government Communications Headquarters (GCHQ) in Cheltenham has agreed in principle to sponsor two PhD/Doctoral Studentships at Bristol University in the area of Cryptography.

The studentships are only open to UK nationals and the successful candidate will be required to spend in the region of 2 - 4 weeks per year at GCHQ headquarters in Cheltenham. To be considered for this studentship, candidates must therefore be prepared to undergo GCHQ\\\'s security clearance procedures.

The two studentships will be in the following areas:

Title: Authentication, Ciphers, and Encryption

Supervisors: Dan Page and Martijn Stam

Title: Information Leakage aware Verification

Supervisors: Elisabeth Oswald and Kerstin Eder

13:32 [Event][New]

Submission: 27 November 2012
From March 25 to March 29
Location: Yogyakarta, Indonesia

13:32 [Event][New]

Submission: 22 February 2013
From July 29 to July 31
Location: Reykjavk, Iceland

2012-11-14
09:55 [Job][New]

The University of Luxembourg seeks to hire an outstanding researcher for the Applied Security and Information Assurance (APSIA) group at its Interdisciplinary Centre for Security, Reliability and Trust (SnT). SnT is a recently formed centre carrying out interdisciplinary research in secure, reliable and trustworthy ICT systems and services, often in collaboration with industrial, governmental or international partners. The APSIA group is also associated with Laboratory of Algorithmics, Cryptology and Security (LACS) of the Computer Science and Communications Research Unit (CSC), which is part of the international and multidisciplinary Faculty of Science, Technology and Communication (FSTC) in University of Luxembourg.

REF : F1-070079

Fixed-term contract 3 years, full-time (40 hrs/week)

Number of Positions : 1

The PhD topic is to design and analyse lattice-based cryptosystems. The research focus will mainly be on (but not limited to) investigating lattice-related hardness assumptions, both in terms of classical and quantum models of computation, and then designing novel, practical lattice-based public-key cryptosystems. Other classes of “hard” problems, for example based on coding theory and braid groups, will also be investigated.

The student will work closely with Prof. Peter Y. A. Ryan and Dr. Qiang Tang. Moreover, the student will be encouraged to work with other members in the APSIA group and collaborate with researchers from other related research units, such as LACS.

09:55 [Job][New]

The Horst Görtz Institute for IT-Security (HGI) at Ruhr-University Bochum is one of Europe’s leading research centers in IT security. The DFG, or German Research Foundation, awarded more than €4 million to the HGI for the establishment of the interdisciplinary research training group “New Challenges for Cryptography in Ubiquitous Computing”. We are looking for candidates with outstanding Master/Diplom in the fields of computer science, electrical engineering, mathematics or related areas.

The research training group will study problems which are fundamental for securing the Internet of Things. The research is structured in three levels: cryptographic primitives, device and system level. The research topics range from cryptographic foundations such as fully homomorphic encryption for privacy in cloud computing, over security for medical implants to internet security solutions involving new national ID cards. A central goal of the doctoral training is an interdisciplinary and structured education at the highest scientific level. Establishing networks to top internationally research groups is part of the training.

A group of internationally renowned researchers together with excellent funding provides an extremely interesting scientific environment. The HGI is known for its good working atmosphere.

The Ruhr-University Bochum supports women‘s career development. Applications from women are thus explicitly welcome. In those areas in which women are underrepresented they will be considered preferentially according to the regulations of the „Landesgleichstellungsgesetz” if their abilities, aptitude and professional performance are equal with those of the fellow applicants unless reasons concerning the person of a fellow applicant are predominant.

In case of equal qualification, applications of severely disabled persons or persons that are regarded as being on a par with severely disable

06:25 [Job][New]

PhD students and post-docs who wish to do research on mathematical aspects of cryptography (most notably, noncommutative algebraic cryptography), are solicited.

The students will be hosted by and collaborate with Dr. Boaz Tsaban of the Department of Mathematics, Bar-Ilan University (BIU), and have the opportunity to interact with several crypto groups located in BIU.

There are two categories:

1. French citizens under 28 years old.

Details: http://u.cs.biu.ac.il/~tsaban/TXT/France-Israel.txt

2. Danish citizens.

Details: http://u.cs.biu.ac.il/~tsaban/Pdf/Danish-Israel.pdf

06:24 [Event][New]

Submission: 10 May 2013