Post-Doc, Technical University Denmark, Copenhagen
Postdoc within the area of Symmetric Cryptography
Applications are invited for an 18 month (with a possible extension of 6 months) Postdoc position at the Danish-Chinese Center for Applications of Algebraic Geometry in Coding and Cryptology. The center is located at the Department of Mathematics at the Technical University of Denmark. The position is available from July 2012 or earliest thereafter.
The candidate should have a PhD degree or academic qualifications equivalent to the PhD level, and should have a strong background in symmetric cryptography. This is usually demonstrated by having publications in well established journals and/or conferences.
As it is essential for the project to establish research connections with China, applicants are expected to be willing to actively establish these connections. This ideally includes one or several visits to the East China Normal University.
Salary and terms of employment
The appointment will be based on the collective agreement with the Confederation of Professional Associations. The allowance will be agreed with the relevant union.
The period of employment is 18 months.
Further information about the project may be reached by contacting Associate Professor Gregor Leander, tel. (+45) 4525 3055, g.leander (at) mat.dtu.dk
We must have your online application no later than 31 May 2012. See http://www.mat.dtu.dk/English/Om_instituttet/Matjob/JobOversigt.aspx?guid=3ba4aac2-107e-4958-886a-daa25bb444e4 for details.
Research Fellow, Nanyang Technological University, Singapore
Physical Analysis and Cryptographic Engineering (PACE) Labs at Nanyang Technological University are seeking 2 Research Scientists in the area of side-channel and fault attacks. The newly founded lab is dedicated to all aspects of side-channel and fault attacks and offers brand-new facilities, a very diverse international research environment, and the opportunity to undertake independent research.
Candidates shall hold, or expect to obtain, a Ph.D. in Computer Sciences, Electrical Engineering, Mathematics or a related field. A solid background in one or several areas of Information Theory, Digital Signal Processing, Statistics, Mutual Information Analysis, DEMA attacks, fault attacks, practical measurements, lightweight implementations (software and/or hardware) would be considered an advantage.
Starting date is in May 2012 and funding is available for 3 years, thus the contract will be for up to 3 years (depending on the successful candidates\' ability to start working in Singapore).
Salaries are competitive and are determined according to the successful applicants\' accomplishments, experience and qualifications.
Interested applicants with a strong publication record in the fields of side-channel and/or fault attacks are encouraged to submit their application including:
1) cover letter,
2) detailed CV,
3) filled personal particulars form*, and
4) names/contact emails of 2 references
to Prof. Axel Poschmann aposchmann (at) ntu.edu.sg.
Review of applications starts immediately and will continue until positions are filled.
* accesible via http://www.spms.ntu.edu.sg/MAS/Document/Graduate/Personal%20particulars%20form_research%20staff.doc
Logic Minimization Techniques with Applications to Cryptology
Abstract A new technique for combinational logic optimization is described. The technique is a two-step process. In the first step, the nonlinearity of a circuit—as measured by the number of nonlinear gates it contains—is reduced. The second step reduces the number of gates in the linear components of the already reduced circuit. The technique can be applied to arbitrary combinational logic problems, and often yields improvements even after optimization by standard methods has been performed. In this paper we show the results of our technique when applied to the S-box of the Advanced Encryption Standard (FIPS in Advanced Encryption Standard (AES), National Institute of Standards and Technology, 2001). We also show that, in the second step, one is faced with an NP-hard problem, the Shortest Linear Program (SLP) problem, which is to minimize the number of linear operations necessary to compute a set of linear forms. In addition to showing that SLP is NP-hard, we show that a special case of the corresponding decision problem is Max SNP-complete, implying limits to its approximability. Previous algorithms for minimizing the number of gates in linear components produced cancellation-free straight-line programs, i.e., programs in which there is no cancellation of variables in GF(2). We show that such algorithms have approximation ratios of at least 3/2 and therefore cannot be expected to yield optimal solutions to nontrivial inputs. The straight-line programs produced by our techniques are not always cancellation-free. We have experimentally verified that, for randomly chosen linear transformations, they are significantly smaller than the circuits produced by previous algorithms.
- Content Type Journal Article
- Pages 1-33
- DOI 10.1007/s00145-012-9124-7
- Joan Boyar, Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark
- Philip Matthews, Aarhus University, Aarhus, Denmark
- René Peralta, Information Technology Laboratory, NIST, Gaithersburg, MD, USA
From: Thu, 03 May 2012 07:37:37 GMT
- Journal Journal of Cryptology
- Online ISSN 1432-1378
- Print ISSN 0933-2790
Cryptography from tensor problems, by Leonard J. Schulman
We describe a new proposal for a trap-door one-way function.
The new proposal belongs to the ``multivariate quadratic\'\'
family but the trap-door is different from existing methods,
and is simpler.
Known quantum algorithms do not appear to help an adversary
attack this trap-door. (Beyond the asymptotic
square-root-speedup which applies to all oracle search
On the Equivalence between the Set Covering Problem and the Problem of Finding Optimal Cumulative Assignment Schemes, by Qiang Li and Xiangxue Li and Dong Zheng and Zheng Huang and Kefei Chen
A cumulative assignment scheme (CAS for short) is a special type of secret sharing schemes. For any given access structure (AS), a CAS which minimizes the cardinality of the primitive share set (the average information rate, or the worst information rate) is called an optimal CAS and can be constructed via solving some binary integer programming (BIP). The problem of finding optimal CAS\'s for complete AS\'s is solved.
We consider in this paper the problem of finding optimal CAS\'s for incomplete AS\'s. The paper introduces some notions including the connected-super-forbidden-family and the lower-forbidden-family for AS\'s. We show that an optimal CAS can be derived from some smaller sized BIP whose variables (constraints, resp.) are based on the connected-super-forbidden-family (lower-forbidden-family, resp.) of the given AS. The paper further builds the close relationship between the problem of finding optimal CAS\'s and the set covering problem (SCP). We prove that the problem of finding a CAS with minimum cardinality of the primitive share set (or minimum average information rate) is equivalent to the SCP, and thus is NP-hard. Other contributions of the paper include: 1) two types of AS\'s are recognized so that we can construct the corresponding optimal CAS\'s directly; and 2) a greedy algorithm is proposed to find CAS\'s with smaller worst information rate.