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2012-06-13
05:26 [Job][New] Postdoctoral and Research Fellowships, Queensland University of Technology, Brisbane, Australia

 

The Queensland University of Technology (QUT) in Brisbane, Australia, invites applications for its 2012 Vice-Chancellor\'s Research Fellowships. Up to 10 fellowships are available across the university. Areas of interest include all aspects of information security.

QUT has an active research group in cryptography, network security, and digital forensics, with a leading national profile and strong international links.

Applicants for a Postdoctoral Fellowship should have completed (or be under examination for) a PhD and be early career researchers (less than five years in an academic role). Applicants for a Research Fellowship should be established researchers with between five and ten years of research experience since completion of their PhD. Fellows will be offered an appointment on a fixed-term full-time basis for a period of 3 years. Fellowships include a research support grant of $20,000.





2012-06-12
08:23 [PhD][Update] Nicky Mouha: Automated Techniques for Hash Function and Block Cipher Cryptanalysis

  Name: Nicky Mouha
Topic: Automated Techniques for Hash Function and Block Cipher Cryptanalysis
Category:secret-key cryptography

Description:

Cryptography is the study of mathematical techniques that ensure the confidentiality and integrity of information. This relatively new field started out as classified military technology, but has now become commonplace in our daily lives. Cryptography is not only used in banking cards, secure websites and electronic signatures, but also in public transport cards, car keys and garage door openers.

Two building blocks in the domain of cryptography are block ciphers and (cryptographic) hash functions. Block ciphers use a secret key to transform a plaintext into a ciphertext, in such a way that this secret key is needed to recover the original plaintext. Hash functions transform an arbitrary-length message into a fixed-length hash value. These hash values can serve as "fingerprints" for the original messages: it should be infeasible to find two distinct messages with the same hash value (a collision).

Yet, Wang et al. recently showed that finding collisions is feasible for MD5 and SHA-1, two of the most commonly used hash functions today. Although the SHA-2 family currently remains unbroken, its design is very similar. For this reason, the United States National Institute of Standards and Technology (NIST) launched an international competition for a new hash function standard: SHA-3.

The research performed in this Ph.D. thesis closely follows the evaluation period of the SHA-3 competition. Results were obtained for hash functions ARIRANG, BLAKE, ESSENCE, Hamsi, Khichidi-1, LUX, Sarmal, Skein and TIB3. Outside of the competition, results were also obtained for a simplified version of the hash function HAS-V. In the area of cryptographic theory, observations were made on the resistance of regular hash functions against the birthday attack.

The most commonly used hash functions: MD5, SHA-1 and SHA-2, as well two out of the five SHA-3 finalists (BLAKE and Skein) use operations such as addition modulo 2 to the power o[...]


08:20 [Event][New] ESTEL-SEC 2012: ESTEL Security and Privacy Special Track

  Submission: 20 July 2012
Notification: 25 August 2012
From October 2 to October 5
Location: Rome, Italy
More Information: http://estel-sec.dti.unimi.it/


06:17 [Pub][ePrint] The Discrete Logarithm Problem in non-representable rings, by Matan Banin and Boaz Tsaban

  Bergman\'s Ring $E_p$, parameterized by a prime number $p$,

is a ring with $p^5$ elements that cannot be embedded in a ring of matrices over any commutative ring.

This ring was discovered in 1974.

In 2011, Climent, Navarro and Tortosa described an efficient implementation of $E_p$

using simple modular arithmetic, and suggested that this ring may be a useful source

for intractable cryptographic problems.

We present a deterministic polynomial time reduction of the Discrete Logarithm Problem in $E_p$

to the classical Discrete Logarithm Problem in $\\Zp$, the $p$-element field.

In particular, the Discrete Logarithm Problem in $E_p$ can be solved, by conventional computers,

in sub-exponential time.

Along the way, we collect a number of useful basic reductions for the toolbox of discrete logarithm solvers.



06:17 [Pub][ePrint] DECT Security Analysis, by Erik Tews

  DECT is a standard for cordless phones. The intent of this thesis is to evaluate DECT security in a comprehensive way. To secure conversations over the air, DECT uses two proprietary algorithms, namely the DECT Standard Authentication Algorithm (DSAA) for authentication and key derivation, and the DECT Standard Cipher (DSC) for encryption. Both algorithms have been kept secret and were only available to DECT device manufacturers under a None Disclosure Agreement (NDA). The reader is first introduced into the DECT standard. The two algorithms DSAA and DSC have been reverse engineered and are then described in full detail. At first, attacks against DECT devices are presented, that are based on faults made by the manufacturers while implementing the DECT standard. In the next Chapters, attacks against the DSAA and the DSC algorithm are described, that recover the secret keys used by these algorithms faster than by brute force. Thereafter, a attack against the DECT radio protocol is described, that decrypts encrypted DECT voice calls. Finally, an outlook over the next release of the DECT standard is presented, that is expected to counter all attacks against DECT, that are described in this thesis.



06:17 [Pub][ePrint] Revisiting Dedicated and Block Cipher based Hash Functions, by Anupam Pattanayak

  A hash function maps a variable length input into a fixed length output. The hash functions that are used in the information security related applications are referred as cryptographic hash functions. Hash functions are being used as building blocks of many complex cryptographic mechanisms and protocols. Construction of a hash function consists of two components. First component is a compression function and the second component is a domain extender. The various hash function design philosophies try to design the compression function from different angles. Two major categories of hash functions are: dedicated hash functions, and block cipher-based hash functions. These two kinds of design philosophies have been revisited in this paper. Two dedicated has functions from MD4 family - MD4, and SHA-256 constructions have been detailed in this paper. To limit the scope of this paper in this framework, discussions on attacks on hash functions, and SHA-3 finalists have been excluded here.

Keywords:



06:17 [Pub][ePrint] ML Confidential: Machine Learning on Encrypted Data, by Thore Graepel and Kristin Lauter and Michael Naehrig

  We demonstrate that by using a recently proposed somewhat homomorphic encryption (SHE) scheme it is possible to delegate the execution of a machine learning (ML) algorithm to a compute service while retaining confidentiality of the training and test data. Since the computational complexity of the SHE scheme depends primarily on the number of multiplications to be carried out on the encrypted data, we devise a new class of machine learning algorithms in which the algorithm\'s predictions viewed as functions of the input data can be expressed as polynomials of bounded degree. We propose confidential ML algorithms for binary classification based on polynomial approximations to least-squares solutions obtained by a small number of gradient descent steps. We present experimental validation of the confidential ML pipeline and discuss the trade-offs regarding computational complexity, prediction accuracy and cryptographic security.



06:17 [Pub][ePrint] 3D Hardware Canaries, by S├ębastien Briais and St├ęphane Caron and Jean-Michel Cioranesco and Jean-Luc Danger and Sylvain Guilley and Jacques-Henri Jourdan and Arthur Milchior and David Naccache and T

  3D integration is a promising advanced manufacturing process offering a variety of new hardware security protection opportunities. This paper presents a way of securing 3D ICs using Hamiltonian paths as hardware integrity verification sensors. As 3D integration consists in the stacking of many metal layers, one can consider surrounding a security-sensitive circuit part by a wire cage.

After exploring and comparing different cage construction strategies (and reporting preliminary implementation results on silicon), we introduce a \"hardware canary\". The canary is a spatially distributed chain of functions $F_i$ positioned at the vertices of a 3D cage surrounding a protected circuit. A correct answer $(F_n \\circ \\ldots \\circ F_1)(m)$ to a challenge $m$ attests the canary\'s integrity.



06:17 [Pub][ePrint] A note on generalized bent criteria for Boolean functions, by Sugata Gangopadhyay, Enes Pasalic and Pantelimon Stanica

  In this paper, we consider the spectra of Boolean functions

with respect to the action of unitary transforms obtained by

taking tensor products of the Hadamard, denoted by $H$, and the

nega--Hadamard, denoted by $N$,

kernels. The set of all such transforms is denoted by $\\{H, N\\}^n$.

A Boolean function is said to be bent$_4$ if its spectrum

with respect to at least one unitary transform in $\\{H, N\\}^n$ is flat.

We prove that the maximum possible algebraic degree of a bent$_4$

function on $n$ variables is $\\lceil \\frac{n}{2} \\rceil$, and hence

solve an open problem posed by Riera and Parker [cf. IEEE-IT: 52(2)(2006) 4142--4159].

We obtain a relationship between bent and bent$_4$ functions which is

a generalization of the relationship between bent and negabent Boolean

functions proved by Parker and Pott [cf. LNCS: 4893(2007) 9--23].



06:17 [Pub][ePrint] New Proof Methods for Attribute-Based Encryption: Achieving Full Security through Selective Techniques, by Allison Lewko and Brent Waters

  We develop a new methodology for utilizing the prior techniques to prove selective security for functional encryption systems as a direct ingredient in devising proofs of full security. This deepens the relationship between the selective and full security models and provides a path for transferring the best qualities of selectively secure systems to fully secure systems. In particular, we present a Ciphertext-Policy Attribute-Based Encryption scheme that is proven fully secure while matching the efficiency of the state of the art selectively secure systems.



06:17 [Pub][ePrint] Security Analysis of RAPP An RFID Authentication Protocol based on Permutation, by Wang Shao-hui, Han Zhijie, Liu Sujuan, Chen Dan-wei

  One of the key problems in Radio Frequency Identification(RFID) is security and privacy. Many RFID authentication protocols have been proposed to preserve security and privacy of the system. Nevertheless, most of these protocols are analyzed and it is shown that they can not provide security against some RFID attacks. RAPP is a new ultralightweight authentication protocol with permutation. In RAPP, only three operations are involved: bitwise XOR, left rotation and permutation. In this paper, we give an active attack on RAPP. We first collect some authentication messages through impersonating valid tag and readers; Then we forge valid reader to communicate with the tag about times. Using the property of the left rotation and permutation operation, we can deduce the relationship of bits of random number or secret keys at different positions, thus obtain all the secret shared by the reader and the tag.