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15:17 [Pub][ePrint] Combining Leakage-Resilient PRFs and Shuffling (Towards Bounded Security for Small Embedded Devices), by Vincent Grosso and Romain Poussier and François-Xavier Standaert and Lubos Gaspar

  Combining countermeasures is usually assumed to be the best way to protect embedded devices against side-channel attacks. These combinations are at least expected to increase the number of measurements of successful attacks to some reasonable extent, and at best to guarantee a bounded time complexity independent of the number of measurements. This latter guarantee, only possible in the context of leakage-resilient constructions, was only reached either for stateful (pseudo-random generator) constructions, or large parallel implementations so far. In this paper, we describe a first proposal of stateless (pseudo-random function) construction, for which we have strong hints that security bounded implementations are reachable under the constraints of small embedded devices. Our proposal essentially combines the well-known shuffling countermeasure with a tweaked pseudo-random function introduced at CHES 2012. We first detail is performances. Then we analyze it against standard differential power analysis and discuss the different parameters influencing its security bounds. Finally, we put forward that its implementation in 8-bit microcontrollers can provide a better security vs. performance tradeoff than state-of-the art (combinations of) countermeasures.

15:17 [Pub][ePrint] Efficient Selection of Time Samples for Higher-Order DPA with Projection Pursuits, by François Durvaux and François-Xavier Standaert and Nicolas Veyrat-Charvillon and Jean-Baptiste Mairy and Yves De

  The selection of points-of-interest in leakage traces is a frequently neglected problem in the side-channel literature. However, it can become the bottleneck of practical adversaries/evaluators as the size of the measurement traces increases, especially in the challenging context of masked implementations, where only a combination of multiple shares reveals information in higher-order statistical moments. In this paper, we describe new (black box) tools for efficiently dealing with this problem. The proposed techniques exploit projection pursuits and optimized local search algorithms, work with minimum memory requirements and practical time complexity. We validate them with two case-studies of unprotected and first-order masked implementations in an 8-bit device, the latter one being hard to analyze with previously known methods.

15:17 [Pub][ePrint] On the Cost of Lazy Engineering for Masked Software Implementations, by Josep Balasch and Benedikt Gierlichs and Vincent Grosso and Oscar Reparaz and François-Xavier Standaert

  Masking is one of the most popular countermeasures to mitigate side-channel analysis. Yet, its deployment in actual cryptographic devices is well known to be challenging, since designers have to ensure that the leakage corresponding to different shares is independent. Several works have shown that such an independent leakage assumption may be contradicted in practice, because of physical effects such as ``glitches\" or ``transition-based\" leakages. As a result, implementing masking securely can be a time-consuming engineering problem. This is in strong contrast with recent and promising approaches for the automatic insertion of countermeasures exploiting compilers, that aim to limit the development time of side-channel resistant software. Motivated by this contrast, we question what can be hoped for these approaches - or more generally for masked software implementations based on careless assembly generation. For this purpose, our first contribution is a simple reduction from security proofs obtained in a (usual but not always realistic) model where leakages depend on the intermediate variables manipulated by the target device, to security proofs in a (more realistic) model where the transitions between these intermediate variables are leaked. We show that the cost of moving from one context to the other implies a division of the security order by two for masking schemes. Next, our second and main contribution is to provide an exhaustive empirical validation of this reduction, based on two microcontrollers, several (handwritten and compiler-based) ways of generating assembly codes, with and without ``recycling\" the randomness used for sharing. These experiments confirm the relevance of our analysis, and therefore quantify the cost of lazy engineering for masking.

15:17 [Pub][ePrint] A Security Proof of KCDSA using an extended Random Oracle Model, by Vikram Singh

  We describe a tight security reduction to the discrete logarithm problem for KCDSA under an extended Random Oracle Model. This is achieved by generalising the signature scheme and producing a security proof for the generalised scheme. We require the application of Randomized Hashing. We also introduce a Challenger to the Random Oracle Model, who is external to the Simulator and Adversary. The Challenger provides oracle returns for one hash function, and challenges which have a low probability of being met. On presentation of a forged signature the Simulator either identifies an edge case which allows solving of a challenge, or solves the discrete logarithm problem. Hence the tight reduction.

05:36 [Pub] New Reviews


The following reviews shall help the IACR members and the community to buy books in cryptology and related areas. The full list of reviews / books is available at

If you have any questions regarding the IACR book reviewing system, or would like to volunteer a review, please contact Edoardo Persichetti (University of Warsaw, Poland) via /books at

New reviews in 2014:
  • R. Lidl, H. Niederreiter: Finite Fields (2nd Edition)
    "This volume gives a comprehensive coverage of the theory of finite fields and its most important applications such as combinatorics and coding theory. Its simple and reader-friendly style, and the inclusion of many worked examples and exercises make it suitable not only as a reference volume for the topic, but also as a textbook for a dedicated course. I highly recommend the book to any person interested in the theory of finite fields and its applications."
    Year: 2008
    ISBN: 978-0-521-06567-2
    Review by Edoardo Persichetti (Warsaw University, Warsaw, Poland). (Date: 2014-01-30)
  • A. McAndrew: Introduction to Cryptography with Open-Source Software
    "This very well written book is recommended to graduate or final year undergraduate students intended to start research work on both theoretical and experimental cryptography. Most of the cryptographic protocols are illustrated by various examples and implemented using the open-source algebra software Sage. The book provides a rigorous introduction to the mathematics used in cryptographic and covers almost all modern practical cryptosystems. Also, the book is certainly a valuable resource for practitioners looking for experimental cryptography with a computer algebra system."
    Year: 2011
    ISBN: 978-1-4398-2570-9
    Review by Abderrahmane Nitaj (LMNO, Université de Caen Basse Normandie, France). (Date: 2014-02-13)
  • B. Martin: Codage, Cryptologie et Applications [French]
    "This French book succinctly describes the mathematical principles of cryptography and error correcting codes. Once these principles are introduced, the book presents their use in some telecommunication applications (at the state of the art in 2004). The book does not define its target audience. It is probably not enough detailed for a skilled audience, nor particularly suitable for beginners and students, since it requires mathematical background that they would have to find elsewhere."
    Year: 2006
    ISBN: 2-88074-569-1
    Review by Eric Diehl (Technicolor, Paris, France). (Date: 2014-02-12)
  • T. Baignères, P. Junod, Y. Lu, J. Monnerat, S. Vaudenay: A Classical Introduction To Cryptography Exercise Book
    "The book's main goal is to show how some mathematical notions of calculus, algebra, and computer science are used to study the security of various cryptosystems. The volume is a collection of exercises, including hints and solutions, and is suitable for advanced undergraduate and graduate students as well as students in computer science and engineering and practitioners who want to understand the mathematical techniques behind cryptography."
    Year: 2006
    ISBN: 978-0-387-27934-3
    Review by Abdelhak Azhari (Hassan II University, Casablanca, Morocco). (Date: 2014-02-12)
  • J. Buchmann, U. Vollmer: Binary Quadratic Forms
    "The theory of binary quadratic forms is important in algebraic number theory. This book offers a good introduction to binary quadratic forms by following an algorithmic approach. It will be useful for students and teachers interested in binary quadratic forms and their cryptographic applications."
    Year: 2007
    ISBN: 978-3-540-46367-2
    Review by S.V. Nagaraj (RMK Engineering College, Kavaraipettai, Tamil Nadu, India). (Date: 2014-05-19)
  • J. Hoffstein, J. Pipher, J. Silverman: An Introduction to Mathematical Cryptography
    "This volume provides an excellent introduction to the mathematics of cryptography. Its simple style make it accessible even to readers without a consistent mathematical background. I highly recommend this book to anyone, in particular non-specialists that are interested in the topic, and students that want to approach cryptography from a mathematical point of view. It is also very useful for instructors in the same context - I personally found it an an invaluable tool for preparing my graduate cryptography course."
    Year: 2008
    ISBN: 978-0-387-77993-5
    Review by Edoardo Persichetti (University of Warsaw, Poland). (Date: 2014-03-27)

17:33 [Event][New] ICISC 2014: The Annual International Conference on Information Security and Cryptology

  Submission: 4 September 2014
Notification: 21 October 2014
From December 3 to December 5
Location: Seoul, Korea
More Information:

14:08 [Job][New] Research Associate (Post-Doc), University College London, the Greater Britain, Europe

  The Computer Science Department at University College London have two openings for postdoctoral researchers in cryptography. The posts are under the supervision of Dr Jens Groth with a duration of up to 2 years and a flexible starting date. Candidates must have a PhD with a strong publication record in cryptography or theoretical computer science.

UCL is one of Europe\\\'s highest ranked universities, has a large and active Information Security group and has recently been recognized by the EPSRC and GCHQ as one of UK\\\'s Academic Centres of Excellence in Cyber Security Research. The Computer Science Department is one of the largest in the UK and is located at UCL\\\'s main campus in the centre of London.

09:17 [Pub][ePrint] Differential Properties of the HFE Cryptosystem, by Taylor Daniels and Daniel Smith-Tone

  Multivariate Public Key Cryptography (MPKC) has been put forth as a possible post-quantum family of cryptographic schemes. These schemes lack provable security in the reduction theoretic sense, and so their security against yet undiscovered attacks remains uncertain. The effectiveness of differential attacks on various field-based systems has prompted the investigation of differential properties of multivariate schemes to determine the extent to which they are secure from differential adversaries. Due to its role as a basis for both encryption and signature schemes we contribute to this investigation focusing on the HFE cryptosystem. We derive the differential symmetric and invariant structure of the HFE central map and provide a collection of parameter sets which make HFE provably secure against a differential adversary.

09:17 [Pub][ePrint] An Asymptotically Optimal Structural Attack on the ABC Multivariate Encryption Scheme, by Dustin Moody and Ray Perlner and Daniel Smith-Tone

  Historically, multivariate public key cryptography has been less than successful at offering encryption schemes which are both secure and efficient. At PQCRYPTO \'13 in Limoges, Tao, Diene, Tang, and Ding introduced a promising new multivariate encryption algorithm based on a fundamentally new idea: hiding the structure of a large matrix algebra over a finite field. We present an attack based on subspace differential invariants inherent to this methodology. The attack is is a structural key recovery attack which is asymptotically optimal among all known attacks (including algebraic attacks) on the original scheme and its generalizations.

09:17 [Pub][ePrint] Composable Oblivious Extended Permutations, by Peeter Laud and Jan Willemson

  An extended permutation is a function f : {1,...,m} -> {1,...,n}, used to map an n-element vector a to an m-element vector b by b_i = a_{f(i)}. An oblivious extended permutation allows this mapping to be done while preserving the privacy of a, b and f in a secure multiparty computation protocol. Oblivious extended permutations have

several uses, with private function evaluation (PFE) being the theoretically most prominent one.

In this paper, we propose a new technique for oblivious evaluation of

extended permutations. Our construction is at least as efficient as the existing techniques, conceptually simpler, and has wider applicability. Our technique allows the party providing the description of f to be absent during the computation phase of the protocol. Moreover, that party does not even have to exist - we show how to compute the private representation of f from private data that may itself be computed from the inputs of parties. In other words, our oblivious extended permutations can be freely composed with other privacy-preserving operations in a multiparty computation.

09:17 [Pub][ePrint] Software implementation of an Attribute-Based Encryption scheme, by Eric Zavattoni and Luis J. Dominguez Perez and Shigeo Mitsunari and Ana H. Sánchez-Ramírez and Tadanori Teruya and Francisco Rodr

  A ciphertext-policy attribute-based encryption protocol uses bilinear pairings to provide

control access mechanisms, where the set of user\'s attributes is specified by means of a linear secret sharing scheme. In this paper we present the design of a software cryptographic library that achieves record timings for the computation of a 126-bit security level attribute-based encryption scheme. We developed all the required auxiliary building blocks and compared the computational weight that each of them adds to the overall performance of this protocol.

In particular, our single pairing and multi-pairing implementations achieve state-of-the-art

time performance at the 126-bit security level.