On Constrained Implementation of Lattice-based Cryptographic Primitives and Schemes on Smart Cards, by Ahmad Boorghany and Siavash Bayat Sarmadi and Rasool Jalili
Most lattice-based cryptographic schemes with a security proof suffer from large key sizes and heavy computations. This is also true for the simpler case of authentication protocols which are used on smart cards, as a very-constrained computing environment.
Recent progress on ideal lattices has significantly improved the efficiency, and made it possible to implement practical lattice-based cryptography on constrained devices. However, to the best of our knowledge, no previous attempts were made to implement lattice-based schemes on smart cards.
In this paper, we provide the results of our implementation of several state-of-the-art lattice-based authentication protocols on smart cards and a microcontroller widely used in smart cards. Our results show that only a few of the proposed lattice-based authentication protocols can be implemented using limited resources of such constrained devices, however, cutting-edge ones are suitably-efficient to be used practically on smart cards.
Moreover, we have implemented fast Fourier transform (FFT) and discrete Gaussian sampling with different typical parameters sets, as well as versatile lattice-based public-key encryptions. These results have noticeable points which help to design or optimize lattice-based schemes for constrained devices.
On the Connection between Leakage Tolerance and Adaptive Security, by Jesper Buus Nielsen and Daniele Venturi and Angela Zottarel
We revisit the context of leakage-tolerant interactive protocols as
defined by Bitanski, Canetti and Halevi (TCC 2012). Our contributions
can be summarized as follows:
For the purpose of secure message transmission, any encryption
protocol with message space $\\cM$ and secret key space $\\cSK$
tolerating poly-logarithmic leakage on the secret state of the
receiver must satisfy $|\\cSK| \\ge (1-\\epsilon)|\\cM|$, for every $0
Post-Doc, Cryptolux, University of Luxembourg
The Cryptolux team of the Computer Science and Communications research unit of the University of Luxembourg is looking for a postdoc in Cryptography and Information Security. In particular we are interested in candidates who are experts in one of the following topics:
- Symmetric Cryptography
- Privacy and Anonymity (Tor,I2P, etc.)
- Digital Currencies
- Reverse engineering, code obfuscation
- Network Security
Interested candidates are invited to submit their application by email to lacs.application AT gmail.com. The application material should contain a cover letter explaining the candidate\\\'s expertise, motivation and research interests, a CV (including photo, information about the obtained degrees, overall GPA in B.Sc. and M.Sc., transcript of grades for relevant courses). We expect proven expertise in your area of research by publications at top conferences, successful participation in competitions and challenges, etc.
RSA meets DPA: Recovering RSA Secret Keys from Noisy Analog Data, by Noboru Kunihiro and Junya Honda
We discuss how to recover RSA secret keys from noisy analog data
obtained through physical attacks such as cold boot and side channel
attacks. Many studies have focused on recovering correct secret keys
from noisy binary data. Obtaining noisy binary keys typically involves
first observing the analog data and then obtaining the binary data
through quantization process that discards much information pertaining
to the correct keys. In this paper, we propose two algorithms for
recovering correct secret keys from noisy analog data, which are
generalized variants of Paterson et al.\'s algorithm. Our algorithms
fully exploit the analog information. More precisely, consider observed
data which follows the Gaussian distribution
with mean $(-1)^b$ and variance $\\sigma^2$ for a secret key bit $b$.
We propose a polynomial time algorithm based on
the maximum likelihood approach and show that it can recover secret keys
if $\\sigma < 1.767$. The first algorithm works only if the noise
distribution is explicitly known. The second algorithm does not need to
know the explicit form of the noise distribution. We implement the first
algorithm and verify its effectiveness.
Privacy preserving delegated word search in the cloud, by Kaoutar Elkhiyaoui and Melek Onen and Refik Molva
In this paper, we address the problem of privacy preserving delegated word search in the cloud. We consider a scenario where a data owner outsources its data to a cloud server and delegates the search capabilities to a set of third party users. In the face of semi-honest cloud servers, the data owner does not want to disclose any information about the outsourced data; yet it still wants to benefit from the highly parallel cloud environment. In addition, the data owner wants to ensure that delegating the search functionality to third parties does not allow these third parties to jeopardize the confidentiality of the outsourced data, neither does it prevent the data owner from efficiently revoking the access of these authorized parties. To these ends, we propose a word search protocol that builds upon techniques of keyed hash functions, oblivious pseudo-random functions and Cuckoo hashing to construct a searchable index for the outsourced data, and uses private information retrieval of short information to guarantee that word search queries do not reveal any information about the data to the cloud server. Moreover, we combine attribute-based encryption and oblivious pseudo-random functions to achieve an efficient revocation of authorized third parties. The proposed scheme is suitable for the cloud as it
can be easily parallelized.
A Probabilistic Algebraic Attack on the Grain Family of Stream Cipher, by Pratish Datta and Dibyendu Roy and Sourav Mukhopadhyay
In 2005, Hell, Johansson and Meier submitted a stream cipher proposal named Grain
v1 to the estream call for stream cipher proposals and it also became one estream nalists in the
hardware category. The output function of Grain v1 connects its 160 bits internal state divided
equally between an LFSR and an NFSR, using a non-linear lter function in a complex way. Over
the last years many cryptanalyst identied several weaknesses in Grain v1. As a result in 2011 the
inventors modied Grain v1 and published a new version of Grain named Grain-128a which has
a similar structure as Grain v1 but with a 256 bits internal state with an optional authentication
is the latest version of Grain family resisting all known attacks on Grain v1. However both these
ciphers are quite resistant against the classical algebraic attack due to the rapid growth of the degree
of the key-stream equations in subsequent clockings caused by the NFSR. This paper presents a
probabilistic algebraic attack on both these Grain versions. The basic idea of our attack is to
develop separate probabilistic equations for the LFSR and the NFSR bits from each key-stream
equations. Surprisingly it turns out that in case of Grain-128a our proposed equations hold with all
most sure probability, which makes the sure retrieval of the LFSR bits. We also outline a technique
to reduce the growth of degree of the equations involving the NFSR bits for Grain v1. Further
we high light that the concept of probabilistic algebraic attack as proposed in this paper can be
considered as a generic attack strategy against any stream cipher having similar structure of the
output function as in case of the Grain family.