A Distinguisher-Based Attack of a Homomorphic Encryption Scheme Relying on Reed-Solomon Codes

Bogdanov and Lee suggested a homomorphic public-key encryption scheme based on error correcting codes. The underlying public code is a modified Reed-Solomon code obtained from inserting a zero submatrix in the Vandermonde generating matrix defining it. The columns that define this submatrix are kept secret and form a set $L$. We give here a distinguisher that detects if one or several columns belong to $L$ or not. This distinguisher is obtained by considering the code generated by component-wise products of codewords of the public code (the so called "square code"). This operation is applied to punctured versions of this square code obtained by picking a subset $I$ of the whole set of columns. It turns out that the dimension of the punctured square code is directly related to the cardinality of the intersection of $I$ with $L$. This allows an attack which recovers the full set $L$ and which can then decrypt any ciphertext.Comment: 11 page

A Distinguisher-Based Attack on a Variant of McEliece's Cryptosystem Based on Reed-Solomon Codes

Baldi et \textit{al.} proposed a variant of McEliece's cryptosystem. The main idea is to replace its permutation matrix by adding to it a rank 1 matrix. The motivation for this change is twofold: it would allow the use of codes that were shown to be insecure in the original McEliece's cryptosystem, and it would reduce the key size while keeping the same security against generic decoding attacks. The authors suggest to use generalized Reed-Solomon codes instead of Goppa codes. The public code built with this method is not anymore a generalized Reed-Solomon code. On the other hand, it contains a very large secret generalized Reed-Solomon code. In this paper we present an attack that is built upon a distinguisher which is able to identify elements of this secret code. The distinguisher is constructed by considering the code generated by component-wise products of codewords of the public code (the so-called "square code"). By using square-code dimension considerations, the initial generalized Reed-Solomon code can be recovered which permits to decode any ciphertext. A similar technique has already been successful for mounting an attack against a homomorphic encryption scheme suggested by Bogdanoc et \textit{al.}. This work can be viewed as another illustration of how a distinguisher of Reed-Solomon codes can be used to devise an attack on cryptosystems based on them.Comment: arXiv admin note: substantial text overlap with arXiv:1203.668

Household Food Consumption, Individual Caloric Intake and Obesity in France

We show how to use a long period of observation of all food purchases at the household level to infer the profile of average individual caloric intakes according to the gender, age and the body mass index of household members. Using data from France, we apply this method to analyze the relationship between obesity and individual food consumption. The results show that obese or overweight individuals do absorb more calories at all ages but with differences that vary across gender and ages and across food nutrients such as carbohydrates, lipids or proteins.

Household Food Consumption, Individual Caloric Intake and Obesity in France

We show how to use a long period of observation of all food purchases at the household level to infer the profile of average individual caloric intakes according to the gender, age and the body mass index of household members. Using data from France, we apply this method to analyze the relationship between obesity and individual food consumption. The results show that obese or overweight individuals do absorb more calories at all ages but with differences that vary across gender and ages and across food nutrients such as carbohydrates, lipids or proteins.

Collective and Unitary Models: a Clarification

No abstractunitary; collective; intrahousehold allocation; distribution factors; demand

Distributional Effects in Household Models: Separate Spheres and Income Pooling

We derive distributional effects for a non-cooperative alternative to the unitary model of household behaviour. We consider the Nash equilibria of a voluntary contributions to public goods game. Our main result is that, in general, the two partners either choose to contribute to different public goods or they contribute to at most one common good. The former case corresponds to the separate spheres case of Lundberg and Pollak (1993). The second outcome yields (local) income pooling. A household will be in different regimes depending on the distribution of income within the household. Any bargaining model with this non-cooperative case as a breakdown point will inherit the local income pooling. We conclude that targetting benefits such as child benefits to one household member may not always have an effect on outcomes.Nash equilibrium; Nash bargaining; collective models; intra-household allocation; local income pooling; separate spheres

Distributional effects in household models: separate spheres and income pooling

We derive distributional effects for a non-cooperative alternative to the unitary model of household behaviour. We consider the Nash equilibria of a voluntary contributions to public goods game. Our main result is that, in general, the two partners either choose to contribute to di¤erent public goods or they contribute to at most one common good. The former case corresponds to the separate spheres case of Lundberg and Pollak (1993). The second outcome yields (local) income pooling. A household will be in different regimes depending on the distribution of income within the household. Any bargaining model with this non-cooperative case as a breakdown point will inherit the local income pooling. We conclude that targeting benefits such as child benefits to one household member may not always have an effect on outcomes.

Smart EMI monitoring of thin composite structures

This paper presents a structural health monitoring (SHM) method for in-situ damage detection and localization in carbon fibre reinforced plates (CFRP). The detection is achieved using the electromechanical impedance (EMI) technique employing piezoelectric transducers as high-frequency modal sensors. Numerical simulations based on the finite element method are carried out so as to simulate more than a hundred damage scenarios. Damage metrics are then used to quantify and detect changes between the electromechanical impedance spectrum of a pristine and damaged structure. The localization process relies on artificial neural networks (ANN) whose inputs are derived from a principal component analysis of the damage metrics. It is shown that the resulting ANN can be used as a tool to predict the in-plane position of a single damage in a laminated composite plate