Oblivious Transfers and Privacy Amplification

Oblivious transfer (OT) is an important primitive in cryptography. In chosen one-out-of-two string OT, a sender offers two strings, one of which the other party, called the receiver, can choose to read, not learning any information about the other string. The sender on the other hand does not obtain any information about the receivers choice. We consider the problem of reducing this primitive to OT for single bits. Previous attempts to doing this were based on self-intersecting codes. We present a new technique for the same task, based on so-called privacy amplification. It is shown that our method has two important advantages over the previous approaches. First, it is more efficient in terms of the number of required realizations of bit OT, and second, the technique even allows for reducing string OT to (apparently) much weaker primitives. An example of such a primitive is universal OT, where the receiver can adaptively choose what type of information he wants to obtain about the two bits sent by the sender subject to the only constraint that some, possibly very small, uncertainty must remain about the pair of bits.     

Generating efficient protocol code from an abstract specification

A protocol compiler takes as input an abstract specification of a protocol and generates an implementation of that protocol. Protocol compilers usually produce inefficient code both in terms of code speed and code size. We show that the combination of two techniques makes it possible to build protocol compilers that generate efficient code. These techniques are: (i) the use of a compiler that generates from the specification a unique tree-shaped automation (rather than multiple independent automata) and (ii) the use of optimization techniques applied at the automation level, i.e., on the branches of the trees. We have developed a protocol compiler that uses both these techniques. The compiler takes as the input a protocol specification written in the synchronous language Esterel. The specification is compiled into a unique automation by the Esterel front end compiler. The automation is then optimized and converted into C code by our protocol optimizer called HIPPCO. HIPPCO improves the code performance and reduces the code size by simultaneously optimizing the performance of the common path and optimizing the size of the uncommon path. We evaluate the gain expected with our approach on a real-life example, namely a working subset of the TCP protocol generated from an Esterel specification. We compare the protocol code generated with our approach to that derived from the standard BSD TCP implementation. The results are very encouraging. HIPPCO-generated code executes up to 25% fewer instructions than the BSD code for input packet processing while only increasing the code size by 25%     

Standards and industrial property

This article is primarily concerned with standards seen as a means for collective appropriation of technological information. It begins with an attempt to throw light on the relationships between standards, patents and licenses. Then we develop a two-stage duopolistic model whereby each firm must decide on a programme of standardization before choosing its level of production. The risks of multiple or inefficient equilibria are strong enough to justify the intervention of standardization organizations to inform and coordinate individual firms. But the paper also explains why some organizations likeetsi try to play a new role by promoting open access to master patents when used in the definition of a standard.     

Système de protection contre les erreurs pour la liaison ionosphérique

This paper presents an error correcting system designed for a 1 200 bit/s self adaptative modem operating on the HF channel. An analysis of error statistics has been made simulating a specific link whose characteristics had been measured beforehand by a HF backscattering probe. The coding system which has been chosen consists of a cascade of two cyclic codes. One corrects long bursts of errors (Kasami code), the other corrects single errors and small bursts (Reed Solomon code). Both codes are interleaved. The overall rate is 50 %. An error correction simulation has shown that in most of the cases studied, with a ber of 10^?4 a coding gain of at least 10^?2 has been achieved.     

Nutritional effects of extrusion-cooking

HTST extrusion-cooking, as a multi-step, multi-function thermal/mechanical process, has permitted a large number of food applications. Beneficial or detrimental changes in the bioavailability and in the content of nutrients may take place during extrusion and are of special interest in the case of bread or meat replacers and of infant or dietetic foods. The present paper reviews the mechanisms underlying these changes, as well as the influence of process conditions and of food mix composition. Special emphasis is placed on the physico-chemical and chemical modifications of protein, starch and dietary fibre.     

Fate and effects of Camembert cheese micro-organisms in the human colonic microbiota of healthy volunteers after regular Camembert consumption

The objective of this study was to determine i) if Camembert cheese micro-organisms could be detected in fecal samples after regular consumption by human subjects and ii) the consequence of this consumption on global metabolic activities of the host colonic microbiota. An open human protocol was designed where 12 healthy volunteers were included: a 2-week period of fermented products exclusion followed by a 4-weeks Camembert ingestion period where 2x40 g/day of Camembert cheese was consumed. Stools were collected from the volunteers before consumption, twice during the ingestion period (2nd and 4th week) and once after a wash out period of 2 weeks. During the consumption of Camembert cheese, high levels of Lactococcus lactis and Leuconostoc mesenteroides were measured in fecal samples using real-time quantitative PCR, reaching median values of 8.2 and 7.5 Log(10) genome equivalents/g of stool. For Ln. mesenteroides, persistence was observed 15 days after the end of Camembert consumption. The survival of Geotrichum candidum was also assessed and the fecal concentration reached a median level of 7.1 Log(10) CFU/g in stools. Except a decreasing trend of the nitrate reductase activity, no significant modification was shown in the metabolic activities during this study.     

Genetic analysis of geraniol metabolism during fermentation

Geraniol produced by grape is the main precursor of terpenols which play a key role in the floral aroma of white wines. We investigated the fate of geraniol during wine fermentation by Saccharomyces cerevisiae. The volatile compounds produced during fermentation of a medium enriched with geraniol were extracted by Stir-bar sorptive extraction and analysed by GC–MS. We were able to detect and quantify geranyl acetate but also citronellyl- and neryl-acetate. The presence of these compounds partly explains the disparition of geraniol. The amounts of terpenyl esters are strain dependant. We demonstrated both by gene overexpression and gene-deletion the involvement of ATF1 enzyme but not ATF2 in the acetylation of terpenols. The affinity of ATF1 enzyme for several terpenols and for isoamyl alcohol was compared. We also demonstrated that OYE2 is the enzyme involved in geraniol to citronellol reduction. Fermenting strain deleted from OYE2 gene produces far less citronellol than wild type strain. Moreover lab strain over-expressing OYE2 allows 87% geraniol to citronellol reduction in bioconversion experiment compared to about 50% conversion with control strain.     

Geographical origin classification of olive oils by PTR-MS

The volatile compositions of 192 olive oil samples from five different European countries were investigated by PTR-MS sample headspace analysis. The mass spectra of all samples showed many masses with high abundances, indicating the complex VOC composition of olive oil. Three different PLS-DA models were fitted to the data to classify samples into ‘country’, ‘region’ and ‘district’ of origin, respectively. Correct classification rates were assessed by cross-validation. The first fitted model produced an 86% success rate in classifying the samples into their country of origin. The second model, which was fitted to the Italian oils only, also demonstrated satisfactory results, with 74% of samples successfully classified into region of origin. The third model, classifying the Italian samples into district of origin, yielded a success rate of only 52%. This lower success rate might be due to either the small class set, or to genuine similarities between olive oil VOC compositions on this tight scale.