Cryptanalysis of a multi-chaotic systems based image cryptosystem

This paper is a cryptanalysis of a recently proposed multi-chaotic systems based image cryptosystem. The cryptosystem is composed of two shuffling stages parameterized by chaotically generated sequences. We propose and implement two different attacks which completely break this encryption scheme.Ercan Solak is supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under Project No. 106E143Publisher's Versio

Breaking an orbit-based symmetric cryptosystem

We report a break for a recently proposed class of cryptosystems. The cryptosystem uses constant points of a periodic secret orbit to encrypt the plaintext. In order to break the system, it suffices to sort the constant points and find the initial fixed point. We also report breaks for modified versions of the cryptosystem. In addition, we discuss some efficiency issues of the cryptosystem.Publisher's VersionAuthor's Cop

LA DIVULGATION ENVIRONNEMENTALE DES GRANDES ENTREPRISES FRANCAISES : ETUDE DES DETERMINANTS

International audienceL'objectif de notre recherche est double : explorer l'évolution de la qualité et de l'étendue de la divulgation environnementale des entreprises françaises et développer un modèle empirique de détermination des facteurs susceptibles d'expliquer les stratégies de communication de ce type d'informations. Notre étude est fondée sur la théorie des coûts de l'information (l'approche coûts et bénéfices), la théorie de la légitimité ainsi que certains paramètres de gouvernance qui relèvent du cadre de la théorie de l'agence. En ce qui concerne notre premier objectif, il ressort de nos résultats que nous assistons à un phénomène de convergence au fil du temps dans les pratiques de diffusion environnementale. Par rapport à notre second objectif, les résultats suggèrent que les pressions des parties prenantes financières, la légitimité de l'entreprise, les coûts exclusifs à la firme de même que les coûts de collecte d'informations pour les utilisateurs et quelques paramètres de gouvernance (taille du conseil et présence de membres indépendants en son sein) influencent les stratégies de communication des informations environnementales adoptées par les entreprises françaises

MESURE DE LA QUALITE DE LA DIVULGATION SOCIETALE DES ENTREPRISES FRANCAISES

Le propos de ce papier est de présenter quelques résultats empiriques concernant la mesure du niveau et de la qualité de la divulgation sociétale. Notre outil de mesure est une grille de codage similaire à celle de Wiseman (1982) et Cormier et Magnan (1999 et 2003) et adaptée au contexte légal et réglementaire français, les résultats montrent qu'il y a une progression dans le niveau et la qualité de divulgation sociétale des entreprises françaises.divulgation sociale; divulgation environnementale; coûts de l'information; pressions publiques

LA DIVULGATION ENVIRONNEMENTALE DES GRANDES ENTREPRISES FRANCAISES : ETUDE DES DETERMINANTS

L'objectif de notre recherche est double : explorer l'évolution de la qualité et de l'étendue de la divulgation environnementale des entreprises françaises et développer un modèle empirique de détermination des facteurs susceptibles d'expliquer les stratégies de communication de ce type d'informations. Notre étude est fondée sur la théorie des coûts de l'information (l'approche coûts et bénéfices), la théorie de la légitimité ainsi que certains paramètres de gouvernance qui relèvent du cadre de la théorie de l'agence. En ce qui concerne notre premier objectif, il ressort de nos résultats que nous assistons à un phénomène de convergence au fil du temps dans les pratiques de diffusion environnementale. Par rapport à notre second objectif, les résultats suggèrent que les pressions des parties prenantes financières, la légitimité de l'entreprise, les coûts exclusifs à la firme de même que les coûts de collecte d'informations pour les utilisateurs et quelques paramètres de gouvernance (taille du conseil et présence de membres indépendants en son sein) influencent les stratégies de communication des informations environnementales adoptées par les entreprises françaises.Divulgation environnementale; coûts de l'information; coût exclusifs; gouvernance; légitimité, GRI; NRE

LES NOUVELLES TENDANCES DU REPORTING DEVELOPPEMENT DURABLE : LE SECTEUR AUTOMOBILE EN EUROPE

Cet article se propose d'étudier les nouvelles tendances du reporting DD à la lumière du cadre de la théorie institutionnelle. Nous considérons le reporting DD comme un méta-processus composé de deux principaux processus : 1) l'exercice de pressions institutionnelles motivant le reporting et 2) la livraison du discours de divulgation. Les pressions institutionnelles sont à la fois réglementaires, normatives auxquelles se rajoutent les pressions institutionnelles visant à promouvoir un comportement responsable au sein du secteur d'activité. Ces dernières pressions dépendent du degré de visibilité du secteur d'activité. Le secteur européen de l'automobile est spécialement exposé en raison de l'existence de centaines de PME et son effet multiplicateur sur d'autres secteurs. Ce secteur présente donc des enjeux DD importants. Selon le principe de matérialité, le reporting de ce secteur doit refléter ses propres enjeux DD. Les résultats de cette recherche confirment que le reporting DD dans le secteur automobile est le résultat de différentes catégories de pressions institutionnelles. Nos résultats contribuent aussi à éclairer les relations entre le concept de RSE et les technologies de l'information. Ces résultats suggèrent que nous entrions dans une nouvelle phase de reporting qui met plus l'accent sur les informations clés convenant mieux aux demandes des parties prenantes. Cette évolution a été favorisée par l'utilisation d'Internet.théorie institutionnelle, reporting DD, web, principe de matérialité, GRI

Epidemiology, socio-demographic determinants and outcomes of paediatric facial and dental injuries in Scotland

Facial injury is less common in childhood than adulthood. However, it is still a significant cause of morbidity and presentation in hospital emergency departments. The pattern, time trends, and key socio-demographic determinants of facial injuries in Scottish adults admitted to hospital have previously been reported but this is not the case in the paediatric population and the question of whether such injuries are equally distributed across all socio-economic groups has not been answered. In contrast to the epidemiology of facial injuries in the paediatric population, traumatic dental injuries in children and adolescents have become one of the most frequent forms of treatment in dental practice. This suggests that traumatic dental injuries are common in childhood and are a significant cause of morbidity and presentation in hospital emergency departments. The relationship between socio-economic circumstances and the commonest dental disease (dental caries) in Scotland is well established and children resident in the most deprived areas experience more dental disease. However, this relationship with regard to dental injuries in Scotland has not yet been established. In the same way, many answers to questions regarding the sequelae and prognosis of pulpal and endodontic treatment among traumatised teeth remain unclear. Furthermore, numerous studies have been published examining the long term variables that might have an effect on treatment outcomes of avulsed teeth, but none have yet been able to estimate the long term prognosis of avulsed and replanted teeth. Two studies presented in this thesis are largely the result of population based studies investigating the epidemiology of facial and dental injuries in relation to individual demographics. An additional two studies explore the occurrence of paediatric dental trauma and its general treatment outcomes with a specific focus on estimation of the long term prognosis of avulsed and replanted teeth. To establish the epidemiology of paediatric facial injuries in children and adolescents requiring in-patient hospital admission in Scotland and to report the pattern, time trends, and key socio-demographic determinants of paediatric facial injury in Scotland, a descriptive epidemiological population-based study of the incidence of facial injuries in Scotland (2001-2009) was undertaken. Poisson regression models were employed to assess trends. There were 45,388 (4.7 per 1000 population) facial injury cases registered (2001-2009). 60% of injuries were due to non-intentional causes, 15% to motor vehicle incidents, and 9% to assault. 4.5% were alcohol related. The incidence decreased over time from 5.5/1000 in 2001 to 4.0/1000 in 2009. The risk ratio (RR) for males was 1.98 times greater than females (p < 0.001). RR varied significantly between Health Board areas from 0.68 (Dumfries and Galloway) to 1.76 (Grampian) (p < 0.001). There was a significant association between facial injury and deprivation (p<0.001); SIMD 1 (most deprived) had the highest incidence (6.3 per 1000 population; RR =1.89). The findings of this study provide evidence of a continuing increase in the burden of facial injuries in males especially for those who are living in areas of social deprivation, and in certain geographical areas of Scotland. A population-based investigation was undertaken to investigate the pattern and time trends of dental injuries and their socio-demographic determinants among primary one (P1) children in Scotland. Records of Scottish Health Boards' Dental Epidemiological Programme (SHBDEP) and National Dental Inspection Programme (NDIP) for the period 1993 to 2007 were retrieved from the Dental Health Services Research unit - Dundee. Annual incidences of dental injuries were calculated by age, gender, Health Board and DEPCAT (Carstairs deprivation categories). 68,354 P1 children were examined and only 405 (0.6%) had suffered dental injuries (5.9 per 1000 population). There was a significant decrease in incidence over time (1993 figures were three times greater than 2007). Virtually the same incidence rates were recorded for the two genders. However incidence varied significantly between Health Boards (p<0.001); the highest rate being reported in Dumfries (14.2 per 1000 population), which was 11 times greater than Ayrshire (1.3 per 1000 population). There was no significant association between risk of dental injuries and deprivation; in DEPCAT 1 (most affluent) the incidence rate was 6.4 per 1000 population, while in DEPCAT 7 (most deprived) the incidence rate was 5.7 per 1000 population. The findings of this study provide evidence that the incidence of dental injuries had significantly decreased between 1993 and 2007; gender and deprivation level had no effect on the incidence and risk of dental injuries. A retrospective investigation was undertaken to study the sequelae of non-surgical root canal treatment in traumatised anterior permanent teeth of patients referred to a secondary referral centre. The department dental trauma database was used to randomly identify patients who had sustained dental trauma to their permanent anterior teeth between 1994 and 2008 which required pulpal intervention. A data extraction form was designed and completed for each tooth, and then the data was transcribed and processed. The association between treatment outcomes and clinical variables was studied. 100 permanent anterior teeth (72 patients) were studied. Dental trauma was frequent in the age group 9-11yrs (53.9%). Upper central incisors were the most common teeth involved (43.8%). The male: female ratio was 2:1 with an average age at the time of trauma of 10.31 yrs (SD 2.16 yrs). Home and immediate home environs were the commonest location (18%) while falls (34.8%) and injuries during sport/play (34.8%) were the commonest causes. The commonest injuries in this randomly selected group were enamel-dentine fracture with pulp exposure (34.8%) and avulsion (28%). 66.3% received a first treatment intervention less than 24 hours following the injury. Root canal treatment was the most frequent treatment provided, especially for dental avulsion cases (100%). Treatment outcomes were split into three categories: Success (53.4%); Short-term success but long-term failure (35.6%); and Failure (11%). Significantly fewer failures occurred with: developing roots compared to completed roots (P=0.05); a good quality temporary filling (P<0.003); no mobility (P<0.001); and less than one hour extra alveolar dry time (P =0.02). No significance was reached with regard to: condition of root canal (P=0.095); extra alveolar time (EAT) (P=0.191); and type of storage medium (P=0.43). To assess and identify early clinical variables that are most predictive of treatment outcomes for avulsed and replanted permanent anterior teeth and to develop a model that will allow estimation of treatment outcome based on these variables, a retrospective study was designed and undertaken, where the dental trauma database was used to randomly identify patients who had sustained dental trauma on their permanent teeth leading to avulsion between 1998 and 2007. A data extraction form was designed and completed for each tooth. Demographic, diagnostic and treatment information recorded in the patient’s records, in addition to radiographs, were viewed and then transcribed and processed. The significance for each early clinical variable was assessed using a univariate logistic regression model. Only significant variables (P ≤ 0.05) were considered eligible for the prediction model and a c-index was then constructed for their respective predictive power. 213 patients who had received treatment for avulsed and replanted teeth between 1998 and 2007 were studied and only 105 fulfilled the criteria for evaluation. Two models (‘at first visit’ and ‘at initial treatment visits’) were produced with a total of five variables holding statistical significance and the greatest predictive power (P ≤ 0.05, high c-index): patient age (P ≤ 0.001, c = 0.80); stage of root formation (P ≤ 0.001, c = 0.76); storage medium (P ≤ 0.047, c = 0.58); tooth mobility after dressing (P ≤ 0.001, c = 0.70); and tooth mobility after splinting (P = 0.03, c = 0.70) (0.5 = no predictive power, 1.0 = perfect prediction). These underwent multivariate analysis and the final models had high predictive abilities (c-index of 0.80 and 0.74). These findings provide an indication that patient age; stage of root formation; storage medium; tooth mobility after dressing and tooth mobility after splinting were the early clinical variables that were most predictive of treatment outcome. These models will enable clinicians to estimate the long term prognosis of avulsed and replanted teeth and will make it easier to plan further treatment with a realistic view of outcome at an early stage. To conclude, this thesis has made contributions in several areas. The descriptive elements have described the ‘recent’ trends in facial and dental injuries among the paediatric population across Scotland in relation to age, gender, aetiology, socio-economic circumstances and geographic region. The socio-economic analysis has improved the understanding of the extent of socio-demographic trends in paediatric dental and facial injuries in Scotland. The findings of these studies, having been described, will become a baseline reference for the recent burden of dental and facial injury in Scotland with relation to socio-demographic determinants. The retrospective descriptive analysis of dental trauma and especially dental avulsion will enable clinicians to identify and determine the clinical variables that are the most predictive of treatment outcomes and permit the development of models that will enable the prediction of outcomes for future replanted avulsed teeth. These models will make it easier to plan for further treatment with a realistic view of outcome at an early stage

LE CONCEPT DE LA VALEUR DURABLE : UNE APPLICATION AU SECTEUR DE L'ENERGIE EN FRANCE

Cette recherche applique l'approche de la Valeur Durable aux grands groupes du secteur de l'énergie en France au cours de la période 2005-2007. La valeur durable étend la logique de l'évaluation classique de la performance d'un investissement aux ressources environnementales et sociales. L'utilisation des ressources par l'entreprise est ainsi comparée à l'utilisation des ressources par un benchmark. Le coût de la ressource est donc défini par son coût d'opportunité et la contribution de l'entreprise à la durabilité est exprimée en termes monétaires. Nos résultats montrent des tendances à la variabilité de la valeur durable des multinationales de l'énergie. TOTAL est le « leader » du secteur en réalisant une valeur durable positive tout au long de la période. Ce groupe utilise les ressources « triple-bottom-line » d'une manière créatrice de valeur.valeur durable, mesure, coût d'opportunité, benchmark

On the security of a new image encryption scheme based on chaotic map lattices

This paper reports a detailed cryptanalysis of a recently proposed encryption scheme based on the logistic map. Some problems are emphasized concerning the key space definition and the implementation of the cryptosystem using floating-point operations. It is also shown how it is possible to reduce considerably the key space through a ciphertext-only attack. Moreover, a timing attack allows the estimation of part of the key due to the existent relationship between this part of the key and the encryption/decryption time. As a result, the main features of the cryptosystem do not satisfy the demands of secure communications. Some hints are offered to improve the cryptosystem under study according to those requirements.Comment: 8 pages, 8 Figure