Depuis la fin des années 90, les cryptosystèmes implantés sur carte à puce doivent faire face à deux grandes catégories d'attaques : les attaques par canaux cachés et les attaques par injection de fautes. Pour s'en prémunir, des contre-mesures sont élaborées, puis validées en considérant un modèle d'attaquant bien défini. Les travaux réalisés dans cette thèse se concentrent sur la protection des cryptosystèmes symétriques contre les attaques par canaux cachés. Plus précisément, on s'intéresse aux contre-mesures de masquage permettant de se prémunir des attaques statistiques d'ordre supérieur pour lesquelles un attaquant est capable de cibler t valeurs intermédiaires. Après avoir rappelé l'analogie entre les contre-mesures de masquage et les schémas de partage de secret, on présente la construction des schémas de partage de secret à partir de codes linéaires, introduite par James L. Massey en 1993. En adaptant cette construction et des outils issus du calcul multi-parties, on propose une méthode générique de contre-mesure de masquage résistante aux attaques statistiques d'ordre supérieur. De plus, en fonction des cryptosystèmes à protéger et donc des opérations à effectuer, cette solution permet d'optimiserle coût induit par les contre-mesures en sélectionnant les codes les plus adéquats. Dans cette optique, on propose deux contre-mesures de masquage pour implanter le cryptosystème AES. La première est basée sur une famille de code d'évaluation proche de celle utilisée pour le schéma de partage de secret de Shamir, tandis que la seconde considéré la famille des codes auto-duaux et faiblement auto-duaux ayant leur matrice génératrice à coefficient sur F2 ou F4. Ces deux alternatives se révèlent plus efficaces que les contremesures de masquage publiées en 2011 et basées sur le schéma de partage de secret de Shamir. De plus la seconde s'avère compétitive pour t=1 comparée aux solutions usuelles. / Since the late 90s, the implementation of cryptosystems on smart card faces two kinds of attacks : side-channel attacks and fault injection attacks. Countermeasures are then developed and validated by considering a well-defined attacker model. This thesis focuses on the protection of symmetric cryptosystems against side-channel attacks. Specifically, we are interested in masking countermeasures in order to tackle high-order attacks for which an attacker is capable of targeting t intermediate values. After recalling the analogy between masking countermeasures and secret sharing schemes, the construction of secret sharing schemes from linear codes introduced by James L. Massey in 1993 is presented.By adapting this construction together with tools from the field of Multi-Party Computation, we propose a generic masking countermeasure resistant to high-order attacks. Furthermore, depending on the cryptosystem to protect, this solution optimizes the cost of the countermeasure by selecting the most appropriate code. In this context, we propose two countermeasures to implement the AES cryptosystem. The first is based on a family of evaluation codes similar to the Reed Solomon code used in the secret sharing scheme of Shamir. The second considers the family of self-dual and self-orthogonal codes generated by a matrix defined over GF(2) or GF(4). These two alternatives are more effective than masking countermeasures from 2011 based on Shamir's secret sharing scheme. Moreover, for t=1, the second solution is competitive with usual solutions.

In the present work, CO2 corrosion of API 5L X65 pipeline steel in the presence of acetic acid (HAc) was investigated. The objective of this research was to study a qualitative behaviour frequently found in the case of the so-called top-of-line corrosion (TLC). That is, increasing corrosion rates and steep shrinkage after certain - not predictable - time delay. The focus was on the role of HAc in the growth and stifling of localized attacks in CO2-containing media. The kinetic behaviours of carbon steel in such brines indicated that the overall effect of HAc is a balance between an enhanced cathodic reaction rate and a slightly inhibited anodic reaction rate. Results also showed that the active dissolution is not directly related to the presence of acetic acid but rather to what is generically referred to as CO2 corrosion. Zero resistance ammeter (ZRA) measurements on artificial pit electrode assembly, coupled to numerical simulation results, indicated that local HAc concentration gradients sustain the pit growth mechanism to a certain critical depth. Beyond this critical depth, the coupling current sharply drops off and the pit undergoes a process of stifling. However, a substantial effect of the purely ohmic drop on the pit stabilization process appeared unlikely in such conditions. Instead, initiated pits were shown to propagate and stifle mainly according to the counteracting depletions of HAc and CO2. On the basis of the obtained results, a complete scenario was therefore proposed for the morphological trend of localized attacks, which is in good agreement with field occurring TLC cases.

<p>The aim of this study was to find out if the use of the concepts ‘terrorism' and ‘organized crime' has changed after the event on 11 September, 2001 when terrorists attacked World Trade Center and Pentagon. In this study I make use of discourse theory in a way which is inspired by the writings of Winther Jorgensen and Phillips. Knowledge acquired through this research has been primarily generated from two Swedish Government Official Reports concerning questions arising from introducing secret police surveillance. In these reports, there are many opinions from authorities whom have given their thoughts on introducing new ways of policing which are very interesting to analyze. The results shows that the ways the concepts have been used have changed after the terrorists attacks. The same holds true for how the authorities describe their will to combat crime. Terrorism has been described as something that pose a near none existent problem before the terrorist attack, afterwards it is described as a risk that poses a major threat to the whole society. The organized crime has been described as something which has been going from a relatively controllable problem to one that undermines the judicial system and the democratic state.</p>

<p>Biometrics deals with identifying individuals with help of their biological data. Fingerprint scanning is the most common method of the biometric methods available today. The security of fingerprint scanners has however been questioned and previous studies have shown that fingerprint scanners can be fooled with artificial fingerprints, i.e. copies of real fingerprints. The fingerprint recognition systems are evolving and this study will discuss the situation of today. </p><p>Two approaches have been used to find out how good fingerprint recognition systems are in distinguishing between live fingers and artificial clones. The first approach is a literature study, while the second consists of experiments. </p><p>A literature study of liveness detection in fingerprint recognition systems has been performed. A description of different liveness detection methods is presented and discussed. Methods requiring extra hardware use temperature, pulse, blood pressure, electric resistance, etc., and methods using already existent information in the system use skin deformation, pores, perspiration, etc. </p><p>The experiments focus on making artificial fingerprints in gelatin from a latent fingerprint. Nine different systems were tested at the CeBIT trade fair in Germany and all were deceived. Three other different systems were put up against more extensive tests with three different subjects. All systems werecircumvented with all subjects'artificial fingerprints, but with varying results. The results are analyzed and discussed, partly with help of the A/R value defined in this report.</p>

Thesis (M.A.)--Ohio University, June, 2006. / Title from PDF t.p. Includes bibliographical references (p. 78-81)

The aim of this study was to find out if the use of the concepts ‘terrorism' and ‘organized crime' has changed after the event on 11 September, 2001 when terrorists attacked World Trade Center and Pentagon. In this study I make use of discourse theory in a way which is inspired by the writings of Winther Jorgensen and Phillips. Knowledge acquired through this research has been primarily generated from two Swedish Government Official Reports concerning questions arising from introducing secret police surveillance. In these reports, there are many opinions from authorities whom have given their thoughts on introducing new ways of policing which are very interesting to analyze. The results shows that the ways the concepts have been used have changed after the terrorists attacks. The same holds true for how the authorities describe their will to combat crime. Terrorism has been described as something that pose a near none existent problem before the terrorist attack, afterwards it is described as a risk that poses a major threat to the whole society. The organized crime has been described as something which has been going from a relatively controllable problem to one that undermines the judicial system and the democratic state.

Panikattacken sind mit einer Lebenszeitprävalenz von ungefähr 15% ein relativ häufiges Phänomen im Gegensatz zu einer vollen Panikstörung, die eine Prävalenz von 2,3–3% aufweist. In der vorliegenden epidemiologischen Untersuchung (n = 481) einer bundesweiten repräsentativen Stichprobe wurde geprüft, ob früh (vor dem 25. Lebensjahr) und spat auftretende Panikattacken sich hinsichtlich Symptomatik, Verlaufs- und Komorbiditätsmustern unterscheiden. Neben einer erhöhten Angstsymptomatik, insbesondere bezüglich respiratorischer Beschwerden und der Angst zu sterben, zeigte sich bei Panikattacken mit spätem Beginn ein erhöhtes Risiko für Multimorbidität. Auch entwickelten sich bei dieser Gruppe komorbide Bedingungen schneller. Dagegen waren Panikattacken mit frühem Beginn und einem erhöhten Risiko für Agoraphobie sowie phobische Störungen verbunden. Die Ergebnisse werden im Hinblick auf pathogenetische Mechanismen und Implikationen für die Planung therapeutischer Interventionen diskutiert.

Background: The learning perspective of panic disorder distinguishes between acute panic and anxious apprehension as distinct emotional states. Following animal models, these clinical entities reflect different stages of defensive reactivity depending upon the imminence of interoceptive or exteroceptive threat cues. The current study tested this model by investigating the dynamics of defensive reactivity in a large group of patients with panic disorder and agoraphobia (PD/AG). Methods: Three hundred forty-five PD/AG patients participated in a standardized behavioral avoidance test (being entrapped in a small, dark chamber for 10 minutes). Defense reactivity was assessed measuring avoidance and escape behavior, self-reports of anxiety and panic symptoms, autonomic arousal (heart rate and skin conductance), and potentiation of the startle reflex before and during exposure of the behavioral avoidance test. Results: Panic disorder and agoraphobia patients differed substantially in their defensive reactivity. While 31.6% of the patients showed strong anxious apprehension during this task (as indexed by increased reports of anxiety, elevated physiological arousal, and startle potentiation), 20.9% of the patients escaped from the test chamber. Active escape was initiated at the peak of the autonomic surge accompanied by an inhibition of the startle response as predicted by the animal model. These physiological responses resembled the pattern observed during the 34 reported panic attacks. Conclusions: We found evidence that defensive reactivity in PD/AG patients is dynamically organized ranging from anxious apprehension to panic with increasing proximity of interoceptive threat. These data support the learning perspective of panic disorder.

Design and analysis of lightweight block ciphers have become more popular due to the fact that the future use of block ciphers in ubiquitous devices is generally assumed to be extensive. In this respect, several lightweight block ciphers are designed, of which HIGHT is proposed by Hong et al. at CHES 2006 as a constrained hardware oriented block cipher. HIGHT is shown to be highly convenient for extremely constrained devices such as RFID tags and sensor networks and it became a standard encryption algorithm in South Korea. Impossible differential cryptanalysis is a technique discovered by Biham et al. and is applied to many block ciphers including Skipjack, IDEA, Khufu, Khafre, HIGHT, AES, Serpent, CRYPTON, Twofish, TEA, XTEA and ARIA. The security of HIGHT against impossible differential attacks is investigated both by Hong et al. and Lu: An 18-round impossible differential attack is given in the proposal of HIGHT and Lu improved this result by giving a 25-round impossible differential attack. Moreover, Lu found a 28-round related-key impossible differential attack which is the best known attack on HIGHT. In related-key attacks, the attacker is assumed to know the relation between the keys but not the keys themselves. In this study, we further analyzed the resistance of HIGHT against impossible differential attacks by mounting a new 26-round impossible differential attack and a new 31-round related-key impossible differential attack. Although our results are theoretical in nature, they show new results in HIGHT and reduce its security margin further.

Worldwide computer systems continue to execute malicious software that degrades the systemsâ performance and consumes network capacity by generating high volumes of unwanted traffic. Network-based detectors can effectively identify machines participating in the ongoing attacks by monitoring the traffic to and from the systems. But, network detection alone is not enough; it does not improve the operation of the Internet or the health of other machines connected to the network. We must identify malicious code running on infected systems, participating in global attack networks. This dissertation describes a robust and secure approach that identifies malware present on infected systems based on its undesirable use of network. Our approach, using virtualization, attributes malicious traffic to host-level processes responsible for the traffic. The attribution identifies on-host processes, but malware instances often exhibit parasitic behaviors to subvert the execution of benign processes. We then augment the attribution software with a host-level monitor that detects parasitic behaviors occurring at the user- and kernel-level. User-level parasitic attack detection happens via the system-call interface because it is a non-bypassable interface for user-level processes. Due to the unavailability of one such interface inside the kernel for drivers, we create a new driver monitoring interface inside the kernel to detect parasitic attacks occurring through this interface. Our attribution software relies on a guest kernelâ s data to identify on-host processes. To allow secure attribution, we prevent illegal modifications of critical kernel data from kernel-level malware. Together, our contributions produce a unified research outcome --an improved malicious code identification system for user- and kernel-level malware.