A Vector Approach to Cryptography Implementation

International audienceThe current deployment of Digital Right Management (DRM) schemes to distribute protected contents and rights is leading the way to massive use of sophisticated embedded cryptographic applications. Embedded microprocessors have been equipped with bulky and power-consuming co-processors designed to suit particular data sizes. However, flexible cryptographic platforms are more desirable than devices dedicated to a particular cryptographic algorithm as the increasing cost of fabrication chips favors large volume production. This paper proposes a novel approach to embedded cryptography whereby we propose a vector-based general purpose machine capable of implementing a range of cryptographic algorithms. We show that vector processing ideas can be used to perform cryptography in an e±cient manner which we believe is appropriate for high performance, flexible and power efficient embedded systems

Hardware-Software Codesign of a Vector Co-processor for Public Key Cryptography

International audienceUntil now, most cryptography implementations on parallel architectures have focused on adapting the software to SIMD architectures initially meant for media applications. In this paper, we review some of the most significant contributions in this area. We then propose a vector architecture to efficiently implement long precision modular multiplications. Having such a data level parallel hardware provides a circuit whose decode and schedule units are at least of the same complexity as those of a scalar processor. The excess transistors are mainly found in the data path. Moreover, the vector approach gives a very modular architecture where resources can be easily redefined. We built a functional simulator onto which we performed a quantitative analysis to study how the resizing of those resources affects the performance of the modular multiplication operation. Hence we not only propose a vector architecture for our Public Key cryptographic operations but also show how we can analyze the impact of design choices on performance. The proposed architecture is also flexible in the sense that the software running on it would offer room for the implementation of counter-measures against side-channel or fault attacks

Tightly-Coupled Multiprocessing for a Global Illumination Algorithm

{dret | elf} @ dgp.toronto.edu A prevailing trend in computer graphics is the demand for increasingly realistic global illumination models and algorithms. Despite the fact that the computational power of uniprocessors is increasing, it is clear that much greater computational power is required to achieve satisfactory throughput. The obvious next step is to employ parallel processing. The advent of affordable, tightly-coupled multiprocessors makes such an approach widely available for the first time. We propose a tightly-coupled parallel decomposition of FIAT, a global illumination algorithm, based on space subdivision and power balancing, that we have recently developed. This algorithm is somewhat ambitious, and severely strains existing uniprocessor environments. We discuss techniques for reducing memory contention and maximising parallelism. We also present empirical data on the actual performance of our parallel solution. Since the model of parallel computation that we have employed is likely to persist for quite some time, our techniques are applicable to other algorithms based on space subdivision. 1

Typologie morpho-génétique des marelles du marais littoral de la baie de Kangiqsualujjuaq, estuaire du George, Québec nordique

Des marées d'un très grand marnage (12 m aux vives-eaux) caractérisent l'estuaire du George. Dans la partie supérieure des marais littoraux, la faible fréquence des submersions et l'importance des surfaces à découvert permettent la croissance de gel intertidal sous forme de buttes de pergélisol et de gel saisonnier épais. Sur le marais littoral de la baie de Kangiqsualujjuaq, la dynamique du gel intertidal, l'activité glacielle et l'action sédimentaire des vagues, de la marée et de l'eau de ruissellement sont responsables de la formation et du développement de plus de 170 marelles littorales. On peut distinguer 10 types de marelles se répartissant selon le gradient inondation sur le marais, qui se divise topographiquement en marais inférieur, en marais supérieur sans gel intertidal et en marais supérieur avec gel intertidal. Les marelles créées par l'action du gel se trouvent dans les parties les plus hautes du marais qui sont protégées de l'action des vagues et des glaces flottantes. Les marelles produites par la dynamique sédimentaire de la baie se situent dans les secteurs exposés aux agents littoraux, surtout dans l'axe de l'ouverture de la baie sur l'estuaire. Le régime de température et de salinité des marelles dépend de facteurs externes, comme la fréquence de submersion par la marée ou les précipitations, mais également de facteurs internes, comme la situation topographique et la morphologie des bassins.Very large spring tides with a range of 12 m characterize the George River Estuary. In the upper marsh, unfrequent tidal covering and significant unsheltered areas permit the development of small mounds and heaved marsh surfaces. In the Kangiqsualujjuaq salt marsh, processes related to intertidal ground frost, shore-ice processes and sedimentological processes due to waves, tidal currents and overland flow are responsible of the existence of 170 pans. Ten types of pans are defined. They are distributed along the intertidal topographical gradient including three zones : lower marsh, upper marsh without frost and upper marsh underlain by permafrost. Pans formed by processes related to permafrost are located at the highest parts on the intertidal zone in areas sheltered from waves and ice drifting. Pans originating from hydraulic and sedimentological processes are concentrated in exposed sites that lie opposite of the opening of the bay. Temperature and salinity regimes of the pans depend on the frequency of tidal submersions and precipitations, as well as on topographic situation and basin morphology.Gezeiten mit sehr hoher Fluthôhe (12 m Springtiden) charakterisieren die Mundung des George-Flusses. Im oberen Teil der Kusten-Moraste ermoglichen die geringe Ùberschwemmungs-frequenz und erhebliche ungeschutzte Oberflachen die Zunahme von Gezeitenfrost in Form von Dauerfrost-Hugeln und von dichtem, saisonbedingtem Frost. Auf dem Kiisten-Morast der Bucht von Kangiqsualujjuaq sind die Dynamik des Frosts zwischen den Gezeiten, die Frost-Aktivitàt und die sedimentologische Wirkung der Wellen, der Gezeiten und des rieselnden Wassers verantwortlich fur die Bildung und Entwicklung von mehr als 170 kleinen Kusten-Pfuhlen. Man kann 10 Typen von kleinen Pfuhlen unterscheiden, die sich entsprechend dem Ùberschwemmungsgefàlle ùber den Morast verteilen, welcher sich topographisch in unteren Morast, hôheren Morast ohne Zwischengezeitenfrost und hôheren Morast mit Zwischengezeitenfrost teilt. Die kleinen, durch Frostwirkung geformten Pfùhle befinden sich in den hôchsten Teilen des Morasts, die vom Einflup der Wellen und des Treibeises geschùtzt sind. Die durch die Sediment-Dynamik der Bucht geschaffenen kleinen Pfùhle befinden sich in den Abschnitten, die den Einflussen der Kuste ausgesetzt sind, vor allem in der Achse der Ôffnung der Bucht auf die Flufi-Mundung. Das System der Temperatur und des Salzgehalts der kleinen Pfùhle hàngt von âuperen Faktoren ab, wie die Hàufigkeit der Uberschwemmung durch die Flut oder die Niederschlàge, aber auch von inneren Faktoren, wie die topographische Lage und die Morphologie der Becken