Simulation model for the study of overhead rail current collector systems dynamics, focused on the design of a new conductor rail

Overhead rigid conductor arrangements for current collection for railway traction have some advantages compared to other, more conventional, energy supply systems. They are simple, robust and easily maintained, not to mention their flexibility as to the required height for installation, which makes them particularly suitable for use in subway infrastructures. Nevertheless, due to the increasing speeds of new vehicles running on modern subway lines, a more efficient design is required for this kind of system. In this paper, the authors present a dynamic analysis of overhead conductor rail systems focused on the design of a new conductor profile with a dynamic behaviour superior to that of the system currently in use. This means that either an increase in running speed can be attained, which at present does not exceed 110 km/h, or an increase in the distance between the rigid catenary supports with the ensuing saving in installation costs. This study has been carried out using simulation techniques. The ANSYS programme has been used for the finite element modelling and the SIMPACK programme for the elastic multibody systems analysis.

Safety assessment of underground vehicles passing over highly resilient straight tracks in the presence of a broken rail

In this paper, vehicle-track interaction for a new slab track design, conceived to reduce noise and vibration levels has been analyzed, assessing the derailment risk for trains running on curved track when encountering a broken rail. Two different types of rail fastening systems with different elasticities have been analysed and compared. Numerical methods were used in order to simulate the dynamic behaviour of the train-track interaction. Multibody system (MBS) modelling techniques were combined with techniques based on the finite element method (FEM). MBS modelling was used for modelling the vehicle and FEM for simulating the elastic track. The simulation model was validated by comparing simulated results to experimental data obtained in field testing. During the simulations various safety indices, characteristic of derailment risk, were analysed. The simulations realised at the maximum running velocity of 110 km/h showed a similar behaviour for several track types. When reducing the running speed, the safety indices worsened for both cases. Although the worst behaviour was observed for the track with a greater elasticity, in none of the simulations did a derailment occur when running over the broken rail.

Safety assessment of underground vehicles passing over highly resilient curved tracks in the presence of a broken rail

Vehicle–track interaction for a new resilient slab track designed to reduce noise and vibration levels was analysed, in order to assess the derailment risk on a curved track when encountering a broken rail. Sensitivity of the rail support spacing of the relative position of the rail breakage between two adjacent rail supports and of running speed were analysed for two different elasticities of the rail fastening system. In none of the cases analysed was observed an appreciable difference between either of the elastic systems. As was expected, the most unfavourable situations were those with greater rail support spacing and those with greater distance from the breakage to the nearest rail support, although in none of the simulations performed did a derailment occur when running over the broken rail. When varying the running speed, the most favourable condition was obtained for an intermediate speed, due to the superposition of two antagonistic effects.

Improved design of an overhead rail current conductor for application in underground lines

Overhead rail current collector systems for railway traction offer certain features, such as low installation height and reduced maintenance, which make them predominantly suitable for use in underground train infrastructures. Due to the increased demands of modern catenary systems and higher running speeds of new vehicles, a more capable design of the conductor rail is needed. A new overhead conductor rail has been developed and its design has been patented [13]. Modern simulation and modelling techniques were used in the development approach. The new conductor rail profile has a dynamic behaviour superior to that of the system currently in use. Its innovative design permits either an increase of catenary support spacing or a higher vehicle running speed. Both options ensure savings in installation or operating costs. The simulation model used to optimise the existing conductor rail profile included both a finite element model of the catenary and a three-dimensional multi-body system model of the pantograph. The contact force that appears between pantograph and catenary was obtained in simulation. A sensitivity analysis of the key parameters that influence in catenary dynamics was carried out, finally leading to the improved design.

Pantograph wear assesment in overhead conductor rail systems

Wear is the phenomenon that determines the lifetime of the collector strips. Since wear is an inevitable effect on pantograph-catenary systems, it is necessary to determine optimal operating conditions that can mitigate its effects. In this study we have performed a simulation model of the pantograph-overhead conductor rail system which allows the evaluation of the dynamic conditions of the system through the contact force. With these results we have made an evaluation of the quality of current collection, a calculation of the pantograph wear and a definition of the optimal operation conditions of the pantograph-overhead conductor rail system.

Simulation techniques for design of overhead conductor rail lines for speeds over 140 km/h

In overhead conductor rail lines, aluminium beams are usually mounted with support spacing between 8 and 12 meters, to limit the maximum vertical deflection in the center of the span. This small support spacing limits the use of overhead conductor rail to tunnels, therefore it has been used almost exclusively in metropolitan networks, with operation speeds below 110 km/h. Nevertheless, due to the lower cost of maintenance required for this electrification system, some railway administrations are beginning to install it in some tunnels on long-distance lines, requesting higher operation speeds [1]. Some examples are the Barcelona and Madrid suburban networks (Spain), and recent lines in Turkey and Malaysia. In order to adapt the design of the overhead conductor for higher speeds (V > 160 km/h), particular attention must be paid to the geometry of the conductor rail in critical zones as overlaps, crossings and, especially, transitions between conductor rail and conventional catenary, since the use of overhead conductor rail is limited to tunnels, as already mentioned. This paper describes simulation techniques developed in order to take into account these critical zones. Furthermore, some specific simulations results are presented that have been used to analyze and optimizes the geometry of this special zones to get a better current collection quality, in a real suburban network. This paper presents the work undertaken by the Railways Technology Research Centre (CITEF), having over 10 years of experience in railways research [1-4].

High-Speed Rail Versus Air Transportation: Case Study of Madrid–Barcelona, Spain.

Travel time savings, better quality of the supplied services, greater comfort for the users, and improved accessibility are the main factors of success of High Speed Rail(HSR)links. This paper presents the results from a revealed and stated preference survey conducted to both HSR and air transport users in the Madrid Barcelona corridor. The data gathered from the stated preference survey was used to calibrate a modal choice model aiming at explaining competition between HSR and air transportation in the corridor. From the model, the authors obtain that prices and service frequency are the most important variables to compete with the other mode. In addition, they found that check-in and security controls at the airport are a crucial variable for the users in their modal choice. Other policies, such as the improvement of parking facilities at the train stations, play a secondary role.

Efficiency and spatial equity impacts of high-speed rail extensions in urban areas

Urban areas benefit from significant improvements in accessibility when a new high speed rail (HSR) project is built. These improvements, which are due mainly to a rise in efficiency, produce locational advantagesand increase the attractiveness of these cities, thereby possibly enhancing their competitivenessand economic growth. However, there may be equity issues at stake, as the main accessibility benefits are primarily concentrated in urban areas with a HSR station, whereas other locations obtain only limited benefits. HSR extensions may contribute to an increase in spatial imbalance and lead to more polarized patterns of spatial development. Procedures for assessing the spatial impacts of HSR must therefore follow a twofold approach which addresses issues of both efficiency and equity. This analysis can be made by jointly assessing both the magnitude and distribution of the accessibility improvements deriving from a HSR project. This paper describes an assessment methodology for HSR projects which follows this twofold approach. The procedure uses spatial impact analysis techniques and is based on the computation of accessibility indicators, supported by a Geographical Information System (GIS). Efficiency impacts are assessed in terms of the improvements in accessibility resulting from the HSR project, with a focus on major urban areas; and spatial equity implications are derived from changes in the distribution of accessibility values among these urban agglomerations.

Wheel-Rail Contact Forces in High-Speed Simply Supported Bridges at Resonance

The response of high-speed bridges at resonance, particularly under flexural vibrations, constitutes a subject of research for many scientists and engineers at the moment. The topic is of great interest because, as a matter of fact, such kind of behaviour is not unlikely to happen due to the elevated operating speeds of modern rains, which in many cases are equal to or even exceed 300 km/h ( [1,2]). The present paper addresses the subject of the evolution of the wheel-rail contact forces during resonance situations in simply supported bridges. Based on a dimensionless formulation of the equations of motion presented in [4], very similar to the one introduced by Klasztorny and Langer in [3], a parametric study is conducted and the contact forces in realistic situations analysed in detail. The effects of rail and wheel irregularities are not included in the model. The bridge is idealised as an Euler-Bernoulli beam, while the train is simulated by a system consisting of rigid bodies, springs and dampers. The situations such that a severe reduction of the contact force could take place are identified and compared with typical situations in actual bridges. To this end, the simply supported bridge is excited at resonace by means of a theoretical train consisting of 15 equidistant axles. The mechanical characteristics of all axles (unsprung mass, semi-sprung mass, and primary suspension system) are identical. This theoretical train permits the identification of the key parameters having an influence on the wheel-rail contact forces. In addition, a real case of a 17.5 m bridges traversed by the Eurostar train is analysed and checked against the theoretical results. The influence of three fundamental parameters is investigated in great detail: a) the ratio of the fundamental frequency of the bridge and natural frequency of the primary suspension of the vehicle; b) the ratio of the total mass of the bridge and the semi-sprung mass of the vehicle and c) the ratio between the length of the bridge and the characteristic distance between consecutive axles. The main conclusions derived from the investigation are: The wheel-rail contact forces undergo oscillations during the passage of the axles over the bridge. During resonance, these oscillations are more severe for the rear wheels than for the front ones. If denotes the span of a simply supported bridge, and the characteristic distance between consecutive groups of loads, the lower the value of , the greater the oscillations of the contact forces at resonance. For or greater, no likelihood of loss of wheel-rail contact has been detected. The ratio between the frequency of the primary suspension of the vehicle and the fundamental frequency of the bridge is denoted by (frequency ratio), and the ratio of the semi-sprung mass of the vehicle (mass of the bogie) and the total mass of the bridge is denoted by (mass ratio). For any given frequency ratio, the greater the mass ratio, the greater the oscillations of the contact forces at resonance. The oscillations of the contact forces at resonance, and therefore the likelihood of loss of wheel-rail contact, present a minimum for approximately between 0.5 and 1. For lower or higher values of the frequency ratio the oscillations of the contact forces increase. Neglecting the possible effects of torsional vibrations, the metal or composite bridges with a low linear mass have been found to be the ones where the contact forces may suffer the most severe oscillations. If single-track, simply supported, composite or metal bridges were used in high-speed lines, and damping ratios below 1% were expected, the minimum contact forces at resonance could drop to dangerous values. Nevertheless, this kind of structures is very unusual in modern high-speed railway lines.

Coupled models for the dynamics of bridges under high-speed rail traffic

The dynamic effects of high-speed trains on viaducts are important issues for the design of the structures, as well as for determining safe running conditions of trains. In this work we start by reviewing the relevance of some basic moving load models for the dynamic action of vertical traffic loads. The study of lateral dynamics of running trains on bridges is of importance mainly for the safety of the traffic, and may be relevant for laterally compliant bridges. These studies require 3D coupled vehicle-bridge models and consideration of wheel to rail contact. We describe here a fully nonlinear coupled model, formulated in absolute coordinates and incorporated into a commercial finite element framework. An application example is presented for a vehicle subject to a strong wind gust traversing a bridge, showing the relevance of the nonlinear wheel-rail contact model as well as the interaction between bridge and vehicle.

Energy consumption and carbon dioxide emissions in rail and road freight transport in Spain: a case study of car carriers and bulk petrochemicals

This article provides a new methodology for estimating fuel consumption and emissions by enabling a correct comparison between freight transportation modes. The approach is developed and integrated as a part of an intelligent transportation system dealing with goods movement. A key issue is related to energy consumption ratios and consequent CO2 emissions. Energy consumption ratios are often used based on transport demand. However, including other ratios based on transport supply can be useful. Furthermore, it is important to indicate which factors are associated with variations in energy consumption and emissions; especially of interest are parameters that have a higher incidence and order of magnitude, in order to fairly compare and understand the difference between transport modes and sub-modes. The study finds that the use of an energy consumption equation can improve the quality of the estimates. The study proposes that coefficients that define the energy consumption equation should be tested to determine market niches and sources of improvement in energy consumption according to the category of vehicles, fuel types used, and classes of products transported.

PPP in light rail transit systems in Spain

Light rail systems have proliferated in Spain in the last decade, following a tendency that is common not only in other European countries but also in other parts of the world. This paper reviews the benefits of light rail systems, both related to environmental issues and mobility issues. It analyses the evolution of light rail projects in Spain and shows that light rail systems in this country have evolved towards an extensive use of public-private partnerships. The analysis of the Spanish projects, however, does not contribute any conclusive evidence about whether public-private partnerships have been more efficient than publicly owned enterprises in building and operating light rail systems.

Does high speed rail compete fairly with other transportation modes? Madrid-Barcelona case study

Transportation modes produce many external costs such as congestion, accidents, and environmental impacts (pollution, noise and so on). From the microeconomic theory it is well known that in order to maximize social welfare, transportation modes should internalize the marginal costs they produce. Allocative efficiency is achieved when all transportation modes are priced at their social marginal cost. The objective of this research is to evaluate to what extent different passenger transport modes internalize their social marginal costs. This analysis is important since it affects the competitiveness of the different transport modes for a given OD pair. The case study analyzed is the corridor Madrid-Barcelona in Spain and the different transport modes have been considered (cars, buses, high-speed train and air). The research calculates the marginal social cost per user for each transportation mode, and it compares it with the average fare—allowing for the effect of discriminatory taxes—currently paid by the users. The external costs are calculated according to the guidelines established by the European Union. The gap between the marginal social cost and the price paid by users will provide the extra cost per passenger that each transport mode should have to pay for internalizing the external cost it produces. The research shows that external costs already produced by road and air transport modes are much higher than those produced by rail. However, the results show that road transport already internalizes every external costs it produces because users pay high fuel taxes. In other words, although rail transportation produces lower external costs, road transportation pays more than it should on the basis of the social marginal costs. The results of this work might be of help for Europ ean policy actions to be undertaken in the future.

Side-Channel Attack Protection Techniques in FPGA Systems using Enhanced Dual-Rail Solutions

Esta tesis doctoral se centra principalmente en técnicas de ataque y contramedidas relacionadas con ataques de canal lateral (SCA por sus siglas en inglés), que han sido propuestas dentro del campo de investigación académica desde hace 17 años. Las investigaciones relacionadas han experimentado un notable crecimiento en las últimas décadas, mientras que los diseños enfocados en la protección sólida y eficaz contra dichos ataques aún se mantienen como un tema de investigación abierto, en el que se necesitan iniciativas más confiables para la protección de la información persona de empresa y de datos nacionales. El primer uso documentado de codificación secreta se remonta a alrededor de 1700 B.C., cuando los jeroglíficos del antiguo Egipto eran descritos en las inscripciones. La seguridad de la información siempre ha supuesto un factor clave en la transmisión de datos relacionados con inteligencia diplomática o militar. Debido a la evolución rápida de las técnicas modernas de comunicación, soluciones de cifrado se incorporaron por primera vez para garantizar la seguridad, integridad y confidencialidad de los contextos de transmisión a través de cables sin seguridad o medios inalámbricos. Debido a las restricciones de potencia de cálculo antes de la era del ordenador, la técnica de cifrado simple era un método más que suficiente para ocultar la información. Sin embargo, algunas vulnerabilidades algorítmicas pueden ser explotadas para restaurar la regla de codificación sin mucho esfuerzo. Esto ha motivado nuevas investigaciones en el área de la criptografía, con el fin de proteger el sistema de información ante sofisticados algoritmos. Con la invención de los ordenadores se ha acelerado en gran medida la implementación de criptografía segura, que ofrece resistencia eficiente encaminada a obtener mayores capacidades de computación altamente reforzadas. Igualmente, sofisticados cripto-análisis han impulsado las tecnologías de computación. Hoy en día, el mundo de la información ha estado involucrado con el campo de la criptografía, enfocada a proteger cualquier campo a través de diversas soluciones de cifrado. Estos enfoques se han fortalecido debido a la unificación optimizada de teorías matemáticas modernas y prácticas eficaces de hardware, siendo posible su implementación en varias plataformas (microprocesador, ASIC, FPGA, etc.). Las necesidades y requisitos de seguridad en la industria son las principales métricas de conducción en el diseño electrónico, con el objetivo de promover la fabricación de productos de gran alcance sin sacrificar la seguridad de los clientes. Sin embargo, una vulnerabilidad en la implementación práctica encontrada por el Prof. Paul Kocher, et al en 1996 implica que un circuito digital es inherentemente vulnerable a un ataque no convencional, lo cual fue nombrado posteriormente como ataque de canal lateral, debido a su fuente de análisis. Sin embargo, algunas críticas sobre los algoritmos criptográficos teóricamente seguros surgieron casi inmediatamente después de este descubrimiento. En este sentido, los circuitos digitales consisten típicamente en un gran número de celdas lógicas fundamentales (como MOS - Metal Oxide Semiconductor), construido sobre un sustrato de silicio durante la fabricación. La lógica de los circuitos se realiza en función de las innumerables conmutaciones de estas células. Este mecanismo provoca inevitablemente cierta emanación física especial que puede ser medida y correlacionada con el comportamiento interno del circuito. SCA se puede utilizar para revelar datos confidenciales (por ejemplo, la criptografía de claves), analizar la arquitectura lógica, el tiempo e incluso inyectar fallos malintencionados a los circuitos que se implementan en sistemas embebidos, como FPGAs, ASICs, o tarjetas inteligentes. Mediante el uso de la comparación de correlación entre la cantidad de fuga estimada y las fugas medidas de forma real, información confidencial puede ser reconstruida en mucho menos tiempo y computación. Para ser precisos, SCA básicamente cubre una amplia gama de tipos de ataques, como los análisis de consumo de energía y radiación ElectroMagnética (EM). Ambos se basan en análisis estadístico y, por lo tanto, requieren numerosas muestras. Los algoritmos de cifrado no están intrínsecamente preparados para ser resistentes ante SCA. Es por ello que se hace necesario durante la implementación de circuitos integrar medidas que permitan camuflar las fugas a través de "canales laterales". Las medidas contra SCA están evolucionando junto con el desarrollo de nuevas técnicas de ataque, así como la continua mejora de los dispositivos electrónicos. Las características físicas requieren contramedidas sobre la capa física, que generalmente se pueden clasificar en soluciones intrínsecas y extrínsecas. Contramedidas extrínsecas se ejecutan para confundir la fuente de ataque mediante la integración de ruido o mala alineación de la actividad interna. Comparativamente, las contramedidas intrínsecas están integradas en el propio algoritmo, para modificar la aplicación con el fin de minimizar las fugas medibles, o incluso hacer que dichas fugas no puedan ser medibles. Ocultación y Enmascaramiento son dos técnicas típicas incluidas en esta categoría. Concretamente, el enmascaramiento se aplica a nivel algorítmico, para alterar los datos intermedios sensibles con una máscara de manera reversible. A diferencia del enmascaramiento lineal, las operaciones no lineales que ampliamente existen en criptografías modernas son difíciles de enmascarar. Dicho método de ocultación, que ha sido verificado como una solución efectiva, comprende principalmente la codificación en doble carril, que está ideado especialmente para aplanar o eliminar la fuga dependiente de dato en potencia o en EM. En esta tesis doctoral, además de la descripción de las metodologías de ataque, se han dedicado grandes esfuerzos sobre la estructura del prototipo de la lógica propuesta, con el fin de realizar investigaciones enfocadas a la seguridad sobre contramedidas de arquitectura a nivel lógico. Una característica de SCA reside en el formato de las fuentes de fugas. Un típico ataque de canal lateral se refiere al análisis basado en la potencia, donde la capacidad fundamental del transistor MOS y otras capacidades parásitas son las fuentes esenciales de fugas. Por lo tanto, una lógica robusta resistente a SCA debe eliminar o mitigar las fugas de estas micro-unidades, como las puertas lógicas básicas, los puertos I/O y las rutas. Las herramientas EDA proporcionadas por los vendedores manipulan la lógica desde un nivel más alto, en lugar de realizarlo desde el nivel de puerta, donde las fugas de canal lateral se manifiestan. Por lo tanto, las implementaciones clásicas apenas satisfacen estas necesidades e inevitablemente atrofian el prototipo. Por todo ello, la implementación de un esquema de diseño personalizado y flexible ha de ser tomado en cuenta. En esta tesis se presenta el diseño y la implementación de una lógica innovadora para contrarrestar SCA, en la que se abordan 3 aspectos fundamentales: I. Se basa en ocultar la estrategia sobre el circuito en doble carril a nivel de puerta para obtener dinámicamente el equilibrio de las fugas en las capas inferiores; II. Esta lógica explota las características de la arquitectura de las FPGAs, para reducir al mínimo el gasto de recursos en la implementación; III. Se apoya en un conjunto de herramientas asistentes personalizadas, incorporadas al flujo genérico de diseño sobre FPGAs, con el fin de manipular los circuitos de forma automática. El kit de herramientas de diseño automático es compatible con la lógica de doble carril propuesta, para facilitar la aplicación práctica sobre la familia de FPGA del fabricante Xilinx. En este sentido, la metodología y las herramientas son flexibles para ser extendido a una amplia gama de aplicaciones en las que se desean obtener restricciones mucho más rígidas y sofisticadas a nivel de puerta o rutado. En esta tesis se realiza un gran esfuerzo para facilitar el proceso de implementación y reparación de lógica de doble carril genérica. La viabilidad de las soluciones propuestas es validada mediante la selección de algoritmos criptográficos ampliamente utilizados, y su evaluación exhaustiva en comparación con soluciones anteriores. Todas las propuestas están respaldadas eficazmente a través de ataques experimentales con el fin de validar las ventajas de seguridad del sistema. El presente trabajo de investigación tiene la intención de cerrar la brecha entre las barreras de implementación y la aplicación efectiva de lógica de doble carril. En esencia, a lo largo de esta tesis se describirá un conjunto de herramientas de implementación para FPGAs que se han desarrollado para trabajar junto con el flujo de diseño genérico de las mismas, con el fin de lograr crear de forma innovadora la lógica de doble carril. Un nuevo enfoque en el ámbito de la seguridad en el cifrado se propone para obtener personalización, automatización y flexibilidad en el prototipo de circuito de bajo nivel con granularidad fina. Las principales contribuciones del presente trabajo de investigación se resumen brevemente a continuación: Lógica de Precharge Absorbed-DPL logic: El uso de la conversión de netlist para reservar LUTs libres para ejecutar la señal de precharge y Ex en una lógica DPL. Posicionamiento entrelazado Row-crossed con pares idénticos de rutado en redes de doble carril, lo que ayuda a aumentar la resistencia frente a la medición EM selectiva y mitigar los impactos de las variaciones de proceso. Ejecución personalizada y herramientas de conversión automática para la generación de redes idénticas para la lógica de doble carril propuesta. (a) Para detectar y reparar conflictos en las conexiones; (b) Detectar y reparar las rutas asimétricas. (c) Para ser utilizado en otras lógicas donde se requiere un control estricto de las interconexiones en aplicaciones basadas en Xilinx. Plataforma CPA de pruebas personalizadas para el análisis de EM y potencia, incluyendo la construcción de dicha plataforma, el método de medición y análisis de los ataques. Análisis de tiempos para cuantificar los niveles de seguridad. División de Seguridad en la conversión parcial de un sistema de cifrado complejo para reducir los costes de la protección. Prueba de concepto de un sistema de calefacción auto-adaptativo para mitigar los impactos eléctricos debido a la variación del proceso de silicio de manera dinámica. La presente tesis doctoral se encuentra organizada tal y como se detalla a continuación: En el capítulo 1 se abordan los fundamentos de los ataques de canal lateral, que abarca desde conceptos básicos de teoría de modelos de análisis, además de la implementación de la plataforma y la ejecución de los ataques. En el capítulo 2 se incluyen las estrategias de resistencia SCA contra los ataques de potencia diferencial y de EM. Además de ello, en este capítulo se propone una lógica en doble carril compacta y segura como contribución de gran relevancia, así como también se presentará la transformación lógica basada en un diseño a nivel de puerta. Por otra parte, en el Capítulo 3 se abordan los desafíos relacionados con la implementación de lógica en doble carril genérica. Así mismo, se describirá un flujo de diseño personalizado para resolver los problemas de aplicación junto con una herramienta de desarrollo automático de aplicaciones propuesta, para mitigar las barreras de diseño y facilitar los procesos. En el capítulo 4 se describe de forma detallada la elaboración e implementación de las herramientas propuestas. Por otra parte, la verificación y validaciones de seguridad de la lógica propuesta, así como un sofisticado experimento de verificación de la seguridad del rutado, se describen en el capítulo 5. Por último, un resumen de las conclusiones de la tesis y las perspectivas como líneas futuras se incluyen en el capítulo 6. Con el fin de profundizar en el contenido de la tesis doctoral, cada capítulo se describe de forma más detallada a continuación: En el capítulo 1 se introduce plataforma de implementación hardware además las teorías básicas de ataque de canal lateral, y contiene principalmente: (a) La arquitectura genérica y las características de la FPGA a utilizar, en particular la Xilinx Virtex-5; (b) El algoritmo de cifrado seleccionado (un módulo comercial Advanced Encryption Standard (AES)); (c) Los elementos esenciales de los métodos de canal lateral, que permiten revelar las fugas de disipación correlacionadas con los comportamientos internos; y el método para recuperar esta relación entre las fluctuaciones físicas en los rastros de canal lateral y los datos internos procesados; (d) Las configuraciones de las plataformas de pruebas de potencia / EM abarcadas dentro de la presente tesis. El contenido de esta tesis se amplia y profundiza a partir del capítulo 2, en el cual se abordan varios aspectos claves. En primer lugar, el principio de protección de la compensación dinámica de la lógica genérica de precarga de doble carril (Dual-rail Precharge Logic-DPL) se explica mediante la descripción de los elementos compensados a nivel de puerta. En segundo lugar, la lógica PA-DPL es propuesta como aportación original, detallando el protocolo de la lógica y un caso de aplicación. En tercer lugar, dos flujos de diseño personalizados se muestran para realizar la conversión de doble carril. Junto con ello, se aclaran las definiciones técnicas relacionadas con la manipulación por encima de la netlist a nivel de LUT. Finalmente, una breve discusión sobre el proceso global se aborda en la parte final del capítulo. El Capítulo 3 estudia los principales retos durante la implementación de DPLs en FPGAs. El nivel de seguridad de las soluciones de resistencia a SCA encontradas en el estado del arte se ha degenerado debido a las barreras de implantación a través de herramientas EDA convencionales. En el escenario de la arquitectura FPGA estudiada, se discuten los problemas de los formatos de doble carril, impactos parásitos, sesgo tecnológico y la viabilidad de implementación. De acuerdo con estas elaboraciones, se plantean dos problemas: Cómo implementar la lógica propuesta sin penalizar los niveles de seguridad, y cómo manipular un gran número de celdas y automatizar el proceso. El PA-DPL propuesto en el capítulo 2 se valida con una serie de iniciativas, desde características estructurales como doble carril entrelazado o redes de rutado clonadas, hasta los métodos de aplicación tales como las herramientas de personalización y automatización de EDA. Por otra parte, un sistema de calefacción auto-adaptativo es representado y aplicado a una lógica de doble núcleo, con el fin de ajustar alternativamente la temperatura local para equilibrar los impactos negativos de la variación del proceso durante la operación en tiempo real. El capítulo 4 se centra en los detalles de la implementación del kit de herramientas. Desarrollado sobre una API third-party, el kit de herramientas personalizado es capaz de manipular los elementos de la lógica de circuito post P&R ncd (una versión binaria ilegible del xdl) convertido al formato XDL Xilinx. El mecanismo y razón de ser del conjunto de instrumentos propuestos son cuidadosamente descritos, que cubre la detección de enrutamiento y los enfoques para la reparación. El conjunto de herramientas desarrollado tiene como objetivo lograr redes de enrutamiento estrictamente idénticos para la lógica de doble carril, tanto para posicionamiento separado como para el entrelazado. Este capítulo particularmente especifica las bases técnicas para apoyar las implementaciones en los dispositivos de Xilinx y su flexibilidad para ser utilizado sobre otras aplicaciones. El capítulo 5 se enfoca en la aplicación de los casos de estudio para la validación de los grados de seguridad de la lógica propuesta. Se discuten los problemas técnicos detallados durante la ejecución y algunas nuevas técnicas de implementación. (a) Se discute el impacto en el proceso de posicionamiento de la lógica utilizando el kit de herramientas propuesto. Diferentes esquemas de implementación, tomando en cuenta la optimización global en seguridad y coste, se verifican con los experimentos con el fin de encontrar los planes de posicionamiento y reparación optimizados; (b) las validaciones de seguridad se realizan con los métodos de correlación y análisis de tiempo; (c) Una táctica asintótica se aplica a un núcleo AES sobre BCDL estructurado para validar de forma sofisticada el impacto de enrutamiento sobre métricas de seguridad; (d) Los resultados preliminares utilizando el sistema de calefacción auto-adaptativa sobre la variación del proceso son mostrados; (e) Se introduce una aplicación práctica de las herramientas para un diseño de cifrado completa. Capítulo 6 incluye el resumen general del trabajo presentado dentro de esta tesis doctoral. Por último, una breve perspectiva del trabajo futuro se expone, lo que puede ampliar el potencial de utilización de las contribuciones de esta tesis a un alcance más allá de los dominios de la criptografía en FPGAs. ABSTRACT This PhD thesis mainly concentrates on countermeasure techniques related to the Side Channel Attack (SCA), which has been put forward to academic exploitations since 17 years ago. The related research has seen a remarkable growth in the past decades, while the design of solid and efficient protection still curiously remain as an open research topic where more reliable initiatives are required for personal information privacy, enterprise and national data protections. The earliest documented usage of secret code can be traced back to around 1700 B.C., when the hieroglyphs in ancient Egypt are scribed in inscriptions. Information security always gained serious attention from diplomatic or military intelligence transmission. Due to the rapid evolvement of modern communication technique, crypto solution was first incorporated by electronic signal to ensure the confidentiality, integrity, availability, authenticity and non-repudiation of the transmitted contexts over unsecure cable or wireless channels. Restricted to the computation power before computer era, simple encryption tricks were practically sufficient to conceal information. However, algorithmic vulnerabilities can be excavated to restore the encoding rules with affordable efforts. This fact motivated the development of modern cryptography, aiming at guarding information system by complex and advanced algorithms. The appearance of computers has greatly pushed forward the invention of robust cryptographies, which efficiently offers resistance relying on highly strengthened computing capabilities. Likewise, advanced cryptanalysis has greatly driven the computing technologies in turn. Nowadays, the information world has been involved into a crypto world, protecting any fields by pervasive crypto solutions. These approaches are strong because of the optimized mergence between modern mathematical theories and effective hardware practices, being capable of implement crypto theories into various platforms (microprocessor, ASIC, FPGA, etc). Security needs from industries are actually the major driving metrics in electronic design, aiming at promoting the construction of systems with high performance without sacrificing security. Yet a vulnerability in practical implementation found by Prof. Paul Kocher, et al in 1996 implies that modern digital circuits are inherently vulnerable to an unconventional attack approach, which was named as side-channel attack since then from its analysis source. Critical suspicions to theoretically sound modern crypto algorithms surfaced almost immediately after this discovery. To be specifically, digital circuits typically consist of a great number of essential logic elements (as MOS - Metal Oxide Semiconductor), built upon a silicon substrate during the fabrication. Circuit logic is realized relying on the countless switch actions of these cells. This mechanism inevitably results in featured physical emanation that can be properly measured and correlated with internal circuit behaviors. SCAs can be used to reveal the confidential data (e.g. crypto-key), analyze the logic architecture, timing and even inject malicious faults to the circuits that are implemented in hardware system, like FPGA, ASIC, smart Card. Using various comparison solutions between the predicted leakage quantity and the measured leakage, secrets can be reconstructed at much less expense of time and computation. To be precisely, SCA basically encloses a wide range of attack types, typically as the analyses of power consumption or electromagnetic (EM) radiation. Both of them rely on statistical analyses, and hence require a number of samples. The crypto algorithms are not intrinsically fortified with SCA-resistance. Because of the severity, much attention has to be taken into the implementation so as to assemble countermeasures to camouflage the leakages via "side channels". Countermeasures against SCA are evolving along with the development of attack techniques. The physical characteristics requires countermeasures over physical layer, which can be generally classified into intrinsic and extrinsic vectors. Extrinsic countermeasures are executed to confuse the attacker by integrating noise, misalignment to the intra activities. Comparatively, intrinsic countermeasures are built into the algorithm itself, to modify the implementation for minimizing the measurable leakage, or making them not sensitive any more. Hiding and Masking are two typical techniques in this category. Concretely, masking applies to the algorithmic level, to alter the sensitive intermediate values with a mask in reversible ways. Unlike the linear masking, non-linear operations that widely exist in modern cryptographies are difficult to be masked. Approved to be an effective counter solution, hiding method mainly mentions dual-rail logic, which is specially devised for flattening or removing the data-dependent leakage in power or EM signatures. In this thesis, apart from the context describing the attack methodologies, efforts have also been dedicated to logic prototype, to mount extensive security investigations to countermeasures on logic-level. A characteristic of SCA resides on the format of leak sources. Typical side-channel attack concerns the power based analysis, where the fundamental capacitance from MOS transistors and other parasitic capacitances are the essential leak sources. Hence, a robust SCA-resistant logic must eliminate or mitigate the leakages from these micro units, such as basic logic gates, I/O ports and routings. The vendor provided EDA tools manipulate the logic from a higher behavioral-level, rather than the lower gate-level where side-channel leakage is generated. So, the classical implementations barely satisfy these needs and inevitably stunt the prototype. In this case, a customized and flexible design scheme is appealing to be devised. This thesis profiles an innovative logic style to counter SCA, which mainly addresses three major aspects: I. The proposed logic is based on the hiding strategy over gate-level dual-rail style to dynamically overbalance side-channel leakage from lower circuit layer; II. This logic exploits architectural features of modern FPGAs, to minimize the implementation expenses; III. It is supported by a set of assistant custom tools, incorporated by the generic FPGA design flow, to have circuit manipulations in an automatic manner. The automatic design toolkit supports the proposed dual-rail logic, facilitating the practical implementation on Xilinx FPGA families. While the methodologies and the tools are flexible to be expanded to a wide range of applications where rigid and sophisticated gate- or routing- constraints are desired. In this thesis a great effort is done to streamline the implementation workflow of generic dual-rail logic. The feasibility of the proposed solutions is validated by selected and widely used crypto algorithm, for thorough and fair evaluation w.r.t. prior solutions. All the proposals are effectively verified by security experiments. The presented research work attempts to solve the implementation troubles. The essence that will be formalized along this thesis is that a customized execution toolkit for modern FPGA systems is developed to work together with the generic FPGA design flow for creating innovative dual-rail logic. A method in crypto security area is constructed to obtain customization, automation and flexibility in low-level circuit prototype with fine-granularity in intractable routings. Main contributions of the presented work are summarized next: Precharge Absorbed-DPL logic: Using the netlist conversion to reserve free LUT inputs to execute the Precharge and Ex signal in a dual-rail logic style. A row-crossed interleaved placement method with identical routing pairs in dual-rail networks, which helps to increase the resistance against selective EM measurement and mitigate the impacts from process variations. Customized execution and automatic transformation tools for producing identical networks for the proposed dual-rail logic. (a) To detect and repair the conflict nets; (b) To detect and repair the asymmetric nets. (c) To be used in other logics where strict network control is required in Xilinx scenario. Customized correlation analysis testbed for EM and power attacks, including the platform construction, measurement method and attack analysis. A timing analysis based method for quantifying the security grades. A methodology of security partitions of complex crypto systems for reducing the protection cost. A proof-of-concept self-adaptive heating system to mitigate electrical impacts over process variations in dynamic dual-rail compensation manner. The thesis chapters are organized as follows: Chapter 1 discusses the side-channel attack fundamentals, which covers from theoretic basics to analysis models, and further to platform setup and attack execution. Chapter 2 centers to SCA-resistant strategies against generic power and EM attacks. In this chapter, a major contribution, a compact and secure dual-rail logic style, will be originally proposed. The logic transformation based on bottom-layer design will be presented. Chapter 3 is scheduled to elaborate the implementation challenges of generic dual-rail styles. A customized design flow to solve the implementation problems will be described along with a self-developed automatic implementation toolkit, for mitigating the design barriers and facilitating the processes. Chapter 4 will originally elaborate the tool specifics and construction details. The implementation case studies and security validations for the proposed logic style, as well as a sophisticated routing verification experiment, will be described in Chapter 5. Finally, a summary of thesis conclusions and perspectives for future work are included in Chapter 5. To better exhibit the thesis contents, each chapter is further described next: Chapter 1 provides the introduction of hardware implementation testbed and side-channel attack fundamentals, and mainly contains: (a) The FPGA generic architecture and device features, particularly of Virtex-5 FPGA; (b) The selected crypto algorithm - a commercially and extensively used Advanced Encryption Standard (AES) module - is detailed; (c) The essentials of Side-Channel methods are profiled. It reveals the correlated dissipation leakage to the internal behaviors, and the method to recover this relationship between the physical fluctuations in side-channel traces and the intra processed data; (d) The setups of the power/EM testing platforms enclosed inside the thesis work are given. The content of this thesis is expanded and deepened from chapter 2, which is divided into several aspects. First, the protection principle of dynamic compensation of the generic dual-rail precharge logic is explained by describing the compensated gate-level elements. Second, the novel DPL is originally proposed by detailing the logic protocol and an implementation case study. Third, a couple of custom workflows are shown next for realizing the rail conversion. Meanwhile, the technical definitions that are about to be manipulated above LUT-level netlist are clarified. A brief discussion about the batched process is given in the final part. Chapter 3 studies the implementation challenges of DPLs in FPGAs. The security level of state-of-the-art SCA-resistant solutions are decreased due to the implementation barriers using conventional EDA tools. In the studied FPGA scenario, problems are discussed from dual-rail format, parasitic impact, technological bias and implementation feasibility. According to these elaborations, two problems arise: How to implement the proposed logic without crippling the security level; and How to manipulate a large number of cells and automate the transformation. The proposed PA-DPL in chapter 2 is legalized with a series of initiatives, from structures to implementation methods. Furthermore, a self-adaptive heating system is depicted and implemented to a dual-core logic, assumed to alternatively adjust local temperature for balancing the negative impacts from silicon technological biases on real-time. Chapter 4 centers to the toolkit system. Built upon a third-party Application Program Interface (API) library, the customized toolkit is able to manipulate the logic elements from post P&R circuit (an unreadable binary version of the xdl one) converted to Xilinx xdl format. The mechanism and rationale of the proposed toolkit are carefully convoyed, covering the routing detection and repairing approaches. The developed toolkit aims to achieve very strictly identical routing networks for dual-rail logic both for separate and interleaved placement. This chapter particularly specifies the technical essentials to support the implementations in Xilinx devices and the flexibility to be expanded to other applications. Chapter 5 focuses on the implementation of the case studies for validating the security grades of the proposed logic style from the proposed toolkit. Comprehensive implementation techniques are discussed. (a) The placement impacts using the proposed toolkit are discussed. Different execution schemes, considering the global optimization in security and cost, are verified with experiments so as to find the optimized placement and repair schemes; (b) Security validations are realized with correlation, timing methods; (c) A systematic method is applied to a BCDL structured module to validate the routing impact over security metric; (d) The preliminary results using the self-adaptive heating system over process variation is given; (e) A practical implementation of the proposed toolkit to a large design is introduced. Chapter 6 includes the general summary of the complete work presented inside this thesis. Finally, a brief perspective for the future work is drawn which might expand the potential utilization of the thesis contributions to a wider range of implementation domains beyond cryptography on FPGAs.

Sophisticated security verification on routing repaired balanced cell-based dual-rail logic against side channel analysis

Conventional dual-rail precharge logic suffers from difficult implementations of dual-rail structure for obtaining strict compensation between the counterpart rails. As a light-weight and high-speed dual-rail style, balanced cell-based dual-rail logic (BCDL) uses synchronised compound gates with global precharge signal to provide high resistance against differential power or electromagnetic analyses. BCDL can be realised from generic field programmable gate array (FPGA) design flows with constraints. However, routings still exist as concerns because of the deficient flexibility on routing control, which unfavourably results in bias between complementary nets in security-sensitive parts. In this article, based on a routing repair technique, novel verifications towards routing effect are presented. An 8 bit simplified advanced encryption processing (AES)-co-processor is executed that is constructed on block random access memory (RAM)-based BCDL in Xilinx Virtex-5 FPGAs. Since imbalanced routing are major defects in BCDL, the authors can rule out other influences and fairly quantify the security variants. A series of asymptotic correlation electromagnetic (EM) analyses are launched towards a group of circuits with consecutive routing schemes to be able to verify routing impact on side channel analyses. After repairing the non-identical routings, Mutual information analyses are executed to further validate the concrete security increase obtained from identical routing pairs in BCDL.