Tendering is a method for entering into a sales contract. Numerous electronic tendering systems have been established with the intent of improving the efficiency of the tendering process. Although providing adequate security services is a desired feature in an e-tendering system, current e-tendering systems are usually designed with little consideration of security and legal compliance. This research focuses on designing secure protocols for e-tendering systems. It involves developing methodologies for establishing security requirements, constructing security protocols and using formal methods in protocol security verification. The implication is that it may prove suitable for developing secure protocols in other electronic business domains. In depth investigations are conducted into a range of issues in relation to establishing generic security requirements for e-tendering systems. The outcomes are presented in a form of basic and advanced security requirements for e-tendering process. This analysis shows that advanced security services are required to secure e-tender negotiation integrity and the submission process. Two generic issues discovered in the course of this research, functional difference and functional limitations, are fundamental in constructing secure protocols for tender negotiation and submission processes. Functional difference identification derives advanced security requirements. Functional limitation assessment defines how the logic of generic security mechanisms should be constructed. These principles form a proactive analysis applied prior to the construction of security protocols. Security protocols have been successfully constructed using generic cryptographic security mechanisms. These protocols are secure e-tender negotiation integrity protocol suite, and secure e-tender submission protocols. Their security has been verified progressively during the design. Verification results show that protocols are secure against common threat scenarios. The primary contribution of this stage are the procedures developed for the complex e-business protocol analysis using formal methods. The research shows that proactive analysis has made this formal security verification possible and practical for complex protocols. These primary outcomes have raised awareness of security issues in e-tendering. The security solutions proposed in the protocol format are the first in e-tendering with verifiable security against common threat scenarios, and which are also practical for implementation. The procedures developed for securing the e-tendering process are generic and can be applied to other business domains. The study has made improvements in: establishing adequate security for a business process; applying proactive analysis prior to secure protocol construction; and verifying security of complex e-business protocols using tool aided formal methods.

En cryptographie, l'utilisation de nombres aléatoires est fréquente (graine, token, ...) et une mauvaise génération d'aléa peut compromettre toute la sécurité d'un protocole, comme en témoigne régulièrement l'actualité. Les générateurs de nombres aléatoires à usage cryptographique sont des composants formés de trois modules : la source brute qui produit de l'aléa (un algorithme ou un phénomène physique), un retraitement pour corriger les défauts de la source, et un retraitement cryptographique pour obtenir l'aléa final. Cette thèse se focalise sur l'analyse des générateurs issus d'une source physique, en vue de dégager des retraitements adaptés à leurs propriétés et résistants à des perturbations de leur environnement d'utilisation. La complexité des dispositifs entravant souvent la formulation explicite d'un modèle stochastique prouvé, leur évaluation repose principalement sur une analyse statistique. Or, les tests statistiques, principale méthode recommandée par les institutions gouvernementales (ANSSI, BSI, NIST) pour certifier ces composants, peuvent détecter des anomalies mais ne permettent pas de les identifier, et de les caractériser. Les travaux de cette thèse structurent la modélisation d'une source d'aléa, vue comme une suite de variables aléatoires, affinent les tests statistiques, et ajoutent une analyse temporelle pour détecter et expliciter ses anomalies au niveau global ou local. Les résultats ont été implantés dans une librairie composée d'un simulateur de perturbations, des outils statistiques et temporels obtenus, des batteries de tests recommandées (FIPS, AIS31, Test U01, SP800), et de retraitements appropriés à certaines anomalies. La structure mise en place a permis d'extraire des familles d'anomalies de motifs dont les propriétés rendent certains tests incapables de distinguer la source anormale d'une source idéalement aléatoire. L'analyse des faiblesses inhérentes aux méthodes statistiques a montré que l'interprétation d'un test par intervalle de rejet ou taux de réussite n'est pas adapté à la détection de certaines fautes de transition. Elle a aussi permis d'étudier les méthodes d'estimations d'entropie, notamment les estimateurs proposés dans la norme SP800-90. Par ailleurs, les paramètres de spécifications de certains générateurs, dont un déduit du standard de chiffrement AES, se sont avérés distinguables grâce aux statistiques de test. Les outils temporels développés évaluent la structure des anomalies, leur évolution au cours du temps et analysent les motifs déviants au voisinage d'un motif donné. Cela a permis d'une part d'appliquer les tests statistiques avec des paramètres pertinents, et d'autre part de présenter des retaitements dont la validité repose sur la structure des anomalies et non sur leur amplitude. / While random numbers are frequently used in cryptography (seed, token, ...), news regurlarly prove how bad randomness generation can compromise the wole security of a protocol. Random number generators for crypthography are components with three steps : a source (an algorithm or physical phenomenon) produces raw numbers which are two times postprocessed to fix anomalies. This thesis focuses on the analysis of physical random bit generators in order to extract postprocessing which will be adapted to the anomalies of the source. As the design of a physical random bit generator is complex, its evaluation is mainly a statistical analysis with hypothesis testing. However, the current standards (AIS31, FIPS140-2, Test U01, SP800) can not provide informations to characterize anomalies. Thus, this thesis adjust several tests and add a time analysis to identify and to make global and local anomalies explicit. A C library was developped, providing anomalies simulator and tools to apply statistical and time analysis results on random bit generators.

This diploma’s thesis discourses the cryptographic systems and ciphers, whose function, usage and practical implementation are analysed. In the first chapter basic cryptographic terms, symmetric and asymetric cryptographic algorithms and are mentioned. Also usage and reliability are analysed. Following chapters mention substitution, transposition, block and stream ciphers, which are elementary for most cryptographic algorithms. There are also mentioned the modes, which the ciphers work in. In the fourth chapter are described the principles of some chosen cryptographic algorithms. The objective is to make clear the essence of the algorithms’ behavior. When describing some more difficult algorithms the block scheme is added. At the end of each algorithm’s description the example of practical usage is written. The chapter no. five discusses the hardware implementation. Hardware and software implementation is compared from the practical point of view. Several design instruments are described and different hardware design programming languages with their progress, advantages and disadvantages are mentioned. Chapter six discourses the hardware implementation design of chosen ciphers. Concretely the design of stream cipher with pseudo-random sequence generator is designed in VHDL and also in Matlab. As the second design was chosen the block cipher GOST, which was designed in VHDL too. Both designs were tested and verified and then the results were summarized.