Dissertationen zum Thema „Partage de secrets“
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Qian, Liqin. „Contributions to the theory of algebraic coding on finite fields and rings and their applications“. Electronic Thesis or Diss., Paris 8, 2022. http://www.theses.fr/2022PA080064.
Der volle Inhalt der QuelleAlgebraic coding theory over finite fields and rings has always been an important research topic in information theory thanks to their various applications in secret sharing schemes, strongly regular graphs, authentication and communication codes.This thesis addresses several research topics according to the orientations in this context, whose construction methods are at the heart of our concerns. Specifically, we are interested in the constructions of optimal codebooks (or asymptotically optimal codebooks), the constructions of linear codes with a one-dimensional hull, the constructions of minimal codes, and the constructions of projective linear codes. The main contributions are summarized as follows. This thesis gives an explicit description of additive and multiplicative characters on finite rings (precisely _\mathbb{F}_q+u\mathbb{F}_q~(u^2= 0)s and S\mathbb{F}_q+u\mathbb{F}_q~(u^2=u)S), employees Gaussian, hyper Eisenstein and Jacobi sums and proposes several classes of optimal (or asymptotically optimal) new codebooks with flexible parameters. Next, it proposes(optimal or nearly optimal) linear codes with a one-dimensional hull over finite fields by employing tools from the theory of Gaussian sums. It develops an original method to construct these codes. It presents sufficient conditions for one-dimensional hull codes and a lower bound on its minimum distance. Besides, this thesis explores several classes of (optimal for the well-known Griesmer bound) binary linear codes over finite fields based on two generic constructions using functions. It determines their parameters and weight distributions and derives several infinite families of minimal linear codes. Finally, it studies (optimal for the sphere packing bound) constructions of several classes of projective binary linear codes with a few weight and their corresponding duals codes
Huysmans, Guillaume. „Partage de secret : integrite, performances et applications“. Aix-Marseille 2, 1998. http://www.theses.fr/1998AIX22032.
Der volle Inhalt der QuelleKaced, Tarik. „Partage de secret et théorie algorithmique de l'information“. Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2012. http://tel.archives-ouvertes.fr/tel-00763117.
Der volle Inhalt der QuelleKaced, Tarik. „Partage de secret et théorie algorithmique de l'information“. Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20170/document.
Der volle Inhalt der QuelleOur work deals with secret sharing in the theoretical point of views of Shannon's Information Theory and Kolmogorov's Algorithmic Information Theory. We are going to explain how these three subjects are naturally deeply intertwined.Information inequalities play a central role in this text. They are the inequalities for Shannon entropy, but also they are in exact correspondence with the inequalities for Kolmogorov complexity. Kolmogorov complexity formalizes the idea of randomness for strings.These two reasons alone justify to consider the notion of secret sharing in the Algorithmic framework (if one can share a random secret one can share anything).Originally, secret sharing was first studied under the combinatorial lens, only later was it more generally formalized using information-theoretic measures. This step allowed the use of information inequalities which revealed to bevery important to understand the existence of secret-sharing schemes with respect to efficiency.The investigation of information inequalities is at its debut. We contribute to the subject by introducing the notion of essentially conditional inequalities, which shows once again that information inequalities are yet not fully understood
Zorn, Caroline. „Données de santé et secret partagé : pour un droit de la personne à la protection de ses données de santé partagées“. Thesis, Nancy 2, 2009. http://www.theses.fr/2009NAN20011.
Der volle Inhalt der QuelleThe medical professional secret is a legal exception to the professional secret; it allows a patient's caregivers to exchange health information that is relevant to that patient's care without being punished for revealing confidential information. That caregivers discuss patient's health information with other medical professional involved in that patient's care is to the benefit of the patient. Nonetheless, there is a fine balance to be struck between a "need to know" professional exchange of information, which is essential to care of the patient, and a broad exchange of information, which may ultimately comprise the confidentiality of the patient's private life. The emergence of an electronic tool, which multiplies the potential possibilities for data exchange, further disrupts this balance. Consequently, the manipulation of this shared health information must be subject to the medical professional secret, the "Informatique et Libertés" legislation, and all of the numerous norms and standards as defined by the French national electronic medical record (DMP), the pharmaceutical medical record (Dossier pharmaceutique), or the reimbursement repository (Historique des remboursements). As the patient's health information is increasingly shared between health care providers - through means such as the DMP or DP - the patient's right and ability to control the access to his/her health information have to become more and more important. A study regarding the importance of obtaining the patient's consent lead to the following proposal: to inscribe in the French Constitution the patient's right to confidentiality regarding health information
Breton-Rahali, Céline. „Le secret professionnel et l’action médico-sociale“. Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0355.
Der volle Inhalt der QuelleProfessional confidentiality, understood as the obligation not to reveal certain information, is the subject of a number of exceptions. Its study within the particular context of specialised institutions reveals a number of issues. First, professionals working together from different disciplines are each subject to a different patchwork of applicable standards. As a result, it is necessary to clarify these rules, both within the interests of professionals and health-care users. Second, the effectiveness of patient care requires coordination between different professionals based upon shared confidentiality within the same department or health-care centre. Collaboration between professionals is an issue not only affecting the quality of care but also one of economics which allows for the effective management of the supply of health and social care within a given area. As a major challenge of public health policy, such coordination provokes a consideration of the adaptation of the existing legal framework and that of the organisation of the means of sharing confidential patient information within the health care system as a whole for both medical and social care services. This thesis makes a proposal for the necessary amendments to the current legislative framework for derogating from the general principle of confidentiality to allow for an exchange of information between professionals involved in the care of a patient. The evolution of shared confidentiality for the benefit of the patient requires an emphasis upon determining the most highly protective regime for patients without compromising the reality – and constraints – of providing effective health care
Renner, Soline. „Protection des algorithmes cryptographiques embarqués“. Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0057/document.
Der volle Inhalt der QuelleSince 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
Brasselet, Renato. „La circulation de la donnée à caractère personnel relative à la santé : disponibilité de l’information et protection des droits de la personne“. Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0333/document.
Der volle Inhalt der QuelleHealth, m-health and self quantification connect the body and disrupt the traditional model of care. They are moving it from curative and monopoly medicine to preventive medicine and taking a WHO-defined approach to health. By this means, the person is no longer simply placed at the center of the care device he becomes one of the actors including in the intimacy of his privacy.On the other hand, in search of the realization of economy but also of quality, the health system, has mutated, under the effect of the deployment of e-health. As a result, it is now substantially landscaped and can no longer be synthesized into the classic dichotomy between health and social medicine. The vector and resultant of this phenomenon consists in the circulation of health information. From now on, it has become largely digital and essential for the care and functioning of the healthcare system. The care is now conceived around categorical and inter-categorical exchange and sharing, even man-machine or machine-machine and no longer on a medicine based on secrecy. The Man who has become a homo Numericus is not without all rights and privacy. Law and techno-law are part of this scholarly game, the slightest inconsistent reform of which could upset its precarious balance
Smith, Guillaume. „Concevoir des applications temps-réel respectant la vie privée en exploitant les liens entre codes à effacements et les mécanismes de partages de secrets“. Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0045/document.
Der volle Inhalt der QuelleData from both individuals and companies is increasingly aggregated and analysed to provide new and improved services. There is a corresponding research effort to enable processing of such data in a secure and privacy preserving way, in line with the increasing public concerns and more stringent regulatory requirements for the protection of such data. Secure Multi-Party Computation (MPC) and secret sharing are mechanisms that can enable both secure distribution and computations on private data. In this thesis, we address the inefficiencies of these mechanisms by utilising results from a theoretically related rich area, erasure codes. We derive links between erasure codes and secret sharing, and use Maximum Distance Separable (MDS) codes as a basis to provide real-time applications relying on private user's data, revealing this data only to the selected group (which can be empty). The thesis has three contributions. A new class of erasure code called on-the-fly coding, have been introduced for their improvements in terms of recovery delay and achievable capacity. However little is known about the complexity of the systematic and non-systematic variants of this code, notably for live multicast transmission of multimedia content which is their ideal use case. The evaluation of both variants demonstrate that the systematic code outperforms the non-systematic one in regard to both the buffer sizes and the computation complexity. Then, we propose a new Layered secret sharing scheme and its application to Online Social Network (OSN). In current OSN, access to the user's profile information is managed by the service provider based on a limited set of rules. The proposed scheme enables automated profile sharing in OSN's groups with fine grained privacy control, via a multi-secret sharing scheme comprising of layered shares, without relying on a trusted third party. We evaluate the security of the scheme and the resulting profile's level of protection in an OSN scenario. Finally, after showing that erasure codes are efficient for real-time applications and that the security offered by secret sharing schemes can be applied to real-case applications, we derive the theoretical links between MDS codes and secret sharing to enable the implementation of efficient secret sharing scheme built from MDS codes. To illustrate this efficiency, we implement two of these schemes and evaluate their benefits in regard to computation and communication costs in an MPC application
Beugnon, Sébastien. „Sécurisation des maillages 3D pour l'industrie de la chaussure et la maroquinerie“. Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS097.
Der volle Inhalt der QuelleWith the increase of data exchange and latest technological and social developments, multimedia contents are becoming an important part of global trafic. Today, 3D objects are used in a large number of applications, for example, medical applications, simulations, video games, animation and special effects. 3D object usage by the general public has become a lucrative market that can take the form of 3D object downloading platforms with various 3D formats.This thesis, in collaboration with the company STRATEGIES, concerns the 3D object protection, and more particularly 3D meshes against fradulent and illegal uses. These 3D meshes represent surface models of shoes and leather goods produced by customers using digital solutions proposed by STRATEGIES. First, we propose a new method to insert secret data much more efficiently in terms of execution time on very large meshes than the previous method developed in collaboration with the company STRATEGIES. We are also exploring selective encryption approaches to control access to very high quality content according to user needs. In this context, we propose to use selective encryption approaches on the geometric data of 3D objects in order to protect the visual content of these objects according to different use cases and different data representations.In a second research axis, we study the application of secret sharing methods to the domain of 3D objects. Secret sharing is an approach that seeks to divide secret content between multiple users and allows certain subgroups of users to reconstruct the secret. Secret sharing is a redundancy system that allows you to reconstruct the secret even if some users have lost their information. Secret 3D object sharing is a poorly researched domain used to protect a 3D object between collaborators. We propose new secret 3D object sharing methods using selective encryption approaches and providing hierarchical properties where users have different access rights to 3D content based on their position in a hierarchical structure.Finally, the third research axis developed in this thesis deals with the analysis of the visual confidentiality of 3D objects selectively encrypted more or less strongly. Indeed, depending on the scenario, our 3D selective encryption methods provide results that can be more or less recognizable by users. However, the metrics used to evaluate the quality of 3D objects do not distinguish two selectively encrypted 3D objects with different levels of confidentiality. So, we present the construction of a databse of selectively encrypted 3D objects in order to realize subjective assessments of visual confidentiality and try to build a new metric correlated with evaluations obtained by the human visual system
Engel, Jean. „Assistants de service social et éducateurs spécialisés (en Alsace) face au secret partagé avec les élus : entre conflits de territoires et conflits de valeurs“. Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/ENGEL_Jean_2010.pdf.
Der volle Inhalt der QuelleThe goal of this thesis is to understand why social workers and educators are reluctant to enforce a "shared confidentiality" policy between them and mayors as advocated by the 2007 Law of Prevention of Delinquency. Basing my research on 70 semi-directive interviews of students and social workers conducted between 2005 and 2009, l have focused on the representations and use of professional confidentiality by those two professions. First, l discuss the hypothesis that the actual use of confidentiality is closely related to processes of recognition and exclusion in keeping with their professional identity. The first part is an analysis of the way interviewees perceive their peers and the work partners with whom they are supposed to share information. L address the issue of trust and competition in their mutual dealings, without ignoring the problem of power. The second part aims at demonstrating how relevant values are in the mechanisms of justification when workers choose to share or withhold information they have collected about users of social services. L underline the relativity of collective values within that field of activity and analyse to what extent with holding information and questioning the enforcement of the Law of Prevention of Delinquency may illustrate processes which enable social workers to make sure they hold on to the values that pertain to their professional activity. With regard to the prevention of delinquency, those values may induce an ideological stance which, even thongh it impedes effective partnership working, does not necessarily mean giving up transactional processes leading to practical compromises
Attasena, Varunya. „Secret sharing approaches for secure data warehousing and on-line analysis in the cloud“. Thesis, Lyon 2, 2015. http://www.theses.fr/2015LYO22014/document.
Der volle Inhalt der QuelleCloud business intelligence is an increasingly popular solution to deliver decision support capabilities via elastic, pay-per-use resources. However, data security issues are one of the top concerns when dealing with sensitive data. Many security issues are raised by data storage in a public cloud, including data privacy, data availability, data integrity, data backup and recovery, and data transfer safety. Moreover, security risks may come from both cloud service providers and intruders, while cloud data warehouses should be both highly protected and effectively refreshed and analyzed through on-line analysis processing. Hence, users seek secure data warehouses at the lowest possible storage and access costs within the pay-as-you-go paradigm.In this thesis, we propose two novel approaches for securing cloud data warehouses by base-p verifiable secret sharing (bpVSS) and flexible verifiable secret sharing (fVSS), respectively. Secret sharing encrypts and distributes data over several cloud service providers, thus enforcing data privacy and availability. bpVSS and fVSS address five shortcomings in existing secret sharing-based approaches. First, they allow on-line analysis processing. Second, they enforce data integrity with the help of both inner and outer signatures. Third, they help users minimize the cost of cloud warehousing by limiting global share volume. Moreover, fVSS balances the load among service providers with respect to their pricing policies. Fourth, fVSS improves secret sharing security by imposing a new constraint: no cloud service provide group can hold enough shares to reconstruct or break the secret. Five, fVSS allows refreshing the data warehouse even when some service providers fail. To evaluate bpVSS' and fVSS' efficiency, we theoretically study the factors that impact our approaches with respect to security, complexity and monetary cost in the pay-as-you-go paradigm. Moreover, we also validate the relevance of our approaches experimentally with the Star Schema Benchmark and demonstrate its superiority to related, existing methods
Cornejo-Ramirez, Mario. „Security for the cloud“. Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEE049/document.
Der volle Inhalt der QuelleCryptography has been a key factor in enabling services and products trading over the Internet. Cloud computing has expanded this revolution and it has become a highly demanded service or utility due to the advantages of high computing power, cheap cost of services, high performance, scalability, accessibility as well as availability. Along with the rise of new businesses, protocols for secure computation have as well emerged. The goal of this thesis is to contribute in the direction of securing existing Internet protocols by providing an analysis of the sources of randomness of these protocols and to introduce better protocols for cloud computing environments. We propose new constructions, improving the efficiency of current solutions in order to make them more accessible and practical. We provide a detailed security analysis for each scheme under reasonable assumptions. We study the security in a cloud computing environment in different levels. On one hand, we formalize a framework to study some popular real-life pseudorandom number generators used in almost every cryptographic application. On the other, we propose two efficient applications for cloud computing. The first allows a user to publicly share its high-entropy secret across different servers and to later recover it by interacting with some of these servers using only his password without requiring any authenticated data. The second, allows a client to securely outsource to a server an encrypted database that can be searched and modified later
Meyer, Pierre. „Sublinear-communication secure multiparty computation“. Electronic Thesis or Diss., Université Paris Cité, 2023. http://www.theses.fr/2023UNIP7129.
Der volle Inhalt der QuelleSecure Multi-Party Computation (MPC) [Yao82, GMW87a] allows a set of mutually distrusting parties to perform some joint computation on their private inputs without having to reveal anything beyond the output. A major open question is to understand how strongly the communication complexity of MPC and the computational complexity of the function being computed are correlated. An intriguing starting point is the study of the circuit-size barrier. The relevance of this barrier is a historical, and potentially absolute, one: all seminal protocols from the 1980s and 1990s use a "gate-by-gate" approach, requiring interaction between the parties for each (multiplicative) gate of the circuit to be computed, and this remains the state of the art if we wish to provide the strongest security guarantees. The circuit-size barrier has been broken in the computational setting from specific, structured, computational assumption, via Fully Homomorphic Encryption (FHE) [Gen09] and later Homomorphic Secret Sharing [BGI16a]. Additionally, the circuit-size barrier for online communication has been broken (in the correlated randomness model) information-theoretically [IKM + 13, DNNR17, Cou19], but no such result is known for the total communication complexity (in the plain model). Our methodology is to draw inspiration from known approaches in the correlated randomness model, which we view simultaneously as fundamental (because it provides information-theoretic security guarantees) and inherently limited (because the best we can hope for in this model is to understand the online communication complexity of secure computation), in order to devise new ways to break the circuit-size barrier in the computational setting. In the absence of a better way to decide when concrete progress has been made, we take extending the set of assumptions known to imply sublinear-communication secure computation as "proof of conceptual novelty". This approach has allowed us to break the circuit-size barrier under quasipolynomial LPN [CM21] or QR and LPN [BCM22]. More fundamentally, these works constituted a paradigm shift, away from the "homomorphism-based" approaches of FHE and HSS, which ultimately allowed us to break the two-party barrier for sublinear-communication secure computation and provide in [BCM23] the first sublinear-communication protocol with more than two parties, without FHE. Orthogonally to this line of work, purely focusing on computational security, we showed in [CMPR23] that [BGI16a] could be adapted to provide information-theoretic security for one of the two parties, and computational security for the other: these are provably the strongest security guarantees one can hope to achieve in the two-party setting (without setup), and ours is the first sublinear-communication protocol in this setting which does not use FHE
Hoang, Bao Thien. „Problème de sondage dans les réseaux sociaux décentralisés“. Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0016/document.
Der volle Inhalt der QuelleOne of the current practical, useful but sensitive topic in social networks is polling problem where the privacy of exchanged information and user reputation are very critical. Indeed, users want to preserve the confidentiality of their votes and to hide, if any, their misbehaviors. Recently, Guerraoui et al. proposed polling protocols based on simple secret sharing scheme and without requiring any central authority or cryptography system. However these protocols can be deployed safely and efficiently provided that the social graph structure should be transformed into a ring structure-based overlay and the number of participating users is perfect square. In this thesis, we address the problem of deploying decentralized polling protocols for general social graphs and how to transform these graphs in order to increase the privacy and/or accuracy properties. First, we propose three simple decentralized polling protocols that rely on the current state of social graphs. The two first protocols use synchronous and asynchronous models and verification procedures to detect the misbehaving users. The third protocol is an asynchronous one that does not require any verification procedures and contains a method for efficiently broadcasting message under a family of social graphs satisfying what we call the “m-broadcasting” property. Second, we formalize the “adding friends” problem such that we can reuse the social graphs after some minimum structural modifications consisting in adding new friendship relations. We also devise algorithms for solving this problem in centralized and decentralized networks. We validate our solutions with some performance evaluations which show that our protocols are accurate, and inside the theoretical bounds
Hoang, Bao Thien. „Problème de sondage dans les réseaux sociaux décentralisés“. Electronic Thesis or Diss., Université de Lorraine, 2015. http://www.theses.fr/2015LORR0016.
Der volle Inhalt der QuelleOne of the current practical, useful but sensitive topic in social networks is polling problem where the privacy of exchanged information and user reputation are very critical. Indeed, users want to preserve the confidentiality of their votes and to hide, if any, their misbehaviors. Recently, Guerraoui et al. proposed polling protocols based on simple secret sharing scheme and without requiring any central authority or cryptography system. However these protocols can be deployed safely and efficiently provided that the social graph structure should be transformed into a ring structure-based overlay and the number of participating users is perfect square. In this thesis, we address the problem of deploying decentralized polling protocols for general social graphs and how to transform these graphs in order to increase the privacy and/or accuracy properties. First, we propose three simple decentralized polling protocols that rely on the current state of social graphs. The two first protocols use synchronous and asynchronous models and verification procedures to detect the misbehaving users. The third protocol is an asynchronous one that does not require any verification procedures and contains a method for efficiently broadcasting message under a family of social graphs satisfying what we call the “m-broadcasting” property. Second, we formalize the “adding friends” problem such that we can reuse the social graphs after some minimum structural modifications consisting in adding new friendship relations. We also devise algorithms for solving this problem in centralized and decentralized networks. We validate our solutions with some performance evaluations which show that our protocols are accurate, and inside the theoretical bounds
Chouha, Paul-Robert. „From Classical to Quantum Secret Sharing“. Thèse, 2012. http://hdl.handle.net/1866/12389.
Der volle Inhalt der QuelleIn this thesis, we will focus on a cryptographic primitive known as secret sharing. We will explore both the classical and quantum domains of such schemes culminating our study by presenting a new protocol for sharing a quantum secret using the minimal number of possible quantum shares i.e. one single quantum share per participant. We will start our study by presenting in the preliminary chapter, a brief mathematical survey of quantum information theory (QIT) which has for goal primarily to establish the notation used throughout the manuscript as well as presenting a précis of the mathematical properties of the Greenberger-Horne-Zeilinger (GHZ)-state, which is used thoroughly in cryptography and in communication games. But as we mentioned above, our main focus will be on cryptography. In chapter two, we will pay a close attention to classical and quantum error corrections codes (QECC) since they will become of extreme importance when we introduce quantum secret sharing schemes in the following chapter. In the first part of chapter three, we will focus on classical secret shearing, presenting a general framework for such a primitive all the while illustrating the abstract concepts with examples presented both for their historical and analytical relevance. This first part (chapters one and two) will pave the way for our exposition of the theory of Quantum Secret Sharing (QSS), which will be the focus of the second part of chapter three. We will present then the most general theorems and definitions known to date for the construction of such primitives putting emphasis on the special case of quantum threshold schemes. We will show how quantum error correction codes are related to QSS schemes and show how this relation leads to a very solid correspondence to the point that QECC’s are closer analogues to QSS schemes than are the classical secret sharing primitives. Finally, we will present one of the three results we have in A. Broadbent, P.-R. Chouha, A. Tapp (2009) in particular, a secure minimal quantum threshold protocol (the other two results deal with communication complexity and the classical simulation of the GHZ-state).
Ranellucci, Samuel. „Practical and Foundational Aspects of Secure Computation“. Thèse, 2014. http://hdl.handle.net/1866/11450.
Der volle Inhalt der QuelleThere are seemingly impossible problems to solve without a trusted third-party. How can two millionaires learn who is the richest when neither is willing to tell the other how rich he is? How can satellite collisions be prevented when the trajectories are secret? How can researchers establish correlations between diseases and medication while respecting patient confidentiality? How can an organization insure that the government does not abuse the knowledge that it possesses even though such an organization would be unable to control that information? Secure computation, a branch of cryptography, is a eld that studies how to generate protocols for realizing such tasks without the use of a trusted third party. There are certain goals that such protocols should achieve. The rst concern is privacy: players should learn no more information than what a trusted third party would give them. The second main goal is correctness: players should only receive what a trusted third party would give them. The protocols should also be efficient. Another important property is robustness, the protocols should not abort even if a small set of players is cheating. Secure computation has four basic building blocks : Oblivious Transfer, secret sharing, commitment schemes, and garbled circuits. Protocols can be built based only on these building blocks or alternatively, they can be constructed from specific computational assumptions. Protocols constructed solely from these primitives are flexible and are not as vulnerable to technological or algorithmic improvements. Many protocols are nevertheless based on computational assumptions. It is important to ask if efficiency requires computational assumptions. We show that this is not the case by building efficient protocols from these primitives. It is the conclusion of this thesis that building protocols from black-box primitives can also lead to e cient protocols. This thesis is a collection of four articles written in collaboration with other researchers. This constitutes the mature part of my investigation and is my main contributions to the field during that period of time. In the first work presented in this thesis we study the commitment capacity of noisy channels. We first show a tight lower bound that implies that in contrast to Oblivious Transfer, there exists no constant rate protocol for bit commitments. We then demonstrate that by restricting the way the commitments can be opened, we can achieve better efficiency and in particular cases, a constant rate. This is done by exploiting the notion of cover-free families. In the second article, we show that for certain problems, there exists a trade-off between robustness, correctness and privacy. This is done by using verifiable secret sharing, zero-knowledge, the concept of ghosts and a technique which we call \balls and bins". In our third contribution, we show that many protocols in the literature based on specific computational assumptions can be instantiated from a primitive known as Verifiable Oblivious Transfer, via the concept of Generalized Oblivious Transfer. The protocol uses secret sharing as its foundation. In the last included publication, we construct a constant-round protocol for secure two-party computation that is very efficient and only uses black-box primitives. The remarkable efficiency of the protocol is achieved by replacing the core of a standard protocol by a faulty but very efficient primitive. The fault is then dealt with by a non-trivial use of privacy amplification.