New Insights on cryptographic hierarchical access control: models, schemes and analysis

2014 - 2015Nowadays the current network-centric world has given rise to several security concerns regarding the access control management, which en- sures that only authorized users are given access to certain resources or tasks. In particular, according to their respective roles and respon- sibilities, users are typically organized into hierarchies composed of several disjoint classes (security classes). A hierarchy is characterized by the fact that some users may have more access rights than others, according to a top-down inclusion paradigm following speci c hier- archical dependencies. A user with access rights for a given class is granted access to objects stored in that class, as well as to all the de- scendant ones in the hierarchy. The problem of key management for such hierarchies consists in assigning a key to each class of the hierar- chy, so that the keys for descendant classes can be e ciently obtained from users belonging to classes at a higher level in the hierarchy. In this thesis we analyze the security of hierarchical key assignment schemes according to di erent notions: security with respect to key indistinguishability and against key recovery [4], as well as the two recently proposed notions of security with respect to strong key in- distinguishability and against strong key recovery [42]. More precisely, we rst explore the relations between all security notions and, in par- ticular, we prove that security with respect to strong key indistin- guishability is not stronger than the one with respect to key indistin- guishability. Afterwards, we propose a general construction yielding a hierarchical key assignment scheme that ensures security against strong key recovery, given any hierarchical key assignment scheme which guarantees security against key recovery. Moreover, we de ne the concept of hierarchical key assignment schemes supporting dynamic updates, formalizing the relative secu- rity model. In particular, we provide the notions of security with respect to key indistinguishability and key recovery, by taking into ac- count the dynamic changes to the hierarchy. Furthermore, we show how to construct a hierarchical key assignment scheme supporting dy- namic updates, by using as a building block a symmetric encryption scheme. The proposed construction is provably secure with respect to key indistinguishability, provides e cient key derivation and updat- ing procedures, while requiring each user to store only a single private key. Finally, we propose a novel model that generalizes the conventional hierarchical access control paradigm, by extending it to certain addi- tional sets of quali ed users. Afterwards, we propose two construc- tions for hierarchical key assignment schemes in this new model, which are provably secure with respect to key indistinguishability. In par- ticular, the former construction relies on both symmetric encryption and perfect secret sharing, whereas, the latter is based on public-key threshold broadcast encryption. [edited by author]XIV n.s

MODELING, LEARNING AND REASONING ABOUT PREFERENCE TREES OVER COMBINATORIAL DOMAINS

In my Ph.D. dissertation, I have studied problems arising in various aspects of preferences: preference modeling, preference learning, and preference reasoning, when preferences concern outcomes ranging over combinatorial domains. Preferences is a major research component in artificial intelligence (AI) and decision theory, and is closely related to the social choice theory considered by economists and political scientists. In my dissertation, I have exploited emerging connections between preferences in AI and social choice theory. Most of my research is on qualitative preference representations that extend and combine existing formalisms such as conditional preference nets, lexicographic preference trees, answer-set optimization programs, possibilistic logic, and conditional preference networks; on learning problems that aim at discovering qualitative preference models and predictive preference information from practical data; and on preference reasoning problems centered around qualitative preference optimization and aggregation methods. Applications of my research include recommender systems, decision support tools, multi-agent systems, and Internet trading and marketing platforms

Static Analysis of Circuits for Security

The purpose of the present work is to define a methodology to analyze a system description given in VHDL code and test its security properties. In particular the analysis is aimed at ensuring that a malicious user cannot make a circuit output the secret data it contains

Classification, Formalization and Automatic Verification of Untraceability in RFID Protocols

Résumé Les protocoles sécurité RFID sont des sous-ensembles des protocoles cryptographiques mais avec des fonctions cryptographiques légères. Leur objectif principal est l'identification à l'égard de certaines propriétés de intimité comme la non-traçabilité et la confidentialité de l'avant. La intimité est un point essentielle de la société d'aujourd'hui. Un protocole d'identification RFID devrait non seulement permettre à un lecteur légitime d'authentifier un tag, mais il faut aussi protéger la intimité du tag. Des failles de sécurité ont été découvertes dans la plupart de ces protocoles, en dépit de la quantité considérable de temps et d'efforts requis pour la conception et la mise en œuvre de protocoles cryptographiques. La responsabilité de la vérification adéquate devient cruciale. Les méthodes formelles peuvent jouer un rôle essentiel dans le développement de protocoles de sécurité fiables. Les systèmes critiques qui nécessitent une haute fiabilité tels que les protocoles de sécurité sont difficiles à évaluer en utilisant les tests conventionnels et les techniques de simulation. Cela a eu comme effet de concentrer les recherches sur les techniques de vérification formelle de tels systèmes pour assurer un degré élevé de fiabilité. Par conséquent, certaines recherches ont été faites dans ce domaine, mais une définition explicite de certaines de ces propriétés de sécurité n'ont pas encore été donnée. L'objectif principal de cette thèse est de démontrer l'utilisation de méthodes formelles pour analyser les propriétés de intimité du protocole RFID. Plusieurs définitions sont données dans la littérature pour les propriétés non-traçabilité, mais il n'y a pas d'accord sur sa définition exacte. Nous avons introduit trois niveaux différents pour cette propriété en ce qui concerne les expériences de intimité existantes. Nous avons également classé toutes les définitions existantes avec différents points forts de la propriété non-traçabilité dans la littérature. De plus, notre approche utilise spécifiquement les techniques de calculs de processus pi calcul appliqués pour créer un modèle pour un protocole. Nous démontrons les définitions formelles de nos niveaux de non-traçabilité proposées et l'applique à des études de cas sur les protocoles existants.----------Abstract RFID protocols are subsets of cryptographic protocols but with lightweight cryptographic functions. Their main objective is identification with respect to some privacy properties, like anonymity, untraceability and forward secrecy. Privacy is the essential part of today's society. An RFID identification protocol should not only allow a legitimate reader to authenticate a tag but also it should protect the privacy of the tag. Although design and implementation of cryptographic protocols are tedious and time consuming, security flaws have been discovered in most of these protocols. Therefore the responsibility for reliable and proper verification becomes crucial. Formal methods can play an essential role in the development of reliable security protocols. Critical systems which require high reliability such as security protocols are difficult to be evaluated using conventional tests and simulation techniques. This has encouraged the researchers to focus on the formal verification techniques to ensure a high degree of reliability in such systems. In spite of the studies which have been carried out in this field, an explicit definition for some of these security properties is still missing

Foundations of Software Science and Computation Structures

This open access book constitutes the proceedings of the 25th International Conference on Foundations of Software Science and Computational Structures, FOSSACS 2022, which was held during April 4-6, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 23 regular papers presented in this volume were carefully reviewed and selected from 77 submissions. They deal with research on theories and methods to support the analysis, integration, synthesis, transformation, and verification of programs and software systems

Proceedings of the 21st Conference on Formal Methods in Computer-Aided Design – FMCAD 2021

The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing

Investigation, Development, and Evaluation of Performance Proving for Fault-tolerant Computers

A number of methodologies for verifying systems and computer based tools that assist users in verifying their systems were developed. These tools were applied to verify in part the SIFT ultrareliable aircraft computer. Topics covered included: STP theorem prover; design verification of SIFT; high level language code verification; assembly language level verification; numerical algorithm verification; verification of flight control programs; and verification of hardware logic

ISIPTA'07: Proceedings of the Fifth International Symposium on Imprecise Probability: Theories and Applications

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