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De, Caro Angelo. "On the Generalizations of Identity-Based Encryption." Doctoral thesis, Universita degli studi di Salerno, 2013. http://hdl.handle.net/10556/899.
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2011 - 2012<br>Today public-key cryptographic is widely deployed and successfully used but still a major drawback
exists. In fact, from encrypted data a party can either decrypt or cannot learn anything at all about the
message other than intentionally leaked information such as its length. In the recent years, the cloud
computing paradigm has emerged as the new standard to use computing resources, such as storage
devices, that are delivered as a service over a network. In such a scenario, the notion of public key
cryptography is not enough. It would be desirable to specify a decryption policy in the encrypted data
in such a way that only the parties who satisfy the policy can decrypt. In a more general form, we may
want to only give access to a function of the message, depending on the decryptor’s authorization.
Thus, in the last decade researchers have started looking at a more sophisticated type of encryption
called functional encryption. A functionality F is a function F : K × M ! where K is the key
space and M is the message space. In the public-key setting, a functional encryption scheme for F
is a special encryption scheme in which, for every key k 2 K, the owner of the master secret key
msk associated with the master public key mpk can generate a special secret-key skk that allows the
computation of F(k,m) from a ciphertext of m 2 M computed under public key mpk . In other words,
whereas in traditional encryption schemes decryption is an all-or-nothing affair, in functional encryption
it is possible to finely control the amount of information that is revealed by a ciphertext. One of the most
notable example of functional encryption is identity-based encryption first introduced by Shamir as an
alternative to the standard notion of public-key encryption.
In this thesis, we discuss several instantiations of function encryption that can all be seen as generalisations
of identity-based encryption. We improve on previous constructions in terms of performance
and security guarantees. [edited by author]<br>XI n.s.
2
Odyurt, Uraz. "Application of Fuzzy Logic in Identity-Based Cryptography." Thesis, Linnéuniversitetet, Institutionen för matematik (MA), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35134.
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This work explains the fundamental definitions required to define and create Fuzzy Identity-Based Encryption schemes as an error-tolerant version of Identity-Based Encryption schemes, along with three different examples of such creations. These examples are Sahai-Waters' FIBE, Baek et al.'s EFIBE-I and EFIBE-II. The required Set-up, Key Generation, Encryption and Decryption algorithms for each scheme are formalized and the proofs of security using the Selective-ID model are introduced. Subtle differences between the three schemes are discussed, including their computational efficiency comparison. The writing is intended as a self-sufficient resource for readers, containing the schemes and background definitions.
3
Hedges, Mary. "Elliptic curve cryptography and identity-based encryption." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1442908.
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Srinivasan, Sriramkrishnan. "New security notions for identity based encryption." Thesis, Royal Holloway, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529038.
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Tam, Tony. "Identity-Based Encryption on resource constrained embedded system." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1569592.
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<p> The use of smart embedded device has been growing rapidly recently because of the miniaturization of sensors and platforms. A resource-efficient Public Key Cryptography (PKC) is very desirable for the resource-constrained embedded system. Whereas most public key security protocols requires both public and private keys to be generated together, Identity Based Encryption (IBE), a public key cryptography protocol, allows the public key to be generated from an arbitrary string. IBE has been actively researched and deployed, but conventional IBE primitives are still computationally demanding and may not be suitable for all embedded system. Simplified version of the identity based encryption is available and satisfies the tight budget of the embedded platform. In this thesis, we describe the implementation of lightweight IBE based on elliptic curve in resource-constrained embedded sensor nodes. We also compare and contrast its performance with the conventional pairing-based approach. </p>
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Germouty, Paul. "Identity-based cryptography." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0041/document.
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Dans cette thèse nous étudions les possibilités que les chiffrements basés sur l’identité offrent quand ils sont utilisés dans un but différent qu’un simple chiffrement. Nous avons pu généraliser différents types de chiffrement basés sur l’identité en une nouvelle primitive nommé Downgradable Identity-based Encryption (DIBE). Nous avons trouvé un moyen générique de transformer de simple IBE en des IBE en blanc, dans le cas où l’IBE est affine nous rendons le coût de communication très faible (de linéaire à logarithmique). Ces deux primitives ont donné lieux à différentes applications : les chiffrements basés sur les attributs pour la première et le transfère inconscient pour la deuxième. Une autre application est l’utilisation d’IBE hiérarchiques pour créer des signatures à vérifieur désigné basées sur l’identité. Ensuite nous avons regardé le transfère inconscient seul et avons réussi à le généraliser en un nouveau protocole nommé Oblivious Language-based Envelope. Finalement, nous avons construit une transformation d’un protocole à un autre, d’un échange authentifié de clés par mot de passe nous avons construit un transfère inconscient. En prenant une instanciation particulière nous obtenons un protocole plus efficace que tous les précédents pour le même niveau de sécurité. La primitive chiffrement basé sur l’identité est notre outil principal pour réaliser nos constructions. Nous avons donc besoin d’une instanciation efficace de cette primitive. Nous avons utilisé celle de Blazy Kiltz et Pan à CRYPTO’14 qui est très efficace mais possède aussi une structure particulière dite affine<br>During this Thesis we investigated the possibilities that Identity-based Encryption offers when used out of their original purpose. We managed to generalize a whole class of different identity-based encryption schemes into Downgradable Identity-based Encryptions. We found a generic way to construct Blind Identity-based Encryptions. These two works leads both to applications that are not a priori linked with IBE: Attribute-based Encryption from Downgradable IBE and Oblivious Transfer for Blind IBE, in the case of Affine IBE we manage to reduce the communication cost from a linear to logarithmic. As application we also find a way to use Hierarchical IBE to construct a special type of signature called Identity-based Designated Verifier Signature. We continue the research out of the context of IBE's application with Oblivious Transfer. We manage to generalize the concept of Oblivious Transfer into a new protocol called Oblivious Language-based Envelope encompassing many kind of protocols. Finally, in the image of the whole Thesis we construct Oblivious Transfer with a very different primitive called Password Authenticated Key Exchange. Surprisingly, with some optimizations this last transformation leads to a very efficient Oblivious Transfer Protocol. The Identity-based Encryption is our main basis of work, thus efficient instantiations of this primitive were the key of our own efficiency, thus we used the instanciation from the paper of Blazy et als at crypto 2014 which is efficient, tight secure and affine
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Kwok, Hon-man Sammy, and 郭漢文. "A scalable and secure networking paradigm using identity-based cryptography." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46971713.
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Li, Qinyi. "Lattice public-key encryption: Richer, tighter, stronger." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/107651/1/Qinyi_Li_Thesis.pdf.
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Public-key encryption allows anyone to encrypt messages that only the intended recipient can decrypt. It is an essential component of most network security protocols; however, the algorithms in widespread use are inherently vulnerable to attacks by quantum computers, should they become a practical reality. This thesis looks at public-key encryption from computationally hard problems based on high-dimensional lattices, believed to resist classical and quantum attacks. On those foundations, it proposes three post-quantum public-key encryption schemes, respectively featuring richer access control, tighter reductionist security proofs, and stronger confidentiality in the presence of external leakage.
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Incebacak, Davut. "Design And Implementation Of A Secure And Searchable Audit Logging System." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608431/index.pdf.
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Logs are append-only time-stamped records to represent events in computers or network devices. Today, in many real-world networking applications, logging is a central service however it is a big challenge to satisfy the conflicting requirements when the security of log records is of concern. On one hand, being kept on mostly untrusted hosts, the logs should be preserved against unauthorized modifications and privacy breaches. On the other, serving as the primary evidence for digital crimes, logs are often needed for analysis by investigators.
In this thesis, motivated by these requirements we define a model which integrates forward integrity techniques with search capabilities of encrypted logs. We also implement this model with advanced cryptographic primitives such as Identity
Based Encryption. Our model, in one side, provides secure delegation of search capabilities to authorized users while protecting information privacy, on the other, these search capabilities set boundaries of a user&rsquo<br>s search operation. By this way user can not access logs which are not related with his case. Also, in this dissertation, we propose an improvement to Schneier and Kelsey&rsquo<br>s idea of forward integrity mechanism.
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Prest, Thomas. "Gaussian sampling in lattice-based cryptography." Thesis, Paris, Ecole normale supérieure, 2015. http://www.theses.fr/2015ENSU0045/document.
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Bien que relativement récente, la cryptographie à base de réseaux euclidiens s’est distinguée sur de nombreux points, que ce soit par la richesse des constructions qu’elle permet, par sa résistance supposée à l’avènement des ordinateursquantiques ou par la rapidité dont elle fait preuve lorsqu’instanciée sur certaines classes de réseaux. Un des outils les plus puissants de la cryptographie sur les réseaux est le Gaussian sampling. À très haut niveau, il permet de prouver qu’on connaît une base particulière d’un réseau, et ce sans dévoiler la moindre information sur cette base. Il permet de réaliser une grande variété de cryptosystèmes. De manière quelque peu surprenante, on dispose de peu d’instanciations pratiques de ces schémas cryptographiques, et les algorithmes permettant d’effectuer du Gaussian sampling sont peu étudiés. Le but de cette thèse est de combler le fossé qui existe entre la théorie et la pratique du Gaussian sampling. Dans un premier temps, nous étudions et améliorons les algorithmes existants, à la fois par une analyse statistique et une approche géométrique. Puis nous exploitons les structures sous-tendant de nombreuses classes de réseaux, ce qui nous permet d’appliquer à un algorithme de Gaussian sampling les idées de la transformée de Fourier rapide, passant ainsi d’une complexité quadratique à quasilinéaire. Enfin, nous utilisons le Gaussian sampling en pratique et instancions un schéma de signature et un schéma de chiffrement basé sur l’identité. Le premierfournit des signatures qui sont les plus compactes obtenues avec les réseaux à l’heure actuelle, et le deuxième permet de chiffrer et de déchiffrer à une vitesse près de mille fois supérieure à celle obtenue en utilisant un schéma à base de couplages sur les courbes elliptiques<br>Although rather recent, lattice-based cryptography has stood out on numerous points, be it by the variety of constructions that it allows, by its expected resistance to quantum computers, of by its efficiency when instantiated on some classes of lattices. One of the most powerful tools of lattice-based cryptography is Gaussian sampling. At a high level, it allows to prove the knowledge of a particular lattice basis without disclosing any information about this basis. It allows to realize a wide array of cryptosystems. Somewhat surprisingly, few practical instantiations of such schemes are realized, and the algorithms which perform Gaussian sampling are seldom studied. The goal of this thesis is to fill the gap between the theory and practice of Gaussian sampling. First, we study and improve the existing algorithms, byboth a statistical analysis and a geometrical approach. We then exploit the structures underlying many classes of lattices and apply the ideas of the fast Fourier transform to a Gaussian sampler, allowing us to reach a quasilinearcomplexity instead of quadratic. Finally, we use Gaussian sampling in practice to instantiate a signature scheme and an identity-based encryption scheme. The first one yields signatures that are the most compact currently obtained in lattice-based cryptography, and the second one allows encryption and decryption that are about one thousand times faster than those obtained with a pairing-based counterpart on elliptic curves
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Brouilhet, Laura. "Généralisation des protocoles en cas multi-utilisateurs." Thesis, Limoges, 2020. http://www.theses.fr/2020LIMO0062.
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Dans cette thèse, nous utilisons des protocoles cryptographiques existants afin d’en proposer de nouveaux ou avec de nouvelles propriétés intéressantes.Nous avons tout d’abord proposer un protocole de signature à base d’attributs à partir d’un chiffrement basé sur l’identité. La sécurité de cette construction est prouvée sous une hypothèse classique. Par la suite, nous proposons une signature en blanc en tour optimal et de taille constante grâce à la méthode de construction de Fischlin et des preuves non-interactives à divulgation nulle de connaissance. De plus, cette signature est prouvée sûre sous une hypothèse classique. En résultat annexe, nous proposons une signature sur chiffré randomizable de taille constante est également présentée et prouvée sous la même hypothèse.Ensuite, nous introduisons un nouveau protocole de chiffrement basé sur l’identité (IBE) qui permet a un traceur, avec une clé associé à une identité, de filtrer tout les chiffrés envoyé à cette identité précise (et seulement celle-ci).Finalement nous proposons un protocole de signature à trois parties prouvée sûr sous des hypothèses standards. Cette construction utilise différents outils tels que des SPHF ou la signature asymétrique de Waters<br>In this thesis, we use building blocks to propose new one or with new interesting properties. First, we propose a attribute-based designated verifier signature thanks to an IBE. Security properties are proven under usual hypothesis. Then, we introduce our round-optimal constant-size blind signature thanks to Fischlin framework and NIZK. As a side result, we propose a constant-size signature on randomizable ciphertexts. Then, we introduce a new IBE which allows a tracer, given a tracing key associated to an identity, to filter all the ciphertexts that are sent to this specific identity (and only those). Two applications of this protocols are proposed. We show that our modification doesn’t alter the security of IBE. Finally, we present a threshold signature between an user, a token and a server thanks to different building blocks like SPHF or assymetric Waters signature. The security of the construction is proven under regular assumptions like CDH+ or DDH
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Misaghi, Mehran. "Um ambiente criptográfico baseado na identidade." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-15092008-135036/.
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O crescimento acelerado de negócios voltado para Internet aumenta significativamente a necessidade por mecanismos que possam garantir a confidencialidade dos dados, fornecendo ferramentas para autenticidade e irretratabilidade dos usuários em qualquer meio de comunicação, mesmo em equipamentos que possuem recursos computacionais limitados, como um telefone celular, por exemplo. Este trabalho apresenta um esquema de criptografia que utiliza os dados pessoais para geração de chave e cifração, chamado Criptografia Baseada na Identidade, sem necessidade de um certificado digital. São apresentados diversos modelos de cifração, assinatura, acordo de chaves, bem como principais características, diferenças operacionais e respectivos aspectos relevantes de segurança. Algumas aplicabilidades como busca de dados cifrados, por exemplo, são implementadas, para melhor entendimento das operações e fases envolvidas. Os comparativos de custos computacionais das operações envolvidas destacam o esquema de assinatura de Barreto et al. (2005) e esquema de acordo de chave Mc- Cullagh e Barreto (2004b). São descritos também os pré-requisitos de um ambiente criptográfico baseado na identidade, o qual permite realizar as operações de cifração, assinatura e acordo de chaves com menor custo computacional possível.<br>The accelerated growth of Internet-based business increase significantly the need for mechanisms that can guarantee the data confidentiality, providing tools for authenticity and non-repudiation users in any medium of communication, even with computer resources becoming increasingly scarce, eg into a cell phone. This paper describes an encryption scheme that uses personal data for key generation and encryption, called the Identity Based Encryption, without need for a digital certificate. Various encryption schemes, signature, key agreement are shown, and its main characteristics, operational differences and their respective relevant aspects of security. Some aplicabilities such as encrypted data search, for example, are implemented, for better understanding of the operations and stages involved. The comparative computataional costs of operations highlight the Barreto et al. (2005) signature scheme and McCullagh e Barreto (2004b) key agreement scheme. They are also described, the prerequisites of an Identity-based cryptography environment, which allows to perform the operations of encryption, signing and key agreement with lower computational cost possible.
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Zitouni, Mohammed. "L’étude et l’implémentation des algorithmes de couplages sur des courbes hyperelliptiques sur des corps premiers." Electronic Thesis or Diss., Paris 8, 2021. http://www.theses.fr/2021PA080031.
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La recherche de nouveaux groupes autres que le groupe multiplicatif pour concevoir des protocoles plus constructifs en cryptographie est devenue un défi depuis 2000. Plusieurs groupes ont émergé tels que le groupe des points rationnels d'une courbe elliptique et la Jacobienne d'une courbe hyperelliptique. De plus, les couplages sont devenus des outils encore plus pratiques pour concevoir de nouveaux protocoles en cryptographie tels que le chiffrement basé sur l'identité et la signature courte. Cette thèse étudie l'implémentation des algorithmes de couplages sur des courbes hyperelliptiques sur des corps premiers. D'une part, nous considérons le choix des courbes hyperelliptiques à utiliser et la construction des courbes hyperelliptiques de genre deux avec une Jacobienne ordinaire sur des corps premiers. D'autre part, nous améliorons les calculs de couplages sur différentes courbes hyperelliptiques. L'implémentation du couplage de Tate sur des jacobiennes ordinaires des courbes de genre 2 sur de large corps premiers et à plusieurs niveaux de sécurité. L'optimisation de la quantité non négligeable d'opérations qui doivent être optimisées pour rendre le coût de l'utilisation des appariements en cryptographie plus raisonnable. Enfin, nous donnons un schéma concret de cryptage basé sur l'identité en utilisant le couplage de Tate sur une courbe hyperelliptique de genre 2<br>Looking for new groups other than multiplicative group to design more constructive protocols in cryptography became the challenge since 2000. Several groups have emerged such as the group of rational points of an elliptic curve and the Jacobian of a hyperelliptic curve. Furthermore, pairings became even more practical tool to design new protocols in cryptography such as identity-based encryption and short signature. This thesis studies the implementation of pairing algorithms on hyperelliptic curves over prime fields. On the one hand, we regard the choice of the hyperelliptic curves to be used and the construction of genus two hyperelliptic curve of the ordinary Jacobian over a large prime field. On the other hand, we improve the pairing computations on different hyperelliptic curves. Tate pairing are implemented on ordinary Jacobian curves over a large prime field for several security levels. The optimization of the non negligible amount of operations that must be optimised to make the cost of using pairings in cryptography more reasonable. Finally, we give a concrete identity-based encryption scheme using the Tate pairing over genus two hyperelliptic curve
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Du, Rong. "Secure electronic tendering." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16606/1/Rong_Du_Thesis.pdf.
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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.
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Du, Rong. "Secure electronic tendering." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16606/.
Full textAbstract:
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.
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Khandavilli, Ambica Pawan. "A MOBILE ROLE BASED ACCESS CONTROL SYSTEM USING IDENTITY BASED ENCRYPTION WITH NON-INTERACTIVE ZERO KNOWLEDGE PROOF OF AUTHENTICATION." 2012. http://hdl.handle.net/10222/14604.
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Controlled access to confidential information and resources is a critical element in security systems. Role based access control (RBAC) has gained widespread usage in modern enterprise systems. Extensions have been proposed to RBAC for incorporating spatial constraints into such systems. Several solutions have been proposed for such models and much research has now been directed towards enforcing system policies.
The thesis proposes a security framework for RBAC systems with spatial constraints based on identity based encryption. Integration of identity based encryption and with zero knowledge proof is proposed to provide authentication and information security. We also show how Near Field Communication can be used to establish the integrity of a user’s proof of location. We discuss the design choices made in the protocol and explain the protocol implementation. Simulation results in Java validate our model. Furthermore, security analysis has been done to show how our framework protects against well-known attacks.
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Agrawal, Shweta Prem. "Efficient, provably secure code constructions." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-2675.
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The importance of constructing reliable and efficient methods for securing digital information in the modern world cannot be overstated. The urgency of this need is reflected in mainstream media--newspapers and websites are full of news about critical user information, be it credit card numbers, medical data, or social security information, being compromised and used illegitimately. According to news reports, hackers probe government computer networks millions of times a day, about 9 million Americans have their identities stolen each year and cybercrime costs large American businesses 3.8 million dollars a year. More than 1 trillion worth of intellectual property has already been stolen from American businesses. It is this evergrowing problem of securing valuable information that our thesis attempts to address (in part). In this thesis, we study methods to secure information that are fast, convenient and reliable. Our overall contribution has four distinct threads. First, we construct efficient, "expressive" Public Key Encryption systems (specifically, Identity Based Encryption systems) based on the hardness of lattice problems. In Identity Based Encryption (IBE), any arbitrary string such as the user's email address or name can be her public key. IBE systems are powerful and address several problems faced by the deployment of Public Key Encryption. Our constructions are secure in the standard model. Next, we study secure communication over the two-user interference channel with an eavesdropper. We show that using lattice codes helps enhance the secrecy rate of this channel in the presence of an eavesdropper. Thirdly, we analyze the security requirements of network coding. Network Coding is an elegant method of data transmission which not only helps achieve capacity in several networks, but also has a host of other benefits. However, network coding is vulnerable to "pollution attacks" when there are malicious users in the system. We design mechanisms to prevent pollution attacks. In this setting, we provide two constructions -- a homomorphic Message Authentication Code (HMAC) and a Digital Signature, to secure information that is transmitted over such networks. Finally, we study the benefits of using Compressive Sensing for secure communication over the Wyner wiretap channel. Compressive Sensing has seen an explosion of interest in the last few years with its elegant mathematics and plethora of applications. So far however, Compressive Sensing had not found application in the domain of secrecy. Given its inherent assymetry, we ask (and answer in the affirmative) the question of whether it can be deployed to enable secure communication. Our results allow linear encoding and efficient decoding (via LASSO) at the legitimate receiver, along with infeasibility of message recovery (via an information theoretic analysis) at the eavesdropper, regardless of decoding strategy.<br>text
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Lin, Chih-Wen, and 林稚雯. "Attribute-based Encryption from Identity-based Encryption." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/4jmp26.
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碩士<br>國立中山大學<br>資訊工程學系研究所<br>104<br>Ciphertext-policy attribute-based encryption (CP-ABE) is an access control mechanism where a data provider encrypts a secret message and then sends the ciphertext to the receivers according to the access policy which she/he decides. If the attributes of the receivers match the access policy, then they can decrypt the ciphertext. This thesis shows a relation between ABE and identity-based encryption (IBE), and presents a bi-directional conversion between an access structure and identities. By the proposed conversion, the ABE scheme constructed from an IBE scheme will inherit the features, such as constant-size ciphertexts and anonymity, from the IBE scheme, and vice versa. It turns out that the proposed conversion also gives the first ABE achieving access structures with wildcard and constant-size ciphertexts/private keys. Finally, we prove the CCA security for confidentiality and anonymity.
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Huang, Ling-Ying, and 黃齡瑩. "Anonymous Multi-Receiver Identity-Based Encryption." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/cpt5zq.
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碩士<br>國立中山大學<br>資訊工程學系研究所<br>95<br>Recently, many multi-receiver identity-based encryption schemes have been proposed in the literature. However, none can protect the privacy of message receivers among these schemes. In this thesis, we present an anonymous multi-receiver identity-based encryption scheme where we adopt Lagrange interpolating polynomial mechanisms to cope with the above problem. Our scheme makes it impossible for an attacker or any other message receiver to derive the identity of a message receiver such that the privacy of every receiver can be guaranteed. Furthermore, the proposed scheme is quite receiver efficient since each of the receivers merely needs to perform constant times (twice in fact) of pairing computation, which is the most time-consuming computation in pairing-based cryptosystems, to decrypt the received message. Furthermore, we prove that our scheme is secure against
adaptive chosen plaintext attacks and adaptive chosen ciphertext attacks. Finally, we also prove that the receivers of the scheme can be anonymous.
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Vahlis, Eugene. "Chosen ciphertext security in identity based encryption." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=452820&T=F.
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Wen, Ting-Hui, and 溫玎薈. "Identity-Based Broadcast Encryption Scheme with Keyword Search." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/07603382282619045997.
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Yoshida, Kayo. "Boneh-Boyen Signatures and the Strong Diffie-Hellman Problem." Thesis, 2009. http://hdl.handle.net/10012/4219.
Full textAbstract:
The Boneh-Boyen signature scheme is a short signature scheme which is provably secure in the standard model under the q-Strong Diffie-Hellman (SDH) assumption.
The primary objective of this thesis is to examine the relationship between the Boneh-Boyen signature scheme and SDH. The secondary objective is to survey surrounding topics such as the generic group model, related signature schemes, intractability assumptions, and the relationship to identity-based encryption (IBE) schemes. Along these lines, we analyze the plausibility of the SDH assumption using the generic bilinear group model. We present the security proofs for the Boneh-Boyen signature scheme, with the addition of a small improvement in one of the probability bounds.
Our main contribution is to give the reduction in the reverse direction; that is, to show that if the SDH problem can be solved then the Boneh-Boyen signature scheme can be forged. This contribution represents the first known proof of equivalence between the SDH problem and Boneh-Boyen signatures. We also discuss the algorithm of Cheon for solving the SDH problem. We analyze the implications of Cheon's algorithm for the security of the Boneh-Boyen signature scheme, accompanied by a brief discussion on how to counter the attack.
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Tseng, Yi-Fan, and 曾一凡. "Anonymous Multi-Receiver Identity-Based Encryption with Complete CCA Security." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/rjq64z.
Full textAbstract:
碩士<br>國立中山大學<br>資訊工程學系研究所<br>102<br>In a multi-receiver encryption system, a sender chooses a set of authorized receivers and sends them a massage securely and efficiently as the message is well encrypted and only one ciphertext corresponding to the message is generated no matter how many receivers the sender has chosen. It can be applied to video conferencing systems, pay-per-view channels, distance education, and so forth. Due to privacy consideration, an authorized receiver may not expect that his identity is revealed. In 2010, anonymous multi-receiver identity-based (ID-based) encryption was first discussed, and furthermore, many works on the topic have been presented so far. Unfortunately, we find that all of those schemes are not CCA-secure in either confidentiality or anonymity. In this manuscript, we propose the first anonymous multi-receiver ID-based encryption scheme with CCA security in both confidentiality and anonymity. It also is the first CCA-secure scheme against insider attacks, and moreover, only one pairing computation is required in decryption.
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"Identity based cryptography from pairings." 2006. http://library.cuhk.edu.hk/record=b5892794.
Full textAbstract:
Yuen Tsz Hon.<br>Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.<br>Includes bibliographical references (leaves 109-122).<br>Abstracts in English and Chinese.<br>Abstract --- p.i<br>Acknowledgement --- p.iii<br>List of Notations --- p.viii<br>Chapter 1 --- Introduction --- p.1<br>Chapter 1.1 --- Identity Based Cryptography --- p.3<br>Chapter 1.2 --- Hierarchical Identity Based Cryptosystem --- p.4<br>Chapter 1.3 --- Our contributions --- p.5<br>Chapter 1.4 --- Publications --- p.5<br>Chapter 1.4.1 --- Publications Produced from This Thesis --- p.5<br>Chapter 1.4.2 --- Publications During Author's Study in the Degree --- p.6<br>Chapter 1.5 --- Thesis Organization --- p.6<br>Chapter 2 --- Background --- p.8<br>Chapter 2.1 --- Complexity Theory --- p.8<br>Chapter 2.1.1 --- Order Notation --- p.8<br>Chapter 2.1.2 --- Algorithms and Protocols --- p.9<br>Chapter 2.1.3 --- Relations and Languages --- p.11<br>Chapter 2.2 --- Algebra and Number Theory --- p.12<br>Chapter 2.2.1 --- Groups --- p.12<br>Chapter 2.2.2 --- Elliptic Curve --- p.13<br>Chapter 2.2.3 --- Pairings --- p.14<br>Chapter 2.3 --- Intractability Assumptions --- p.15<br>Chapter 2.4 --- Cryptographic Primitives --- p.18<br>Chapter 2.4.1 --- Public Key Encryption --- p.18<br>Chapter 2.4.2 --- Digital Signature --- p.19<br>Chapter 2.4.3 --- Zero Knowledge --- p.21<br>Chapter 2.5 --- Hash Functions --- p.23<br>Chapter 2.6 --- Random Oracle Model --- p.24<br>Chapter 3 --- Literature Review --- p.26<br>Chapter 3.1 --- Identity Based Signatures --- p.26<br>Chapter 3.2 --- Identity Based Encryption --- p.27<br>Chapter 3.3 --- Identity Based Signcryption --- p.27<br>Chapter 3.4 --- Identity Based Blind Signatures --- p.28<br>Chapter 3.5 --- Identity Based Group Signatures --- p.28<br>Chapter 3.6 --- Hierarchical Identity Based Cryptography --- p.29<br>Chapter 4 --- Blind Identity Based Signcryption --- p.30<br>Chapter 4.1 --- Schnorr's ROS problem --- p.31<br>Chapter 4.2 --- BIBSC and Enhanced IBSC Security Model --- p.32<br>Chapter 4.2.1 --- Enhanced IBSC Security Model --- p.33<br>Chapter 4.2.2 --- BIBSC Security Model --- p.36<br>Chapter 4.3 --- Efficient and Secure BIBSC and IBSC Schemes --- p.38<br>Chapter 4.3.1 --- Efficient and Secure IBSC Scheme --- p.38<br>Chapter 4.3.2 --- The First BIBSC Scheme --- p.43<br>Chapter 4.4 --- Generic Group and Pairing Model --- p.47<br>Chapter 4.5 --- Comparisons --- p.52<br>Chapter 4.5.1 --- Comment for IND-B --- p.52<br>Chapter 4.5.2 --- Comment for IND-C --- p.54<br>Chapter 4.5.3 --- Comment for EU --- p.55<br>Chapter 4.6 --- Additional Functionality of Our Scheme --- p.56<br>Chapter 4.6.1 --- TA Compatibility --- p.56<br>Chapter 4.6.2 --- Forward Secrecy --- p.57<br>Chapter 4.7 --- Chapter Conclusion --- p.57<br>Chapter 5 --- Identity Based Group Signatures --- p.59<br>Chapter 5.1 --- New Intractability Assumption --- p.61<br>Chapter 5.2 --- Security Model --- p.62<br>Chapter 5.2.1 --- Syntax --- p.63<br>Chapter 5.2.2 --- Security Notions --- p.64<br>Chapter 5.3 --- Constructions --- p.68<br>Chapter 5.3.1 --- Generic Construction --- p.68<br>Chapter 5.3.2 --- An Instantiation: IBGS-SDH --- p.69<br>Chapter 5.4 --- Security Theorems --- p.73<br>Chapter 5.5 --- Discussions --- p.81<br>Chapter 5.5.1 --- Other Instantiations --- p.81<br>Chapter 5.5.2 --- Short Ring Signatures --- p.82<br>Chapter 5.6 --- Chapter Conclusion --- p.82<br>Chapter 6 --- Hierarchical IBS without Random Oracles --- p.83<br>Chapter 6.1 --- New Intractability Assumption --- p.87<br>Chapter 6.2 --- Security Model: HIBS and HIBSC --- p.89<br>Chapter 6.2.1 --- HIBS Security Model --- p.89<br>Chapter 6.2.2 --- Hierarchical Identity Based Signcryption (HIBSC) --- p.92<br>Chapter 6.3 --- Efficient Instantiation of HIBS --- p.95<br>Chapter 6.3.1 --- Security Analysis --- p.96<br>Chapter 6.3.2 --- Ordinary Signature from HIBS --- p.101<br>Chapter 6.4 --- Plausibility Arguments for the Intractability of the OrcYW Assumption --- p.102<br>Chapter 6.5 --- Efficient HIBSC without Random Oracles --- p.103<br>Chapter 6.5.1 --- Generic Composition from HIBE and HIBS --- p.104<br>Chapter 6.5.2 --- Concrete Instantiation --- p.105<br>Chapter 6.6 --- Chapter Conclusion --- p.107<br>Chapter 7 --- Conclusion --- p.108<br>Bibliography --- p.109
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"Identity-based cryptography from paillier cryptosystem." 2005. http://library.cuhk.edu.hk/record=b5892374.
Full textAbstract:
Au Man Ho Allen.<br>Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.<br>Includes bibliographical references (leaves 60-68).<br>Abstracts in English and Chinese.<br>Abstract --- p.i<br>Acknowledgement --- p.iii<br>Chapter 1 --- Introduction --- p.1<br>Chapter 2 --- Preliminaries --- p.5<br>Chapter 2.1 --- Complexity Theory --- p.5<br>Chapter 2.2 --- Algebra and Number Theory --- p.7<br>Chapter 2.2.1 --- Groups --- p.7<br>Chapter 2.2.2 --- Additive Group Zn and Multiplicative Group Z*n --- p.8<br>Chapter 2.2.3 --- The Integer Factorization Problem --- p.9<br>Chapter 2.2.4 --- Quadratic Residuosity Problem --- p.11<br>Chapter 2.2.5 --- Computing e-th Roots (The RSA Problem) --- p.13<br>Chapter 2.2.6 --- Discrete Logarithm and Related Problems --- p.13<br>Chapter 2.3 --- Public key Cryptography --- p.16<br>Chapter 2.3.1 --- Encryption --- p.17<br>Chapter 2.3.2 --- Digital Signature --- p.20<br>Chapter 2.3.3 --- Identification Protocol --- p.22<br>Chapter 2.3.4 --- Hash Function --- p.24<br>Chapter 3 --- Paillier Cryptosystems --- p.26<br>Chapter 3.1 --- Introduction --- p.26<br>Chapter 3.2 --- The Paillier Cryptosystem --- p.27<br>Chapter 4 --- Identity-based Cryptography --- p.30<br>Chapter 4.1 --- Introduction --- p.31<br>Chapter 4.2 --- Identity-based Encryption --- p.32<br>Chapter 4.2.1 --- Notions of Security --- p.32<br>Chapter 4.2.2 --- Related Results --- p.35<br>Chapter 4.3 --- Identity-based Identification --- p.36<br>Chapter 4.3.1 --- Security notions --- p.37<br>Chapter 4.4 --- Identity-based Signature --- p.38<br>Chapter 4.4.1 --- Security notions --- p.39<br>Chapter 5 --- Identity-Based Cryptography from Paillier System --- p.41<br>Chapter 5.1 --- Identity-based Identification schemes in Paillier setting --- p.42<br>Chapter 5.1.1 --- Paillier-IBI --- p.42<br>Chapter 5.1.2 --- CGGN-IBI --- p.43<br>Chapter 5.1.3 --- GMMV-IBI --- p.44<br>Chapter 5.1.4 --- KT-IBI --- p.45<br>Chapter 5.1.5 --- Choice of g for Paillier-IBI --- p.46<br>Chapter 5.2 --- Identity-based signatures from Paillier system . . --- p.47<br>Chapter 5.3 --- Cocks ID-based Encryption in Paillier Setting . . --- p.48<br>Chapter 6 --- Concluding Remarks --- p.51<br>A Proof of Theorems --- p.53<br>Chapter A.1 --- "Proof of Theorems 5.1, 5.2" --- p.53<br>Chapter A.2 --- Proof Sketch of Remaining Theorems --- p.58<br>Bibliography --- p.60
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Pan, Wen Chieh, and 潘彣杰. "Effective Identity-Based Encryption Schemes with Outsourced Revocation for Cloud Computing." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/25g23p.
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Tseng, Yi-Fan, and 曾一凡. "Anonymous Multi-Receiver Identity-Based Encryption with Tight Reducible Full Security in the Standard Model." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3f4ay2.
Full textAbstract:
博士<br>國立中山大學<br>資訊工程學系研究所<br>107<br>Multi-receiver identity-based encryption is a cryptographic primitive, which allows a sender to encrypt a message for multiple receivers efficiently and securely. In some applications, the receivers may not want their identities to be revealed. Motivated by this issue, in 2010, Fan et al. first proposed the concept of anonymous multi-receiver identity-based encryption (AMRIBE). Since then, lots of literatures in this field have been proposed. After surveying the existing works, however, we found that most of then fails to achieve provable anonymity with tight reduction. A security proof with tight reduction means better quality of security and better efficiency of implementation. In this dissertation, we focus on solving the open problem in this field, that is to achieve the ANON-IND-CCA security with tight reduction by giving an AMRIBE schemes. The proposed scheme is proven to be IND-MID-CCA and ANON-MID-CCA secure with tight reduction under the DBDH assumption. To the best of our knowledge, this is the first scheme proven with tight reducible full CCA security in the standard model. At the same time, we also consider AMRIBE with different properties and give three other schemes: 1) anonymous multi-receiver identity-based authenticated encryption; 2) anonymous multi-receiver certificateless encryption; 3) generic construction for CCA secure AMRIBE. The security proofs are presented in the corresponding chapter.
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Kate, Aniket. "Distributed Key Generation and Its Applications." Thesis, 2010. http://hdl.handle.net/10012/5285.
Full textAbstract:
Numerous cryptographic applications require a trusted authority to hold a secret. With a plethora of malicious attacks over the Internet, however, it is difficult to establish and maintain such an authority in online systems. Secret-sharing schemes attempt to solve this problem by distributing the required trust to hold and use the secret over multiple servers; however, they still require a trusted {\em dealer} to choose and share the secret, and have problems related to single points of failure and key escrow. A distributed key generation (DKG) scheme overcomes these
hurdles by removing the requirement of a dealer in secret sharing. A (threshold) DKG scheme achieves this using a complete distribution of the trust among a number of servers such that any subset of servers of size greater than a given threshold can reveal or use the shared secret, while
any smaller subset cannot. In this thesis, we make contributions to DKG in the computational security setting and describe three applications of it.
We first define a constant-size commitment scheme for univariate polynomials over finite fields and use it to reduce the size of broadcasts required for DKG protocols in the synchronous communication model by a linear factor. Further, we observe that the existing (synchronous) DKG protocols do not provide a liveness guarantee over the Internet and design the first DKG protocol for use over the Internet. Observing the necessity of long-term stability, we then present proactive security and group modification protocols for our DKG system. We also demonstrate the practicality of our DKG protocol over the Internet by testing our implementation over PlanetLab.
For the applications, we use our DKG protocol to define IND-ID-CCA secure distributed private-key generators (PKGs) for three important identity-based encryption (IBE) schemes: Boneh and Franklin's BF-IBE, Sakai and Kasahara's SK-IBE, and Boneh and Boyen's BB1-IBE.
These IBE schemes cover all three important IBE frameworks: full-domain-hash IBEs, exponent-inversion IBEs and commutative-blinding IBEs respectively, and our distributed PKG constructions can easily be
modified for other IBE schemes in these frameworks. As the second application, we use our distributed PKG for BF-IBE to define an onion routing circuit construction mechanism in the identity-based setting,
which solves the scalability problem in single-pass onion routing circuit construction without hampering forward secrecy. As the final application, we use our DKG implementation to design a threshold signature architecture for quorum-based distributed hash tables and use it to define two robust communication protocols in these peer-to-peer systems.
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(6620474), Denis A. Ulybyshev. "Data Protection in Transit and at Rest with Leakage Detection." Thesis, 2019.
Find full textAbstract:
<p>In service-oriented
architecture, services can communicate and share data among themselves. This
thesis presents a solution that allows detecting several types of data leakages
made by authorized insiders to unauthorized services. My solution provides
role-based and attribute-based access control for data so that each service can
access only those data subsets for which the service is authorized, considering
a context and service’s attributes such as security level of the web browser
and trust level of service. My approach provides data protection in transit and
at rest for both centralized and peer-to-peer service architectures. The methodology
ensures confidentiality and integrity of data, including data stored in untrusted
cloud. In addition to protecting data against malicious or curious cloud or
database administrators, the capability of running a search through encrypted
data, using SQL queries, and building analytics over encrypted data is
supported. My solution is implemented in the “WAXEDPRUNE” (Web-based Access to
Encrypted Data Processing in Untrusted Environments) project, funded by
Northrop Grumman Cybersecurity Research Consortium. WAXEDPRUNE methodology is
illustrated in this thesis for two use cases, including a Hospital Information
System with secure storage and exchange of Electronic Health Records and a Vehicle-to-Everything
communication system with secure exchange of vehicle’s and drivers’ data, as
well as data on road events and road hazards. </p><p>To help with
investigating data leakage incidents in service-oriented architecture,
integrity of provenance data needs to be guaranteed. For that purpose, I
integrate WAXEDPRUNE with IBM Hyperledger Fabric blockchain network, so that every
data access, transfer or update is recorded in a public blockchain ledger, is
non-repudiatable and can be verified at any time in the future. The work on
this project, called “Blockhub,” is in progress.</p>