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Cryptographic Protection of Digital Identity
Dzurenda, Petr ; Švenda,, Petr (oponent) ; Castella-Roca, Jordi (oponent) ; Hajný, Jan (vedoucí práce)
The doctoral thesis deals with privacy-preserving cryptographic schemes in access control and data collection areas. Currently, card-based physical access control systems are used by most people on a daily basis, for example, at work, in public transportation and at hotels. However, these systems have often very poor cryptographic protection. For instance, user identifiers and keys can be easily eavesdropped and counterfeited. Furthermore, privacy-preserving features are almost missing and, therefore, user’s movement and behavior can by easily tracked. Service providers (and even eavesdroppers) can profile users, know what they do, where they go, and what they are interested in. In order to improve this state, we propose four novel cryptographic schemes based on efficient zero-knowledge proofs and elliptic curve cryptography. In particular, the thesis presents three novel privacy-friendly authentication schemes for access control and one for data collection application scenarios. The first scheme supports distributed multi-device authentication with multiple Radio-Frequency IDentification (RFID) user’s devices. This feature is particularly important in applications for controlling access to dangerous areas where the presence of protective equipment is checked during each access control session. The other two presented schemes use attribute-based approach to protect user’s privacy, i.e. these schemes allow users to anonymously prove the ownership of their attributes, such as age, citizenship, and gender. While one of our scheme brings efficient revocation and identification mechanisms, the other one provides the fastest authentication phase among the current state of the art solutions. The last (fourth) proposed scheme is a novel short group signature scheme for data collection scenarios. Data collection schemes are used for secure and reliable data transfer from multiple remote nodes to a central unit. With the increasing importance of smart meters in energy distribution, smart house installations and various sensor networks, the need for secure data collection schemes becomes very urgent. Such schemes must provide standard security features, such as confidentiality and authenticity of transferred data, as well as novel features, such as strong protection of user’s privacy and identification of malicious users. The proposed schemes are provably secure and provide the full set of privacy-enhancing features, namely anonymity, untraceability and unlinkability of users. Besides the full cryptographic specification and security analysis, we also show the results of our implementations on devices commonly used in access control and data collection applications.
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Moderní kryptografické protokoly s ochranou soukromí
Hlučková, Pavla ; Dzurenda, Petr (oponent) ; Malina, Lukáš (vedoucí práce)
Tato práce se zabývá průnikem dvou moderních a rozrůstajících se odvětví kryptografie, a to technologií umožňujících ochranu soukromí a postkvantové kryptografie. Obecně popisuje vybraná schémata zvyšující ochranu soukromí (PETs) a rodiny postkvantové kryptografie. Podrobněji je práce zaměřena na skupinové podpisy využívající matematických problémů odolných vůči hrozbě kvantových počítačů. Práce dále shrnuje stav techniky a porovnává efektivitu těchto schémat na základě dostupných informací. Hlavní částí práce je implementace skupinového podpisu založeného na hash funkcích a jeho reálné porovnání oproti implementacím skupinových podpisů založeným na mřížkách a teorii kódování, které byly získány od vědeckých týmů aktivních v tomto oboru. Tyto postkvantové skupinové podpisy jsou také porovnány vůči klasickým schématům skupinových podpisů implementovaným pomocí knihovny libgroupsig.
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Privacy Preserving Cryptographic Protocols for Secure Heterogeneous Networks
Malina, Lukáš ; Dočkal, Jaroslav (oponent) ; Vaněk, Tomáš (oponent) ; Zeman, Václav (vedoucí práce)
The dissertation thesis deals with privacy-preserving cryptographic protocols for secure communication and information systems forming heterogeneous networks. The thesis focuses on the possibilities of using non-conventional cryptographic primitives that provide enhanced security features, such as the protection of user privacy in communication systems. In the dissertation, the performance of cryptographic and mathematic primitives on various devices that participate in the security of heterogeneous networks is evaluated. The main objectives of the thesis focus on the design of advanced privacy-preserving cryptographic protocols. There are three designed protocols which use pairing-based group signatures to ensure user privacy. These proposals ensure the protection of user privacy together with the authentication, integrity and non-repudiation of transmitted messages during communication. The protocols employ the optimization techniques such as batch verification to increase their performance and become more practical in heterogeneous networks.
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Moderní kryptografické protokoly s ochranou soukromí
Hlučková, Pavla ; Dzurenda, Petr (oponent) ; Malina, Lukáš (vedoucí práce)
Tato práce se zabývá průnikem dvou moderních a rozrůstajících se odvětví kryptografie, a to technologií umožňujících ochranu soukromí a postkvantové kryptografie. Obecně popisuje vybraná schémata zvyšující ochranu soukromí (PETs) a rodiny postkvantové kryptografie. Podrobněji je práce zaměřena na skupinové podpisy využívající matematických problémů odolných vůči hrozbě kvantových počítačů. Práce dále shrnuje stav techniky a porovnává efektivitu těchto schémat na základě dostupných informací. Hlavní částí práce je implementace skupinového podpisu založeného na hash funkcích a jeho reálné porovnání oproti implementacím skupinových podpisů založeným na mřížkách a teorii kódování, které byly získány od vědeckých týmů aktivních v tomto oboru. Tyto postkvantové skupinové podpisy jsou také porovnány vůči klasickým schématům skupinových podpisů implementovaným pomocí knihovny libgroupsig.
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Cryptographic Protection of Digital Identity
Dzurenda, Petr ; Švenda,, Petr (oponent) ; Castella-Roca, Jordi (oponent) ; Hajný, Jan (vedoucí práce)
The doctoral thesis deals with privacy-preserving cryptographic schemes in access control and data collection areas. Currently, card-based physical access control systems are used by most people on a daily basis, for example, at work, in public transportation and at hotels. However, these systems have often very poor cryptographic protection. For instance, user identifiers and keys can be easily eavesdropped and counterfeited. Furthermore, privacy-preserving features are almost missing and, therefore, user’s movement and behavior can by easily tracked. Service providers (and even eavesdroppers) can profile users, know what they do, where they go, and what they are interested in. In order to improve this state, we propose four novel cryptographic schemes based on efficient zero-knowledge proofs and elliptic curve cryptography. In particular, the thesis presents three novel privacy-friendly authentication schemes for access control and one for data collection application scenarios. The first scheme supports distributed multi-device authentication with multiple Radio-Frequency IDentification (RFID) user’s devices. This feature is particularly important in applications for controlling access to dangerous areas where the presence of protective equipment is checked during each access control session. The other two presented schemes use attribute-based approach to protect user’s privacy, i.e. these schemes allow users to anonymously prove the ownership of their attributes, such as age, citizenship, and gender. While one of our scheme brings efficient revocation and identification mechanisms, the other one provides the fastest authentication phase among the current state of the art solutions. The last (fourth) proposed scheme is a novel short group signature scheme for data collection scenarios. Data collection schemes are used for secure and reliable data transfer from multiple remote nodes to a central unit. With the increasing importance of smart meters in energy distribution, smart house installations and various sensor networks, the need for secure data collection schemes becomes very urgent. Such schemes must provide standard security features, such as confidentiality and authenticity of transferred data, as well as novel features, such as strong protection of user’s privacy and identification of malicious users. The proposed schemes are provably secure and provide the full set of privacy-enhancing features, namely anonymity, untraceability and unlinkability of users. Besides the full cryptographic specification and security analysis, we also show the results of our implementations on devices commonly used in access control and data collection applications.
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Privacy Preserving Cryptographic Protocols for Secure Heterogeneous Networks
Malina, Lukáš ; Dočkal, Jaroslav (oponent) ; Vaněk, Tomáš (oponent) ; Zeman, Václav (vedoucí práce)
The dissertation thesis deals with privacy-preserving cryptographic protocols for secure communication and information systems forming heterogeneous networks. The thesis focuses on the possibilities of using non-conventional cryptographic primitives that provide enhanced security features, such as the protection of user privacy in communication systems. In the dissertation, the performance of cryptographic and mathematic primitives on various devices that participate in the security of heterogeneous networks is evaluated. The main objectives of the thesis focus on the design of advanced privacy-preserving cryptographic protocols. There are three designed protocols which use pairing-based group signatures to ensure user privacy. These proposals ensure the protection of user privacy together with the authentication, integrity and non-repudiation of transmitted messages during communication. The protocols employ the optimization techniques such as batch verification to increase their performance and become more practical in heterogeneous networks.
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