Secure Session Framework: An Identity-based Cryptographic Key Agreement and Signature Protocol

Die vorliegende Dissertation beschäftigt sich mit der Methode der identitätsbasierten Verschlüsselung. Hierbei wird der Name oder die Identität eines Zielobjekts zum Verschlüsseln der Daten verwendet. Diese Eigenschaft macht diese Methode zu einem passenden Werkzeug für die moderne elektronische Kommunikation, da die dort verwendeten Identitäten oder Endpunktadressen weltweit eindeutig sein müssen. Das in der Arbeit entwickelte identitätsbasierte Schlüsseleinigungsprotokoll bietet Vorteile gegenüber existierenden Verfahren und eröffnet neue Möglichkeiten. Eines der Hauptmerkmale ist die komplette Unabhängigkeit der Schlüsselgeneratoren. Diese Unabhängigkeit ermöglicht es, dass verschiedene Sicherheitsdomänen ihr eigenes System aufsetzen können. Sie sind nicht mehr gezwungen, sich untereinander abzusprechen oder Geheimnisse auszutauschen. Auf Grund der Eigenschaften des Protokolls sind die Systeme trotzdem untereinander kompatibel. Dies bedeutet, dass Anwender einer Sicherheitsdomäne ohne weiteren Aufwand verschlüsselt mit Anwendern einer anderen Sicherheitsdomäne kommunizieren können. Die Unabhängigkeit wurde ebenfalls auf ein Signatur-Protokoll übertragen. Es ermöglicht, dass Benutzer verschiedener Sicherheitsdomänen ein Objekt signieren können, wobei auch der Vorgang des Signierens unabhängig sein kann. Neben dem Protokoll wurde in der Arbeit auch die Analyse von bestehenden Systemen durchgeführt. Es wurden Angriffe auf etablierte Protokolle und Vermutungen gefunden, die aufzeigen, ob oder in welchen Situationen diese nicht verwendet werden sollten. Dabei wurde zum einen eine komplett neue Herangehensweise gefunden, die auf der (Un-)Definiertheit von bestimmten Objekten in diskreten Räumen basiert. Zum anderen wurde die bekannte Analysemethode der Gitterreduktion benutzt und erfolgreich auf neue Bereiche übertragen. Schlussendlich werden in der Arbeit Anwendungsszenarien für das Protokoll vorgestellt, in denen dessen Vorteile besonders relevant sind. Das erste Szenario bezieht sich auf Telefonie, wobei die Telefonnummer einer Zielperson als Schlüssel verwendet. Sowohl GSM-Telefonie als auch VoIP-Telefonie werden in der Arbeit untersucht. Dafür wurden Implementierungen auf einem aktuellen Mobiltelefon durchgeführt und bestehende VoIP-Software erweitert. Das zweite Anwendungsbeispielsind IP-Netzwerke. Auch die Benutzung der IP-Adresse eines Rechners als Schlüssel ist ein gutes Beispiel, jedoch treten hier mehr Schwierigkeiten auf als bei der Telefonie. Es gibt beispielsweise dynamische IP-Adressen oder die Methode der textit{Network Address Translation}, bei der die IP-Adresse ersetzt wird. Diese und weitere Probleme wurden identifiziert und jeweils Lösungen erarbeitet

An architecture for secure data management in medical research and aided diagnosis

Programa Oficial de Doutoramento en Tecnoloxías da Información e as Comunicacións. 5032V01[Resumo] O Regulamento Xeral de Proteccion de Datos (GDPR) implantouse o 25 de maio de 2018 e considerase o desenvolvemento mais importante na regulacion da privacidade de datos dos ultimos 20 anos. As multas fortes definense por violar esas regras e non e algo que os centros sanitarios poidan permitirse ignorar. O obxectivo principal desta tese e estudar e proponer unha capa segura/integracion para os curadores de datos sanitarios, onde: a conectividade entre sistemas illados (localizacions), a unificacion de rexistros nunha vision centrada no paciente e a comparticion de datos coa aprobacion do consentimento sexan as pedras angulares de a arquitectura controlar a sua identidade, os perfis de privacidade e as subvencions de acceso. Ten como obxectivo minimizar o medo a responsabilidade legal ao compartir os rexistros medicos mediante o uso da anonimizacion e facendo que os pacientes sexan responsables de protexer os seus propios rexistros medicos, pero preservando a calidade do tratamento do paciente. A nosa hipotese principal e: os conceptos Distributed Ledger e Self-Sovereign Identity son unha simbiose natural para resolver os retos do GDPR no contexto da saude? Requirense solucions para que os medicos e investigadores poidan manter os seus fluxos de traballo de colaboracion sen comprometer as regulacions. A arquitectura proposta logra eses obxectivos nun ambiente descentralizado adoptando perfis de privacidade de datos illados.[Resumen] El Reglamento General de Proteccion de Datos (GDPR) se implemento el 25 de mayo de 2018 y se considera el desarrollo mas importante en la regulacion de privacidad de datos en los ultimos 20 anos. Las fuertes multas estan definidas por violar esas reglas y no es algo que los centros de salud puedan darse el lujo de ignorar. El objetivo principal de esta tesis es estudiar y proponer una capa segura/de integración para curadores de datos de atencion medica, donde: la conectividad entre sistemas aislados (ubicaciones), la unificacion de registros en una vista centrada en el paciente y el intercambio de datos con la aprobacion del consentimiento son los pilares de la arquitectura propuesta. Esta propuesta otorga al titular de los datos un rol central, que le permite controlar su identidad, perfiles de privacidad y permisos de acceso. Su objetivo es minimizar el temor a la responsabilidad legal al compartir registros medicos utilizando el anonimato y haciendo que los pacientes sean responsables de proteger sus propios registros medicos, preservando al mismo tiempo la calidad del tratamiento del paciente. Nuestra hipotesis principal es: .son los conceptos de libro mayor distribuido e identidad autosuficiente una simbiosis natural para resolver los desafios del RGPD en el contexto de la atencion medica? Se requieren soluciones para que los medicos y los investigadores puedan mantener sus flujos de trabajo de colaboracion sin comprometer las regulaciones. La arquitectura propuesta logra esos objetivos en un entorno descentralizado mediante la adopcion de perfiles de privacidad de datos aislados.[Abstract] The General Data Protection Regulation (GDPR) was implemented on 25 May 2018 and is considered the most important development in data privacy regulation in the last 20 years. Heavy fines are defined for violating those rules and is not something that healthcare centers can afford to ignore. The main goal of this thesis is to study and propose a secure/integration layer for healthcare data curators, where: connectivity between isolated systems (locations), unification of records in a patientcentric view and data sharing with consent approval are the cornerstones of the proposed architecture. This proposal empowers the data subject with a central role, which allows to control their identity, privacy profiles and access grants. It aims to minimize the fear of legal liability when sharing medical records by using anonymisation and making patients responsible for securing their own medical records, yet preserving the patient’s quality of treatment. Our main hypothesis is: are the Distributed Ledger and Self-Sovereign Identity concepts a natural symbiosis to solve the GDPR challenges in the context of healthcare? Solutions are required so that clinicians and researchers can maintain their collaboration workflows without compromising regulations. The proposed architecture accomplishes those objectives in a decentralized environment by adopting isolated data privacy profiles

New Conditional Privacy-preserving Encryption Schemes in Communication Network

Nowadays the communication networks have acted as nearly the most important fundamental infrastructure in our human society. The basic service provided by the communication networks are like that provided by the ubiquitous public utilities. For example, the cable television network provides the distribution of information to its subscribers, which is much like the water or gas supply systems which distribute the commodities to citizens. The communication network also facilitates the development of many network-based applications such as industrial pipeline controlling in the industrial network, voice over long-term evolution (VoLTE) in the mobile network and mixture reality (MR) in the computer network, etc. Since the communication network plays such a vital role in almost every aspect of our life, undoubtedly, the information transmitted over it should be guarded properly. Roughly, such information can be categorized into either the communicated message or the sensitive information related to the users. Since we already got cryptographical tools, such as encryption schemes, to ensure the confidentiality of communicated messages, it is the sensitive personal information which should be paid special attentions to. Moreover, for the benefit of reducing the network burden in some instances, it may require that only communication information among legitimated users, such as streaming media service subscribers, can be stored and then relayed in the network. In this case, the network should be empowered with the capability to verify whether the transmitted message is exchanged between legitimated users without leaking the privacy of those users. Meanwhile, the intended receiver of a transmitted message should be able to identify the exact message sender for future communication. In order to cater to those requirements, we re-define a notion named conditional user privacy preservation. In this thesis, we investigate the problem how to preserve user conditional privacy in pubic key encryption schemes, which are used to secure the transmitted information in the communication networks. In fact, even the term conditional privacy preservation has appeared in existing works before, there still have great differences between our conditional privacy preservation definition and the one proposed before. For example, in our definition, we do not need a trusted third party (TTP) to help tracing the sender of a message. Besides, the verification of a given encrypted message can be done without any secret. In this thesis, we also introduce more desirable features to our redefined notion user conditional privacy preservation. In our second work, we consider not only the conditional privacy of the message sender but also that of the intended message receiver. This work presents a new encryption scheme which can be implemented in communication networks where there exists a blacklist containing a list of blocked communication channels, and each of them is established by a pair of sender and receiver. With this encryption scheme, a verifier can confirm whether one ciphertext is belonging to a legitimated communication channel without knowing the exact sender and receiver of that ciphertext. With our two previous works, for a given ciphertext, we ensure that no one except its intended receiver can identify the sender. However, the receiver of one message may behave dishonest when it tries to retrieve the real message sender, which incurs the problem that the receiver of a message might manipulate the origin of the message successfully for its own benefit. To tackle this problem, we present a novel encryption scheme in our third work. Apart from preserving user conditional privacy, this work also enforces the receiver to give a publicly verifiable proof so as to convince others that it is honest during the process of identifying the actual message sender. In our forth work, we show our special interest in the access control encryption, or ACE for short, and find this primitive can inherently achieve user conditional privacy preservation to some extent. we present a newly constructed ACE scheme in this work, and our scheme has advantages over existing ACE schemes in two aspects. Firstly, our ACE scheme is more reliable than existing ones since we utilize a distributed sanitizing algorithm and thus avoid the so called single point failure happened in ACE systems with only one sanitizer. Then, since the ciphertext and key size of our scheme is more compact than that of the existing ACE schemes, our scheme enjoys better scalability

Key management for beyond 5G mobile small cells: a survey

The highly anticipated 5G network is projected to be introduced in 2020. 5G stakeholders are unanimous that densification of mobile networks is the way forward. The densification will be realized by means of small cell technology, and it is capable of providing coverage with a high data capacity. The EU-funded H2020-MSCA project “SECRET” introduced covering the urban landscape with mobile small cells, since these take advantages of the dynamic network topology and optimizes network services in a cost-effective fashion. By taking advantage of the device-to-device communications technology, large amounts of data can be transmitted over multiple hops and, therefore, offload the general network. However, this introduction of mobile small cells presents various security and privacy challenges. Cryptographic security solutions are capable of solving these as long as they are supported by a key management scheme. It is assumed that the network infrastructure and mobile devices from network users are unable to act as a centralized trust anchor since these are vulnerable targets to malicious attacks. Security must, therefore, be guaranteed by means of a key management scheme that decentralizes trust. Therefore, this paper surveys the state-of-the-art key management schemes proposed for similar network architectures (e.g., mobile ad hoc networks and ad hoc device-to-device networks) that decentralize trust. Furthermore, these key management schemes are evaluated for adaptability in a network of mobile small cells

Authentication in Protected Core Networking

Protected Core Networking (PCN) is a concept that aims to increase information sharing between nations in coalition military operations. PCN specifies the interconnection of national transport networks, called Protected Core Segments (PCSs), to a federated transport network called Protected Core (PCore). PCore is intended to deliver high availability differentiated transport services to its user networks, called Colored Clouds (CCs). To achieve this goal, entity authentication of all connecting entities is specified as a protective measure. In resource constrained environments, the distribution of service policy can be challenging. That is, which transport services are associated with a given entity. The thesis proposes two new and original protocols where CCs push service policy to the network by performing authentication based on attributes. Using identity-based signatures, attributes constituting a service policy are used directly for an entity's identity, and no external mechanism linking identity and policy is needed. For interoperability, the idea has been incorporated into PKINIT Kerberos and symmetric key Kerberos by carrying the authorized attributes within tickets. The proposed protocols are formally verified in the symbolic model using scyther-proof. The experiment shows that both CCs, and PCSs achieve greater assurance on agreed attributes, and hence on expected service delivery. A CC and a visiting PCS are able to negotiate, and agree on the expected service depending on the situation. The proposed solution provides benefits to CCs on expected service when connecting to a visiting PCS, with poor connectivity to the home PCS. In that respect, interconnection of entities with little pre-established relationship is simplified, and hence fulfillment of the PCN concept is facilitated

A reliable trust-aware reinforcement learning based routing protocol for wireless medical sensor networks.

Interest in the Wireless Medical Sensor Network (WMSN) is rapidly gaining attention thanks to recent advances in semiconductors and wireless communication. However, by virtue of the sensitive medical applications and the stringent resource constraints, there is a need to develop a routing protocol to fulfill WMSN requirements in terms of delivery reliability, attack resiliency, computational overhead and energy efficiency. This doctoral research therefore aims to advance the state of the art in routing by proposing a lightweight, reliable routing protocol for WMSN. Ensuring a reliable path between the source and the destination requires making trustaware routing decisions to avoid untrustworthy paths. A lightweight and effective Trust Management System (TMS) has been developed to evaluate the trust relationship between the sensor nodes with a view to differentiating between trustworthy nodes and untrustworthy ones. Moreover, a resource-conservative Reinforcement Learning (RL) model has been proposed to reduce the computational overhead, along with two updating methods to speed up the algorithm convergence. The reward function is re-defined as a punishment, combining the proposed trust management system to defend against well-known dropping attacks. Furthermore, with a view to addressing the inborn overestimation problem in Q-learning-based routing protocols, we adopted double Q-learning to overcome the positive bias of using a single estimator. An energy model is integrated with the reward function to enhance the network lifetime and balance energy consumption across the network. The proposed energy model uses only local information to avoid the resource burdens and the security concerns of exchanging energy information. Finally, a realistic trust management testbed has been developed to overcome the limitations of using numerical analysis to evaluate proposed trust management schemes, particularly in the context of WMSN. The proposed testbed has been developed as an additional module to the NS-3 simulator to fulfill usability, generalisability, flexibility, scalability and high-performance requirements

Regulating the technological actor: how governments tried to transform the technology and the market for cryptography and cryptographic services and the implications for the regulation of information and communications technologies

The formulation, adoption, and transformation of policy involves the interaction of actors as they negotiate, accept, and reject proposals. Traditional studies of policy discourse focus on social actors. By studying cryptography policy discourses, I argue that considering both social and technological actors in detail enriches our understanding of policy discourse. The case-based research looks at the various cryptography policy strategies employed by the governments of the United States of America and the United Kingdom. The research method is qualitative, using hermeneutics to elucidate the various actors’ interpretations. The research aims to understand policy discourse as a contest of principles involving various government actors advocating multiple regulatory mechanisms to maintain their surveillance capabilities, and the reactions of industry actors, non-governmental organisations, parliamentarians, and epistemic communities. I argue that studying socio-technological discourse helps us to understand the complex dynamics involved in regulation and regulatory change. Interests and alignments may be contingent and unstable. As a result, technologies can not be regarded as mere representations of social interests and relationships. By capturing the interpretations and articulations of social and technological actors we may attain a better understanding of the regulatory landscape for information and communications technologies

Accountable privacy preserving attribute based framework for authenticated encrypted access in clouds

In this paper, we propose an accountable privacy preserving attribute-based framework, called Ins-PAbAC, that combines attribute based encryption and attribute based signature techniques for securely sharing outsourced data contents via public cloud servers. The proposed framework presents several advantages. First, it provides an encrypted access control feature, enforced at the data owner’s side, while providing the desired expressiveness of access control policies. Second, Ins-PAbAC preserves users’ privacy, relying on an anonymous authentication mechanism, derived from a privacy preserving attribute based signature scheme that hides the users’ identifying information. Furthermore, our proposal introduces an accountable attribute based signature that enables an inspection authority to reveal the identity of the anonymously-authenticated user if needed. Third, Ins-PAbAC is provably secure, as it is resistant to both curious cloud providers and malicious users adversaries. Finally, experimental results, built upon OpenStack Swift testbed, point out the applicability of the proposed scheme in real world scenarios

A secure architecture enabling end-user privacy in the context of commercial wide-area location-enhanced web services

Mobile location-based services have raised privacy concerns amongst mobile phone users who may need to supply their identity and location information to untrustworthy third parties in order to access these applications. Widespread acceptance of such services may therefore depend on how privacy sensitive information will be handled in order to restore users’ confidence in what could become the “killer app” of 3G networks. The work reported in this thesis is part of a larger project to provide a secure architecture to enable the delivery of location-based services over the Internet. The security of transactions and in particular the privacy of the information transmitted has been the focus of our research. In order to protect mobile users’ identities, we have designed and implemented a proxy-based middleware called the Orient Platform together with its Orient Protocol, capable of translating their real identity into pseudonyms. In order to protect users’ privacy in terms of location information, we have designed and implemented a Location Blurring algorithm that intentionally downgrades the quality of location information to be used by location-based services. The algorithm takes into account a blurring factor set by the mobile user at her convenience and blurs her location by preventing real-time tracking by unauthorized entities. While it penalizes continuous location tracking, it returns accurate and reliable information in response to sporadic location queries. Finally, in order to protect the transactions and provide end-to-end security between all the entities involved, we have designed and implemented a Public Key Infrastructure based on a Security Mediator (SEM) architecture. The cryptographic algorithms used are identitybased, which makes digital certificate retrieval, path validation and revocation redundant in our environment. In particular we have designed and implemented a cryptographic scheme based on Hess’ work [108], which represents, to our knowledge, the first identity-based signature scheme in the SEM setting. A special private key generation process has also been developed in order to enable entities to use a single private key in conjunction with multiple pseudonyms, which significantly simplifies key management. We believe our approach satisfies the security requirements of mobile users and can help restore their confidence in location-based services