Public auditing with privacy protection in a multi-user model of cloud-assisted body sensor networks.

Wireless Body Sensor Networks (WBSNs) are gaining importance in the era of the Internet of Things (IoT). The modern medical system is a particular area where the WBSN techniques are being increasingly adopted for various fundamental operations. Despite such increasing deployments of WBSNs, issues such as the infancy in the size, capabilities and limited data processing capacities of the sensor devices restrain their adoption in resource-demanding applications. Though providing computing and storage supplements from cloud servers can potentially enrich the capabilities of the WBSNs devices, data security is one of the prevailing issues that affects the reliability of cloud-assisted services. Sensitive applications such as modern medical systems demand assurance of the privacy of the users' medical records stored in distant cloud servers. Since it is economically impossible to set up private cloud servers for every client, auditing data security managed in the remote servers has necessarily become an integral requirement of WBSNs' applications relying on public cloud servers. To this end, this paper proposes a novel certificateless public auditing scheme with integrated privacy protection. The multi-user model in our scheme supports groups of users to store and share data, thus exhibiting the potential for WBSNs' deployments within community environments. Furthermore, our scheme enriches user experiences by offering public verifiability, forward security mechanisms and revocation of illegal group members. Experimental evaluations demonstrate the security effectiveness of our proposed scheme under the Random Oracle Model (ROM) by outperforming existing cloud-assisted WBSN models.N/

A full privacy-preserving distributed batch-based certificate-less aggregate signature authentication scheme for healthcare wearable wireless medical sensor networks (HWMSNs)

The dynamic connectivity and functionality of sensors has revolutionized remote monitoring applications thanks to the combination of IoT and wireless sensor networks (WSNs). Wearable wireless medical sensor nodes allow continuous monitoring by amassing physiological data, which is very useful in healthcare applications. These text data are then sent to doctors via IoT devices so they can make an accurate diagnosis as soon as possible. However, the transmission of medical text data is extremely vulnerable to security and privacy assaults due to the open nature of the underlying communication medium. Therefore, a certificate-less aggregation-based signature system has been proposed as a solution to the issue by using elliptic curve public key cryptography (ECC) which allows for a highly effective technique. The cost of computing has been reduced by 93% due to the incorporation of aggregation technology. The communication cost is 400 bits which is a significant reduction when compared with its counterparts. The results of the security analysis show that the scheme is robust against forging, tampering, and man-in-the-middle attacks. The primary innovation is that the time required for signature verification can be reduced by using point addition and aggregation. In addition, it does away with the reliance on a centralized medical server in order to do verification. By taking a distributed approach, it is able to fully preserve user privacy, proving its superiority

Types of lightweight cryptographies in current developments for resource constrained machine type communication devices: challenges and opportunities

Machine-type communication devices have become a vital part of the autonomous industrial internet of things and industry 4.0. These autonomous resource-constrained devices share sensitive data, and are primarily acquired for automation and to operate consistently in remote environments under severe conditions. The requirements to secure the sensitive data shared between these devices consist of a resilient encryption technique with affordable operational costs. Consequently, devices, data, and networks are made secure by adopting a lightweight cryptosystem that should achieve robust security with sufficient computational and communication costs and counter modern security threats. This paper offers in-depth studies on different types and techniques of hardware and software-based lightweight cryptographies for machine-type communication devices in machine-to-machine communication networks

Capability-based Authentication and Access Control in Internet of Things

Internet of Things (IoT) foresees the interaction and communication between different physical entities, which are constrained devices in this physical world. The entities also communicate with the Internet to provide solution for different complex problems. It goes for empowering future advances and dreams like, smart apartment, building automation, intelligent city construction, and e-health service. Secure data transmission is of prime importance in these scenarios. Standard IP-based security arrangements don’t address this issue as they are not composed in view of the restrictions of obliged gadgets. Consequently, more lightweight security components are required. The entities in the domain of IoT come from different vendors. Authentication and Authorization of these entities in a network demands the exchange of identity, certificates and protocol suites. High computation power and memory is required for this transmission. We propose a framework in which the authentication, authorization and key distribution is delegated. It also integrates capability-based fine-grained access control of services. Our evaluation implements different cryptographic algorithms to manage authentication and authorization of the entities in the domain of IoT using this framework. The simulation measures the time unit taken for managing these security aspects. The framework is also tested in a hardware-based testbed and justifies that this framework might be used in most of the IoT domain

Contributions to Securing Software Updates in IoT

The Internet of Things (IoT) is a large network of connected devices. In IoT, devices can communicate with each other or back-end systems to transfer data or perform assigned tasks. Communication protocols used in IoT depend on target applications but usually require low bandwidth. On the other hand, IoT devices are constrained, having limited resources, including memory, power, and computational resources. Considering these limitations in IoT environments, it is difficult to implement best security practices. Consequently, network attacks can threaten devices or the data they transfer. Thus it is crucial to react quickly to emerging vulnerabilities. These vulnerabilities should be mitigated by firmware updates or other necessary updates securely. Since IoT devices usually connect to the network wirelessly, such updates can be performed Over-The-Air (OTA). This dissertation presents contributions to enable secure OTA software updates in IoT. In order to perform secure updates, vulnerabilities must first be identified and assessed. In this dissertation, first, we present our contribution to designing a maturity model for vulnerability handling. Next, we analyze and compare common communication protocols and security practices regarding energy consumption. Finally, we describe our designed lightweight protocol for OTA updates targeting constrained IoT devices. IoT devices and back-end systems often use incompatible protocols that are unable to interoperate securely. This dissertation also includes our contribution to designing a secure protocol translator for IoT. This translation is performed inside a Trusted Execution Environment (TEE) with TLS interception. This dissertation also contains our contribution to key management and key distribution in IoT networks. In performing secure software updates, the IoT devices can be grouped since the updates target a large number of devices. Thus, prior to deploying updates, a group key needs to be established among group members. In this dissertation, we present our designed secure group key establishment scheme. Symmetric key cryptography can help to save IoT device resources at the cost of increased key management complexity. This trade-off can be improved by integrating IoT networks with cloud computing and Software Defined Networking (SDN).In this dissertation, we use SDN in cloud networks to provision symmetric keys efficiently and securely. These pieces together help software developers and maintainers identify vulnerabilities, provision secret keys, and perform lightweight secure OTA updates. Furthermore, they help devices and systems with incompatible protocols to be able to interoperate

Efficient signature verification and key revocation using identity based cryptography

Cryptography deals with the development and evaluation of procedures for securing digital information. It is essential whenever multiple entities want to communicate safely. One task of cryptography concerns digital signatures and the verification of a signer’s legitimacy requires trustworthy authentication and authorization. This is achieved by deploying cryptographic keys. When dynamic membership behavior and identity theft come into play, revocation of keys has to be addressed. Additionally, in use cases with limited networking, computational, or storage resources, efficiency is a key requirement for any solution. In this work we present a solution for signature verification and key revocation in constraned environments, e.g., in the Internet of Things (IoT). Where other mechanisms generate expensive overheads, we achieve revocation through a single multicast message without significant computational or storage overhead. Exploiting Identity Based Cryptography (IBC) complements the approach with efficient creation and verification of signatures. Our solution offers a framework for transforming a suitable signature scheme to a so-called Key Updatable Signature Scheme (KUSS) in three steps. Each step defines mathematical conditions for transformation and precise security notions. Thereby, the framework allows a novel combination of efficient Identity Based Signature (IBS) schemes with revocation mechanisms originally designed for confidentiality in group communications. Practical applicability of our framework is demonstrated by transforming four well-established IBS schemes based on Elliptic Curve Cryptography (ECC). The security of the resulting group Identity Based Signature (gIBS) schemes is carefully analyzed with techniques of Provable Security. We design and implement a testbed for evaluating these kind of cryptographic schemes on different computing- and networking hardware, typical for constrained environments. Measurements on this testbed provide evidence that the transformations are practicable and efficient. The revocation complexity in turn is significantly reduced compared to existing solutions. Some of our new schemes even outperform the signing process of the widely used Elliptic Curve Digital Signature Algorithm (ECDSA). The presented transformations allow future application on schemes beyond IBS or ECC. This includes use cases dealing with Post-Quantum Cryptography, where the revocation efficiency is similarly relevant. Our work provides the basis for such solutions currently under investigation.Die Kryptographie ist ein Instrument der Informationssicherheit und beschäftigt sich mit der Entwicklung und Evaluierung von Algorithmen zur Sicherung digitaler Werte. Sie ist für die sichere Kommunikation zwischen mehreren Entitäten unerlässlich. Ein Bestandteil sind digitale Signaturen, für deren Erstellung man kryptographische Schlüssel benötigt. Bei der Verifikation muss zusätzlich die Authentizität und die Autorisierung des Unterzeichners gewährleistet werden. Dafür müssen Schlüssel vertrauensvoll verteilt und verwaltet werden. Wenn sie in Kommunikationssystemen mit häufig wechselnden Teilnehmern zum Einsatz kommen, müssen die Schlüssel auch widerruflich sein. In Anwendungsfällen mit eingeschränkter Netz-, Rechen- und Speicherkapazität ist die Effizienz ein wichtiges Kriterium. Diese Arbeit liefert ein Rahmenwerk, mit dem Schlüssel effizient widerrufen und Signaturen effizient verifiziert werden können. Dabei fokussieren wir uns auf Szenarien aus dem Bereich des Internets der Dinge (IoT, Internet of Things). Im Gegensatz zu anderen Lösungen ermöglicht unser Ansatz den Widerruf von Schlüsseln mit einer einzelnen Nachricht innerhalb einer Kommunikationsgruppe. Dabei fällt nur geringer zusätzlicher Rechen- oder Speicheraufwand an. Ferner vervollständigt die Verwendung von Identitätsbasierter Kryptographie (IBC, Identity Based Cryptography) unsere Lösung mit effizienter Erstellung und Verifikation der Signaturen. Hierfür liefert die Arbeit eine dreistufige mathematische Transformation von geeigneten Signaturverfahren zu sogenannten Key Updatable Signature Schemes (KUSS). Neben einer präzisen Definition der Sicherheitsziele werden für jeden Schritt mathematische Vorbedingungen zur Transformation festgelegt. Dies ermöglicht die innovative Kombination von Identitätsbasierten Signaturen (IBS, Identity Based Signature) mit effizienten und sicheren Mechanismen zum Schlüsselaustausch, die ursprünglich für vertrauliche Gruppenkommunikation entwickelt wurden. Wir zeigen die erfolgreiche Anwendung der Transformationen auf vier etablierten IBSVerfahren. Die ausschließliche Verwendung von Verfahren auf Basis der Elliptic Curve Cryptography (ECC) erlaubt es, den geringen Kapazitäten der Zielgeräte gerecht zu werden. Eine Analyse aller vier sogenannten group Identity Based Signature (gIBS) Verfahren mit Techniken aus dem Forschungsgebiet der Beweisbaren Sicherheit zeigt, dass die zuvor definierten Sicherheitsziele erreicht werden. Zur praktischen Evaluierung unserer und ähnlicher kryptographischer Verfahren wird in dieser Arbeit eine Testumgebung entwickelt und mit IoT-typischen Rechen- und Netzmodulen bestückt. Hierdurch zeigt sich sowohl die praktische Anwendbarkeit der Transformationen als auch eine deutliche Reduktion der Komplexität gegenüber anderen Lösungsansätzen. Einige der von uns vorgeschlagenen Verfahren unterbieten gar die Laufzeiten des meistgenutzten Elliptic Curve Digital Signature Algorithm (ECDSA) bei der Erstellung der Signaturen. Die Systematik der Lösung erlaubt prinzipiell auch die Transformation von Verfahren jenseits von IBS und ECC. Dadurch können auch Anwendungsfälle aus dem Bereich der Post-Quanten-Kryptographie von unseren Ergebnissen profitieren. Die vorliegende Arbeit liefert die nötigen Grundlagen für solche Erweiterungen, die aktuell diskutiert und entwickelt werden

ISSUES AND SOLUTIONS OF APPLYING IDENTITY-BASED CRYPTOGRAPHY TO MOBILE AD-HOC NETWORKS

Concept of Mobile Ad-hoc Networks (MANETs) was brought up a few decades ago with assumed prosperous future. Unfortunately, we do not see many practical applications of them in real life. Security of MANETs is a big concern considered by investors and industries, and hinders them from putting MANETs into application. Requirements of security, and difficulties to meet these requirements have been stated clearly already; yet solutions to these difficulties are not quite clear. Cryptographic technologies seem to be capable of satisfying most of the requirements, which has been proved in Internet or wired networks. However, most of the technologies, including symmetric and traditional asymmetric cryptography (such as Public Key Infrastructure (PKI)), are inapplicable or inconvenient to use inMANETs context. Identity-based Cryptography (IBC), as a special form of asymmetric cryptography, carries many features interesting for MANETs. IBC has been studied a lot recently by researchers of MANET security, and many applications have been proposed and claimed to address this difficult problem. However, it is still the case that most of the solutions are not sound enough to be used in a practical MANET. This thesis starts with an intensive survey on the proposals of applications of IBC in MANETs, and points out the issues, limitations and weaknesses in these proposals and also in IBC itself. The thesis proposes a novel framework with key management and secure routing scheme integrated aiming to address these issues. This scheme brings these contributions: compared to symmetric key solutions, it has more functionality derived from asymmetric keys, and is more secure due to using 1-to-m broadcasting key instead of only 1 group broadcasting key, and has less keys to store per node due to using asymmetric keys instead of pairwise symmetric keys; compared to traditional asymmetric cryptography solutions, the storage and communication requirements are lower due to IBC properties; compared to previous IBC solutions, it has no key management and secure routing interdependency cycle problem. Security of the proposed scheme is proved and performance of the scheme is simulated and analyzed in the thesis. To the end of a complete solution for an arbitraryMANET running in an arbitrary environment, the thesis proposes enhancements to counter various attacks and options to abate or eliminate limitations and weaknesses of IBC. The proposed scheme has a wide range of applicability for various MANETs with little or no administrative overhead depending on situations where it is considered

Cryptographic Protection of Digital Identity

Dizertační práce se zabývá kryptografickými schématy zvyšující ochranu soukromí uživatelů v systémech řízení přístupu a sběru dat. V současnosti jsou systémy fyzického řízení přístupu na bázi čipových karet využívány téměř dennodenně většinou z nás, například v zaměstnání, ve veřejné dopravě a v hotelech. Tyto systémy však stále neposkytují dostatečnou kryptografickou ochranu a tedy bezpečnost. Uživatelské identifikátory a klíče lze snadno odposlechnout a padělat. Funkce, které by zajišťovaly ochranu soukromí uživatele, téměř vždy chybí. Proto je zde reálné riziko možného sledovaní lidí, jejich pohybu a chovaní. Poskytovatelé služeb nebo případní útočníci, kteří odposlouchávají komunikaci, mohou vytvářet profily uživatelů, ví, co dělají, kde se pohybují a o co se zajímají. Za účelem zlepšení tohoto stavu jsme navrhli čtyři nová kryptografická schémata založená na efektivních důkazech s nulovou znalostí a kryptografii eliptických křivek. Konkrétně dizertační práce prezentuje tři nová autentizační schémata pro využití v systémech řízení přístupu a jedno nové schéma pro využití v systémech sběru dat. První schéma využívá distribuovaný autentizační přístup vyžadující spolupráci více RFID prvků v autentizačním procesu. Tato vlastnost je výhodná zvláště v případech řízení přístupu do nebezpečných prostor, kdy pro povolení přístupu uživatele je nezbytné, aby byl uživatel vybaven ochrannými pomůckami (se zabudovanými RFID prvky). Další dvě schémata jsou založena na atributovém způsobu ověření, tj. schémata umožňují anonymně prokázat vlastnictví atributů uživatele, jako je věk, občanství a pohlaví. Zatím co jedno schéma implementuje efektivní revokační a identifikační mechanismy, druhé schéma poskytuje nejrychlejší verifikaci držení uživatelských atributů ze všech současných řešení. Poslední, čtvrté schéma reprezentuje schéma krátkého skupinového podpisu pro scénář sběru dat. Schémata sběru dat se používají pro bezpečný a spolehlivý přenos dat ze vzdálených uzlů do řídící jednotky. S rostoucím významem chytrých měřičů v energetice, inteligentních zařízení v domácnostech a rozličných senzorových sítí, se potřeba bezpečných systémů sběru dat stává velmi naléhavou. Tato schémata musí podporovat nejen standardní bezpečnostní funkce, jako je důvěrnost a autentičnost přenášených dat, ale také funkce nové, jako je silná ochrana soukromí a identity uživatele či identifikace škodlivých uživatelů. Navržená schémata jsou prokazatelně bezpečná a nabízí celou řadu funkcí rozšiřující ochranu soukromí a identity uživatele, jmenovitě se pak jedná o zajištění anonymity, nesledovatelnosti a nespojitelnosti jednotlivých relací uživatele. Kromě úplné kryptografické specifikace a bezpečnostní analýzy navržených schémat, obsahuje tato práce také výsledky měření implementací jednotlivých schémat na v současnosti nejpoužívanějších zařízeních v oblasti řízení přístupu a sběru dat.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.

Cryptographic Key Distribution In Wireless Sensor Networks Using Bilinear Pairings

It is envisaged that the use of cheap and tiny wireless sensors will soon bring a third wave of evolution in computing systems. Billions of wireless senor nodes will provide a bridge between information systems and the physical world. Wireless nodes deployed around the globe will monitor the surrounding environment as well as gather information about the people therein. It is clear that this revolution will put security solutions to a great test. Wireless Sensor Networks (WSNs) are a challenging environment for applying security services. They differ in many aspects from traditional fixed networks, and standard cryptographic solutions cannot be used in this application space. Despite many research efforts, key distribution in WSNs still remains an open problem. Many of the proposed schemes suffer from high communication overhead and storage costs, low scalability and poor resilience against different types of attacks. The exclusive usage of simple and energy efficient symmetric cryptography primitives does not solve the security problem. On the other hand a full public key infrastructure which uses asymmetric techniques, digital signatures and certificate authorities seems to be far too complex for a constrained WSN environment. This thesis investigates a new approach to WSN security which addresses many of the shortcomings of existing mechanisms. It presents a detailed description on how to provide practical Public Key Cryptography solutions for wireless sensor networks. The contributions to the state-of-the-art are added on all levels of development beginning with the basic arithmetic operations and finishing with complete security protocols. This work includes a survey of different key distribution protocols that have been developed for WSNs, with an evaluation of their limitations. It also proposes Identity- Based Cryptography (IBC) as an ideal technique for key distribution in sensor networks. It presents the first in-depth study of the application and implementation of Pairing- Based Cryptography (PBC) to WSNs. This is followed by a presentation of the state of the art on the software implementation of Elliptic Curve Cryptography (ECC) on typical WSNplatforms. New optimized algorithms for performing multiprecision multiplication on a broad range of low-end CPUs are introduced as well. Three novel protocols for key distribution are proposed in this thesis. Two of these are intended for non-interactive key exchange in flat and clustered networks respectively. A third key distribution protocol uses Identity-Based Encryption (IBE) to secure communication within a heterogeneous sensor network. This thesis includes also a comprehensive security evaluation that shows that proposed schemes are resistant to various attacks that are specific to WSNs. This work shows that by using the newest achievements in cryptography like pairings and IBC it is possible to deliver affordable public-key cryptographic solutions and to apply a sufficient level of security for the most demanding WSN applications

Lightweight payload encryption-based authentication scheme for advanced metering infrastructure sensor networks

The Internet of Things (IoT) connects billions of sensors to share and collect data at any time and place. The Advanced Metering Infrastructure (AMI) is one of the most important IoT applications. IoT supports AMI to collect data from smart sensors, analyse and measure abnormalities in the energy consumption pattern of sensors. However, two-way communication in distributed sensors is sensitive and tends towards security and privacy issues. Before deploying distributed sensors, data confidentiality and privacy and message authentication for sensor devices and control messages are the major security requirements. Several authentications and encryption protocols have been developed to provide confidentiality and integrity. However, many sensors in distributed systems, resource constraint smart sensors, and adaptability of IoT communication protocols in sensors necessitate designing an efficient and lightweight security authentication scheme. This paper proposes a Payload Encryption-based Optimisation Scheme for lightweight authentication (PEOS) on distributed sensors. The PEOS integrates and optimises important features of Datagram Transport Layer Security (DTLS) in Constrained Application Protocol (CoAP) architecture instead of implementing the DTLS in a separate channel. The proposed work designs a payload encryption scheme and an Optimised Advanced Encryption Standard (OP-AES). The PEOS modifies the DTLS handshaking and retransmission processes in PEOS using payload encryption and NACK messages, respectively. It also removes the duplicate features of the protocol version and sequence number without impacting the performance of CoAP. Moreover, the PEOS attempts to improve the CoAP over distributed sensors in the aspect of optimised AES operations, such as parallel execution of S-boxes in SubBytes and delayed Mixcolumns. The efficiency of PEOS authentication is evaluated on Conitki OS using the Cooja simulator for lightweight security and authentication. The proposed scheme attains better throughput while minimising the message size overhead by 9% and 23% than the existing payload-based mutual authentication PbMA and basic DTLS/CoAP scheme in random network topologies with less than 50 nodes