Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

Token Based Authentication and Authorization with Zero-Knowledge Proofs for Enhancing Web API Security and Privacy

This design science study showcases an innovative artifact that utilizes Zero-Knowledge Proofs for API Authentication and Authorization. A comprehensive examination of existing literature and technology is conducted to evaluate the effectiveness of this alternative approach. The study reveals that existing APIs are using slower techniques that don’t scale, can’t take advantage of newer hardware, and have been unable to adequately address current security issues. In contrast, the novel technique presented in this study performs better, is more resilient in privacy sensitive and security settings, and is easy to implement and deploy. Additionally, this study identifies potential avenues for further research that could help advance the field of Web API development in terms of security, privacy, and simplicity

Scaling Distributed Ledgers and Privacy-Preserving Applications

This thesis proposes techniques aiming to make blockchain technologies and smart contract platforms practical by improving their scalability, latency, and privacy. This thesis starts by presenting the design and implementation of Chainspace, a distributed ledger that supports user defined smart contracts and execute user-supplied transactions on their objects. The correct execution of smart contract transactions is publicly verifiable. Chainspace is scalable by sharding state; it is secure against subsets of nodes trying to compromise its integrity or availability properties through Byzantine Fault Tolerance (BFT). This thesis also introduces a family of replay attacks against sharded distributed ledgers targeting cross-shard consensus protocols; they allow an attacker, with network access only, to double-spend resources with minimal efforts. We then build Byzcuit, a new cross-shard consensus protocol that is immune to those attacks and that is tailored to run at the heart of Chainspace. Next, we propose FastPay, a high-integrity settlement system for pre-funded payments that can be used as a financial side-infrastructure for Chainspace to support low-latency retail payments. This settlement system is based on Byzantine Consistent Broadcast as its core primitive, foregoing the expenses of full atomic commit channels (consensus). The resulting system has extremely low-latency for both confirmation and payment finality. Finally, this thesis proposes Coconut, a selective disclosure credential scheme supporting distributed threshold issuance, public and private attributes, re-randomization, and multiple unlinkable selective attribute revelations. It ensures authenticity and availability even when a subset of credential issuing authorities are malicious or offline, and natively integrates with Chainspace to enable a number of scalable privacy-preserving applications

Identification and Mitigation of Information Leakage Caused by Side Channel Vulnerabilities in Network Stack

Keeping users sensitive information secure and private in todays network is challenging. Networks are large, complicated distributed systems and are subject to a wide variety of attacks, such as eavesdropping, identity spoofing, hijacking, etc. What is worse, encrypting data is often not enough in light of advanced threats such as side channel attacks, which enable malicious attackers to infer sensitive data from insignificant network information unexpectedly. For this purpose, we pro- pose series of techniques to prevent such information leakage at different layers in network stacks, and raise awareness of its severity. More specifically, 1) we propose a practical physical (PHY) layer security framework FOG, for effective packet header obfuscation using MIMO, to keep eavesdroppers from receiving any meaningful packet information; 2) we identify and fix a subtle yet serious pure off-path side channel vulnerability (CVE-2016-5696) introduced in both TCP specification and its implementation in Linux kernel, which prevents malicious attackers from exploiting it to indicate arbitrary connections state, reset the connection or even further hijack the connection; 3) we propose a principled TCP side channel vulnerability discovery solution based on model checking and program analysis, and automatically identify 12 new side channel vulnerabilities (and 3 old ones) from TCP implementation in Linux and FreeBSD kernel code. The ultimate goal is to help guide the future design and implementation of network stacks.Keeping users’ sensitive information secure and private in today’s network is challenging. Network nowadays are subject to a wide variety of attacks, such as eavesdropping, identity spoofing, denial of service, etc. What is worse, encrypting sensitive data is often not enough in light of advanced threats such as side channel attacks, which enable malicious attackers to infer sensitive data from “insignificant” network information unexpectedly. For this purpose, we propose series of techniques to prevent such information leakage at different layers in network stack, and raise awareness of its severity. In our first work, we propose a practical physical (PHY) layer security framework FOG, for effective packet header obfuscation using MIMO, to prevent eavesdroppers from receiving any packet headers to profile users. Secondly, we identify and fix a subtle yet serious pure off-path side channel vulnerability (CVE-2016-5696) introduced in both TCP specification and its implementation in Linux kernel. This vulnerability allows malicious attackers to indicate arbitrary TCP connection’s state, reset the connection or even further hijack the connection. Motivated by the fact that most previous TCP side channel vulnerabilities are manually identified, in our last work, we propose a principled TCP side channel vulnerability discovery solution based on model checking and program analysis. It automatically identifies 12 new side channel vulnerabilities (and 3 old ones) from TCP implementation in Linux and FreeBSD kernel code. The ultimate goal of my research is to help guide the future design and implementation of network stacks

SoK: Metadata-Protecting Communication Systems

Protecting metadata of communications has been an area of active research since the dining cryptographers problem was introduced by David Chaum in 1988. The Snowden revelations from 2013 resparked research in this direction. Consequently over the last decade we have witnessed a flurry of novel systems designed to protect metadata of users\u27 communications online. However, such systems leverage different assumptions and design choices to achieve their goal; resulting in a scattered view of the desirable properties, potential vulnerabilities, and limitations of existing metadata-protecting communication systems (MPCS). In this work we survey 31 systems targeting metadata-protected communications, and present a unified view of the current state of affairs. We provide two different taxonomies for existing MPCS, first into four different categories by the precise type of metadata protections they offer, and next into six families based on the core techniques that underlie them. By contrasting these systems we identify potential vulnerabilities, as well as subtle privacy implications of design choices of existing MPCS. Furthermore, we identify promising avenues for future research for MPCS, and desirable properties that merit more attention

Enhancing The Anonymity Of Electronic Transactions

Πολλοί διαφορετικοί τύποι διαδικτυακών πληρωμών έχουν αναπτυχτεί τις περασμένες δεκαετίες. Μέσα από αυτά τα συστήματα δίνεται η δυνατότητα στις συναλλαγές να πραγματοποιούνται αποτελεσματικότερα από τις παραδοσιακές συναλλαγές. Επίσης, οι συναλλαγές ολοκληρώνονται χωρίς να απαιτείται η χρήση φυσικού χρήματος. Παρόλα αυτά, όλα τα διαδικτυακά συστήματα πληρωμών χρησιμοποιούν υποχρεωτικά μια κεντρική οντότητα, η οποία έχει την δυνατότητα να αντιστοιχίσει μια συναλλαγή στους χρήστες που συμμετέχουν σε αυτή. Από το 2009, ένα νέο και καινοτόμο είδος διαδικτυακών πληρωμών σχεδιάστηκε, γνωστό ως κρυπτονόμισμα. Το συγκεκριμένο μοντέλο επέτρεπε στους πελάτες να πραγματοποιούν συναλλαγές με άλλους χρηστές χωρίς να απαιτείται η παρουσία και η χρήση της κεντρικής οντότητας. Αντίθετα με τα πρότερα συστήματα, στα κρυπτονομίσματα οι συναλλαγές υπογράφονται με κρυπτογραφικές τεχνικές και επιβεβαιώνονται από τα υπόλοιπα άτομα του δικτύου. Εξαιτίας του γεγονότος ότι οι συναλλαγές επιβεβαιώνονται από τους χρηστές του δικτύου και όχι από μια κεντρική οντότητα, κάθε συναλλαγή αποθηκεύεται σε ένα δημόσιο πίνακα. Σε αυτόν τον πίνακα έχουν πρόσβαση όλοι οι χρήστες που αποτελούν μέρος του δικτύου. Για να μπορέσουν τα κρυπτονομίσματα να προσφέρουν μια κάποια μορφή ανωνυμίας, τα σχετικά πρωτόκολλα έχουν σχεδιαστεί με τέτοιο τρόπο ώστε οι χρηστές να αντιπροσωπεύονται από ψευδώνυμα. Όμως η τεχνική αυτή εγγυάται μόνο ότι όταν ένας χρηστής εκκινήσει μια συναλλαγή δεν θα είναι δυνατόν να χάσει την ανωνυμία του, από έναν επιτιθέμενο που παρατηρεί αποκλειστικά αυτή τη συναλλαγή. Σε θεωρητικό επίπεδο, από τη στιγμή που όλες οι συναλλαγές αποθηκεύονται στο δημόσιο πίνακα, οι επιτιθέμενοι μπορούν να παραβιάσουν την ανωνυμία τους εκμεταλλευόμενοι τις υπόλοιπες πληροφορίες που τους παρέχει το δίκτυο. Η εργασία αυτή αναλύει σε βάθος τρόπους για να ενισχύσουμε την ανωνυμία των χρηστών στα δίκτυα των κρυπτονομισμάτων, έτσι ώστε οι επιτιθέμενοι να μην μπορούν να αντιστοιχίσουν συναλλαγές με χρήστες. Η κύρια τεχνική που εξετάζουμε είναι τα mixing services.Many kinds of online payment systems have been invented during the last decades that allow transactions to be implemented in a more efficient way than the traditional purchases. Also, the online payments do not require physical money. Nevertheless, all such systems utilize a central authority that has the ability to link transactions back to payees and payers. Since 2009, a new type of independent online monetary system known as cryptocurrency has emerged, permitting clients and recipients to create transactions that are not controlled by a central entity. Such transactions are cryptographically signed transfers of money from client to recipient confirmed by other peers in a global payment network. Due to the fact that confirmation is offered by peers in the network, rather than a central entity, every transaction has to be recorded on a public ledger. This ledger is accessible from every peer inside the network. To offer some form of anonymity to users in the network, cryptocurrencies like Bitcoin and Ethereum have created their protocols to be pseudo-anonymous. However, this technique only guarantees that a user that generates a transaction cannot be deanonymized if the attacker is observing only one transaction. From a theoretical point of view, since all transactions are visible by peers, attackers can expose the real identities of peers by utilizing other information that is revealed by the network. In this thesis we perform an in depth analysis of ways to enhance anonymity in cryptocurrencies, and make the de-anonymization of the peers participating in the corresponding network impossible or at least very hard. The main way to achieve this is through mixing services

Security and Privacy in Heterogeneous Wireless and Mobile Networks: Challenges and Solutions

abstract: The rapid advances in wireless communications and networking have given rise to a number of emerging heterogeneous wireless and mobile networks along with novel networking paradigms, including wireless sensor networks, mobile crowdsourcing, and mobile social networking. While offering promising solutions to a wide range of new applications, their widespread adoption and large-scale deployment are often hindered by people's concerns about the security, user privacy, or both. In this dissertation, we aim to address a number of challenging security and privacy issues in heterogeneous wireless and mobile networks in an attempt to foster their widespread adoption. Our contributions are mainly fivefold. First, we introduce a novel secure and loss-resilient code dissemination scheme for wireless sensor networks deployed in hostile and harsh environments. Second, we devise a novel scheme to enable mobile users to detect any inauthentic or unsound location-based top-k query result returned by an untrusted location-based service providers. Third, we develop a novel verifiable privacy-preserving aggregation scheme for people-centric mobile sensing systems. Fourth, we present a suite of privacy-preserving profile matching protocols for proximity-based mobile social networking, which can support a wide range of matching metrics with different privacy levels. Last, we present a secure combination scheme for crowdsourcing-based cooperative spectrum sensing systems that can enable robust primary user detection even when malicious cognitive radio users constitute the majority.Dissertation/ThesisPh.D. Electrical Engineering 201

Criptografía ligera en dispositivos de identificación por radiofrecuencia- RFID

Esta tesis se centra en el estudio de la tecnología de identificación por radiofrecuencia (RFID), la cual puede ser considerada como una de las tecnologías más prometedoras dentro del área de la computación ubicua. La tecnología RFID podría ser el sustituto de los códigos de barras. Aunque la tecnología RFID ofrece numerosas ventajas frente a otros sistemas de identificación, su uso lleva asociados riesgos de seguridad, los cuales no son fáciles de resolver. Los sistemas RFID pueden ser clasificados, atendiendo al coste de las etiquetas, distinguiendo principalmente entre etiquetas de alto coste y de bajo coste. Nuestra investigación se centra fundamentalmente en estas últimas. El estudio y análisis del estado del arte nos ha permitido identificar la necesidad de desarrollar soluciones criptográficas ligeras adecuadas para estos dispositivos limitados. El uso de soluciones criptográficas estándar supone una aproximación correcta desde un punto de vista puramente teórico. Sin embargo, primitivas criptográficas estándar (funciones resumen, código de autenticación de mensajes, cifradores de bloque/flujo, etc.) exceden las capacidades de las etiquetas de bajo coste. Por tanto, es necesario el uso de criptografía ligera._______________________________________This thesis examines the security issues of Radio Frequency Identification (RFID) technology, one of the most promising technologies in the field of ubiquitous computing. Indeed, RFID technology may well replace barcode technology. Although it offers many advantages over other identification systems, there are also associated security risks that are not easy to address. RFID systems can be classified according to tag price, with distinction between high-cost and low-cost tags. Our research work focuses mainly on low-cost RFID tags. An initial study and analysis of the state of the art identifies the need for lightweight cryptographic solutions suitable for these very constrained devices. From a purely theoretical point of view, standard cryptographic solutions may be a correct approach. However, standard cryptographic primitives (hash functions, message authentication codes, block/stream ciphers, etc.) are quite demanding in terms of circuit size, power consumption and memory size, so they make costly solutions for low-cost RFID tags. Lightweight cryptography is therefore a pressing need. First, we analyze the security of the EPC Class-1 Generation-2 standard, which is considered the universal standard for low-cost RFID tags. Secondly, we cryptanalyze two new proposals, showing their unsuccessful attempt to increase the security level of the specification without much further hardware demands. Thirdly, we propose a new protocol resistant to passive attacks and conforming to low-cost RFID tag requirements. In this protocol, costly computations are only performed by the reader, and security related computations in the tag are restricted to very simple operations. The protocol is inspired in the family of Ultralightweight Mutual Authentication Protocols (UMAP: M2AP, EMAP, LMAP) and the recently proposed SASI protocol. The thesis also includes the first published cryptanalysis of xi SASI under the weakest attacker model, that is, a passive attacker. Fourthly, we propose a new protocol resistant to both passive and active attacks and suitable for moderate-cost RFID tags. We adapt Shieh et.’s protocol for smart cards, taking into account the unique features of RFID systems. Finally, because this protocol is based on the use of cryptographic primitives and standard cryptographic primitives are not supported, we address the design of lightweight cryptographic primitives. Specifically, we propose a lightweight hash function (Tav-128) and a lightweight Pseudo-Random Number Generator (LAMED and LAMED-EPC).We analyze their security level and performance, as well as their hardware requirements and show that both could be realistically implemented, even in low-cost RFID tags