Secure identity management in structured peer-to-peer (P2P) networks

Structured Peer-to-Peer (P2P) networks were proposed to solve routing problems of big distributed infrastructures. But the research community has been questioning their security for years. Most prior work in security services was focused on secure routing, reputation systems, anonymity, etc. However, the proper management of identities is an important prerequisite to provide most of these security services. The existence of anonymous nodes and the lack of a centralized authority capable of monitoring (and/or punishing) nodes make these systems more vulnerable against selfish or malicious behaviors. Moreover, these improper usages cannot be faced only with data confidentiality, nodes authentication, non-repudiation, etc. In particular, structured P2P networks should follow the following secure routing primitives: (1) secure maintenance of routing tables, (2) secure routing of messages, and (3) secure identity assignment to nodes. But the first two problems depend in some way on the third one. If nodes’ identifiers can be chosen by users without any control, these networks can have security and operational problems. Therefore, like any other network or service, structured P2P networks require a robust access control to prevent potential attackers joining the network and a robust identity assignment system to guarantee their proper operation. In this thesis, firstly, we analyze the operation of the current structured P2P networks when managing identities in order to identify what security problems are related to the nodes’ identifiers within the overlay, and propose a series of requirements to be accomplished by any generated node ID to provide more security to a DHT-based structured P2P network. Secondly, we propose the use of implicit certificates to provide more security and to exploit the improvement in bandwidth, storage and performance that these certificates present compared to explicit certificates, design three protocols to assign nodes’ identifiers avoiding the identified problems, while maintaining user anonymity and allowing users’ traceability. Finally, we analyze the operation of the most used mechanisms to distribute revocation data in the Internet, with special focus on the proposed systems to work in P2P networks, and design a new mechanism to distribute revocation data more efficiently in a structured P2P network.Las redes P2P estructuradas fueron propuestas para solventar problemas de enrutamiento en infraestructuras de grandes dimensiones pero su nivel de seguridad lleva años siendo cuestionado por la comunidad investigadora. La mayor parte de los trabajos que intentan mejorar la seguridad de estas redes se han centrado en proporcionar encaminamiento seguro, sistemas de reputación, anonimato de los usuarios, etc. Sin embargo, la adecuada gestión de las identidades es un requisito sumamente importante para proporcionar los servicios mencionados anteriormente. La existencia de nodos anónimos y la falta de una autoridad centralizada capaz de monitorizar (y/o penalizar) a los nodos hace que estos sistemas sean más vulnerables que otros a comportamientos maliciosos por parte de los usuarios. Además, esos comportamientos inadecuados no pueden ser detectados proporcionando únicamente confidencialidad de los datos, autenticación de los nodos, no repudio, etc. Las redes P2P estructuradas deberían seguir las siguientes primitivas de enrutamiento seguro: (1) mantenimiento seguro de las tablas de enrutamiento, (2) enrutamiento seguro de los mensajes, and (3) asignación segura de las identidades. Pero la primera de los dos primitivas depende de alguna forma de la tercera. Si las identidades de los nodos pueden ser elegidas por sus usuarios sin ningún tipo de control, muy probablemente aparecerán muchos problemas de funcionamiento y seguridad. Por lo tanto, de la misma forma que otras redes y servicios, las redes P2P estructuradas requieren de un control de acceso robusto para prevenir la presencia de atacantes potenciales, y un sistema robusto de asignación de identidades para garantizar su adecuado funcionamiento. En esta tesis, primero de todo analizamos el funcionamiento de las redes P2P estructuradas basadas en el uso de DHTs (Tablas de Hash Distribuidas), cómo gestionan las identidades de sus nodos, identificamos qué problemas de seguridad están relacionados con la identificación de los nodos y proponemos una serie de requisitos para generar identificadores de forma segura. Más adelante proponemos el uso de certificados implícitos para proporcionar más seguridad y explotar las mejoras en consumo de ancho de banda, almacenamiento y rendimiento que proporcionan estos certificados en comparación con los certificados explícitos. También hemos diseñado tres protocolos de asignación segura de identidades, los cuales evitan la mayor parte de los problemas identificados mientras mantienen el anonimato de los usuarios y la trazabilidad. Finalmente hemos analizado el funcionamiento de la mayoría de los mecanismos utilizados para distribuir datos de revocación en Internet, con especial interés en los sistemas propuestos para operar en redes P2P, y hemos diseñado un nuevo mecanismo para distribuir datos de revocación de forma más eficiente en redes P2P estructuradas.Postprint (published version

An interoperable and secure architecture for internet-scale decentralized personal communication

Interpersonal network communications, including Voice over IP (VoIP) and Instant Messaging (IM), are increasingly popular communications tools. However, systems to date have generally adopted a client-server model, requiring complex centralized infrastructure, or have not adhered to any VoIP or IM standard. Many deployment scenarios either require no central equipment, or due to unique properties of the deployment, are limited or rendered unattractive by central servers. to address these scenarios, we present a solution based on the Session Initiation Protocol (SIP) standard, utilizing a decentralized Peer-to-Peer (P2P) mechanism to distribute data. Our new approach, P2PSIP, enables users to communicate with minimal or no centralized servers, while providing secure, real-time, authenticated communications comparable in security and performance to centralized solutions.;We present two complete protocol descriptions and system designs. The first, the SOSIMPLE/dSIP protocol, is a P2P-over-SIP solution, utilizing SIP both for the transport of P2P messages and personal communications, yielding an interoperable, single-stack solution for P2P communications. The RELOAD protocol is a binary P2P protocol, designed for use in a SIP-using-P2P architecture where an existing SIP application is modified to use an additional, binary RELOAD stack to distribute user information without need for a central server.;To meet the unique security needs of a fully decentralized communications system, we propose an enrollment-time certificate authority model that provides asserted identity and strong P2P and user-level security. In this model, a centralized server is contacted only at enrollment time. No run-time connections to the servers are required.;Additionally, we show that traditional P2P message routing mechanisms are inappropriate for P2PSIP. The existing mechanisms are generally optimized for file sharing and neglect critical practical elements of the open Internet --- namely link-level security and asymmetric connectivity caused by Network Address Translators (NATs). In response to these shortcomings, we introduce a new message routing paradigm, Adaptive Routing (AR), and using both analytical models and simulation show that AR significantly improves message routing performance for P2PSIP systems.;Our work has led to the creation of a new research topic within the P2P and interpersonal communications communities, P2PSIP. Our seminal publications have provided the impetus for subsequent P2PSIP publications, for the listing of P2PSIP as a topic in conference calls for papers, and for the formation of a new working group in the Internet Engineering Task Force (IETF), directed to develop an open Internet standard for P2PSIP

Security in peer-to-peer multimedia communications

Le architetture peer-to-peer (p2p) sono diventate molto popolari negli ultimi anni in conseguenza della grande varietà di servizi che esse possono fornire. Nate principalmente per l'utilizzo come semplice metodo scalabile e decentralizzato per scambiarsi file, sono adesso diventate molto popolari anche per una gran quantità di altri servizi, sfruttando la possibilità di condividere tra peer la banda, la potenza computazionale, la capacità di memorizzazione ed altre risorse. Tra i possibili usi per cui una tale architettura può essere sfruttata, un campo emergente è lo studio dell’applicazione di tecnologie p2p a comunicazioni VoIP in modo da superare alcuni dei problemi di cui soffrono correntemente le piattaforme centralizzate basate su SIP. Sfortunatamente, i problemi di sicurezza delle reti p2p sono ancora un campo di studio aperto, sia per il recente sviluppo di una tale piattaforma, sia per i rischi intrinseci di un ambiente distribuito stesso. Questa tesi ha lo scopo di studiare i problemi di sicurezza e le possibili soluzioni in modo da garantire una comunicazione sicura p2p. La ricerca è stata condotta in due direzioni: sicurezza a livello di routing e sicurezza a livello applicativo. Questi rappresentano I due possibili step di uno scenario di comunicazione: prima di tutto si deve trovare in modo sicuro la posizione di chi si vuole chiamare (che può essere memorizzata in una rete p2p stessa), e questo è un problema di lookup sicuro; in un secondo momento bisogna assicurarsi che la persona con cui si sta andando a parlare è veramente chi si voleva e che la comunicazione stessa sia confidenziale e non possa essere modificata; questi sono problemi di autenticazione e confidenzialità. Per quanto riguarda il primo punto, si sono studiati molti possibili attacchi a reti p2p strutturate e non strutturate, concentrandosi particolarmente sul Sybil attack da cui molti altri attacchi possono derivare. Dopo un analisi delle possibili contromisure presentate negli anni, ci siamo focalizzati sull’algoritmo DHT Kademlia, uno dei più usati nel mondo, studiando tramite simulazioni la degradazione delle performance in presenza di nodi malevoli. Si sono inoltre studiate contromisure basate su fiducia e reputazione e si è cercato di applicarle ad una rete Kademlia operante in un ambiente con un numero crescente di nodi malevoli. Per quanto riguarda il secondo punto, come prima cosa abbiamo studiato gli attuali key agreement protocol, focalizzandoci sul numero di messaggi scambiati e cercando di trovare possibili punti deboli persino in protocolli ed algoritmi largamente utilizzati. In un secondo tempo si è proposto un nuovo key agreement protocol basato su MIKEY e ZRTP che li integra nella procedura standard di INVITE di SIP. E’ stata inoltre fatta un’analisi del protocollo proposto. Su queste basi, si è andati oltre, aggiungendo anche metodi di autenticazione basati sui certificati ed un modo per gestire in maniera p2p certificati e firme. Infine, si è anche pensato ad un’architettura dove i certificati sono memorizzati in una rete p2p stessa tramite l’utilizzo di DHT.Peer-to-peer (P2P) architectures became very popular in the last years as a consequence of the great variety of services they can provide. When they were born, they were mainly deployed as a simple, decentralized and scalable way to exchange files, but they have now become very popular also for a lot of different services, exploiting the possibility of sharing bandwidth, computing power, storage capacity and other resources between peers. Among the possible uses such an architecture can be deployed for, an emerging field of study is the application of P2P technologies to VoIP communication scenarios in order to overcome some of the current issues centralized SIP-based platforms suffer of. Unfortunately, security issues in P2P networks are still an open field of investigation both because of the recent development of such a platform and for the inherent risks of a distributed environment itself. This thesis is meant to investigate the security issues and the possible solutions in order to setup a secure P2P communication. The research was conducted into two directions: - Security issues at routing level; - Security issues at application level. They represent the two steps of a possible communication scenario: first of all one must find in a secure way the location of the callee (maybe stored in a peer-to-peer network), this is a problem of secure lookup; then one must ensure that the person he is going to talk with is really who he wanted and that the communication itself is secret and cannot be tampered, these are problems of authentication and confidentiality. As regards the first point, we studied several possible attacks to structured and unstructured peer-to-peer networks particularly focalizing onto the disruptive Sybil attack from which many other attack can be derived. After an analysis of the possible countermeasures presented over the years, we focalized onto the Kademlia algorithm, one of the most used in the world, studying through simulations the degradation of performances in presence of malicious nodes. We also studied trust and reputation countermeasures and tried to apply them to a Kademlia-based network operating in an environment where there is a growing number of malicious nodes. For the second point, first of all we studied current key agreement protocols focusing on the number of messages and trying to find out possible drawbacks even in widely accepted protocols and algorithms. In a second time we proposed a new key agreement protocol based upon MIKEY and ZRTP integrating them into the standard SIP invite procedure. An analysis of the proposed protocol is also provided. On this basis we got further, adding also certificate-based authentication to our model and a way to manage in a P2P way certificates and signatures. Finally we also provided an architecture where certificates are stored in a P2P network itself with the use of a DHT

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

Secure Schemes for Semi-Trusted Environment

In recent years, two distributed system technologies have emerged: Peer-to-Peer (P2P) and cloud computing. For the former, the computers at the edge of networks share their resources, i.e., computing power, data, and network bandwidth, and obtain resources from other peers in the same community. Although this technology enables efficiency, scalability, and availability at low cost of ownership and maintenance, peers defined as ``like each other'' are not wholly controlled by one another or by the same authority. In addition, resources and functionality in P2P systems depend on peer contribution, i.e., storing, computing, routing, etc. These specific aspects raise security concerns and attacks that many researchers try to address. Most solutions proposed by researchers rely on public-key certificates from an external Certificate Authority (CA) or a centralized Public Key Infrastructure (PKI). However, both CA and PKI are contradictory to fully decentralized P2P systems that are self-organizing and infrastructureless. To avoid this contradiction, this thesis concerns the provisioning of public-key certificates in P2P communities, which is a crucial foundation for securing P2P functionalities and applications. We create a framework, named the Self-Organizing and Self-Healing CA group (SOHCG), that can provide certificates without a centralized Trusted Third Party (TTP). In our framework, a CA group is initialized in a Content Addressable Network (CAN) by trusted bootstrap nodes and then grows to a mature state by itself. Based on our group management policies and predefined parameters, the membership in a CA group is dynamic and has a uniform distribution over the P2P community; the size of a CA group is kept to a level that balances performance and acceptable security. The muticast group over an underlying CA group is constructed to reduce communication and computation overhead from collaboration among CA members. To maintain the quality of the CA group, the honest majority of members is maintained by a Byzantine agreement algorithm, and all shares are refreshed gradually and continuously. Our CA framework has been designed to meet all design goals, being self-organizing, self-healing, scalable, resilient, and efficient. A security analysis shows that the framework enables key registration and certificate issue with resistance to external attacks, i.e., node impersonation, man-in-the-middle (MITM), Sybil, and a specific form of DoS, as well as internal attacks, i.e., CA functionality interference and CA group subversion. Cloud computing is the most recent evolution of distributed systems that enable shared resources like P2P systems. Unlike P2P systems, cloud entities are asymmetric in roles like client-server models, i.e., end-users collaborate with Cloud Service Providers (CSPs) through Web interfaces or Web portals. Cloud computing is a combination of technologies, e.g., SOA services, virtualization, grid computing, clustering, P2P overlay networks, management automation, and the Internet, etc. With these technologies, cloud computing can deliver services with specific properties: on-demand self-service, broad network access, resource pooling, rapid elasticity, measured services. However, theses core technologies have their own intrinsic vulnerabilities, so they induce specific attacks to cloud computing. Furthermore, since public clouds are a form of outsourcing, the security of users' resources must rely on CSPs' administration. This situation raises two crucial security concerns for users: locking data into a single CSP and losing control of resources. Providing inter-operations between Application Service Providers (ASPs) and untrusted cloud storage is a countermeasure that can protect users from lock-in with a vendor and losing control of their data. To meet the above challenge, this thesis proposed a new authorization scheme, named OAuth and ABE based authorization (AAuth), that is built on the OAuth standard and leverages Ciphertext-Policy Attribute Based Encryption (CP-ABE) and ElGamal-like masks to construct ABE-based tokens. The ABE-tokens can facilitate a user-centric approach, end-to-end encryption and end-to-end authorization in semi-trusted clouds. With these facilities, owners can take control of their data resting in semi-untrusted clouds and safely use services from unknown ASPs. To this end, our scheme divides the attribute universe into two disjointed sets: confined attributes defined by owners to limit the lifetime and scope of tokens and descriptive attributes defined by authority(s) to certify the characteristic of ASPs. Security analysis shows that AAuth maintains the same security level as the original CP-ABE scheme and protects users from exposing their credentials to ASP, as OAuth does. Moreover, AAuth can resist both external and internal attacks, including untrusted cloud storage. Since most cryptographic functions are delegated from owners to CSPs, AAuth gains computing power from clouds. In our extensive simulation, AAuth's greater overhead was balanced by greater security than OAuth's. Furthermore, our scheme works seamlessly with storage providers by retaining the providers' APIs in the usual way

Hybrid routing in delay tolerant networks

This work addresses the integration of today\\u27s infrastructure-based networks with infrastructure-less networks. The resulting Hybrid Routing System allows for communication over both network types and can help to overcome cost, communication, and overload problems. Mobility aspect resulting from infrastructure-less networks are analyzed and analytical models developed. For development and deployment of the Hybrid Routing System an overlay-based framework is presented

Hybrid Routing in Delay Tolerant Networks

This work addresses the integration of today\u27s infrastructure-based networks with infrastructure-less networks. The resulting Hybrid Routing System allows for communication over both network types and can help to overcome cost, communication, and overload problems. Mobility aspect resulting from infrastructure-less networks are analyzed and analytical models developed. For development and deployment of the Hybrid Routing System an overlay-based framework is presented

Misregulation Of Person To Person Lending

Amid a financial crisis and credit crunch, retail investors are lending a billion dollars over the Internet, on an unsecured basis, to total strangers. Technological and financial innovation allows person-to-person (“P2P”) lending to connect lenders and borrowers in inspiring ways never before imagined. However, all is not well with P2P lending. The SEC threatens the entire industry by asserting jurisdiction with a fundamental misunderstanding of P2P lending. This Article illustrates how the SEC has transformed this industry, making P2P lending less safe and more costly, threatening its very existence. The SEC’s misregulation of P2P lending provides an opportunity to theorize about regulation in a rapidly disintermediating world. The Article then proposes a preferable regulatory scheme designed to preserve and discipline P2P lending\u27s innovative mix of social finance, micro lending, and disintermediation. This proposal consists of regulation by the new Consumer Financial Protection Bureau