25 research outputs found

    Efficient and Low-Cost RFID Authentication Schemes

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    Security in passive resource-constrained Radio Frequency Identification (RFID) tags is of much interest nowadays. Resistance against illegal tracking, cloning, timing, and replay attacks are necessary for a secure RFID authentication scheme. Reader authentication is also necessary to thwart any illegal attempt to read the tags. With an objective to design a secure and low-cost RFID authentication protocol, Gene Tsudik proposed a timestamp-based protocol using symmetric keys, named YA-TRAP*. Although YA-TRAP* achieves its target security properties, it is susceptible to timing attacks, where the timestamp to be sent by the reader to the tag can be freely selected by an adversary. Moreover, in YA-TRAP*, reader authentication is not provided, and a tag can become inoperative after exceeding its pre-stored threshold timestamp value. In this paper, we propose two mutual RFID authentication protocols that aim to improve YA-TRAP* by preventing timing attack, and by providing reader authentication. Also, a tag is allowed to refresh its pre-stored threshold value in our protocols, so that it does not become inoperative after exceeding the threshold. Our protocols also achieve other security properties like forward security, resistance against cloning, replay, and tracking attacks. Moreover, the computation and communication costs are kept as low as possible for the tags. It is important to keep the communication cost as low as possible when many tags are authenticated in batch-mode. By introducing aggregate function for the reader-to-server communication, the communication cost is reduced. We also discuss different possible applications of our protocols. Our protocols thus capture more security properties and more efficiency than YA-TRAP*. Finally, we show that our protocols can be implemented using the current standard low-cost RFID infrastructures.Comment: 21 pages, Journal of Wireless Mobile Networks, Ubiquitous Computing, and Dependable Applications (JoWUA), Vol 2, No 3, pp. 4-25, 201

    Building regulatory compliant storage systems

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    In the past decade, informational records have become entirely digital. These include financial statements, health care records, student records, private consumer information and other sensitive data. Because of the delicate nature of the data these records contain, Congress and the courts have begun to recognize the importance of properly storing and securing electronic records. Examples of legislation in-clude the Health Insurance Portability and Accountabilit

    HAIL: A High-Availability and Integrity Layer for Cloud Storage

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    We introduce HAIL (High-Availability and Integrity Layer), a distributed cryptographic system that permits a set of servers to prove to a client that a stored file is intact and retrievable. HAIL strengthens, formally unifies, and streamlines distinct approaches from the cryptographic and distributed-systems communities. Proofs in HAIL are efficiently computable by servers and highly compact---typically tens or hundreds of bytes, irrespective of file size. HAIL cryptographically verifies and reactively reallocates file shares. It is robust against an active, mobile adversary, i.e., one that may progressively corrupt the full set of servers. We propose a strong, formal adversarial model for HAIL, and rigorous analysis and parameter choices. We show how HAIL improves on the security and efficiency of existing tools, like Proofs of Retrievability (PORs) deployed on individual servers. We also report on a prototype implementation

    Energy Efficient Authentication Strategies for Network Coding

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    International audienceRecent advances in information theory and networking, e.g. aggregation, network coding or rateless codes, have significantly modified data dissemination in wireless networks. These new paradigms create new threats for security such as pollution attacks and denial of services (DoS). These attacks exploit the difficulty to authenticate data in such contexts. The particular case of xor network coding is considered herein. We investigate different strategies based on message authentication codes algorithms (MACs) to thwart these attacks. Yet, classical MAC designs are not compatible with the linear combination of network coding. Fortunately, MACs based on universal hash functions (UHFs) match nicely the needs of network coding: some of these functions are linear h(x1⊕x2)=h(x1)⊕h(x2). To demonstrate their efficiency, we consider the case of wireless sensor networks (WSNs). Although these functions can drastically reduce the energy consumption of authentication (up to 68% gain over the classical designs is observed), they increase the threat of DoS. Indeed, an adversary can disrupt all communications by polluting few messages. To overcome this problem, a group testing algorithm is introduced for authentication resulting in a complexity linear in the number of attacks. The energy consumption is analyzed for cross-point and butterfly network topologies with respect to the possible attack scenarios. The results highlight the trade-offs between energy efficiency, authentication and the effective throughput for the different MAC modes

    Secure Remote Storage of Logs with Search Capabilities

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    Dissertação de Mestrado em Engenharia InformáticaAlong side with the use of cloud-based services, infrastructure and storage, the use of application logs in business critical applications is a standard practice nowadays. Such application logs must be stored in an accessible manner in order to used whenever needed. The debugging of these applications is a common situation where such access is required. Frequently, part of the information contained in logs records is sensitive. This work proposes a new approach of storing critical logs in a cloud-based storage recurring to searchable encryption, inverted indexing and hash chaining techniques to achieve, in a unified way, the needed privacy, integrity and authenticity while maintaining server side searching capabilities by the logs owner. The designed search algorithm enables conjunctive keywords queries plus a fine-grained search supported by field searching and nested queries, which are essential in the referred use case. To the best of our knowledge, the proposed solution is also the first to introduce a query language that enables complex conjunctive keywords and a fine-grained search backed by field searching and sub queries.A gerac¸ ˜ao de logs em aplicac¸ ˜oes e a sua posterior consulta s˜ao fulcrais para o funcionamento de qualquer neg´ocio ou empresa. Estes logs podem ser usados para eventuais ac¸ ˜oes de auditoria, uma vez que estabelecem uma baseline das operac¸ ˜oes realizadas. Servem igualmente o prop´ osito de identificar erros, facilitar ac¸ ˜oes de debugging e diagnosticar bottlennecks de performance. Tipicamente, a maioria da informac¸ ˜ao contida nesses logs ´e considerada sens´ıvel. Quando estes logs s˜ao armazenados in-house, as considerac¸ ˜oes relacionadas com anonimizac¸ ˜ao, confidencialidade e integridade s˜ao geralmente descartadas. Contudo, com o advento das plataformas cloud e a transic¸ ˜ao quer das aplicac¸ ˜oes quer dos seus logs para estes ecossistemas, processos de logging remotos, seguros e confidenciais surgem como um novo desafio. Adicionalmente, regulac¸ ˜ao como a RGPD, imp˜oe que as instituic¸ ˜oes e empresas garantam o armazenamento seguro dos dados. A forma mais comum de garantir a confidencialidade consiste na utilizac¸ ˜ao de t ´ecnicas criptogr ´aficas para cifrar a totalidade dos dados anteriormente `a sua transfer ˆencia para o servidor remoto. Caso sejam necess´ arias capacidades de pesquisa, a abordagem mais simples ´e a transfer ˆencia de todos os dados cifrados para o lado do cliente, que proceder´a `a sua decifra e pesquisa sobre os dados decifrados. Embora esta abordagem garanta a confidencialidade e privacidade dos dados, rapidamente se torna impratic ´avel com o crescimento normal dos registos de log. Adicionalmente, esta abordagem n˜ao faz uso do potencial total que a cloud tem para oferecer. Com base nesta tem´ atica, esta tese prop˜oe o desenvolvimento de uma soluc¸ ˜ao de armazenamento de logs operacionais de forma confidencial, integra e autˆ entica, fazendo uso das capacidades de armazenamento e computac¸ ˜ao das plataformas cloud. Adicionalmente, a possibilidade de pesquisa sobre os dados ´e mantida. Essa pesquisa ´e realizada server-side diretamente sobre os dados cifrados e sem acesso em momento algum a dados n˜ao cifrados por parte do servidor..

    Securing the in-vehicle network

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    Recent research into automotive security has shown that once a single electronic vehicle component is compromised, it is possible to take control of the vehicle. These components, called Electronic Control Units, are embedded systems which manage a significant part of the functionality of a modern car. They communicate with each other via the in-vehicle network, known as the Controller Area Network, which is the most widely used automotive bus. In this thesis, we introduce a series of novel proposals to improve the security of both the Controller Area Network bus and the Electronic Control Units. The Controller Area Network suffers from a number of shortfalls, one of which is the lack of source authentication. We propose a protocol that mitigates this fundamental shortcoming in the Controller Area Network bus design, and protects against a number of high profile media attacks that have been published. We derive a set of desirable security and compatibility properties which an authentication protocol for the Controller Area Network bus should possess. We evaluate our protocol, along with other proposed protocols in the literature, with respect to the defined properties. Our systematic analysis of the protocols allows the automotive industry to make an informed choice regarding the adoption suitability of these solutions. However, it is not only the communication of Electronic Control Units that needs to be secure, but the firmware running on them as well. The growing number of Electronic Control Units in a vehicle, together with their increasing complexity, prompts the need for automated tools to test their security. Part of the challenge in designing such a tool is the diversity of Electronic Control Unit architectures. To this end, this thesis presents a methodology for extracting the Control Flow Graph from the Electronic Control Unit firmware. The Control Flow Graph is a platform independent representation of the firmware control flow, allowing us to abstract from the underlying architecture. We present a fuzzer for Electronic Control Unit firmware fuzz-testing via Controller Area Network. The extracted Control Flow Graph is tagged with static data used in instructions which influence the control flow of the firmware. It is then used to create a set of input seeds for the fuzzer, and in altering the inputs during the fuzzing process. This approach represents a step towards an efficient fuzzing methodology for Electronic Control Units. To our knowledge, this is the first proposal that uses static analysis to guide the fuzzing of Electronic Control Units

    Cryptographic Protection of Digital Identity

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    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.
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