Contribution to the construction of fingerprinting and watermarking schemes to protect mobile agents and multimedia content

The main characteristic of fingerprinting codes is the need of high error-correction capacity due to the fact that they are designed to avoid collusion attacks which will damage many symbols from the codewords. Moreover, the use of fingerprinting schemes depends on the watermarking system that is used to embed the codeword into the content and how it honors the marking assumption. In this sense, even though fingerprinting codes were mainly used to protect multimedia content, using them on software protection systems seems an option to be considered. This thesis, studies how to use codes which have iterative-decoding algorithms, mainly turbo-codes, to solve the fingerprinting problem. Initially, it studies the effectiveness of current approaches based on concatenating tradicioanal fingerprinting schemes with convolutional codes and turbo-codes. It is shown that these kind of constructions ends up generating a high number of false positives. Even though this thesis contains some proposals to improve these schemes, the direct use of turbo-codes without using any concatenation with a fingerprinting code as inner code has also been considered. It is shown that the performance of turbo-codes using the appropiate constituent codes is a valid alternative for environments with hundreds of users and 2 or 3 traitors. As constituent codes, we have chosen low-rate convolutional codes with maximum free distance. As for how to use fingerprinting codes with watermarking schemes, we have studied the option of using watermarking systems based on informed coding and informed embedding. It has been discovered that, due to different encodings available for the same symbol, its applicability to embed fingerprints is very limited. On this sense, some modifications to these systems have been proposed in order to properly adapt them to fingerprinting applications. Moreover the behavior and impact over a video produced as a collusion of 2 users by the YouTube’s s ervice has been s tudied. We have also studied the optimal parameters for viable tracking of users who have used YouTube and conspired to redistribute copies generated by a collusion attack. Finally, we have studied how to implement fingerprinting schemes and software watermarking to fix the problem of malicious hosts on mobile agents platforms. In this regard, four different alternatives have been proposed to protect the agent depending on whether you want only detect the attack or avoid it in real time. Two of these proposals are focused on the protection of intrusion detection systems based on mobile agents. Moreover, each of these solutions has several implications in terms of infrastructure and complexity.Els codis fingerprinting es caracteritzen per proveir una alta capacitat correctora ja que han de fer front a atacs de confabulació que malmetran una part important dels símbols de la paraula codi. D'atra banda, la utilització de codis de fingerprinting en entorns reals està subjecta a que l'esquema de watermarking que gestiona la incrustació sigui respectuosa amb la marking assumption. De la mateixa manera, tot i que el fingerprinting neix de la protecció de contingut multimèdia, utilitzar-lo en la protecció de software comença a ser una aplicació a avaluar. En aquesta tesi s'ha estudiat com aplicar codis amb des codificació iterativa, concretament turbo-codis, al problema del rastreig de traïdors en el context del fingerprinting digital. Inicialment s'ha qüestionat l'eficàcia dels enfocaments actuals en la utilització de codis convolucionals i turbo-codis que plantegen concatenacions amb esquemes habituals de fingerprinting. S'ha demostrat que aquest tipus de concatenacions portaven, de forma implícita, a una elevada probabilitat d'inculpar un usuari innocent. Tot i que s'han proposat algunes millores sobre aquests esquemes , finalment s'ha plantejat l'ús de turbocodis directament, evitant així la concatenació amb altres esquemes de fingerprinting. S'ha demostrat que, si s'utilitzen els codis constituents apropiats, el rendiment del turbo-descodificador és suficient per a ser una alternativa aplicable en entorns amb varis centenars d'usuaris i 2 o 3 confabuladors . Com a codis constituents s'ha optat pels codis convolucionals de baix ràtio amb distància lliure màxima. Pel que fa a com utilitzar els codis de fingerprinting amb esquemes de watermarking, s'ha estudiat l'opció d'utilitzar sistemes de watermarking basats en la codificació i la incrustació informada. S'ha comprovat que, degut a la múltiple codificació del mateix símbol, la seva aplicabilitat per incrustar fingerprints és molt limitada. En aquest sentit s'ha plantejat algunes modificacions d'aquests sistemes per tal d'adaptar-los correctament a aplicacions de fingerprinting. D'altra banda s'ha avaluat el comportament i l'impacte que el servei de YouTube produeix sobre un vídeo amb un fingerprint incrustat. A més , s'ha estudiat els paràmetres òptims per a fer viable el rastreig d'usuaris que han confabulat i han utilitzat YouTube per a redistribuir la copia fruït de la seva confabulació. Finalment, s'ha estudiat com aplicar els esquemes de fingerprinting i watermarking de software per solucionar el problema de l'amfitrió maliciós en agents mòbils . En aquest sentit s'han proposat quatre alternatives diferents per a protegir l'agent en funció de si és vol només detectar l'atac o evitar-lo en temps real. Dues d'aquestes propostes es centren en la protecció de sistemes de detecció d'intrusions basats en agents mòbils. Cadascuna de les solucions té diverses implicacions a nivell d'infrastructura i de complexitat.Postprint (published version

Mecanismo para evitar ataques por confabulación basados en code passing

Los agentes móviles son entidades software formadas por código, datos, itinerario y estado, que pueden migrar de host en host autónomamente ejecutando su código. A pesar de sus ventajas, los aspectos de seguridad restringen enormemente el uso de código móvil. La protección del agente ante ataques de hosts maliciosos, es el problema de seguridad más difícil de resolver en los sistemas de agentes móviles. En particular, los ataques por confabulación han sido poco estudiados en la literatura. Este paper presenta un mecanismo de protección ante ataques por confabulación basados en code passing. Nuestra propuesta es un Multi-Code Agent que contiene diferentes variantes del código para cada host. Una Trusted Third Party es la responsable de proporcionar la información para extraer cada variante, y de tomar referencias temporales que se usarán para veri car la coherencia temporal

Artificial Intelligence-Altered Videos (Deepfakes), Image-Based Sexual Abuse, and Data Privacy Concerns

Artificial Intelligence (AI) is a phenomenon that has become embedded in human life, and this symbiotic relationship between technology and humanity is here to stay. One such use of AI is deepfakes. The use of AI for deepfakes is arguably one of the most controversial topics because it raises ethical issues. Deepfakes are images or recordings that have been convincingly altered and manipulated to misrepresent someone as doing or saying something that they did not actually do or say. These manipulations thrive in the political arena and recently in the pornography industry, in which women’s faces are masked onto other bodies to create video illusions that cause non-consensual sexual-image abuse and other harms. It is no surprise that the malicious use of deepfake technology has prompted regulatory legislation like the United States National Defense Authorization Act (NDAA), and the recent ratification of amendments to the Digital Services Act (DSA) on criminalizing malicious deepfakes. Scholars, advocates, and victims continue to call for more specific and stricter laws to regulate deepfakes and assign penalties for non-adherence. This paper presents a timely analysis of deepfake pornography as a type of image-based sexual abuse, and of the position of the law on malicious use of deepfake technology. Data protection concerns under the General Data Protection Regulation, and policy recommendations and measures for redress, control, and eradication are also addressed

Formally designing and implementing cyber security mechanisms in industrial control networks.

This dissertation describes progress in the state-of-the-art for developing and deploying formally verified cyber security devices in industrial control networks. It begins by detailing the unique struggles that are faced in industrial control networks and why concepts and technologies developed for securing traditional networks might not be appropriate. It uses these unique struggles and examples of contemporary cyber-attacks targeting control systems to argue that progress in securing control systems is best met with formal verification of systems, their specifications, and their security properties. This dissertation then presents a development process and identifies two technologies, TLA+ and seL4, that can be leveraged to produce a high-assurance embedded security device. The method presented in this dissertation takes an informal design of an embedded device that might be found in a control system and 1) formalizes the design within TLA+, 2) creates and mechanically checks a model built from the formal design, and 3) translates the TLA+ design into a component-based architecture of a native seL4 application. The later chapters of this dissertation describe an application of the process to a security preprocessor embedded device that was designed to add security mechanisms to the network communication of an existing control system. The device and its security properties are formally specified in TLA+ in chapter 4, mechanically checked in chapter 5, and finally its native seL4 architecture is implemented in chapter 6. Finally, the conclusions derived from the research are laid out, as well as some possibilities for expanding the presented method in the future

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

Mechanism design-based leader election scheme for intrusion detection in MANET

We study the leader election in the presence of selfish nodes for intrusion detection systems (IDS) in a mobile ad hoc network (MANET). To balance the resource consumption among all nodes and prolong the lifetime of a MANET, nodes with the most remaining resources should be elected as the leaders. However, without incentives for serving others, a node may behave selfishly by lying about its remaining resource and avoiding being elected. We present a solution based on mechanism design theory. More specifically, we design a scheme for electing cluster leaders that have the following two advantages: First, the collection of elected leaders is the optimal in the sense that the overall resource consumption will be balanced among all nodes in the network overtime. Second, the scheme provides the leaders with incentives in the form of reputation so that nodes are encouraged to honestly participate in the election process. The design of such incentives is based on the Vickrey, Clarke, and Groves (VCG) model by which truth-telling is the dominant strategy for each node. Simulation results show that our scheme can effectively prolong the overall lifetime of IDS in MANET and balance the resource consumptions among all the nodes

Mechanism design and game theoretical models for intrusion detection

In this thesis, we study the problems related to intrusion detection systems in Mobile Ad hoc Networks (MANETs). Specifically, we are addressing the leader election in the presence of selfish nodes, the tradeoff between security and IDS's resource consumption, and the multi-fragment intrusion detection via sampling. To balance the resource consumption among all the nodes and prolong the lifetime of a MANET, the nodes with the most remaining resources should be elected as the leaders. Selfishness is one of the main problems facing such a model where nodes can behave selfishly during the election or after. To address this issue, we present a solution based on the theory of mechanism design. More specifically, the solution provides nodes with incentives in the form of reputations to encourage nodes in participating honestly in the election process. The amount of incentives is based on the Vickrey-Clarke-Groves (VCG) mechanism to ensure that truth-telling is the dominant strategy of any node. To catch and punish a misbehaving elected leader, checkers are selected randomly to monitor the behavior of a leader. To reduce the false-positive rate, a cooperative game-theoretic model is proposed to analyze the contribution of each checker on the catch decision. A multi-stage catch mechanism is also introduced to reduce the performance overhead of checkers. Additionally, we propose a series of local election algorithms that lead to globally optimal election results. Note that the leader election model, which is known as moderate model is only suitable when the probability of attacks is low. Once the probability of attacks is high, victims should launch their own IDSs. Such a robust model is, however, costly with respect to energy, which leads nodes to die fast. Clearly, to reduce the resource consumption of IDSs and yet keep its effectiveness, a critical issue is: When should we shift from moderate to robust mode? Here, we formalize this issue as a nonzero-sum non-cooperative game-theoretical model that takes into consideration the tradeoff between security and IDS resource consumption. Last but not least, we consider the problem of detecting multi-fragments intrusions that are launched from a MANET targeting another network. To generalize our solution, we consider the intrusion to be launched from any type of networks. The detection is accomplished by sampling a subset of the transmitted packets over selected network links or router interfaces. Given a sampling budget, our framework aims at developing a network packet sampling strategy to effectively reduce the success chances of an intruder. Non-cooperative game theory is used to express the problem formally. Finally, empirical results are provided to support our solutions

Intrusion Detection System for detecting internal threats in 6LoWPAN

6LoWPAN (IPv6 over Low-power Wireless Personal Area Network) is a standard developed by the Internet Engineering Task Force group to enable the Wireless Sensor Networks to connect to the IPv6 Internet. This standard is rapidly gaining popularity for its applicability, ranging extensively from health care to environmental monitoring. Security is one of the most crucial issues that need to be considered properly in 6LoWPAN. Common 6LoWPAN security threats can come from external or internal attackers. Cryptographic techniques are helpful in protecting the external attackers from illegally joining the network. However, because the network devices are commonly not tampered-proof, the attackers can break the cryptography codes of such devices and use them to operate like an internal source. These malicious sources can create internal attacks, which may downgrade significantly network performance. Protecting the network from these internal threats has therefore become one of the centre security problems on 6LoWPAN. This thesis investigates the security issues created by the internal threats in 6LoWPAN and proposes the use of Intrusion Detection System (IDS) to deal with such threats. Our main works are to categorise the 6LoWPAN threats into two major types, and to develop two different IDSs to detect each of this type effectively. The major contributions of this thesis are summarised as below. First, we categorise the 6LoWPAN internal threats into two main types, one that focuses on compromising directly the network performance (performance-type) and the other is to manipulate the optimal topology (topology-type), to later downgrade the network service quality indirectly. In each type, we select some typical threats to implement, and assess their particular impacts on network performance as well as identify performance metrics that are sensitive in the attacked situations, in order to form the basis detection knowledge. In addition, on studying the topology-type, we propose several novel attacks towards the Routing Protocol for Low Power and Lossy network (RPL - the underlying routing protocol in 6LoWPAN), including the Rank attack, Local Repair attack and DIS attack. Second, we develop a Bayesian-based IDS to detect the performance-type internal threats by monitoring typical attacking targets such as traffic, channel or neighbour nodes. Unlike other statistical approaches, which have a limited view by just using a single metric to monitor a specific attack, our Bayesian-based IDS can judge an abnormal behaviour with a wiser view by considering of different metrics using the insightful understanding of their relations. Such wiser view helps to increase the IDS’s accuracy significantly. Third, we develop a Specification-based IDS module to detect the topology-type internal threats based on profiling the RPL operation. In detail, we generalise the observed states and transitions of RPL control messages to construct a high-level abstract of node operations through analysing the trace files of the simulations. Our profiling technique can form all of the protocol’s legal states and transitions automatically with corresponding statistic data, which is faster and easier to verify compare with other manual specification techniques. This IDS module can detect the topology-type threats quickly with a low rate of false detection. We also propose a monitoring architecture that uses techniques from modern technologies such as LTE (Long-term Evolution), cloud computing, and multiple interface sensor devices, to expand significantly the capability of the IDS in 6LoWPAN. This architecture can enable the running of both two proposed IDSs without much overhead created, to help the system to deal with most of the typical 6LoWPAN internal threats. Overall, the simulation results in Contiki Cooja prove that our two IDS modules are effective in detecting the 6LoWPAN internal threats, with the detection accuracy is ranging between 86 to 100% depends on the types of attacks, while the False Positive is also satisfactory, with under 5% for most of the attacks. We also show that the additional energy consumptions and the overhead of the solutions are at an acceptable level to be used in the 6LoWPAN environment