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C. Alcaraz, and J. Lopez, "Digital Twin: A Comprehensive Survey of Security Threats",
IEEE Communications Surveys & Tutorials, IEEE, In Press. DOI (I.F.: 25.249)More..
Impact Factor: 25.249
Journal Citation Reports® Science Edition (Thomson Reuters, 2020)

J. Lopez, J. E. Rubio, and C. Alcaraz, "Digital Twins for Intelligent Authorization in the B5G-enabled Smart Grid",
IEEE Wireless Communications, vol. 28, issue 2, IEEE, pp. 48-55, 04/2021. DOI (I.F.: 11.979)More..


Beyond fifth generation (B5G) communication networks and computation paradigms in the edge are expected to be integrated into power grid infrastructures over the coming years. In this sense, AI technologies will play a fundamental role to efficiently manage dynamic information flows of future applications, which impacts the authorization policies applied in such a complex scenario. This article studies how digital twins can evolve their context awareness capabilities and simulation technologies to anticipate faults or to detect cyber-security issues in real time, and update access control policies accordingly. Our study analyzes the evolution of monitoring platforms and architecture decentralization, including the application of machine learning and blockchain technologies in the smart grid, toward the goal of implementing autonomous and self-learning agents in the medium and long term. We conclude this study with future challenges on applying digital twins to B5G-based smart grid deployments.

Impact Factor: 11.979
Journal Citation Reports® Science Edition (Thomson Reuters, 2020)

PDF icon lopez2020.pdf (1.72 MB)
J. E. Rubio, C. Alcaraz, R. Rios, R. Roman, and J. Lopez, "Distributed Detection of APTs: Consensus vs. Clustering",
25th European Symposium on Research in Computer Security (ESORICS 2020), vol. 12308, pp. 174-192, 09/2020. DOI More..
PDF icon 1846.pdf (1.07 MB)
I. Agudo, and M. Montenegro-Gómez, "Desarrollo de un semáforo inteligente basado en comunicaciones seguras",
XIV Jornadas de Ingeniería Telemática (JITEL 2019), 10/2019. More..


En los nuevos paradigmas de movilidad surgidos durante los últimos años y en aquellos aún por llegar ha quedado patente la necesidad de modernizar la infraestructura viaria y los elementos de señalización y gestión del tráfico. En el presente trabajo se presenta una propuesta para esta nueva generación de dispositivos de gestión del tráfico: un prototipo de semáforo inteligente conectado que implementa diversas medidas de seguridad. Además de las tradicionales señales luminosas, los usuarios de la vía pueden conocer a través de sus dispositivos el estado del semáforo, además de otra información complementaria a través de la difusión de mensajes BLE firmados con criptografía de curva elíptica. A su vez, el semáforo puede ser gestionado remotamente a través de la tecnología LTE Cat M1 protegida por TLS. Esto abre la puerta, entre otros, a facilitar el tránsito de los vehículos de emergencia cuando estos se acercan a un cruce o modificar el tiempo de los estados del ciclo en función de las necesidades del tráfico.

PDF icon 1985.pdf (355.41 KB)
S. Agrawal, M. Lal Das, and J. Lopez, "Detection of Node Capture Attack in Wireless Sensor Networks",
IEEE Systems Journal, vol. 13, issue 1, IEEE, pp. 238 - 247, 03/2019. (I.F.: 3.987)More..
Impact Factor: 3.987
Journal Citation Reports® Science Edition (Thomson Reuters, 2019)

J. Garcia-Alfaro, J. Herrera-Joancomarti, G. Livraga, and R. Rios, Data Privacy Management, Cryptocurrencies and Blockchain Technology , LNCS, vol. 11025, Springer International Publishing, 2018. DOI More..


ESORICS 2018 International Workshops, DPM 2018 and CBT 2018, Barcelona, Spain, September 6-7, 2018, Proceedings

A. Acien, A. Nieto, G. Fernandez, and J. Lopez, "Definición de procedimientos para fabricar honeypots IoT basados en criterios de búsqueda",
XV Reunión Española sobre Criptología y Seguridad de la Información, 10/2018. More..


Con la revolución tecnológica que ha supuesto la Internet de las Cosas (Internet of Things, IoT) se han presentado escenarios donde la preocupación por la seguridad en dicho entorno es cada vez más relevante. Están comenzando a surgir vulnerabilidades en varios dispositivos, y los sistemas trampa son una excelente manera de lidiar con este problema. En este trabajo se analizan soluciones para honeypots en el entorno IoT (y en otros que se puedan adaptar) para sentar las bases de una metodología que permita el despliegue de honeypots IoT.

PDF icon 1706.pdf (1.16 MB)
A. Nieto, R. Rios, and J. Lopez, "Digital Witness and Privacy in IoT: Anonymous Witnessing Approach",
16th IEEE International Conference On Trust, Security And Privacy In Computing And Communications (TrustCom 2017), IEEE, pp. 642-649, 08/2017. DOI More..


The digital witness approach defines the collaboration between IoT devices - from wearables to vehicles - to provide digital evidence through a Digital Chain of Custody to an authorised entity. As one of the cores of the digital witness, binding credentials unequivocally identify the user behind the digital witness. The objective of this article is to perform a critical analysis of the digital witness approach from the perspective of privacy, and to propose solutions that help include some notions of privacy in the scheme (for those cases where it is possible). In addition, digital anonymous witnessing as a tradeoff mechanism between the original approach and privacy requirements is proposed. This is a clear challenge in this context given the restriction that the identities of the links in the digital chain of custody should be known. 

PDF icon 1654.pdf (1.44 MB)
A. Nieto, N. Nomikos, J. Lopez, and C. Skianis, "Dynamic Knowledge-based Analysis in non-Secure 5G Green Environments using Contextual Data",
IEEE Systems Journal, vol. 11, issue 4, no. 99, IEEE, pp. 2479-2489, 12/2017. DOI (I.F.: 4.337)More..


The growing number of parameters in heteroge- neous networks, as is the case of the fifth generation (5G) Green networks, greatly complicates the analysis of the Security and Quality of Service Tradeoff (SQT). However, studying these types of relationships is crucial in Future Internet scenarios to prevent potential points of failure and to enhance the use of limited resources, increasing the user’s experience. Therefore, it is fundamental to provide tools and models for training, so that the users understand these dependencies and solve them prior to deploying new solutions. In this paper, a Recommendation System for SQT (SQT-RS) is deployed in 5G Green systems, considering the particular case of relay networks and the impact of eavesdropping and jamming contexts on the models generated by the user, aided by SQT-RS. With this goal in mind, we provide a component for the user to automatically select specific contexts based on 5G Green capabilities. 

Impact Factor: 4.337
Journal Citation Reports® Science Edition (Thomson Reuters, 2017)

PDF icon NietNLS15.pdf (1.13 MB)
A. Nieto, R. Roman, and J. Lopez, "Digital Witness: Digital Evidence Management Framework for the Internet of Things",
ERCIM News, no. 106, ERCIM EEIG, pp. 9-9, 07/2016.
A. Nieto, R. Roman, and J. Lopez, "Digital Witness: Safeguarding Digital Evidence by using Secure Architectures in Personal Devices",
IEEE Network, IEEE Communications Society, pp. 12-19, 2016. DOI (I.F.: 7.230)More..


Personal devices contain electronic evidence associated with the behaviour of their owners and other devices in their environment, which can help clarify the facts of a cyber-crime scene. These devices are usually analysed as containers of proof. However, it is possible to harness the boom of personal devices to define the concept of digital witnesses, where personal devices are able to actively acquire, store, and transmit digital evidence to an authorised entity, reliably and securely. This article introduces this novel concept, providing a preliminary analysis on the management of digital evidence and the technologies that can be used to implement it with security guarantees in IoT environments. Moreover, the basic building blocks of a digital witness are defined.

Impact Factor: 7.230
Journal Citation Reports® Science Edition (Thomson Reuters, 2016)

PDF icon ieeenet16-nrl.pdf (1002.02 KB)
C. Alcaraz, J. Lopez, and K-K. Raymond Choo, "Dynamic Restoration in Interconnected RBAC-based Cyber-Physical Control Systems",
Proceedings of the 13th International Joint Conference on e-Business and Telecommunications (SECRYPT 2016), pp. 19-27, 2016. DOI More..


Increasingly, automatic restoration is an indispensable security measure in control systems (e.g. those used in critical infrastructure sectors) due to the importance of ensuring the functionality of monitoring infrastructures. Modernizing the interconnection of control systems to provide interoperability between different networks, at a low cost, is also a critical requirement in control systems. However, automated recovery mechanisms are currently costly, and ensuring interoperability particularly at a low cost remains a topic of scientific challenge. This is the gap we seek to address in this paper. More specifically, we propose a restoration model for interconnected contexts, taking into account the theory of supernode and structural controllability, as well as the recommendations given by the IEC-62351-8 standard (which are mainly based on the implementation of a role-based access control system).

PDF icon 1585.pdf (2.17 MB)
D. Nuñez, I. Agudo, and J. Lopez, "Delegated Access for Hadoop Clusters in the Cloud",
IEEE International Conference on Cloud Computing Technology and Science (CloudCom 2014), IEEE, pp. 374-379, 12/2014. DOI More..


Among Big Data technologies, Hadoop stands out for its capacity to store and process large-scale datasets. However, although Hadoop was not designed with security in mind, it is widely used by plenty of organizations, some of which have strong data protection requirements. Traditional access control solutions are not enough, and cryptographic solutions must be put in place to protect sensitive information. In this paper, we describe a cryptographically-enforced access control system for Hadoop, based on proxy re-encryption. Our proposed solution fits in well with the outsourcing of Big Data processing to the cloud, since information can be stored in encrypted form in external servers in the cloud and processed only if access has been delegated. Experimental results show that the overhead produced by our solution is manageable, which makes it suitable for some applications.

PDF icon nunez2014delegated.pdf (600.22 KB)
C. Alcaraz, and J. Lopez, "Diagnosis Mechanism for Accurate Monitoring in Critical Infrastructure Protection",
Computer Standards & Interfaces, vol. 36, issue 3, Elsevier, pp. 501-512, 2014. DOI (I.F.: 0.879)More..


 Situational awareness for critical infrastructure protection, such as for energy control systems, has become a topic of interest in recent years. Despite attempts to address this area of research, more progress is still necessary to find attractive solutions that help bring about prevention and response at all times from anywhere and at any time. Given this need, we therefore propose in this paper, a smart mechanism able to offer a wide-area situational awareness with the ability to: (i) Control the real state of the observed infrastructure, (ii) respond to emergency situations and (iii) assess the degree of  ccuracy of the entire control system. To address these aspects, the mechanism is based on a hierarchical configuration of industrial sensors for control, the ISA100.11a standard for the prioritization and alarm management, and the F-Measure technique to study the level of accuracy of a sensor inside a neighbourhood. As proof of the functionality and feasibility of the mechanism for critical contexts, a software application implemented in nesC and Java is also presented in this paper.

Impact Factor: 0.879
Journal Citation Reports® Science Edition (Thomson Reuters, 2014)

PDF icon alcaraz2013a.pdf (1.94 MB)
F. Paci, C. Fernandez-Gago, and F. Moyano, "Detecting Insider Threats: a Trust-Aware Framework",
8th International Conference on Availability, Reliability and Security, IEEE, pp. 121-130, Nov 2013. DOI More..


The number of insider threats hitting organizations and big enterprises is rapidly growing. Insider threats occur when trusted employees misuse their permissions on organizational assets. Since insider threats know the organization and its processes, very often they end up undetected. Therefore, there is a pressing need for organizations to adopt preventive mechanisms to defend against insider threats. In this paper, we propose a framework for insiders identification during the early requirement analysis of organizational settings and of its IT systems. The framework supports security engineers in the detection of insider threats and in the prioritization of them based on the risk they represent to the organization. To enable the automatic detection of insider threats, we extend the SI* requirement modeling language with an asset model and a trust model. The asset model allows associating security properties and sensitivity levels to assets. The trust model allows specifying the trust level that a user places in another user with respect to a given permission on an asset. The insider threats identification leverages the trust levels associated with the permissions assigned to users, as well as the sensitivity of the assets to which access is granted. We illustrate the approach based on a patient monitoring scenario.

PDF icon moyano2013ares.pdf (552.98 KB)
R. Carbou, M. Diaz, E. Exposito, and R. Roman, Digital Home Networking , Wiley-ISTE, 2011. More..
R. Bars, J. Gomez, M. Mahdi, C. Alcaraz, and R. Roman, "Digital Home Networking: Standards",
Digital Home Networking, R. Carbou, E. Exposito, R. Roman, and M. Diaz Eds., no. 7130, John Wiley & Sons Inc., pp. 60-96, 2011.
D. G. Rosado, E. Fernandez-Medina, J. Lopez, and M. Piattini, "Developing a Secure Mobile Grid System through a UML Extension",
Journal of Universal Computer Science, vol. 16, no. 17, Springer, pp. 2333-2352, Sep 2010. DOI (I.F.: 0.578)More..


The idea of developing software through systematic development processes toimprove software quality is not new. Nevertheless, there are still many information systemssuch as those of Grid Computing which are not developed through methodologies that areadapted to their most differentiating features. A systematic development process for Gridsystems that supports the participation of mobile nodes and incorporates security aspects intothe entire software lifecycle will thus play a significant role in the development of systemsbased on Grid computing. We are creating a development process for the construction ofinformation systems based on Grid Computing, which is highly dependent on mobile devices,in which security plays a highly important role. One of the activities in this process is that ofanalysis which is focused on ensuring that the system’s security and functional requirements areelicited, specified and modelled. In our approach, this activity is driven by use cases andsupported by the reusable repository. This obtains, builds, defines and refines the use cases ofthe secure Mobile Grid systems which represent the functional and non-functional requirementsof this kind of systems. In this paper, we present the proposed development process throughwhich we introduce the main aspects of the UML profile defined for building use case diagramsin the mobile Grid context through which it is possible to represent specific mobile Gridfeatures and security aspects, showing in detail how to build use case diagrams for a real mobile Grid application by using our UML profile, denominated as GridUCSec-Profile.

Impact Factor: 0.578
Journal Citation Reports® Science Edition (Thomson Reuters, 2010)

I. Agudo, "Digital Identity and Identity Management Technologies",
UPGRADE - The European Journal of the Informatics Professional, vol. 2010, CEPIS, pp. 6 - 12, 2010. More..


There are many technologies for identity management available in the form of open specifications, open source tools and commercial applications. Currently, there are some competing standards for identity management. At the beginning SAML was the only viable choice with a higher enough acceptance level. Recently, another technology called WS-Federation has also gain some attention from the community. Although this technology is not as mature as SAML, it modular design gives it some advantages over SAML. It this work we mainly focus on the WS-Federation and the family of specifications that surround it.

PDF icon 1589.pdf (319.75 KB)
I. Agudo, J. A. Onieva, and D. Merida, "Distribución segura de componentes software basada en OpenID",
XI Reunión Española sobre Criptología y Seguridad de la Información (RECSI 2010), September, 2010. More..


En la actualidad, cada vez son más frecuentes los ataques software mediante la utilización de malware o sustitución de programas (o componentes) en los repositorios a los cuales los usuarios finales (o máquinas) acceden. Esta situación se ve de alguna manera acentuada con el dinamismo existente en la programación y ejecución de estos componentes, en la que distintos desarrolladores pueden participar para desplegar un determinado servicio o parte de él. Por ello, en este artículo se presenta una solución para la distribución de código de forma segura usando OpenID y firmas con certificados de clave pública de corta duración. De esta forma, se consigue un compromiso de seguridad que permite distribuir código firmado sin la necesidad de que los desarrolladores dispongan a priori de un certificado específico. Presentamos además algunos detalles acerca de la implementación realizada para hacer realidad este diseño.

PDF icon Agudo2010.pdf (932.46 KB)
R. Roman, J. Lopez, and C. Alcaraz, "Do Wireless Sensor Networks Need to be Completely Integrated into the Internet?",
3rd CompanionAble Workshop - Future Internet of People, Things and Services (IoPTS) eco-Systems, xxxx, pp. xxxx, December, 2009. More..


Wireless sensor networks are considered as an integral part of the Internet of Things paradigm. Not only they provide a virtual presence to elements of the real world, but also allow any computationalsystem to know about the physical state of those elements thanks to the use of embedded sensors. In order to belong to the Internet of Things, the elements of a sensor network can implement Internet protocols and services such as the TCP/IP stack and web services. Still, a question that must be raised at this point of time is whether all sensor network applications should be completely integrated into the Internet or not. The purpose of this paper is to analyze this question, reviewing the challenges and security requirements of Internet-enabled sensor networks.

PDF icon roman2009.pdf (106.88 KB)
I. Agudo, C. Fernandez-Gago, and J. Lopez, "Delegating Privileges over Finite Resources: A Quota Based Delegation Approach",
5th International Workshop on Formal Aspects in Security and Trust (FAST’08), LNCS 5491, Springer, pp. 302-315, 2008. DOI More..


When delegation in real world scenarios is considered, the delegator (the entity that posses the privileges) usually passes the privileges on to the delegatee (the entity that receives the privileges) in such a way that the former looses these privileges while the delegation is effective. If we think of a physical key that opens a door, the privilege being delegated by the owner of the key is opening the door. Once the owner of the key delegates this privilege to another entity, by handing over the key, he is not able to open the door any longer. This is due to the fact that the key is not copied and handed over but handed over to the delegatee. When delegation takes place in the electronic world, the delegator usually retains also the privileges. Thus, both users have them simultaneously. This situation, which in most cases is not a problem, may be undesirable when dealing with certain kind of resources. In particular, if we think of finite resources, those in which the number of users accessing simultaneously is finite, we can not allow that a user delegating his access privilege is also granted access when the delegation if effective. In this paper we propose an approach where each user is delegated an access quota for a resource. If further delegating of the delegated quota occurs, this is subtracted from his quota. That is, when delegating, part of the quota remains with the delegator and another part goes to the delegatee. This allows a more fairly access to the resource. Moreover, we show that this approach can also be applied to any kind of resources by defining appropriate authorization policies.

PDF icon Agudo2008.pdf (304.18 KB)
J. Lopez, I. Agudo, and J. A. Montenegro, "On the deployment of a real scalable delegation service",
Information Security Technical Report, vol. 12, no. 3, Elsevier, pp. 139-147, Jun 2007. DOI More..


      This paper explains the evolution of the concept of delegation since its first references in the context of distributed authorization to the actual use as a fundamental part of a privilege management architecture. The work reviews some of the earliest contributions that pointed out the relevance of delegation when dealing with distributed authorization, in particular we comment on PolicyMaker and Keynote, and also on SDSI/SPKI. Then, we elaborate on Federation as a particular case of delegation, and remark the importance given to federation by the industry. Finally, the paper discusses about privilege management infrastructures, introducing a new mechanism to extend their functionality using advanced delegation services.

PDF icon JavierLopez2007.pdf (366.06 KB)
I. Agudo, J. Lopez, J. A. Montenegro, E. Okamoto, and E. Dawson, "Delegation Perspective of Practical Authorization Schemes",
Fifth International Network Conference (INC’05), pp. 157-164, 2005. More..
PDF icon IsaacAgudo2005a.pdf (64.72 KB)
J. A. Montenegro, J. Lopez, and F. Moya, "Diseño e Implementación del Marco de Trabajo de Certificado de Atributos X509 para la Delegación de Privilegios",
VIII Reunión Española sobre Criptología y Seguridad de la información (VIII RECSI),Madrid, pp. 571-581, Septiembre, 2004. More..


Este trabajo muestra los detalles de una implementacion prototipo del marco de trabajo de Certificados de Atributos X.509 (Xac), propuesto por la recomendacion ITU-T. La implementacion utiliza como base de la plataforma la librer

PDF icon JoseA.Montenegro2004.pdf (177.35 KB)
J. Lopez, J. A. Montenegro, R. Roman, and J. Davila, "Design of a VPN Software Solution Integrating TCP and UDP Services",
International Conference on Infrastructure Security (InfraSec’02), LNCS 2437, Springer-Verlag, pp. 325-337, October, 2002. More..


The main aims of Virtual Private Network (VPN) are to isolate a distributed network from outsiders, as well as to protect the confidentiality and integrity of sensitive information traversing a non-trusted network such as the Internet. However, some problems arise when security is considered as the unique problem because VPN users suffer from restrictions in their access to the network. They are not free to use traditional Internet services such as electronic mail exchange with non-VPN users, and to access Web and FTP servers external to the organization. This paper presents a new solution that allows the open use of traditional network services running over TCP and UDP layers, while maintaining strong security features. The new scheme works at the TCP/IP transport layer and does not require the addition of new hardware because it is a totally software solution. As a consequence, the application is totally portable. Moreover, and because of its implementation at the transport layer, there is no need to modify any traditional communication applications previously installed in the network system.

PDF icon JavierLopez2002c.pdf (126.07 KB)
J. Lopez, A. Mana, J. A. Montenegro, J. J. Ortega, and J. M. Troya, "Designing Software Tools for the Use of Secure Electronic Forms",
3rd ACIS Int. Conf. on Software Engineering, Artificial Intelligence Networking and Parallel/Distributed Computing (SNPD’02), pp. 157-163, Junio, 2002. More..


Interaction of organizations and their clients by using the Internet can produce meaningful benefits in the accessibility, efficiency and availability of documents, regardless of time and location. However, some types of problems hinder a higher degree of communication. This paper presents some of the results of a Research Project that focuses on the influence of typical open networks risks in electronic interactions and on the need of creating software tools to manage electronic versions of the paper-based forms, as this is the traditional way of interaction through the Web.

PDF icon JavierLopez2002f.pdf (257.49 KB)
J. Davila, J. Lopez, A. Mana, J. J. Ortega, and J. maria troya, "Development of Secure Internet Applications for Governmental Environments",
IEEE International Workshop on Electronic Government (in DEXA’00), IEEE Press, pp. 362-365, 2000.
J. Davila, J. Lopez, and F. Rosello, "Diseño de Protocolos de No-Repudio",
Revista SIC: Seguridad en Informática y Comunicaciones, vol. 38, pp. 1-5, 2000.
J. Lopez, A. Mana, J. J. Ortega, and J. M. Troya, "Distributed Storage and Revocation in Digital Certificate Databases",
11th International Conference on Database and Expert Systems Applications (DEXA’00), LNCS 1873, Springer, pp. 929-938, September, 2000. More..


Public-key cryptography is fast becoming the foundation for those applications that require security and authentication in open networks. But the widespread use of a global public-key cryptosystem requires that public-key certificates are always available and up-to-date. Problems associated to digital certificates management, like storage, retrieval, maintenance, and, specially, revocation, require special procedures that ensure reliable features because of the critical significance of inaccuracies. Most of the existing systems use a Certificate Revocation List, a repository of certificates that have been revoked before their expiration date. The need to access CRLs in order to check certificate revocations becomes a performance handicap. Furthermore, they introduce a source of vulnerability in the whole security infrastructure, as it is impossible to produce a new CRL each time a revocation takes place. This paper introduces an alternative for the storage of digital certificates that avoids the use of CRLs. The system is designed to provide a distributed management of digital certificates by using Certification Authorities that, while being part of a whole Public-Key Infrastructure, operate over local certificates databases. Communication protocols between local databases have been designed to minimize network traffic without a lack of security and efficiency.

PDF icon JavierLopez2000a.pdf (205.62 KB)
F. Lopez, J. Lopez, A. Vergara, and L. Pino, "Determination of Objects Orientation in Assembly Lines using Neural Networks",
5th Intern. Conf. on Computer Aided Systems Theory and Technology (EUROCAST’97), pp. 183-189, February, 1997. More..


This paper is a first approach to the use of artificial neural networks as a tool to estimate the orientation of an object, and is mainly directed towards industrial applications. The capability of neural networks to generalise is a key element in the calculation of an object’s orientation. In this sense, a neural network can identify the angle of a part never seen before. To evaluate the efficiency of this method we have performed a series of tests with the different parts used in a car assembly line.

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