@inproceedings {2033, title = {CCBHash (Compound Code Block Hash) para An{\'a}lisis de Malware}, booktitle = {XVII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n}, year = {2022}, month = {11/2022}, pages = {168-173}, author = {Pablo P{\'e}rez Jim{\'e}nez and Jose A. Onieva and Gerardo Fernandez} } @inproceedings {1978, title = {Comunicaciones VoIP cifradas usando Intel SGX}, booktitle = {V Jornadas Nacionales de Investigaci{\'o}n en Ciberseguridad (JNIC)}, year = {2019}, month = {06/2019}, abstract = {

Cada d{\'\i}a es m{\'a}s frecuente encontrar servicios en internet gestionados desde plataformas online y con la expansi{\'o}n de la tecnolog{\'\i}a IoT, los smartphones, las smartTV\ y otros tantos dispositivos: la autenticaci{\'o}n, la distribuci{\'o}n y al fin y al cabo, la comunicaci{\'o}n entre extremos puede verse seriamente comprometida si dicha plataforma es atacada. La inclusi{\'o}n de nuevas medidas de seguridad en este tipo de ecosistemas requiere de un cambios sustancial de la arquitectura subyacente en muchos casos, por lo que su avance es lento.\ 
En este trabajo se trata de forma concreta el desarrollo de una alternativa OpenSource\ a uno de estos servicios, la telefon{\'\i}a IP (VoIP), que esta expandi{\'e}ndose cada d{\'\i}a m{\'a}s, empezando por redes locales y privadas y llegando a grandes centralitas de conmutaci{\'o}n de tele operadoras, consiguiendo as{\'\i} una transmisi{\'o}n de voz segura extremo a extremo transparente para los servidores VoIP, que no requiera modificar la infraestructura subyacente.

}, author = {Ra{\'u}l Oca{\~n}a and Isaac Agudo} } @inproceedings {rios2018mob, title = {Location Proximity Attacks against Mobile Targets: Analytical Bounds and Attacker Strategies}, booktitle = {23rd European Symposium on Research in Computer Security (ESORICS 2018)}, series = {LNCS}, volume = {11099}, year = {2018}, pages = {373-392}, publisher = {Springer}, organization = {Springer}, address = {Barcelona}, abstract = {

Location privacy has mostly focused on scenarios where users remain static. However, investigating scenarios where the victims present a particular mobility pattern is more realistic. In this paper, we consider abstract attacks on services that provide location information on other users in the proximity. In that setting, we quantify the required effort of the attacker to localize a particular mobile victim. We prove upper and lower bounds for the effort of an optimal attacker. We experimentally show that a Linear Jump Strategy\ (LJS) practically achieves the upper bounds for almost uniform initial distributions of victims. To improve performance for less uniform distributions known to the attacker, we propose a Greedy Updating Attack Strategy\ (GUAS). Finally, we derive a realistic mobility model from a real-world dataset and discuss the performance of our strategies in that setting.

}, isbn = {978-3-319-98988-4}, doi = {10.1007/978-3-319-98989-1}, author = {Xueou Wang and Xiaolu Hou and Ruben Rios and Per Hallgren and Nils Ole Tippenhauer and Martin Ochoa} } @inproceedings {Ruben2017smog, title = {From Smog to Fog: A Security Perspective}, booktitle = {2nd IEEE International Conference on Fog and Edge Mobile Computing (FMEC 2017)}, year = {2017}, month = {06/2017}, pages = {56-61}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, address = {Valencia, Spain. 8-11 May 2017}, abstract = {

Cloud computing has some major limitations that hinder its application to some specific scenarios (e.g., Industrial IoT, and remote surgery) where there are particularly stringent requirements, such as extremely low latency. Fog computing is a specialization of the Cloud that promises to overcome the aforementioned limitations by bringing the Cloud closer to end-users. Despite its potential benefits, Fog Computing is still a developing paradigm which demands further research, especially on security and privacy aspects. This is precisely the focus of this paper: to make evident the urgent need for security mechanisms in Fog computing, as well as to present a research strategy with the necessary steps and processes that are being undertaken within the scope of the SMOG project, in order to enable a trustworthy and resilient Fog ecosystem.

}, isbn = {978-1-5386-2859-1}, doi = {10.1109/FMEC.2017.7946408}, author = {Ruben Rios and Rodrigo Roman and Jose A. Onieva and Javier Lopez} } @inproceedings {onieva2014, title = {An{\'a}lisis y Desarrollo de un Canal Encubierto en una Red de Sensores}, booktitle = { XIII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (RECSI 2014)}, year = {2014}, month = {09/2014}, pages = {333-338}, publisher = {Universidad de Alicante}, organization = {Universidad de Alicante}, address = {Alicante, Spain}, abstract = {

Continuamente aparecen nuevos estudios as{\'\i} como nuevos desarrollos de canales encubiertos. Como veremos, existen m{\'a}s de cien dise{\~n}os distintos para redes de ordenadores, pero no hemos encontrado en la literatura ning{\'u}n an{\'a}lisis, dise{\~n}o e implementaci{\'o}n de canales encubiertos sobre redes de sensores. En este art{\'\i}culo presentamos los resultados del dise{\~n}o e implementaci{\'o}n de un canal multitasa basado en los tiempos de monitorizaci{\'o}n sobre una red de sensores. En este proceso se han establecido las principales propiedades necesarias y, en base a ellas, se desarrolla e implementa el canal encubierto. Se describe el proceso de desarrollo y se analiza su detectabilidad.

}, keywords = {Covert channels, Information Security, Information Warfare, Intrusion Detection, Network Security, Wireless Sensor Network}, isbn = {978-84-9717-323-0}, author = {Jose A. Onieva and Ruben Rios and Bernardo Palenciano} } @inproceedings {rios2013b, title = {Ocultaci{\'o}n de la estaci{\'o}n base en redes inal{\'a}mbricas de sensores}, booktitle = {XI Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL 2013)}, year = {2013}, month = {Oct 2013}, pages = {481-486}, publisher = {Asociaci{\'o}n de Telem{\'a}tica}, organization = {Asociaci{\'o}n de Telem{\'a}tica}, address = {Granada}, abstract = {

La estaci{\'o}n base es el elemento m{\'a}s importante en un red de sensores y, por tanto, es necesario evitar que un atacante pueda hacerse con el control de este valioso dispositivo. Para ello, el atacante puede valerse tanto de t{\'e}cnicas de an{\'a}lisis de tr{\'a}fico como de la captura de nodos. En este trabajo presentamos un esquema que consta de dos fases, la primera est{\'a} dedicada a homogeneizar los patrones de tr{\'a}fico y la segunda encargada de perturbar las tablas de rutas de los nodos. Ambas fases permiten mantener a la estaci{\'o}n base fuera del alcance del atacante con un coste computacional insignificante y un consumo energ{\'e}tico moderado. La validez de nuestro esquema ha sido validada anal{\'\i}ticamente y a trav{\'e}s de numerosas simulaciones.

}, isbn = {978-84-616-5597-7}, author = {Ruben Rios and Jorge Cuellar and Javier Lopez}, editor = {Jes{\'u}s E. D{\'\i}az Verdejo and Jorge Navarro Ortiz and Juan J. Ramos Mu{\~n}oz} } @inproceedings {onieva2012, title = {Como proteger la privacidad de los usuarios en Internet. Verificaci{\'o}n an{\'o}nima de la mayor{\'\i}a de edad}, booktitle = {XII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n - RECSI 2012}, year = {2012}, month = {Sep 2012}, pages = {297-302}, publisher = {Mondragon}, organization = {Mondragon}, address = {San Sebastian (Spain)}, isbn = {978-84-615-9933-2}, author = {Jose A. Onieva and Isaac Agudo and Javier Lopez and G. Drapper-Gil and M.F. Hinarejos} } @inproceedings {Rios2012, title = {HIDE_DHCP: Covert Communications Through Network Configuration Messages}, booktitle = {Proceedings of the 27th IFIP TC 11 International Information Security and Privacy Conference (SEC 2012)}, series = {IFIP AICT}, volume = {376}, year = {2012}, month = {June 2012}, pages = {162-173}, publisher = {Springer Boston}, organization = {Springer Boston}, address = {Heraklion, Crete, Greece}, abstract = {

Covert channels are a form of hidden communication that may violate the integrity of systems. Since their birth in multilevel security systems in the early 70{\textquoteright}s they have evolved considerably, such that new solutions have appeared for computer networks mainly due to vague protocols specifications. We analyze a protocol extensively used today, the Dynamic Host Configuration Protocol (DHCP), in search of new forms of covert communication. From this analysis we observe several features that can be effectively exploited for subliminal data transmission. This results in the implementation of HIDE_DHCP, which integrates three covert channels that accommodate to different stealthiness and bandwidth requirements

}, keywords = {Covert channels, Network Security, System Information Security}, isbn = {978-3-642-30435-4}, issn = {1868-4238}, doi = {http://dx.doi.org/10.1007/978-3-642-30436-1_14}, author = {Ruben Rios and Jose A. Onieva and Javier Lopez}, editor = {Dimitris Gritzalis and Steve Furnell and Marianthi Theoharidou} } @inproceedings {Cuellar2012, title = {Indistinguishable Regions in Geographic Privacy}, booktitle = {Proceedings of the 27th Annual ACM Symposium on Applied Computing (SAC 2012)}, year = {2012}, month = {26-30 March 2012}, pages = {1463-1469}, publisher = {ACM}, organization = {ACM}, address = {Riva del Garda (Trento), Italy}, abstract = {

The ubiquity of positioning devices poses a natural security challenge: users want to take advantage of location-related services as well as social sharing of their position but at the same time have security concerns about how much information should be shared about their exact position. This paper discusses different location-privacy problems, their formalization and the novel notion of indistinguishability regions that allows one to proof that a given obfuscation function provides a good trade-off between location sharing and privacy.

}, keywords = {indistinguishability, Location Privacy, obfuscation}, isbn = {978-1-4503-0857-1}, doi = {10.1145/2245276.2232010}, author = {Jorge Cuellar and Martin Ochoa and Ruben Rios}, editor = {Sascha Ossowski and Paola Lecca} } @inproceedings {422, title = {Un protocolo para la firma de contratos en escenarios multi-two-party con atomicidad}, booktitle = {XII Reuni{\'o}n Espa{\~n}ola de Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n}, year = {2012}, month = {09/2012}, pages = {357-362}, abstract = {

Los avances tecnol{\'o}gicos que est{\'a} experimentando el mundo digital (Internet, comunicaciones, etc.) est{\'a}n acercando a consumidores y proveedores. Los proveedores pueden ofrecer sus productos directamente a los consumidores finales, y {\'e}stos son capaces de acceder a los proveedores desde cualquier lugar y en cualquier momento. A la hora de adquirir productos o
servicios, esta facilidad de acceso permite a los consumidores consultar distintas ofertas de diferentes proveedores. Pero en el caso de que el consumidor quiera m{\'u}ltiples productos, como los paquetes tur{\'\i}sticos, formados por vuelos, hoteles, excursiones, etc, los consumidores carecen de herramientas que les permitan realizar la contrataci{\'o}n multi-two-party de manera at{\'o}mica. En
este art{\'\i}culo presentamos un protocolo de firma de contratos multi-two-party con atomicidad que garantiza la equitatividad de todas las partes.

}, author = {Gerard Draper-Gil and Josep L. Ferrer-Gomilla and M.F. Hinarejos and Jose A. Onieva and Javier Lopez} } @inproceedings {Agudo2010, title = {Distribuci{\'o}n segura de componentes software basada en OpenID}, booktitle = {XI Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (RECSI 2010)}, year = {2010}, month = {September}, address = {Tarragona, Spain}, abstract = {

En la actualidad, cada vez son m\ás frecuentes los ataques software mediante la utilizaci\ón de malware o sustituci\ón de programas (o componentes) en los repositorios a los cuales los usuarios finales (o m\áquinas) acceden. Esta situaci\ón se ve de alguna manera acentuada con el dinamismo existente en la programaci\ón y ejecuci\ón de estos componentes, en la que distintos desarrolladores pueden participar para desplegar un determinado servicio o parte de \él. Por ello, en este art\ículo se presenta una soluci\ón para la distribuci\ón de c\ódigo de forma segura usando OpenID y firmas con certificados de clave p\ública de corta duraci\ón. De esta forma, se consigue un compromiso de seguridad que permite distribuir c\ódigo firmado sin la necesidad de que los desarrolladores dispongan a priori de un certificado espec\ífico. Presentamos adem\ás algunos detalles acerca de la implementaci\ón realizada para hacer realidad este dise\ño.

}, isbn = {978-84-693-3304-4}, author = {Isaac Agudo and Jose A. Onieva and Daniel Merida} } @inproceedings {Rios2008, title = {Clasificaci{\'o}n de canales encubiertos. Un nuevo canal: Covert_DHCP}, booktitle = {X Reuni{\'o}n Espa{\~n}ola de Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (RECSI{\textquoteright}08)}, year = {2008}, month = {Sept.}, pages = {325-336}, address = {Salamanca (Spain)}, abstract = {

Los canales encubiertos son una forma de comunicaci\ón oculta que puede vulnerar la integridad de los sistemas. Desde sus inicios en sistemas de seguridad multinivel a principios de los a\ños 70 han evolucionado considerablemente, apareciendo soluciones para redes de computadores debido a la especificaci\ón de algunos protocolos. Por este motivo, se hace un estudio sobre las t\écnicas que se han utilizado para crear los canales, as\í como sobre las distintos obst\áculos que han tratado de mermar su actividad. Asimismo, se presenta una nueva clasificaci\ón que trata de albergar la mayor cantidad de canales encubiertos existentes en la actualidad. Por \último, se analiza un protocolo ampliamente extendido en la actualidad, DHCP, en busca de posibilidades de albergar informaci\ón encubierta. A partir de este an\álisis se implementan distintas versiones de un canal encubierto haciendo uso de este protocolo.

}, keywords = {Canales encubiertos, control de accesos y detecci{\'o}n de intrusos, seguridad en redes, seguridad en sistemas de informaci{\'o}n}, isbn = {978-84-691-5158-7}, author = {Ruben Rios and Jose A. Onieva}, editor = {Luis Hern{\'a}ndez Encinas and Angel Martin del Rey} } @inproceedings {MildreyCarbonell2007a, title = {Estimation of TTP Features in Non-repudiation Service}, booktitle = {7th International Conference on Computational Science and Its Applications (ICCSA{\textquoteright}07)}, series = {LNCS}, volume = {4706}, year = {2007}, pages = {549-558}, publisher = {Springer}, organization = {Springer}, abstract = {In order to achieve a high performance in a real implementation of the non-repudiation service it is necessary to estimate timeouts, TTP features, publication key time, number of originators and recipients, and other relevant parameters. An initial work of the authors focused on a basic event-oriented simulation model for the estimation of timeouts. In the actual work, we present a set of extensions to that basic model for the estimation of the TTP features (storage capacity and ftp connection capacity). We present and analyze the new and valuable results obtained.}, author = {Mildrey Carbonell and Jose Maria Sierra and Jose A. Onieva and Javier Lopez and Jianying Zhou} } @inproceedings {M.MagdalenaPayerasCapella2007, title = {Incompatibilidades entre Propiedades de los Protocolos de Intercambio Equitativo de Valores}, booktitle = {VI Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL{\textquoteright}07)}, year = {2007}, pages = {605-608}, publisher = {Universidad de Malaga}, organization = {Universidad de Malaga}, abstract = {

Sets of ideal properties are defined for different kinds of protocols designed for e-commerce applications. These sets are used as a start point in the design and then as a tool to evaluate the quality of the protocols. This is the case of fair exchange protocols and their application to electronic contract signing and certified electronic mail. However, in this area does not exist an agreement about which properties are ideal. Instead we can find properties described by different authors to his convenience. We illustrate the contradictions that appear between some of these properties.

}, author = {Magdalena Payeras and Josep L. Ferrer Gomila and Lloren Huguet Rotger and Jose A. Onieva} } @inproceedings {JoseA.Onieva2006a, title = {Extension de una plataforma DRM basada en OMA con servicios de No Repudio}, booktitle = {IX Reunion Espa{\~n}ola sobre Criptologia y Seguridad de la Informacion (RECSI{\textquoteright}06)}, year = {2006}, pages = {129-141}, publisher = {UOC S.L.}, organization = {UOC S.L.}, abstract = {

Digital Rights Management (DRM) es un t\érmino general para cualesquiera de las soluciones que permite a un vendedor de contenido en forma electr\ónica controlar el material y restringir su uso de distintas maneras. Estas soluciones son posibles, por un lado gracias a t\écnicas de la Seguridad de la Informaci\ón, principalmente cifrado de datos, y por otro a la distribuci\ón, de manera independiente, de contenido y derechos digitales. Esto permite que los consumidores puedan acceder libremente al contenido, pero s\ólo aquellos que adquieran el derecho digital apropiado (RO) podr\án procesarlo. Como servicio de seguridad considerado en diversas capas del marco de seguridad definido por la recomendaci\ón ITU X.805, casi todas las aplicaciones necesitan considerar la propiedad de no repudio en las etapas iniciales de su dise\ño. Desafortunadamente, esto no ha sido as\í en general, y m\ás concretamente en especificaciones DRM; debido a consideraciones en la pr\áctica y al tipo de contenido a distribuir. Analizamos este servicio para un marco de DRM y proporcionamos una soluci\ón que permita que la adquisici\ón de derechos digitales sea un operaci\ón que no pueda repudiarse.

}, keywords = {aplicaciones moviles, comercio electronico seguro, digital rights management, no repudio}, author = {Jose A. Onieva and Javier Lopez and Rodrigo Roman and Jianying Zhou} } @inproceedings {JianyingZhou2006, title = {A Synchronous Multi-Party Contract Signing Protocol Improving Lower Bound of Steps}, booktitle = {21st International Information Security Conference (IFIP SEC{\textquoteright}06)}, series = {LNCS}, number = {201}, year = {2006}, month = {May}, pages = {221-232}, publisher = {Springer}, organization = {Springer}, abstract = {

Contract signing is a fundamental service in doing business. The Internet has facilitated the electronic commerce, and it is necessary to find appropriate mechanisms for contract signing in the digital world. A number of two-party contract signing protocols have been proposed with various features. Nevertheless, in some applications, a contract may need to be signed by multiple parties. Less research has been done on multi-party contract signing. In this paper, we propose a new synchronous multi-party contract signing protocol that, with n parties, it reaches a lower bound of 3(n \− 1) steps in the all-honest case and 4n \− 2 steps in the worst case (i.e., all parties contact the trusted third party). This is so far the most efficient synchronous multi-party contract signing protocol in terms of the number of messages required. We further consider the additional features like timeliness and abuse-freeness in the improved version.

}, author = {Jianying Zhou and Jose A. Onieva and Javier Lopez} } @inproceedings {Onieva2005a, title = {Attacking an asynchronous multi-party contract signing protocol}, booktitle = {Proceedings of 6th International Conference on Cryptology in India}, series = {LNCS}, volume = {3797}, year = {2005}, month = {Decemeber}, pages = {311{\textendash}321}, publisher = {Springer}, organization = {Springer}, abstract = {

Contract signing is a fundamental service in doing business. The Internet has facilitated the electronic commerce, and it is necessary to find appropriate mechanisms for contract signing in the digital world. From a designing point of view, digital contract signing is a particular form of electronic fair exchange. Protocols for generic exchange of digital signatures exist. There are also specific protocols for two-party contract signing. Nevertheless, in some applications, a contract may need to be signed by multiple parties. Less research has been done on multi-party contract signing. In this paper, we analyze an optimistic N-party contract signing protocol, and point out its security problem, thus demonstrating further work needs to be done on the design and analysis of secure and optimistic multi-party contract signing protocols.

}, keywords = {multi-party contract signing, Secure electronic commerce, security protocol analysis}, author = {Jose A. Onieva and Jianying Zhou and Javier Lopez} } @inproceedings {JavierLopez2005a, title = {Classifying Public Key Certificates}, booktitle = {2nd European PKI Workshop: Research and Applications (EuroPKI{\textquoteright}05)}, series = {LNCS}, volume = {3545}, year = {2005}, month = {June}, pages = {135-143}, publisher = {Springer}, organization = {Springer}, address = {Canterbury, U.K.}, abstract = {

In spite of the fact that there are several companies that (try to) sell public key certificates, there is still no unified or standardized classification scheme that can be used to compare and put into perspective the various offerings. In this paper, we try to start filling this gap and propose a four-dimensional scheme that can be used to uniformly describe and classify public key certificates. The scheme distinguishes between (i) who owns a certificate, (ii) how the certificate owner is registered, (iii) on what medium the certificate (or the private key, respectively) is stored, and (iv) what type of functionality the certificate is intended to be used for. We think that using these or similar criteria to define and come up with unified or even standardized classes of public key certificate is useful and urgently needed in practice.

}, author = {Javier Lopez and Rolf Oppliger and Guenther Pernul} } @inproceedings {IsaacAgudo2005a, title = {Delegation Perspective of Practical Authorization Schemes}, booktitle = {Fifth International Network Conference (INC{\textquoteright}05)}, year = {2005}, pages = {157-164}, address = {Samos Island, Greece}, isbn = {960-7475-32-1}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro and Eiji Okamoto and Ed Dawson} } @inproceedings {Onieva2005, title = {Extending an OMA-based DRM Framework with Non-Repudiation Services}, booktitle = {5th Symposium on Signal Processing and Information Technology (ISSPIT{\textquoteright}05)}, year = {2005}, pages = {472-477}, publisher = {IEEE}, organization = {IEEE}, abstract = {

Digital Rights Management (DRM) is an umbrella term for any of several arrangements which allows a vendor of content in electronic form to control the material and restrict its usage in various ways that can be specified by the vendor. These arrangements are provided through security techniques, mainly encryption, and the distribution, in a detached manner, of content and rights. This allows free access to the content by the consumers, but only those carrying the proper Right Object (RO) will be able to process such content. As a security service considered in different layers of the security framework defined by ITU X.805, almost all applications need to consider non-repudiation in the very beginning of their design. Unfortunately this has not been done so far in DRM specifications due to practical issues and the type of content distributed. We analyze this service for the a DRM framework and provide a solution which allows the right objects acquisition to be undeniable.

}, keywords = {digital rights management, Mobile applications, Non-repudiation, Secure electronic commerce}, author = {Jose A. Onieva and Jianying Zhou and Javier Lopez and Rodrigo Roman} } @inproceedings {MildreyCarbonell2005, title = {Modelo de Simulacion para la Estimacion de Parametros en los protocolos de no Repudio}, booktitle = {III Simposio Espa{\~n}ol de Comercio Electronico (SCE{\textquoteright}05)}, year = {2005}, pages = {151-164}, publisher = {Universitat de les Illes Balears}, organization = {Universitat de les Illes Balears}, abstract = {

El no repudio es un requisito de seguridad cuya importancia se ha hecho evidente con el crecimiento del comercio electr\ónico. Muchos protocolos se han desarrollado como soluci\ón a este requisito. La gran mayor\ía incluye en su especificaci\ón par\ámetros cuyos valores no son f\áciles de especificar pues dependen de las condiciones reales de implementaci\ón del mismo como los tiempos l\ímites, las caracter\ísticas de la TTP, tiempo de publicaci\ón de las claves, etc. En este trabajo proponemos un modelo que nos ayudar\á en la estimaci\ón de esos par\ámetros basado en la simulaci\ón del escenario real. Para la explicaci\ón y prueba del modelo mostramos un conjunto de experimentos.

}, author = {Mildrey Carbonell and Jose A. Onieva and Javier Lopez and Jianying Zhou} } @inproceedings {1716, title = {A Novel Method To Maintain Privacy in Mobile Agent Applications}, booktitle = {Fourth International Conference on Cryptology and Network Security (CANS{\textasciiacute}05)}, series = {LNCS}, volume = {3810}, year = {2005}, pages = {247-260}, publisher = {Springer}, organization = {Springer}, isbn = {978-3-540-30849-2}, author = {K. Peng and Ed Dawson and J Gonzalez-Nieto and Eiji Okamoto and J. Lopez} } @inproceedings {AntonioMunoz2005a, title = {Perfiles Seguros para Comercio Movil}, booktitle = {III Simposio Espa{\~n}ol de Comercio Electronico (SCE{\textquoteright}05)}, year = {2005}, pages = {235-244}, publisher = {Universitat de les Illes Balears}, organization = {Universitat de les Illes Balears}, abstract = {

Los escenarios de comercio m{\'o}vil existentes en la actualidad presentan muchas deficiencias. La mayor{\'\i}a de estos escenarios, como no podr{\'\i}a ser de otra forma, tienen en cuenta aspectos relativos a la seguridad, prestando especial atenci{\'o}n a las propiedades de Autenticaci{\'o}n y Autorizaci{\'o}n. De entre los elementos esenciales que se utilizan para proporcionar estos servicios de seguridad, los perfiles son un elemento com{\'u}n que permiten la personalizaci{\'o}n de los servicios del usuario m{\'o}vil. Sin embargo, los perfiles tambi{\'e}n precisan de una administraci{\'o}n segura. En este trabajo presentamos unas consideraciones iniciales respecto a los distintos tipos de perfiles, sus niveles de seguridad para cada tipo, as{\'\i} como indicaciones para el almacenamiento de manera segura. Por lo tanto, analizaremos las distintas alternativas como medio de almacenamiento, discuti{\'e}ndolas y prestando especial atenci{\'o}n a las tarjetas inteligentes.

}, author = {Mu{\~n}oz, Antonio and Jose A. Onieva and Javier Lopez} } @inproceedings {Roman2005d, title = {Protection Against Spam using Pre-Challenges}, booktitle = {20th IFIP International Information Security Conference (IFIP-SEC{\textquoteright}05)}, year = {2005}, month = {May}, pages = {281-294}, publisher = {Springer}, organization = {Springer}, address = {Chiba (Japan)}, abstract = {

Spam turns out to be an increasingly serious problem to email users. A number of anti-spam schemes have been proposed and deployed, but the problem has yet been well addressed. One of those schemes is challenge-response, in which a challenge is imposed on an email sender. However, such a scheme introduces new problems for the users, e.g., delay of service and denial of service attacks. In this paper, we introduce a pre-challenge scheme that avoids those problems. It assumes each user has a challenge that is defined by the user himself/herself and associated with his/her email address, in such a way that an email sender can simultaneously retrieve a new receiver{\textquoteright}s email address and challenge before sending an email in the first contact. Some new mechanisms are employed to reach a good balance between security against spam and convenience to email users.

}, isbn = {0-387-25658-X}, author = {Rodrigo Roman and Jianying Zhou and Javier Lopez}, editor = {Ry{\^o}ichi Sasaki and Sihan Qing and Eiji Okamoto and Hiroshi Yoshiura} } @inproceedings {AntonioMunoz2005, title = {On Secure Profiling}, booktitle = {1st International Workshop on Secure Ubiquitous Networks (SUN{\textquoteright}05)}, year = {2005}, month = {August}, pages = {214-218}, publisher = {IEEE Press}, organization = {IEEE Press}, abstract = {

Ubiquitous environments have several drawbacks to be solved. Most of them are focused on security, and relevant ones are authorization and authentication. Amongst the essential elements to adequately provide solutions, we can find profiles. A profile can be defined as a repository to store structured data from users, networks, devices, applications, etc. As profiles are needed in ubiquitous environments, and these need of secure management as well, in this paper, we provide some initial guidance on the security storage of profiles and on security levels needed for each type of profile. Additionally, we review different alternatives to bear profiles, concluding that smartcards are the most suitable devices.

}, author = {Mu{\~n}oz, Antonio and Jose A. Onieva and Javier Lopez} } @inproceedings {JianyingZhou2004, title = {Analysis of a Free Roaming Agent Result-Truncation Defense Scheme}, booktitle = {6th Conference on E-Commerce (CEC{\textquoteright}04)}, year = {2004}, month = {June}, pages = {221-226}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, abstract = {

Mobile agents play an important role in electronic commerce. Security in free-roaming agents is especially hard to achieve when the mobile code is executed in hosts that may behave maliciously. Some schemes have been proposed to protect agent data (or computation results). However, a known vulnerability of these techniques is the truncation attack where two visited hosts (or one revisited host) can collude to discard the partial results collected between their respective visits. Cheng and Wei proposed a scheme in ICICS{\textquoteright}02 to defense against the truncation of computation results of free-roaming agents. Cheng-Wei scheme is effective against such an attack in most cases. However, we demonstrate that it still suffers from the truncation attack when a special loop is established on the path of a free-roaming agent. We further propose two amendments to Cheng-Wei scheme to avoid such an attack.

}, author = {Jianying Zhou and Jose A. Onieva and Javier Lopez} } @inproceedings {Onieva2004b, title = {Enhancing Certified Email Service for Timeliness and Multicast}, booktitle = {Fourth International Network Conference}, year = {2004}, pages = {327-335}, publisher = {University of Plymouth}, organization = {University of Plymouth}, abstract = {

Certified email is a value-added service of ordinary email, in which a sender wants to obtain a receipt from a recipient. Fair exchange protocols are a key component for certified email service to ensure fairness, i.e., the items held by two parties are exchanged without one party obtaining an advantage. We can find in the literature simple and fast optimistic protocols for fair electronic exchange and, more specifically, for certified electronic mail (CEM) and electronic contract signing (ECS). We have observed that some aspects of those protocols could be substantially improved. This paper presents two major contributions. Firstly, we provide a solution that allows both parties to end the protocol timely in an asynchronous way. Then, we extend the certified email service to the multicast scenario.

}, keywords = {Asynchronous timeliness, Certified Email, fair exchange, Multiparty protocol}, author = {Jose A. Onieva and Jianying Zhou and Javier Lopez} } @inproceedings {1735, title = {Especificaci{\'o}n formal y verificaci{\'o}n de requisitos de Seguridad}, booktitle = {VIII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (VIII RECSI)}, year = {2004}, month = {Sep 2004}, pages = {225-235}, address = {Madrid (Spain)}, isbn = {84-7978-650-7}, author = {Isaac Agudo and Javier Lopez and Juan J. Ortega} } @inproceedings {JoseA.Onieva2004d, title = {Mejorando Servicios de Correo Electronico Certificado con Prontitud Temporal y Multicasting}, booktitle = {VIII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la informaci{\'o}n (RECSI{\textquoteright}04). Avances en Criptologia y Seguridad de la Informacion}, year = {2004}, pages = {537-546}, publisher = {Diaz de Santos}, organization = {Diaz de Santos}, abstract = {

El correo electr\ónico certificado es un servicio a\ñadido al correo electr\ónico est\ándar, en el cual el remitente desea obtener un recibo procedente del destinatario. Para este servicio, encontramos que los protocolos de intercambio (justo) son un componente principal para asegurar la correcci\ón en la ejecuci\ón de los servicios de correo electr\ónico certificado, ya que los \ítems que ambas partes presentan (en este caso espec\ífico, el mensaje de correo y el recibo del mismo) deben ser intercambiados sin que ninguna de las partes obtenga una ventaja durante el proceso sobre la otra. Podemos encontrar en esta l\ínea de investigaci\ón protocolos optimistas eficientes para el intercambio electr\ónico, y mas concretamente para Correo Electr\ónico Certificado (CEC) y Firma Electr\ónica de Contratos (FEC). Realizando un estudio adecuado hemos observado que algunos aspectos de dichos protocolos podr\ían ser mejorados. En este art\ículo proponemos una soluci\ón que permite a ambas entidades terminar el protocolo de forma as\íncrona. Tambi\én extendemos el protocolo a m\últiples usuarios.

}, author = {Jose A. Onieva and Javier Lopez and Jianying Zhou} } @inproceedings {Zhou2004, title = {Protecting Free Roaming Agents against Result-Truncation Attack}, booktitle = {60th IEEE Vehicular Technology Conference (VTC{\textquoteright}04)}, year = {2004}, pages = {3271-3274}, publisher = {IEEE Vehicular Technology Society Press}, organization = {IEEE Vehicular Technology Society Press}, abstract = {

Mobile agents are especially useful in electronic commerce, for both wired and wireless environments. Nevertheless, there are still many security issues on mobile agents to be addressed, for example, data confidentiality, non-repudiability, forward privacy, publicly verifiable forward integrity, insertion defense, truncation defense, etc. One of the hardest security problems for free roaming agents is truncation defense where two visited hosts (or one revisited host) can collude to discard the partial results collected between their respective visits. We present a new scheme satisfying those security requirements, especially protecting free roaming agents against result-truncation attack.

}, keywords = {cryptographic protocol, mobile agent, Secure electronic commerce}, author = {Jianying Zhou and Jose A. Onieva and Javier Lopez} } @inproceedings {JavierLopez2004a, title = {On a Taxonomy of Systems for Authentication and/or Authorization Services}, booktitle = {TERENA Networking Conference}, year = {2004}, month = {June}, address = {Rhodes, Greece}, abstract = {

In this work we elaborate on a taxonomy of systems that provide either joint solutions for both authentication and authorization problems, or solutions for only one of the problems. Basically, we do not focus our work on theoretical systems that have been proposed only in the literature. On the other hand, we focus on: (i) systems that are already developed; (ii) systems that are under development or deployment; and (iii) systems that are still in the initial stages of design but are supported by international working groups or bodies. More precisely, we elaborate on a taxonomy of systems that are (or will be soon) available to final users.

}, author = {Javier Lopez and Jose A. Montenegro and Rolf Oppliger and Guenther Pernul} } @inproceedings {MildreyCarbonell2004, title = {Timeout Estimation using a Simulation Model for Non-repudiation Protocols}, booktitle = {2nd Workshop on Internet Communications Security (WICS{\textquoteright}04), (within Computational Science and its Applications International Conference)}, series = {LNCS}, volume = {3043}, year = {2004}, month = {May}, pages = {903-914}, publisher = {Springer}, organization = {Springer}, abstract = {

An essential issue for the best operation of non-repudiation protocols is to figure out their timeouts. In this paper, we propose a simulation model for this purpose since timeouts depend on specific scenario features such as network speed, TTP characteristics, number of originators and recipients, etc. Based on a one-to-many Markowicth{\textquoteright}s protocol simulation model as a specific example, we have worked out various simulation experiments.

}, author = {Mildrey Carbonell and Jose A. Onieva and Javier Lopez and Deborah Galpert and Jianying Zhou} } @inproceedings {JavierLopez2003b, title = {Applying SDL to Formal Analysis of Security Systems}, booktitle = {11th International SDL Forum (SDL{\textquoteright}03)}, series = {LNCS}, volume = {2708}, year = {2003}, month = {July}, pages = {300-317}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Stuttgart, Germany}, abstract = {

Nowadays, it is widely accepted that critical systems have to be formally analysed in order to achieve well-known formal method benefits. In order to study the security of communication systems, we have developed a methodology for the application of the formal analysis techniques commonly used in communication protocols to the analysis of cryptographic ones. In particular, we have extended the design and analysis phases with security properties. Our proposal uses a specification notation based on MSC, which can be automatically translated into a generic SDL specification. This SDL system can then be used for the analysis of the desired security properties, by using an observer process schema. Apart from our main goal of providing a notation for describing the formal specification of security systems, our proposal also brings additional benefits, such as the study of the possible attacks to the system, and the possibility of re-using the specifications produced to describe and analyse more complex systems.

}, author = {Javier Lopez and Juan J. Ortega and Jose M. Troya} } @inproceedings {EdDawson2003, title = {BAAI: Biometric Authentication and Authorization Infrastructure}, booktitle = {IEEE International Conference on Information Technology (ITRE{\textquoteright}03)}, year = {2003}, pages = {274-278}, publisher = {IEEE}, organization = {IEEE}, abstract = {The combined use of authorization and authentication infrastructures has led to AAIs (authorization and authentication infrastructures). These new infrastructures supply identification and authorization services to a distributed environment There are many possibilities of linkages to get AAIs; one of them is to include the PMI (privilege management infrastructure) as authorization infrastructure and an authentication infrastructure that can be a PKI (public key infrastructure) or kerberos. This symbiosis gives service to applications and servers. However, in physical environments where the physical presence of an individual is required, it is necessary to use biometric systems. This paper describes the development of a solution that combines the relationship between the biometric based systems and the PMIs to finally obtain the biometric AAI.}, isbn = {0780377249}, doi = {10.1109/ITRE.2003.1270620} month={august}, author = {Ed Dawson and Javier Lopez and Jose A. Montenegro and Eiji Okamoto} } @inproceedings {EijiOkamoto2003, title = {Certificate Retrieval and Validation in Online Systems}, booktitle = {Symposium on Cryptography and Information Security (SCIS{\textquoteright}03)}, year = {2003}, month = {January}, pages = {25-30}, address = {Hamamatsu, Japan}, abstract = {

In order to more effectively deal with certificate management issues in PKIs, there is growing interest in supplementing offline X.509 PKI models with online services. An analysis of the security requirements of online models will be presented. Proposed online and delegated processing models will be evaluated in relation to these requirements.

}, author = {Eiji Okamoto and Javier Lopez and Ed Dawson and Juan M. Gonzalez-Nieto and Selwyn Russell and Jason Smith} } @inproceedings {javierlopez2003, title = {High-level Specification of Security Systems}, booktitle = {IEEE Globecom 2003 - Communications Security Track}, year = {2003}, month = {December}, pages = {1506-1510}, publisher = {IEEE Press}, organization = {IEEE Press}, address = {San Francisco}, abstract = {

In order to study the security systems, we have developed a methodology for the application to the analysis of cryptographic protocols of the formal analysis techniques commonly used in communication protocols. In particular, we have extended the design and analysis phases with security properties. Our proposal uses a specification notation based on HMSC/MSC, which can be automatically translated into a generic SDL specification.

}, isbn = {0-7803-7974-8}, author = {Javier Lopez and Juan J. Ortega and Jose M. Troya and Jose L. Vivas} } @inproceedings {javierlopez2003a, title = {How to Specify Security Services: A Practical Approach}, booktitle = {7th IFIP Conference on Multimedia and Communications Security (CMS{\textquoteright}03)}, series = {LNCS}, volume = {2828}, year = {2003}, month = {October}, pages = {158-171}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Torino, Italy}, abstract = {

Security services are essential for ensuring secure communications. Typically no consideration is given to security requirements during the initial stages of system development. Security is only added latter as an afterthought in function of other factors such as the environment into which the system is to be inserted, legal requirements, and other kinds of constraints. In this work we introduce a methodology for the specification of security requirements intended to assist developers in the design, analysis, and implementation phases of protocol development. The methodology consists of an extension of the ITU-T standard requirements language MSC and HMSC, called SRSL, defined as a high level language for the specification of security protocols. In order to illustrate it and evaluate its power, we apply the new methodology to a real world example, the integration of an electronic notary system into a web-based multi-users service platform.

}, isbn = {3-540-20185-8}, author = {Javier Lopez and Juan J. Ortega and Jose M. Troya and Jose L. Vivas} } @inproceedings {Onieva2003b, title = {Intermediary Non-Repudiation Protocols}, booktitle = {5th Conference on Electronic Commerce}, year = {2003}, month = {June}, pages = {207-214}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, abstract = {

n commercial transactions, an intermediary might be involved to help transacting parties to conduct their business. Nevertheless, the intermediary may not be fully trusted. In this paper, we introduce the concept of intermediary (or agent) in a non-repudiation protocol, define the aims of intermediary non-repudiation protocols, and analyze their security requirements. We present a simple scenario with only one recipient, followed by a more complicated framework where multiple recipients are involved and collusion between them is possible.

}, author = {Jose A. Onieva and Jianying Zhou and Mildrey Carbonell and Javier Lopez} } @inproceedings {Onieva2003, title = {A Multi-Party Non-Repudiation Protocol for Exchange of Different Messages}, booktitle = {18th IFIP International Information Security Conference. Security and Privacy in the Age of Uncertainty (IFIP SEC{\textquoteright}03)}, year = {2003}, month = {May}, pages = {37-48}, publisher = {IFIP}, organization = {IFIP}, abstract = {

Non-repudiation is a security service that provides cryptographic evidence to support the settlement of disputes. In this paper, we introduce the state-of-the-art of multi-party non-repudiation protocols, and analyze the previous work where one originator is able to send the same message to many recipients. We propose a new multi-party non-repudiation protocol for sending different messages to many recipients. We also discuss the improvements achieved with respect to the multiple instances of a two-party non-repudiation protocol, and present some applications that would benefit from them.

}, keywords = {fair exchange, group communications, Non-repudiation}, author = {Jose A. Onieva and Jianying Zhou and Mildrey Carbonell and Javier Lopez} } @inproceedings {Onieva2003a, title = {Practical Service Charge for P2P Content Distribution}, booktitle = {Fifth International Conference on Information and Communications Security}, series = {LNCS}, volume = {2836}, year = {2003}, month = {October}, pages = {112 - 123}, publisher = {Springer}, organization = {Springer}, abstract = {

With emerging decentralized technologies, peer-to-peer (P2P) content distribution arises as a new model for storage and transmission of data. In this scenario, one peer can be playing different roles, either as a distributor or as a receiver of digital contents. In order to incentivize the legal distribution of these contents and prevent the network from free riders, we propose a charging model where distributors become merchants and receivers become customers. To help in the advertisement of digital contents and collection of payment details, an intermediary agent is introduced. An underlying P2P payment protocol presented in [1] is applied to this scenario without total trust on the intermediary agent.

}, author = {Jose A. Onieva and Jianying Zhou and Javier Lopez} } @inproceedings {JavierLopez2002f, title = {Designing Software Tools for the Use of Secure Electronic Forms}, booktitle = {3rd ACIS Int. Conf. on Software Engineering, Artificial Intelligence Networking and Parallel/Distributed Computing (SNPD{\textquoteright}02)}, year = {2002}, month = {Junio}, pages = {157-163}, address = {Madrid, Spain)}, abstract = {

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.

}, author = {Javier Lopez and Antonio Mana and Jose A. Montenegro and Juan J. Ortega and Jose M. Troya} } @inproceedings {SelwynRussell2002, title = {Improving Performance in Global PKI using Virtual Certificates and Synthetic Certificates}, booktitle = {Symposium on Cryptography and Information Security (SCIS{\textquoteright}02)}, year = {2002}, month = {January}, pages = {1149-1154}, abstract = {

A digital certificate may be used to inform the world of the public key of its owner. To guard against impersonations and fraud, the receiver needs to perform a series of checks. When a hierarchy of certificates is involved, and when there are large volumes of messages between two parties, as is frequent in commerce, the repeated validation of the same chain of certificates consume significant resources. This paper presents new concepts of virtual certificate and synthetic certificate which can be used to speed up repetitive processing of a chain with improved efficiency.

}, author = {Selwyn Russell and Eiji Okamoto and Ed Dawson and Javier Lopez} } @inproceedings {EdDawson2002, title = {A New Design of Privilege Management Infrastructure (PMIs) for Organizations Using Outsourced PKI}, booktitle = {5th International Conference on Information Security (ISC{\textquoteright}02)}, series = {LNCS}, volume = {2433}, year = {2002}, month = {September}, pages = {136-149}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, abstract = {Authentication services provided by Public Key Infrastructures (PKI) do not satisfy the needs of many e-commerce applications. These applications require additional use of authorization services in order for users to prove what they are allowed to do. Attribute certificates have changed the way in which the authorization problem has been considered until now, and Privilege Management Infrastructures (PMI) provide the necessary support for a wide use of those certificates. Although both types of infrastructures, PKIs and PMIs, keep some kind of relation, they can operate autonomously. This fact is specially interesting for companies who have taken or will take the decision to outsource PKI services. However, outsourcing PMI services is not a good option for many companies because sometimes information contained in attribute certificates is confidential. Therefore attribute certificates must be managed very carefully and, preferably, only inside the company. In this paper we present a new design of PMI that is specially suited for those companies that outsource PKI services but still need to manage the PMI internally. The scheme provides additional advantages that satisfy the needs of intra-company attribute certification, and eliminates some of the problems associated with the revocation procedures.}, isbn = {3540442707}, doi = {10.1007/3-540-45811-5_10}, author = {Ed Dawson and Javier Lopez and Jose A. Montenegro and Eiji Okamoto} } @inproceedings {JavierLopez2002h, title = {Observaciones sobre las t{\'e}cnicas de an{\'a}lisis formal de protocolos de seguridad}, booktitle = {VII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (VII RECSI)}, year = {2002}, month = {Septiembre}, pages = {471-483}, address = {Oviedo, Espa}, abstract = {

La aplicaci\ón de los m\étodos formales para el dise\ño y an\álisis de sistemas cr\íticos est\á ampliamente aceptada en el desarrollo de estos sistemas. Los protocolos de seguridad abordan el objetivo de garantizar servicios y derechos como el de la confidencialidad de los datos personales o el de garantizar la identidad de acceso a un sistema. Por lo tanto, ya que un protocolo de seguridad es un sistema cr\ítico, es necesario utilizar m\étodosformales para su dise\ño y an\álisis. Debido a las caracter\ísticas especiales que presentan este tipo de protocolos, se deben utilizar m\étodos que no son los tradicionales utilizados para los protocolos de comunicaciones, sino que deben utilizarse otros espec\íficos. En este art\ículo vamos a hacer un estudio de las principales propiedades de seguridad que poseen los protocolos criptogr\áficos y de la manera de aplicar los m\étodos formales en su dise\ño y an\álisis.

}, author = {Javier Lopez and Sonia Matamoros and Juan J. Ortega and Jose M. Troya} } @inproceedings {1736, title = {Online Public Key Infrastructure}, booktitle = {VII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (VII RECSI)}, year = {2002}, month = {Sep 2002}, pages = {123-135}, address = {Oviedo (Spain)}, isbn = {84-699-8930-8}, author = {W. Caelli and K. Chen and E. Dawson and M. Henricksen and Javier Lopez and E. Okamoto and S. Russell and J. Smith} } @inproceedings {JavierLopez2002, title = {Protecci{\'o}n de Software basada en Tarjetas Inteligentes}, booktitle = {VII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (VII RECSI)}, year = {2002}, month = {Septiembre}, pages = {485-497}, address = {Oviedo, Espa}, author = {Javier Lopez and Antonio Mana and Juan J. Ortega and Ernesto Pimentel} } @inproceedings {JavierLopez2002b, title = {Protocol Engineering Applied to Formal Analysis of Security Systems}, booktitle = {International Conference on Infrastructure Security (InfraSec{\textquoteright}02)}, series = {LNCS}, volume = {2437}, year = {2002}, month = {October}, pages = {246-259}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Bristol, U.K.}, abstract = {

Every communication system requiring security properties is certainly critical. In order to study the security of communication systems, we have developed a methodology for the application of the formal analysis techniques of communication protocols to the analysis of cryptographic ones. We have extended the design and analysis phases with security properties. Our methodology uses a specification technique based on the HMSC/MSC requirement languages, and translates it into a generic schema for the SDL specification language, which is used for the analysis. Thus, the technique allows the specification of security protocols using a standard formal language and uses Object-Orientation for reusability purposes. The final goal is not only the formal specification of a security system, but to examine the possible attacks, and later use the specification in more complex systems.

}, author = {Javier Lopez and Juan J. Ortega and Jose M. Troya} } @inproceedings {JavierLopez2002g, title = {Towards a Trustful and Flexible Environment for Secure Communications with Public Administrations}, booktitle = {First International Conference on Electronic Government (EGOV{\textquoteright}02)}, series = {LNCS}, volume = {2456}, year = {2002}, month = {September}, pages = {211-214}, publisher = {Springer}, organization = {Springer}, address = {Aix-en-Provence, France)}, abstract = {

Interaction of citizens and private organizations with Public Administrations can produce meaningful benefits in the accessibility, efficiency and availability of documents, regardless of time, location and quantity. Although there are some experiences in the field of e-government there are still some technological and legal difficulties that avoid a higher rate of communications with Public Administrations through Internet, not only from citizens, but also from private companies. We have studied two of the technological problems, the need to work in a trustful environment and the creation of tools to manage electronic versions of the paper-based forms.

}, author = {Javier Lopez and Antonio Mana and Jose A. Montenegro and Juan J. Ortega and Jose M. Troya} } @inproceedings {JavierLopez2002a, title = {Verification of Authentication Protocols using SDL-method}, booktitle = {First International Workshop on Security in Information Systems (SIS{\textquoteright}02)}, year = {2002}, month = {April}, pages = {61-71}, address = {Ciudad Real, Spain}, abstract = {

Authentication between protocol agents is widely studied in the cryptographic protocol analysis area. It is essential in a virtual environment to rely on protocol parties{\textquoteright} identity. In the academic literature there are many protocols that provide the authentication property. We present in this paper a new mechanism to verify authentication using SDL, general purpose specification language. We have defined a generic schema in SDL that allow us to specify a security system and check system behavior when a malicious agent ( the intruder ) is present. We have used the EKE authentication protocol to illustrate how the mechanism works.

}, author = {Javier Lopez and Juan J. Ortega and Jose M. Troya} } @inproceedings {JavierLopez2000, title = {Aspectos de Implementaci{\'o}n de una Infraestructura de Clave P{\'u}blica Distribuida}, booktitle = {Simposio Espa{\~n}ol de Inform{\'a}tica Distribuida (SEID{\textquoteright}00)}, year = {2000}, month = {Septiembre}, pages = {313-320}, address = {Orense, Espa}, abstract = {

La seguridad es uno de los aspectos m\ás conflictivos del uso de Internet. La falta de una pol\ítica de seguridad global est\á frenando el desarrollo de Internet en \áreas tan interesantes y prometedoras como el comercio electr\ónico o la interacci\ón con las administraciones p\úblicas. Las t\écnicas criptogr\áficas actuales proporcionan un alto grado de confidencialidad; no obstante, es dif\ícil garantizar la identificaci\ón segura de los usuarios y, adem\ás, la gesti\ón de las claves de los mismos es poco eficiente y presenta graves problemas de escalabilidad. Este trabajo describe las caracter\ísticas de implementaci\ón de una soluci\ón a ambos problemas basada en una Infraestructura de Clave P\ública (PKI) que proporciona una administraci\ón simple y eficiente de las claves de los usuarios y posibilita la autenticaci\ón segura de los mismos.

}, author = {Javier Lopez and Antonio Mana and Jose A. Montenegro and Juan J. Ortega and Jose M. Troya} } @inproceedings {1721, title = {Development of Secure Internet Applications for Governmental Environments}, booktitle = {IEEE International Workshop on Electronic Government (in DEXA{\textquoteright}00)}, year = {2000}, pages = {362-365}, publisher = {IEEE Press}, organization = {IEEE Press}, isbn = {0-7695-0680-1}, author = {Jorge Davila and Javier Lopez and Antonio Mana and Juan J. Ortega and Jose maria troya} } @inproceedings {JavierLopez2000a, title = {Distributed Storage and Revocation in Digital Certificate Databases}, booktitle = {11th International Conference on Database and Expert Systems Applications (DEXA{\textquoteright}00)}, series = {LNCS}, volume = {1873}, year = {2000}, month = {September}, pages = {929-938}, publisher = {Springer}, organization = {Springer}, address = {London, U.K.}, abstract = {

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.

}, author = {Javier Lopez and Antonio Mana and Juan J. Ortega and Jose M. Troya} } @inproceedings {JavierLopez1999c, title = {Cert{\textquoteright}eM: Certification System Based on Electronic Mail Service Structure}, booktitle = {Secure Networking (CQRE{\textquoteright}99)}, series = {LNCS}, volume = {1740}, year = {1999}, month = {December}, pages = {109-118}, publisher = {Springer}, organization = {Springer}, abstract = {

Public-Key Infrastructures are considered the basis of the protocols and tools needed to guarantee the security demanded for new Internet applications like electronic commerce, government-citizen relationships and digital distribution. This paper introduces a new infrastructure design, Cert{\textquoteright}eM, a key management and certification system that is based on the structure of the electronic mail service and on the principle of near-certification. Cert{\textquoteright}eM provides secure means to identify users and distribute their public-key certificates, enhances the efficiency of revocation procedures, and avoids scalability and synchronization problems. The system, developed and tested at the University of Malaga, was recently selected by RedIRIS, the National Research and Academic Network in Spain, to provide the public key service for its secure electronic mail.

}, author = {Javier Lopez and Antonio Mana and Juan J. Ortega} } @inproceedings {JavierLopez1999a, title = {A Public Key Infrastructure for User Identification}, booktitle = {IFIP Working Conference on User Identification and Privacy Protection}, year = {1999}, month = {June}, pages = {209-227}, address = {Stockholm, Sweden}, abstract = {

While there is wide agreement on the immense potential of Internet, its growth and performance are adversely affected by security issues. Despite its impressive size, scope and reach, the Internet has not yet become a common vehicle for many of these new possibilities. Progress in fields as electronic commerce and government-citizen relationships have been limited by the open design of the network itself. Today, Public-Key Infrastructures are the basis of the protocols and tools needed to guarantee the security demanded in those fields. Trust management and user identification are also important issues that remain unresolved. This paper introduces a key management and user identification system, named Cert\’eM, that is based on the electronic mail service. Cert{\textquoteright}eM provides important advantages over existing Public-Key Infrastructures and user identification proposals.

}, author = {Javier Lopez and Antonio Mana and Juan J. Ortega} } @inproceedings {JavierLopez1999b, title = {An User Authentication Infrastructure for Extranet Applications}, booktitle = {IEEE International Carnahan Conference on Security Technology}, year = {1999}, month = {October}, pages = {354-362}, publisher = {IEEE Press}, organization = {IEEE Press}, address = {Madrid, Spain}, abstract = {

An Extranet is used to connect businesses with their suppliers, customers or other businesses that share common goals in a way that automates their administrative interactions using Internet technology. The security of the communications over Internet is considered an essential feature. To guarantee secure operation the aid of some user authentication infrastructure is needed. This paper introduces a Public Key Infrastructure (PKI) and user identification scheme to be used in extranet applications. The flexibility of the system allows it to fit the usual hierarchical organization structure.

}, author = {Javier Lopez and Antonio Mana and Juan J. Ortega} } @inproceedings {AntonioMana1997, title = {Incremento de la Seguridad del Estandar de Cifrado de Datos basado en la Combinaci{\'o}n de Datos y Clave}, booktitle = {III Jornadas de Inform{\'a}tica y Autom{\'a}tica}, year = {1997}, month = {Julio}, pages = {423-432}, address = {El Puerto de Santa Mar{\'\i}a, Espa}, abstract = {

A pesar del gran esfuerzo investigador llevado a cabo, el ataque al DES ha sido infructuoso desde que a mediados de los setenta fue adoptado como est\ándar por el U. S. National Bureau of Standards. El criptoan\álisis diferencial constituye la base de las primeras t\écnicas capaces de acabar con tal invulnerabilidad. Las t\écnicas de criptoan\álisis basadas en modelos de fallos y su adaptaci\ón a DES, el criptoan\álisis de fallos diferencial, son dos de esas t\écnicas que han conseguido recientemente romper sistemas DES (aunque el ataque est\á limitado a ciertos casos especiales, en particular implementaciones hardware). En este art\ículo se presenta un punto d\ébil de DES sobre el cual puede aumentarse la seguridad y se propone una modificaci\ón de la estructura interna de DES con objeto de mejorar su resistencia ante el criptoan\álisis diferencial y por ende de los ataques derivados de este. La modificaci\ón introducida no supone un coste adicional elevado

}, author = {Antonio Mana and Javier Lopez and Lucia Pino and Juan J. Ortega and Carlos Maraval} } @inproceedings {1741, title = {Sistema Jer{\'a}rquico de Administraci{\'o}n de Claves P{\'u}blicas para el Correo Electr{\'o}nico}, booktitle = {I Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL{\textquoteright}97)}, year = {1997}, month = {Sep 1997}, pages = {295-302}, address = {Bilbao (Spain)}, isbn = {84-89654-04-2}, author = {Lucia Pino and Antonio Mana and Juan J. Ortega and Javier Lopez} } @inproceedings {JavierLopez1996, title = {Generaci{\'o}n de N{\'u}meros Primos mediante Tests de Primalidad Probabil{\'\i}stas}, booktitle = {IV Reuni{\'o}n Espa{\~n}ola de Criptolog{\'\i}a (IV REC)}, year = {1996}, month = {Septiembre}, pages = {27-33}, address = {Valladolid, Espa}, abstract = {
Nowadays cryptography is present in nearly every aspect of our everyday life, in particular public-key cryptosystems. Some of them have a mathematical foundation of number theory working with big integer numbers. Factoring these numbers is more complex and time-consuming than generating and testing prime numbers; this is the main reason for the strenght of some public key cryptosystems. This paper presents three different probabilistic methods for testing big prime numbers in a reasonable amount of time. A comparison of their efficiency to test prime numbers is also introduced.
}, author = {Javier Lopez and Francisco Ona and Lucia Pino and Carlos Maraval} } @inproceedings {JavierLopez1995, title = {Seguridad de Directorios en Criptosistemas de Clave P{\'u}blica mediante Redes Neuronales en Sistemas de Comunicaciones}, booktitle = {X Symposium Nacional de la Uni{\'o}n Cient{\'\i}fica Internacional de Radio (URSI{\textquoteright}95)}, year = {1995}, month = {Septiembre}, pages = {147-150}, address = {Valladolid, Espa}, author = {Javier Lopez and Francisco Ona and Lucia Pino and Carlos Maraval} }