Biblio

Los avances tecnológicos que está experimentando el mundo digital (Internet, comunicaciones, etc.) están acercando a consumidores y proveedores. Los proveedores pueden ofrecer sus productos directamente a los consumidores finales, y éstos 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 múltiples productos, como los paquetes turísticos, formados por vuelos, hoteles, excursiones, etc, los consumidores carecen de herramientas que les permitan realizar la contratación multi-two-party de manera atómica. En
este artículo presentamos un protocolo de firma de contratos multi-two-party con atomicidad que garantiza la equitatividad de todas las partes.

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’s protocol simulation model as a specific example, we have worked out various simulation experiments.

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.

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.

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.

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.

This article introduces a privacy manager for IoT data based on Edge Computing. This poses the advantage that privacy is enforced before data leaves the control of the user, who is provided with a tool to express data sharing preferences based on a novel context-aware privacy language.

Los escenarios de comercio móvil existentes en la actualidad presentan muchas deficiencias. La mayoría de estos escenarios, como no podría ser de otra forma, tienen en cuenta aspectos relativos a la seguridad, prestando especial atención a las propiedades de Autenticación y Autorización. De entre los elementos esenciales que se utilizan para proporcionar estos servicios de seguridad, los perfiles son un elemento común que permiten la personalización de los servicios del usuario móvil. Sin embargo, los perfiles también precisan de una administración segura. En este trabajo presentamos unas consideraciones iniciales respecto a los distintos tipos de perfiles, sus niveles de seguridad para cada tipo, así como indicaciones para el almacenamiento de manera segura. Por lo tanto, analizaremos las distintas alternativas como medio de almacenamiento, discutiéndolas y prestando especial atención a las tarjetas inteligentes.

As a value-added service to deliver important data over the Internet with guaranteed receipt for each successful delivery, certified email has been discussed for years and a number of research papers appeared in the literature. But most of them deal with the two-party scenarios, i.e., there are only one sender and one recipient. In some applications, however, the same certified message may need to be sent to a set of recipients. In this paper, we presents two optimized multi-party certified email protocols. They have three major features. (1) A sender could notify multiple recipients of the same information while only those recipients who acknowledged are able to get the information. (2) Both the sender and the recipients can end a protocol run at any time without breach of fairness. (3) The exchange protocols are optimized, each of which have only three steps.

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 non-repudiation protocols for multiple entities. We extend an existing multi-party non-repudiation (MPNR) protocol to allow an originator to send different messages to many recipients in a single transaction. We further propose an optimistic multi-party non-repudiation protocol for exchange of different messages. The performance of our protocols with enhanced functionalities is still promising in comparison with existing MPNR protocols.

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.

Nonrepudiation is a security service that plays an important role in many Internet applications. Traditional two-party nonrepudiation has been studied intensively in the literature. This survey focuses on multiparty scenarios and provides a comprehensive overview. It starts with a brief introduction of fundamental issues on nonrepudiation, including the types of nonrepudiation service and cryptographic evidence, the roles of trusted third-party, nonrepudiation phases and requirements, and the status of standardization. Then it describes the general multiparty nonrepudiation problem, and analyzes state-of-the-art mechanisms. After this, it presents in more detail the 1-N multiparty nonrepudiation solutions for distribution of different messages to multiple recipients. Finally, it discusses advanced solutions for two typical multiparty nonrepudiation applications, namely, multiparty certified email and multiparty contract signing.

El no repudio es un requisito de seguridad cuya importancia se ha hecho evidente con el crecimiento del comercio electrónico. Muchos protocolos se han desarrollado como solución a este requisito. La gran mayoría incluye en su especificación parámetros cuyos valores no son fáciles de especificar pues dependen de las condiciones reales de implementación del mismo como los tiempos límites, las características de la TTP, tiempo de publicación de las claves, etc. En este trabajo proponemos un modelo que nos ayudará en la estimación de esos parámetros basado en la simulación del escenario real. Para la explicación y prueba del modelo mostramos un conjunto de experimentos.

El correo electrónico certificado es un servicio añadido al correo electrónico estándar, 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 corrección en la ejecución de los servicios de correo electrónico certificado, ya que los ítems que ambas partes presentan (en este caso específico, 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 línea de investigación protocolos optimistas eficientes para el intercambio electrónico, y mas concretamente para Correo Electrónico Certificado (CEC) y Firma Electrónica de Contratos (FEC). Realizando un estudio adecuado hemos observado que algunos aspectos de dichos protocolos podrían ser mejorados. En este artículo proponemos una solución que permite a ambas entidades terminar el protocolo de forma asíncrona. También extendemos el protocolo a múltiples usuarios.

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.

In any kind of electronic transaction, it is extremely important to assure that any of the parties involved can not deny their participation in the information exchange. This security property, which is called non-repudiation, becomes more important in Digital Rights Management (DRM) scenarios, where a consumer can freely access to certain contents but needs to obtain the proper Right Object (RO) from a vendor in order to process it. Any breach in this process could result on financial loss for any peer, thus it is necessary to provide a service that allows the creation of trusted evidence. Unfortunately, non-repudiation services has not been included so far in DRM specifications due to practical issues and the type of content distributed. In this paper we analyze how to allow the integration of non-repudiation services to a DRM framework, providing a set of protocols that allows the right objects acquisition to be undeniable, alongside with a proof-of-concept implementation and a validation process.

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.

The Internet of Things (IoT) and Edge Computing are starting to go hand in hand. By providing cloud services close to end-users, edge paradigms enhance the functionality of IoT deployments, and facilitate the creation of novel services such as augmented systems. Furthermore, the very nature of these paradigms also enables the creation of a proactive defense architecture, an immune system, which allows authorized immune cells (e.g., virtual machines) to traverse edge nodes and analyze the security and consistency of the underlying IoT infrastructure. In this article, we analyze the requirements for the development of an immune system for the IoT, and propose a security architecture that satisfies these requirements. We also describe how such a system can be instantiated in Edge Computing infrastructures using existing technologies. Finally, we explore the potential application of immune systems to other scenarios and purposes.

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’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

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.

Digital Rights Management (DRM) es un término general para cualesquiera de las soluciones que permite a un vendedor de contenido en forma electrónica controlar el material y restringir su uso de distintas maneras. Estas soluciones son posibles, por un lado gracias a técnicas de la Seguridad de la Información, principalmente cifrado de datos, y por otro a la distribución, de manera independiente, de contenido y derechos digitales. Esto permite que los consumidores puedan acceder libremente al contenido, pero sólo aquellos que adquieran el derecho digital apropiado (RO) podrán procesarlo. Como servicio de seguridad considerado en diversas capas del marco de seguridad definido por la recomendación ITU X.805, casi todas las aplicaciones necesitan considerar la propiedad de no repudio en las etapas iniciales de su diseño. Desafortunadamente, esto no ha sido así en general, y más concretamente en especificaciones DRM; debido a consideraciones en la práctica y al tipo de contenido a distribuir. Analizamos este servicio para un marco de DRM y proporcionamos una solución que permita que la adquisición de derechos digitales sea un operación que no pueda repudiarse.

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.

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.

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.

Edge Computing paradigms are expected to solve some major problems affecting current application scenarios that rely on Cloud computing resources to operate. These novel paradigms will bring computational resources closer to the users and by doing so they will not only reduce network latency and bandwidth utilization but will also introduce some attractive context-awareness features to these systems. In this paper we show how the enticing features introduced by Edge Computing paradigms can be exploited to improve security and privacy in the critical scenario of vehicular networks (VN), especially existing authentication and revocation issues. In particular, we analyze the security challenges in VN and describe three deployment models for vehicular edge computing, which refrain from using vehicular- to-vehicular communications. The result is that the burden imposed to vehicles is considerably reduced without sacrificing the security or functional features expected in vehicular scenarios.

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.

Covert channels are a form of hidden communication that may violate the integrity of systems. Since their birth in Multi-Level Security systems in the early 70’s they have evolved considerably, such that new solutions have appeared for computer networks mainly due to vague protocols specifications. In this paper we concentrate on short-range covert channels and analyze the opportunities of concealing data in various extensively used protocols today. From this analysis we observe several features that can be effectively exploited for subliminal data transmission in the Dynamic Host Configuration Protocol (DHCP). The result is a proof-of-concept implementation, HIDE\_DHCP, which integrates three different covert channels each of which accommodate to different stealthiness and capacity requirements. Finally, we provide a theoretical and experimental analysis of this tool in terms of its reliability, capacity, and detectability.

Los canales encubiertos son una forma de comunicación oculta que puede vulnerar la integridad de los sistemas. Desde sus inicios en sistemas de seguridad multinivel a principios de los años 70 han evolucionado considerablemente, apareciendo soluciones para redes de computadores debido a la especificación de algunos protocolos. Por este motivo, se hace un estudio sobre las técnicas que se han utilizado para crear los canales, así como sobre las distintos obstáculos que han tratado de mermar su actividad. Asimismo, se presenta una nueva clasificación 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 información encubierta. A partir de este análisis se implementan distintas versiones de un canal encubierto haciendo uso de este protocolo.

Certified electronic mail is an added value to traditional electronic mail. In the definition of this service some differences arise: a message in exchange for a reception proof, a message and a non repudiation of origin token in exchange for a reception proof, etc. It greatly depends on whether we want to emulate the courier service or improve the service in the electronic world. If the definition of the service seems conflictive, the definition of the properties and requirements of a good certified electronic mail protocol is even more difficult. The more consensuated features are the need of a fair exchange and the existence of a trusted third party (TTP). Each author chooses the properties that considers the most important, and many times the list is conditioned by the proposal. Which kind of TTP must be used? Must it be verifiable, transparent and/or stateless? Which features must the communication channel fulfil? Which temporal requirements must be established? What kind of fairness is desired? What efficiency level is required? Are confidentiality or transferability of the proofs compulsory properties? In this paper we collect the definitions, properties and requirements related with certified electronic mail. The aim of the paper is to create a clearer situation and analyze how some properties cannot be achieved simultaneously. Each protocol designer will have to decide which properties are the most important in the environment in where the service is to be deployed.

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.

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’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.

Continuamente aparecen nuevos estudios así como nuevos desarrollos de canales encubiertos. Como veremos, existen más de cien diseños distintos para redes de ordenadores, pero no hemos encontrado en la literatura ningún análisis, diseño e implementación de canales encubiertos sobre redes de sensores. En este artículo presentamos los resultados del diseño e implementación de un canal multitasa basado en los tiempos de monitorización 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.

Non-repudiation is a security service that provides cryptographic evidence to support the settlement of disputes in electronic commerce. In commercial transactions, an intermediary (or agent) might be involved to help transacting parties to conduct their business. Nevertheless, such an intermediary may not be fully trusted. In this paper, we propose agent-mediated non-repudiation protocols and analyze their security requirements. We first 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. We also identify applications that could take advantage of these agent-mediated non-repudiation protocols.