Toledo y Fray Lorenzo de San Nicolás. Precisiones sobre la Iglesia de las Gaitanas.

Sin resume

Felipe Lázaro de Goiti y sus manuscritos de cantería de la Biblioteca Nacional (Madrid). Una aproximación a autor y obra en su contexto.

Sin resume

El celta ante el espejo

Recensión de: Alfayé Villa, Silvia, 2011, Imagen y ritual en la Céltica peninsular, Toxosoutos, Serie Keltia 50, La Coruña. Entrevista con la autor

A propósito de un proyecto de Antonio Ponz. Realizaciones en Toledo y alrededores de Madrid.

Sin resume

Security in peer-to-peer communication systems

P2PSIP (Peer-to-Peer Session Initiation Protocol) is a protocol developed by the IETF (Internet Engineering Task Force) for the establishment, completion and modi¿cation of communication sessions that emerges as a complement to SIP (Session Initiation Protocol) in environments where the original SIP protocol may fail for technical, ¿nancial, security, or social reasons. In order to do so, P2PSIP systems replace all the architecture of servers of the original SIP systems used for the registration and location of users, by a structured P2P network that distributes these functions among all the user agents that are part of the system. This new architecture, as with any emerging system, presents a completely new security problematic which analysis, subject of this thesis, is of crucial importance for its secure development and future standardization. Starting with a study of the state of the art in network security and continuing with more speci¿c systems such as SIP and P2P, we identify the most important security services within the architecture of a P2PSIP communication system: access control, bootstrap, routing, storage and communication. Once the security services have been identi¿ed, we conduct an analysis of the attacks that can a¿ect each of them, as well as a study of the existing countermeasures that can be used to prevent or mitigate these attacks. Based on the presented attacks and the weaknesses found in the existing measures to prevent them, we design speci¿c solutions to improve the security of P2PSIP communication systems. To this end, we focus on the service that stands as the cornerstone of P2PSIP communication systems¿ security: access control. Among the new designed solutions stand out: a certi¿cation model based on the segregation of the identity of users and nodes, a model for secure access control for on-the-¿y P2PSIP systems and an authorization framework for P2PSIP systems built on the recently published Internet Attribute Certi¿cate Pro¿le for Authorization. Finally, based on the existing measures and the new solutions designed, we de¿ne a set of security recommendations that should be considered for the design, implementation and maintenance of P2PSIP communication systems.Postprint (published version

Presentación

Presentació

Varia: Centenarios, 1506-2006

Brief comentaries about universal works and artists

La Sombra del Quattrocento en las postrimerías del siglo XV hispano. Ideas, ideales, modelos

Resumen Reflexiones sobre el binomio Quattrocento-siglo XV hispano, respecto al primero, incidiendo en el carácter primigenio del foco florentino y, en relación al segundo, con referencia a la familia Mendoza, su mecenazgo, obras y fundaciones. Se plantean tres vías de análisis centradas en Filarete y la planta hospitalaria cruciforme; Filarete, el edificio urbano y su almohadillado y la importancia y significación del Codex Escurialensis [28-II-12]. Palabras clave: Mendoza, Filarete, Hospital, Codex Escurialensis [28-II-12]. Abstract Reflections on the binomial Quattrocento-Hispanic 15th Century, focusing –for the former– on the original nature of the Florentine seat; and –in the latter– on the Mendoza family, its patronage, works and foundations. Three different analysis are set out, based on Filarete and the cruciform hospital plan; Filarete, the urban building and its soft rustication, and the significance of the Codex Escurialensis [28-II-12].Reflexiones sobre el binomio Quattrocento-siglo XV hispano, respecto al primero, incidiendo en el carácter primigenio del foco florentino y, en relación al segundo, con referencia a la familia Mendoza, su mecenazgo, obras y fundaciones. Se plantean tres vías de análisis centradas en Filarete y la planta hospitalaria cruciforme; Filarete, el edificio urbano y su almohadillado y la importancia y significación del Codex Escurialensis [28-II-12].&gt