Aproximación racional a semigrupos de operadores lineales

En este trabajo presentamos una nueva clase de aproximaciones racionales a semigrupos de operadores, que dan lugar a métodos de aproximación estables. Los semigrupos de operadores que se pueden aproximar por estos esquemas son de clase C y si, además, son acotados, se caracterizan por tener un generador infinitesimal A de la forma a=lambda sub 0 p+a sub 1 donde P es un operador proyección, A es un número real negativo y A, un operador cuyo espectro esta" contenido en el semiplano Re z < A del plano complejo. Basándose en la posibilidad de reducir un semigrupo no acotado a uno acotado, se extienden, posteriormente, nuestros resultados a operadores no acotados. En el último capitulo, se dan ejemplos de la aplicación de nuestra teoría a la resolución de algunas ecuaciones de gran importancia en la Física, como son la ecuación de difusión y la del transporte.---ABSTRACT---A new kind of rational approximations to operator semigroups stable approximation methods are presented in this paper. The ope_ rator semigroups that can be approximated through such schemes are of the C class and moreover i f they are bounded they are characterized for having an infinitesimal generator A as follows: a=lambda sub 0 p+a sub 1 where P is the projection operator,X 0 is a negative real number and A, is an operator whose spectrum is inside the semiplañe Re z<Xo of the complex plañe. Based on the possibility of reducing a non - bounded semigroup, to a bounded semigroup, our result may be extended later to non - bounded operators. The last chapter includes examples of the appli catión of our theory to sol ve some extremely important equations in its applications, such as the diffusion and transport equations

Improving network intrusion detection by means of domain-aware genetic programming

Proceeding of: International Conference on Availability, Reliability, and Security, 2010. ARES '10, 15-18 February 2010, Krakow, PolandOne of the central areas in network intrusion detection is how to build effective systems that are able to distinguish normal from intrusive traffic. In this paper we explore the use of Genetic Programming (GP) for such a purpose. Although GP has already been studied for this task, the inner features of network intrusion detection have been systematically ignored. To avoid the blind use of GP shown in previous research, we guide the search by means of a fitness function based on recent advances on IDS evaluation. For the experimental work we use a well-known dataset (i.e. KDD- 99) that has become a standard to compare research although its drawbacks. Results clearly show that an intelligent use of GP achieves systems that are comparable (and even better in realistic conditions) to top state-of-the-art proposals in terms of effectiveness, improving them in efficiency and simplicity.This work was partially supported by CDTI, Ministerio de Industria, Turismo y Comercio of Spain in collaboration with Telefónica I+D, Project SEGUR@ CENIT-2007 2004Publicad

Adaptive agents applied to intrusion detection

Proceeding of: Multi-agent systems and applications III : 3rd International Central and Eastern European Conference on Multi-Agent Systems, CEEMAS 2003 Prague, Czech Republic, June 16–18, 2003This paper proposes a system of agents that make predictions over the presence of intrusions. Some of the agents act as predictors implementing a given Intrusion Detection model, sniffing out the same traffic. An assessment agent weights the forecasts of such predictor agents, giving a final binary conclusion using a probabilistic model. These weights are continuously adapted according to the previous performance of each predictor agent. Other agent establishes if the prediction from the assessor agent was right or not, sending him back the results. This process is continually repeated and runs without human interaction. The effectiveness of our proposal is measured with the usual method applied in Intrusion Detection domain: Receiver Operating Characteristic curves (detection rate versus false alarm rate). Results of the adaptive agents applied to intrusion detection improve ROC curves as it is shown in this paper.Publicad

Leveraging user-related internet of things for continuous authentication: a survey

Among all Internet of Things (IoT) devices, a subset of them are related to users. Leveraging these user-related IoT elements, itis possible to ensure the identity of the user for a period of time, thus avoiding impersonation. This need is known as ContinuousAuthentication (CA). Since 2009, a plethora of IoT-based CA academic research and industrial contributions have been proposed. Weoffer a comprehensive overview of 58 research papers regarding the main components of such a CA system. The status of the industryis studied as well, covering 32 market contributions, research projects and related standards. Lessons learned, challenges and openissues to foster further research in this area are finally presented.This work was supported by the MINECO grant TIN2016-79095-C2-2-R (SMOG-DEV) and by the CAM grants S2013/ICE-3095 (CIBERDINE) and P2018/TCS4566 (CYNAMON-CM) both co-funded with European FEDER funds

Secure and Usable User-in-a-Context Continuous Authentication in Smartphones Leveraging Non-Assisted Sensors

Smartphones are equipped with a set of sensors that describe the environment (e.g., GPS, noise, etc.) and their current status and usage (e.g., battery consumption, accelerometer readings, etc.). Several works have already addressed how to leverage such data for user-in-a-context continuous authentication, i.e., determining if the porting user is the authorized one and resides in his regular physical environment. This can be useful for an early reaction against robbery or impersonation. However, most previous works depend on assisted sensors, i.e., they rely upon immutable elements (e.g., cell towers, satellites, magnetism), thus being ineffective in their absence. Moreover, they focus on accuracy aspects, neglecting usability ones. For this purpose, in this paper, we explore the use of four non-assisted sensors, namely battery, transmitted data, ambient light and noise. Our approach leverages data stream mining techniques and offers a tunable security-usability trade-off. We assess the accuracy, immediacy, usability and readiness of the proposal. Results on 50 users over 24 months show that battery readings alone achieve 97.05% of accuracy and 81.35% for audio, light and battery all together. Moreover, when usability is at stake, robbery is detected in 100 s for the case of battery and in 250 s when audio, light and battery are applied. Remarkably, these figures are obtained with moderate training and storage needs, thus making the approach suitable for current devices.This work has been partially supported by MINECO grants TIN2013-46469-R (SPINY), TIN2016-79095-C2-2-R (SMOG-DEV); CAM grant S2013/ICE-3095 (CIBERDINE), co-funded with European FEDER funds

Security protocols for networks and Internet: a global vision

This work was supported by the MINECO grant TIN2013-46469-R (SPINY: Security and Privacy in the Internet of You), by the CAM grant S2013/ICE-3095 (CIBERDINE: Cybersecurity, Data, and Risks), which is co-funded by European Funds (FEDER), and by the MINECO grant TIN2016-79095-C2-2-R (SMOG-DEV—Security mechanisms for fog computing: advanced security for devices)

Key-recovery attacks on KIDS, a keyed anomaly detection system

Most anomaly detection systems rely on machine learning algorithms to derive a model of normality that is later used to detect suspicious events. Some works conducted over the last years have pointed out that such algorithms are generally susceptible to deception, notably in the form of attacks carefully constructed to evade detection. Various learning schemes have been proposed to overcome this weakness. One such system is Keyed IDS (KIDS), introduced at DIMVA &#34;10. KIDS&#34; core idea is akin to the functioning of some cryptographic primitives, namely to introduce a secret element (the key) into the scheme so that some operations are infeasible without knowing it. In KIDS the learned model and the computation of the anomaly score are both key-dependent, a fact which presumably prevents an attacker from creating evasion attacks. In this work we show that recovering the key is extremely simple provided that the attacker can interact with KIDS and get feedback about probing requests. We present realistic attacks for two different adversarial settings and show that recovering the key requires only a small amount of queries, which indicates that KIDS does not meet the claimed security properties. We finally revisit KIDS&#39; central idea and provide heuristic arguments about its suitability and limitations

Extended U+F social network protocol: interoperability, reusability, data protection and indirect relationships in web based social networks

An interconnected world is what current technologies look for, being Web Based Social Networks (WBSNs) a promising development in this regard. Four desirable WBSN features are identified, namely, interoperability, reusability, protection against WBSNs providers and indirect relationships. A protocol, called U+F, addressed interoperability and reusability of identity data, resources and access control policies between different WBSNs. In order to address the remaining couple of features, that is, achieving the protection of data against WBSNs providers and indirect relationships management across different WBSNs, this paper presents eU+F, an extension of U+F. A prototype is developed to verify the feasibility of implementing the proposed protocol in a real environment, as well as to compare its workload regarding three well-known WBSNs, Facebook, MySpace and LinkedIn

El factor humano en la protección de datos personales

La revolución de las tecnologías de la información no ha calado todavía entre nosotros y aún se requieren muchos años para comprender y manejar los riesgos que acarrea, entre los cuales está la posibilidad de lesionar el derecho a la intimidad

Una breve panorámica de la Criptografía

en este artículo se describen brevemente la historia y las características de la criptografía, disciplina cuyo fin último es garantizar la confidencialidad de la información, y que se ha convertido en una herramienta decisiva para garantizar la seguridad de la información en nuestras sociedadestecnificadas