Persona: Tobarra Abad, María de los Llanos
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llanos@scc.uned.es
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0000-0003-2779-4042
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Tobarra Abad
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María de los Llanos
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Publicación On the optimal selection of Mel-Frequency Cepstral Coefficients for voice deepfake detection(Wiley, 2026-03-24) Falcón López, Sergio A.; Tobarra Abad, María de los Llanos; Robles Gómez, Antonio; Pastor Vargas, RafaelThe continuous evolution of techniques for generating manipulated audio, known as voice deepfakes, and the widespread availability of tools that produce convincing forgeries have created an urgent need for reliable detection methods. This work considers the dimensionality of Mel-Frequency Cepstral Coefficients (MFCCs) as a core design variable for practical, deployable systems. The aim is to identify the smallest number of coefficients that preserves detection performance across heterogeneous models while reducing computational cost, a critical factor for mobile and edge deployment. This study evaluates a hybrid setting on the ASVspoof 2019 Logical Access dataset, in which the same feature family serves as input to five traditional machine learning algorithms (Random Forest, k-Nearest Neighbors, Linear Support Vector Classification, Extreme Gradient Boosting and Support Vector Machine with radial basis function kernel) and five deep learning models (Convolutional Neural Network, Recurrent Neural Network, Convolutional Recurrent Neural Network, Xception and ResNet). Results indicate that deep models reach near-peak performance with a small number of coefficients, whereas classical methods require a larger number to achieve stable performance (except Linear Support Vector Classification, which consistently underperforms). Accordingly, 32 coefficients are considered an effective operating point for hybrid deployments. Overall, the results provide evidence to guide the selection of the number of MFCC coefficients in voice deepfake detection, aiming for efficient, reproducible and explainable systems.Publicación A WoT Platform for Supporting Full-Cycle IoT Solutions from Edge to Cloud Infrastructures: A Practical Case(MDPI, 2020-07-05) Pastor Vargas, Rafael; Tobarra Abad, María de los Llanos; Robles Gómez, Antonio; Martín Gutiérrez, Sergio; Hernández Berlinches, Roberto; Cano, Jesús; MDPI; https://orcid.org/0000-0001-6926-1311Internet of Things (IoT) learning involves the acquisition of transversal skills ranging from the development based on IoT devices and sensors (edge computing) to the connection of the devices themselves to management environments that allow the storage and processing (cloud computing) of data generated by sensors. The usual development cycle for IoT applications consists of the following three stages: stage 1 corresponds to the description of the devices and basic interaction with sensors. In stage 2, data acquired by the devices/sensors are employed by communication models from the origin edge to the management middleware in the cloud. Finally, stage 3 focuses on processing and presentation models. These models present the most relevant indicators for IoT devices and sensors. Students must acquire all the necessary skills and abilities to understand and develop these types of applications, so lecturers need an infrastructure to enable the learning of development of full IoT applications. AWeb of Things (WoT) platform named Labs of Things at UNED (LoT@UNED) has been used for this goal. This paper shows the fundamentals and features of this infrastructure, and how the different phases of the full development cycle of solutions in IoT environments are implemented using LoT@UNED. The proposed system has been tested in several computer science subjects. Students can perform remote experimentation with a collaborativeWoT learning environment in the cloud, including the possibility to analyze the generated data by IoT sensors.Publicación A Cloud Game-based Educative Platform Architecture: the CyberScratch Project(MDPI, 2021) Utrilla, Alejandro; Tobarra Abad, María de los Llanos; Robles Gómez, Antonio; Pastor Vargas, Rafael; Hernández Berlinches, RobertoThe employment of modern technologies is widespread in our society, so the inclusion of practical activities for education has become essential and useful at the same time. These activities are more noticeable in Engineering, in areas such as cybersecurity, data science, artificial intelligence, etc. Additionally, these activities acquire even more relevance with a distance education methodology, as our case is. The inclusion of these practical activities has clear advantages , such as (1) promoting critical thinking and (2) improving students’ abilities and skills for their professional careers. There are several options, such as the use of remote and virtual laboratories, virtual reality and gamebased platforms, among others. This work addresses the development of a new cloud game-based educational platform, which defines a modular and flexible architecture (using light containers). This architecture provides interactive and monitoring services and data storage in a transparent way. The platform uses gamification to integrate the game as part of the instructional process. The CyberScratch project is a particular implementation of this architecture focused on cybersecurity game-based activities. The data privacy management is a critical issue for these kinds of platforms, so the architecture is designed with this feature integrated in the platform components. To achieve this goal, we first focus on all the privacy aspects for the data generated by our cloud game-based platform, by considering the European legal context for data privacy following GDPR and ISO/IEC TR 20748-1:2016 recommendations for Learning Analytics (LA). Our second objective is to provide implementation guidelines for efficient data privacy management for our cloud game-based educative platform. All these contributions are not found in current related works. The CyberScratch project, which was approved by UNED for the year 2020, considers using the xAPI standard for data handling and services for the game editor, game engine and game monitor modules of CyberScratch. Therefore, apart from considering GDPR privacy and LA recommendations, our cloud game-based architecture covers all phases from game creation to the final users’ interactions with the game.Publicación Smart Contracts for Managing the Chain-of-Custody of Digital Evidence: A Practical Case of Study(MDPI, 2023) Santamaría, Pablo; Tobarra Abad, María de los Llanos; Pastor Vargas, Rafael; Robles Gómez, AntonioThe digital revolution is renewing many aspects of our lives, which is also a challenge in judicial processes, such as the Chain-of-Custody (CoC) process of any electronic evidence. A CoC management system must be designed to guarantee them to maintain its integrity in court. This issue is essential for digital evidence’s admissibility and probative value. This work has built and validated a real prototype to manage the CoC process of any digital evidence. Our technological solution follows a process model that separates the evidence registry and any evidence itself for scalability purposes. It includes the development of an open-source smart contract under Quorum, a version of Ethereum oriented to private business environments. The significant findings of our analysis have been: (1) Blockchain networks can become a solution, where integrity, privacy and traceability must be guaranteed between untrustworthy parties; and (2) the necessity of promoting the standardization of CoC smart contracts with a secure, simple process logic. Consequently, these contracts should be deployed in consortium environments, where reliable, independent third parties validate the transactions without having to know their content.Publicación Hispanic Medieval Tagger (HisMeTag): una aplicación web para el etiquetado de entidades en textos medievalesDíez Platas, María Luisa; González-Blanco García, Elena; Rio Riande, Gimena del; Tobarra Abad, María de los Llanos; Ros Muñoz, Salvador; Robles Gómez, Antonio; Caminero Herráez, Agustín CarlosHisMeTag permite localizar entidades nombradas en textos escritos en español medieval, mediante un proceso automático de reconocimiento de entidades nombradas (NER) y técnicas de PLN para el procesamiento lingüístico y la generación de las distintas variantes que existieron en la época medieval. Localiza, etiqueta términos conocidos y propone nuevos términos para su validación.Publicación Researchers’ perceptions of DH trends and topics in the English and Spanish-speaking community. DayofDH data as a case study(Jagiellonian University & Pedagogical University (Cracovia), 2016-07-22) González-Blanco García, Elena; Rio Riande, Gimena del; Robles Gómez, Antonio; Ros Muñoz, Salvador; Hernández Berlinches, Roberto; Tobarra Abad, María de los Llanos; Caminero Herráez, Agustín Carlos; Pastor Vargas, RafaelPublicación Machine learning models and dimensionality reduction for improving the Android malware detection(PeerJ, 2024-12-23) Moran, Pablo; Robles Gómez, Antonio; Duque Fernández, Andrés; Tobarra Abad, María de los Llanos; Pastor Vargas, RafaelToday, a great number of attack opportunities for cybercriminals arise in Android, since it is one of the most used operating systems for many mobile applications. Hence, it is very important to anticipate these situations. To minimize this problem, the analysis of malware search applications is based on machine learning algorithms. Our work uses as a starting point the features proposed by the DREBIN project, which today constitutes a key reference in the literature, being the largest public Android malware dataset with labeled families. The authors only employ the support vector machine to determine whether a sample is malware or not. This work first proposes a new efficient dimensionality reduction of features, as well as the application of several supervised machine learning algorithms for prediction purposes. Predictive models based on Random Forest are found to achieve the most promising results. They can detect an average of 91.72% malware samples, with a very low false positive rate of 0.13%, and using only 5,000 features. This is just over 9% of the total number of features of DREBIN. It achieves an accuracy of 99.52%, a total precision of 96.91%, as well as a macro average F1-score of 96.99%.Publicación Comprehensive AI-Driven Privacy Risk Assessment in Mobile Apps and Social Networks(Springer, 2025-09-29) Blanco Aza, Daniel; Robles Gómez, Antonio; Pastor Vargas, Rafael; Tobarra Abad, María de los Llanos; Vidal Balboa, Pedro; Méndez-Suárez, MarianoThe pervasive use of mobile applications and social networks has intensified privacy concerns due to the widespread collection, processing, and sharing of personal data. To address these challenges, we introduce SafeMountain, a novel AI-driven framework designed to systematically quantify, evaluate, and visualize privacy risks in mobile apps and social platforms, ensuring strict compliance with international regulations, particularly the General Data Protection Regulation (GDPR). SafeMountain combines static and dynamic code analyses to scrutinize real-world data handling practices and detect potential privacy breaches. It also employs advanced Natural Language Processing (NLP) techniques for automated interpretation and evaluation of privacy policies and Terms of Service. By mapping textual policy disclosures to actual app permissions and behaviors, it identifies discrepancies and highlights potential non-compliance and data misuse. The framework introduces an objective risk scoring mechanism aligned with international standards and regulatory requirements, offering a structured methodology to classify and visualize privacy risks. This risk assessment spans multiple dimensions (predictability, manageability, and disassociability) leveraging privacy engineering principles and regulatory risk factors, and uses an intuitive traffic-light system (Green, Yellow, Red) to enhance transparency and user comprehension. SafeMountain addresses major research gaps, notably the absence of standardized privacy risk scoring and comprehensive visualization tools. By delivering actionable insights into permission consistency, policy transparency, compliance gaps, and data leakage vulnerabilities, it empowers users, developers, and organizations to manage privacy risks proactively. Ultimately, SafeMountain fosters trust through more transparent and accountable data privacy practices across digital ecosystems.Publicación Forensic Analysis Laboratory for Sport Devices: A Practical Case of Use(MDPI, 2023) Donaire Calleja, Pablo; Robles Gómez, Antonio; Tobarra Abad, María de los Llanos; Pastor Vargas, RafaelAt present, the mobile device sector is experiencing significant growth. In particular, wear- 1 able devices have become a common element in society. This fact implies that users unconsciously 2 accept the constant dynamic collection of private data about their habits and behaviours. Therefore, 3 this work focuses on highlighting and analyzing some of the main issues that forensic analysts face 4 in this sector, such as the lack of standard procedures for analysis and the common use of private 5 protocols for data communication. Thus, it is almost impossible for a digital forensic specialist to 6 fully specialize in the context of wearables, such as smartwatches for sports activities. With the aim 7 of highlighting these problems, a complete forensic analysis laboratory for such sports devices is 8 described in this paper. We selected a smartwatch belonging to the Garmin Forerunner Series, due to 9 its great popularity. Through an analysis, its strengths and weaknesses in terms of data protection 10 are described. We also analyze how companies are increasingly taking personal data privacy into 11 consideration, in order to minimize unwanted information leaks. Finally, a set of initial security 12 recommendations for the use of these kinds of devices are provided to the reader.Publicación Analyzing Students’ Self-Perception of Success and Learning Effectiveness Using Gamification in an Online Cybersecurity Course(2020-06-05) Ros Muñoz, Salvador; González, S.; Robles Gómez, Antonio; Tobarra Abad, María de los Llanos; Caminero Herráez, Agustín Carlos; Cano, Jesús; Agencia Estatal de Investigación (España); Universidad Nacional de Educación a Distancia (UNED)This paper analyzes students’ self-perception of success and learning effectiveness after using non-compulsory gamification in an online Cybcourse. For this purpose, we designed a cybersecurity game based on cognitive constructivism learning theory. We built the game scenes using metaphors to present the main Cybersecurity contents to the students. We delivered the game in a regular course with two objectives: first, to find the primary design factors that affect students’ self-perception of success. We propose a structural equation model to find out the elements with the most significant impact on the students’ self-perception of success. The results show that the realistic game design and the contextualization of the game do have a notable influence. They are both examples of best practices in game design; second, to evaluate the learning effectiveness of the game. The results suggest a high correlation between playing the game and succeeding in the course. Moreover, chronological analysis of the performance reveals that the intention to play the game could be a simple dropout predictor. Thus, introducing the game in the educational curricula improves student engagement and consolidates their knowledge on cybersecurity.