Publications

@article{diazsanchez011,

title = {Task Scheduling to Constrain Peak Current Consumption in Wearable Healthcare Sensors},

author = {Robert Simon-Sherratt and Balazs Janko and Terence Hui and William S.-Harwin and Nilanjan Dey and Daniel Díaz-Sánchez and Jin Wang and Fuqian Shi},

url = {https://doi.org/10.3390/electronics8070789

https://www.mdpi.com/2079-9292/8/7/789

https://www.mdpi.com/2079-9292/8/7/789/pdf?version=1563172692},

doi = {https://doi.org/10.3390/electronics8070789},

issn = {2079-9292},

year  = {2019},

date = {2019-07-15},

urldate = {2019-07-15},

journal = {Electronics},

volume = {8},

pages = {789},

abstract = {Small embedded systems, in our case wearable healthcare devices, have significant engineering challenges to reduce their power consumption for longer battery life, while at the same time supporting ever-increasing processing requirements for more intelligent applications. Research has primarily focused on achieving lower power operation through hardware designs and intelligent methods of scheduling software tasks, all with the objective of minimizing the overall consumed electrical power. However, such an approach inevitably creates points in time where software tasks and peripherals coincide to draw large peaks of electrical current, creating short-term electrical stress for the battery and power regulators, and adding to electromagnetic interference emissions. This position paper proposes that the power profile of an embedded device using a real-time operating system (RTOS) will significantly benefit if the task scheduler is modified to be informed of the electrical current profile required for each task. This enables the task scheduler to schedule tasks that require large amounts of current to be spread over time, thus constraining the peak current that the system will draw. We propose a solution to inform the task scheduler of a tasks’ power profile, and we discuss our application scenario, which clearly benefited from the proposal.},

keywords = {embedded, health care, joint digital transformation, low-power, task scheduler, wearable},

pubstate = {published},

tppubtype = {article}

}

@article{8704893,

title = {TLS/PKI Challenges and Certificate Pinning Techniques for IoT and M2M Secure Communications},

author = {Daniel Díaz-Sánchez and Andrés Marín-López and Florina Almenárez-Mendoza and Patricia Arias-Cabarcos and R. Simon-Sherratt},

url = {https://doi.org/10.1109/COMST.2019.2914453

https://ieeexplore.ieee.org/document/8704893

https://phpmyadmin.pervasive.it.uc3m.es/download/TLC-PKI-challenges-certificate-pinning.pdf},

doi = {10.1109/COMST.2019.2914453},

issn = {1553-877X},

year  = {2019},

date = {2019-05-02},

urldate = {2019-05-02},

journal = {IEEE Communications Surveys and Tutorials},

volume = {21},

issue = {4},

pages = {3502-3531},

abstract = {Transport layer security (TLS) is becoming the de facto standard to provide end-to-end security in the current Internet. IoT and M2M scenarios are not an exception since TLS is also being adopted there. The ability of TLS for negotiating any security parameter, its flexibility and extensibility are responsible for its wide adoption but also for several attacks. Moreover, as it relies on public key infrastructure (PKI) for authentication, it is also affected by PKI problems. Considering the advent of IoT/M2M scenarios and their particularities, it is necessary to have a closer look at TLS history to evaluate the potential challenges of using TLS and PKI in these scenarios. According to this, this paper provides a deep revision of several security aspects of TLS and PKI, with a particular focus on current certificate pinning solutions in order to illustrate the potential problems that should be addressed.},

keywords = {authentication, certificate pinning, cynamon, DTLS, Internet of Things, Machine to Machine, magos, PKI, Protocols, TLS, Trusted Third Party, Tutorials},

pubstate = {published},

tppubtype = {article}

}

@article{campo006,

title = {Using entropy of social media location data for the detection of crowd dynamics anomalies},

author = {Carlos García-Rubio and Rebeca Diaz-Redondo and Celeste Campo-Vázquez and Ana Fernandez-Vilas },

url = {http://hdl.handle.net/10016/33760},

doi = {https://doi.org/10.3390/electronics7120380},

issn = {2079-9292},

year  = {2018},

date = {2018-12-03},

urldate = {2018-12-03},

journal = {Electronics},

volume = {7},

issue = {12},

pages = {380},

abstract = {Evidence of something unusual happening in urban areas can be collected from different data sources, such as police officers, cameras, or specialized physical infrastructures. In this paper, we propose using geotagged posts on location-based social networks (LBSNs) to detect crowd dynamics anomalies automatically as evidence of a potential unusual event. To this end, we use the Instagram API media/search endpoint to collect the location of the pictures posted by Instagram users in a given area periodically. The collected locations are summarized by their centroid. The novelty of our work relies on using the entropy of the sequence of centroid locations in order to detect abnormal patterns in the city. The proposal is tested on a data set collected from Instagram during seven months in New York City and validated with another data set from Manchester. The results have also been compared with an alternative approach, a training phase plus a ranking of outliers. The main conclusion is that the entropy algorithm succeeds inn finding abnormal events without the need for a training phase, being able to dynamically adapt to changes in crowd behavior.},

keywords = {anomaly detection, city behavior, data mining algorithms, location-based social network},

pubstate = {published},

tppubtype = {article}

}

@article{campo007,

title = {Detecting and reducing biases in cellular-based mobility data sets},

author = {Alicia Rodriguez-Carrion and Celeste Campo-Vázquez and Carlos García-Rubio},

url = {http://hdl.handle.net/10016/28004},

doi = {https://doi.org/10.3390/e20100736},

issn = {1099-4300},

year  = {2018},

date = {2018-09-25},

urldate = {2018-09-25},

journal = {Entropy},

volume = {20},

issue = {10},

abstract = {Correctly estimating the features characterizing human mobility from mobile phone traces is a key factor to improve the performance of mobile networks, as well as for mobility model design and urban planning. Most related works found their conclusions on location data based on the cells where each user sends or receives calls or messages, data known as Call Detail Records (CDRs). In this work, we test if such data sets provide enough detail on users’ movements so as to accurately estimate some of the most studied mobility features. We perform the analysis using two different data sets, comparing CDRs with respect to an alternative data collection approach. Furthermore, we propose three filtering techniques to reduce the biases detected in the fraction of visits per cell, entropy and entropy rate distributions, and predictability. The analysis highlights the need for contextualizing mobility results with respect to the data used, since the conclusions are biased by the mobile phone traces collection approach.},

keywords = {cell-based location, human mobility, inrisco, mobility data sets entropy, mobility data sets predictability, ping-pong effect},

pubstate = {published},

tppubtype = {article}

}

@article{almenarez009,

title = {A study of learning-by-doing in MOOCs through the integration of third-party external tools: comparison of synchronous and asynchronous running modes },

author = {Carlos Alario-Hoyos and Iria Estevez-Ayres and Jesus Gallego-Romero and Carlos Delgado-Kloss and Carmen Fernandez-Panadero and Raquel Crespo-Garcia and Florina Almenares-Mendoza and Blanca Ibañez-Espiga and Julio Villena-Roman and Jorge Ruiz-Magaña and Jorge Blasco-Alis},

url = {http://hdl.handle.net/10016/29864},

doi = {https://doi.org/10.3217/jucs-024-08-1015},

issn = {0948-695X},

year  = {2018},

date = {2018-08-28},

urldate = {2018-08-28},

journal = {JOURNAL OF UNIVERSAL COMPUTER SCIENCE },

volume = {24},

issue = {8},

pages = {1015-1033},

abstract = {Many MOOCs are being designed replicating traditional passive teaching approaches but using video lectures as the means of transmitting information. However, it is well known that learning-by-doing increases retention rates and, thus, allows achieving a more effective learning. To this end, it is worth exploring which tools fit best in the context of each MOOC to enrich learners' experience, including built-in tools already available in the MOOC platform, and third-party external tools which can be integrated in the MOOC platform. This paper presents an example of the integration of a software development tool, called Codeboard, in three MOOCs which serve as an introduction to programming with Java. We analyze the effect this tool has on learners' interaction and engagement when running the MOOCs in synchronous (instructor-paced) or asynchronous (self-paced) modes. Results show that the overall use of the tool is similar, regardless of the course running mode, although in the case of the synchronous mode the use of the tool is concentrated in a shorter period of time. Results also show that in the synchronous mode there is a higher percentage of accesses to the tool from registered learners (who can save their advances and continue the work later); this finding suggests that learners in the synchronous running mode are more engaged with the MOOC.},

keywords = {codeboard, emadrid, instructor-paced, Moocs, programming tools, self-paced},

pubstate = {published},

tppubtype = {article}

}

@article{almenarez009b,

title = {RiskLaine: A Probabilistic Approach for Assessing Risk in Certificate-Based Security. },

author = {Francisca Hinajeros and Florina Almenares-Mendoza and Patricia Arias-Cabarcos Josep-Lluis Ferrer Gomila and Andrés Marín-López},

doi = {https://doi.org/10.1109/tifs.2018.2807788},

issn = {1556-6013},

year  = {2018},

date = {2018-02-19},

urldate = {2018-02-19},

journal = {IEEE Transactions on Information Forensics and Security },

volume = {13},

issue = {8},

pages = {1975-1988},

abstract = {Digital certificates, based on X.509 PKI standard, are located at the core of many security mechanisms implemented in services and applications. However, the usage of certificates has revealed flaws in the certificate validation process (e.g., possibility of unavailable or non-updated data). This fact implies security risks that are not assessed. In order to address these issues that such flaws entail, we propose a novel probabilistic approach for quantitative risk assessment in X.509 PKI, together with trust management when there is uncertainty. We have evaluated our risk assessment approach and demonstrated its usage, considering as a use case the secure installation of mobile applications. The results show that our approach provides more granularity, appropriate values according to the impact, and relevant information in the risk calculation than other approaches.},

keywords = {certificate validation, mobile applications, risk assessment, trust validation},

pubstate = {published},

tppubtype = {article}

}

@article{8246828,

title = {Seamless human-device interaction in the internet of things},

author = {E Rubio-Drosdov and D Díaz-Sánchez and F Almenárez and P Arias-Cabarcos and A Marín},

url = {/download/Seamless_Human-Device_Interaction_in_the_Internet_of_Things.pdf

https://ieeexplore.ieee.org/document/8246828},

doi = {10.1109/TCE.2017.015076},

issn = {1558-4127},

year  = {2017},

date = {2017-11-01},

urldate = {2017-11-01},

journal = {IEEE Transactions on Consumer Electronics},

volume = {63},

issue = {4},

pages = {490-498},

abstract = {The Internet of Things will bring a scenario in which interaction between humans and devices will be critical to allow people to use, monitor or configure Internet of Things devices. Interactions in such applications are based on traditional graphical interfaces. Devices that accept interaction based on Natural Language, e.g., through voice commands, can understand basic human orders or answering questions whenever user expressions fit into a known language pattern. Some devices can understand natural language voice commands but require sophisticated voice assistants located in the cloud, which raises significant privacy concerns. Others devices which handle voice-processing locally can perform a very limited local recognition system, requiring users to be familiar with words the system can process. The purpose of this work is to diminish the complexity of Natural Language processing in the context of IoT. The solution posited in this article allows Internet of Things devices to offload Natural Language processing to a system that improves the use of Natural Language and alleviates the need to learn or remember specific words or terms intended for triggering device actions. We have evaluated the feasibility of the design with a proof-of-concept implemented in a home environment and it was tested by real users.},

keywords = {Human-Device Interaction, inrisco, Internet of Things, Natural Language Processing},

pubstate = {published},

tppubtype = {article}

}

@article{8003467,

title = {Collaborative eHealth Meets Security: Privacy-Enhancing Patient Profile Management},

author = {Rosa Sánchez-Guerrero and Florina Almenárez-Mendoza and Daniel Díaz-Sánchez and Patricia Arias-Cabarcos and Andrés Marín-López},

url = {/download/Collaborative_eHealth_meets_Security_Privacy-Enhancing_Patient_Profile_Management.pdf

https://ieeexplore.ieee.org/document/8003467},

doi = {10.1109/JBHI.2017.2655419},

issn = {2168-2194 },

year  = {2017},

date = {2017-11-01},

urldate = {2017-11-01},

journal = {IEEE Journal of Biomedical and Health Informatics},

volume = {21},

issue = {6},

pages = {1741-1749},

abstract = {Collaborative healthcare environments offer potential benefits, including enhancing the healthcare quality delivered to patients and reducing costs. As a direct consequence, sharing of electronic health records (EHRs) among healthcare providers has experienced a noteworthy growth in the last years, since it enables physicians to remotely monitor patients' health and enables individuals to manage their own health data more easily. However, these scenarios face significant challenges regarding security and privacy of the extremely sensitive information contained in EHRs. Thus, a flexible, efficient, and standards-based solution is indispensable to guarantee selective identity information disclosure and preserve patient's privacy. We propose a privacy-aware profile management approach that empowers the patient role, enabling him to bring together various healthcare providers as well as user-generated claims into an unique credential. User profiles are represented through an adaptive Merkle Tree, for which we formalize the underlying mathematical model. Furthermore, performance of the proposed solution is empirically validated through simulation experiments.},

keywords = {EHR, emadrid2, Merkle Tree, Minimal Disclosure, privacy, Profile Management},

pubstate = {published},

tppubtype = {article}

}

@article{7838091,

title = {Secure store and forward proxy for dynamic IoT applications over M2M networks},

author = {Daniel Díaz-Sánchez and R. Simon-Sherratt and Florina Almenarez and Patricia Arias and Andrés Marín},

url = {https://ieeexplore.ieee.org/document/7838091

https://phpmyadmin.pervasive.it.uc3m.es/download/Secure__Store_and_Forward_Proxy_for_Dynamic_IoT_Applications_over_M2M_Networks.pdf},

doi = {10.1109/TCE.2016.7838091},

issn = {0098-3063},

year  = {2016},

date = {2016-11-01},

urldate = {2016-11-01},

journal = {IEEE Transactions on Consumer Electronics},

volume = {62},

issue = {4},

pages = {389-397},

abstract = {Internet of Things (IoT) applications are expected to generate a huge unforeseen amount of traffic flowing from Consumer Electronics devices to the network. In order to overcome existing interoperability problems, several standardization bodies have joined to bring a new generation of Machine to Machine (M2M) networks as a result of the evolution of wireless sensor/actor networks and mobile cellular networks to converged networks. M2M is expected to enable IoT paradigms and related concepts into a reality at a reasonable cost. As part of the convergence, several technologies preventing new IoT services to interfere with existing Internet services are flourishing. Responsive, message-driven, resilient and elastic architectures are becoming essential parts of the system. These architectures will control the entire data flow for an IoT system requiring sometimes to store, shape and forward data among nodes of a M2M network to improve network performance. However, IoT generated data have an important personal component since it is generated in personal devices or are the result of the observation of the physical world, so rises significant security concerns. This article proposes a novel opportunistic flexible secure store and forward proxy for M2M networks and its mapping to asynchronous protocols that guarantees data confidentiality.},

keywords = {encryption, Internet of Things, Machine to Machine, privacy},

pubstate = {published},

tppubtype = {article}

}

@article{HUI2017358,

title = {Major requirements for building Smart Homes in Smart Cities based on Internet of Things technologies},

author = {Terence K-L-Hui and Simon R-Sherratt and Daniel Díaz-Sánchez},

url = {http://www.sciencedirect.com/science/article/pii/S0167739X16304721

/download/Major_requirements_for_building_Smart_Homes_in_Smart_Cities_based.pdf},

doi = {https://doi.org/10.1016/j.future.2016.10.026},

issn = {0167-739X},

year  = {2016},

date = {2016-11-01},

urldate = {2016-11-01},

journal = {Future Generation Computer Systems},

volume = {76},

pages = {358 - 369},

abstract = {The recent boom in the Internet of Things (IoT) will turn Smart Cities and Smart Homes (SH) from hype to reality. SH is the major building block for Smart Cities and have long been a dream for decades, hobbyists in the late 1970s made Home Automation (HA) possible when personal computers started invading home spaces. While SH can share most of the IoT technologies, there are unique characteristics that make SH special. From the result of a recent research survey on SH and IoT technologies, this paper defines the major requirements for building SH. Seven unique requirement recommendations are defined and classified according to the specific quality of the SH building blocks.},

keywords = {Ambient intelligence, Home Automation, Internet of Things, Smart Cities, Smart Home requirements},

pubstate = {published},

tppubtype = {article}

}

@article{7579116,

title = {Comparing Password Management Software: Toward Usable and Secure Enterprise Authentication},

author = {Patricia Arias-Cabarcos and Andrés Marín and Diego Palacios and Florina Almenárez and Daniel Díaz-Sánchez},

url = {https://ieeexplore.ieee.org/document/7579116

https://doi.org/10.1109/MITP.2016.81

/download/ComparingPasswordManagementSoftware.pdf},

doi = {10.1109/MITP.2016.81},

issn = {1941-045X},

year  = {2016},

date = {2016-09-01},

urldate = {2016-09-01},

journal = {IT Professional},

volume = {18},

issue = {5},

pages = {34-40},

abstract = {In today's corporate IT systems, employees routinely repeat an undeniable pattern: accessing a huge number of password-protected services. In this regard, although deploying a strong enterprise password policy can increase security against online breaches and data leaks, it also imposes a significant usability burden on users. To alleviate this problem, password managers (PMs) are considered user-friendly tools that automate password generation and login processes. But how secure and usable are these tools? The authors analyze the four most popular PMs with free versions from both security and usability perspectives. The comparison leads to recommendations on enterprise PM selection, as well as to the identification of new lines of research and development on usable authentication.},

keywords = {cybersecurity, emadrid2, inrisco, password managers, Security, usability},

pubstate = {published},

tppubtype = {article}

}

@article{campos008,

title = {A Bandwidth-Efficient Dissemination Scheme of Non-Safety Information in Urban VANETs},

author = {Estrella García-Lozano and Celeste Campo-Vázquez and Carlos García-Rubio and Alicia Rodriguez-Carrion },

url = {http://hdl.handle.net/10016/27911},

doi = {https://doi.org/10.3390/s16070988},

issn = {1424-8220},

year  = {2016},

date = {2016-06-27},

urldate = {2016-06-27},

journal = {Sensors },

volume = {16},

issue = {7},

abstract = {The recent release of standards for vehicular communications will hasten the development of smart cities in the following years. Many applications for vehicular networks, such as blocked road warnings or advertising, will require multi-hop dissemination of information to all vehicles in a region of interest. However, these networks present special features and difficulties that may require special measures. The dissemination of information may cause broadcast storms. Urban scenarios are especially sensitive to broadcast storms because of the high density of vehicles in downtown areas. They also present numerous crossroads and signal blocking due to buildings, which make dissemination more difficult than in open, almost straight interurban roadways. In this article, we discuss several options to avoid the broadcast storm problem while trying to achieve the maximum coverage of the region of interest. Specifically, we evaluate through simulations different ways to detect and take advantage of intersections and a strategy based on store-carry-forward to overcome short disconnections between groups of vehicles. Our conclusions are varied, and we propose two different solutions, depending on the requirements of the application.},

keywords = {broadcast suppression scheme, dissemination, inrisco, store-carry-forward, urban scenarios, VANETs},

pubstate = {published},

tppubtype = {article}

}

@article{khaled001,

title = {Analysis of Secure TCP/IP Profile in 61850 Based Substation Automation System for Smart Grids},

author = {Omar Khaled and Andrés Marín and Florina Almenares and Patricia Arias and Daniel Díaz},

url = {https://journals.sagepub.com/doi/10.1155/2016/5793183},

doi = {https://doi.org/10.1155/2016/5793183},

issn = {1550-1477},

year  = {2016},

date = {2016-04-18},

urldate = {2016-04-18},

journal = {International Journal of Distributed Sensor Networks},

volume = {12},

issue = {4},

pages = {1-11},

abstract = {Smart grid is the term used to describe modern power grids. It aims at achieving efficient, sustainable, economic, and secure delivery of electricity supplies. In order to achieve these goals, communication between different components within the grid and control centers is required. In a rapidly growing world, the demands for substation automation are increasing. Recently, two trends have been changing Substation Automation Systems: IEC 61850 and the need for cybersecurity. IEC 61850 specifies very strict performance requirements for message transfer time. The security for the smart grid must be designed to satisfy both performance and reliability requirements. In this paper, we address a study about secure communication in the substation real-time environment, complying with the IEC 61850 specifications. We mainly focus on analyzing the proposed Secure TCP/IP profile for MMS, testing different cipher suite combinations and examining whether by applying TLS we can still achieve the strict performance requirements of IEC 61850 or not. As a result of the study, we propose a list of cipher suite combinations that should be used. The importance of this study lies mainly on future scenarios, because IEC 61850 is thought to support smart metering communications.},

keywords = {inrisco, smart grids},

pubstate = {published},

tppubtype = {article}

}

@article{almenarez005,

title = {PECEVA: An adaptable and energy-saving credential validation solution for pervasive networks},

author = {Florina Almenarez and M. Francisca Hinarejos and Andrés Marín and Josep Lluís Ferrer-Gomila and Daniel Díaz Sánchez},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0020025516301578?via%3Dihub},

doi = {https://doi.org/10.1016/j.ins.2016.03.010},

issn = {0020-0255},

year  = {2016},

date = {2016-03-12},

urldate = {2016-03-12},

journal = {INFORMATION SCIENCES},

volume = {354},

pages = {41-59},

abstract = {Wireless, mobile, and context-awareness applications are considered to be the epitome of pervasive computing, but they bring with them the inherent security challenges of mobile ad-hoc networking. Mobile ad-hoc networks are mainly formed by mobile users, which can belong to different trust domains, in order to leverage the wealth of pervasive resources and available capabilities. The use of digital certificates is suitable for pervasive networking because of its decentralized and dynamic nature. Nevertheless, the validation of such certificates can become a more complex and costly process than it is in fixed-infrastructure networks. This is because pervasive networks face challenges such as environments that change with a certain degree of randomness, ad-hoc interactions with foreign devices, temporal disconnections that make it difficult to access updated and required information, and limited devices running costly processes. For these reasons, we propose a user-centric architecture that extends the validation of digital certificates in an adaptive way. The main contribution consists of a decision engine that takes advantage of the specific local and external resources in an opportunistic fashion. The solution preserves the security level required for each application and the resource consumption of the user device.



},

keywords = {Certificate validation efficiency, Decision engine, inrisco, Pervasive networks, PKIX, Trust management},

pubstate = {published},

tppubtype = {article}

}

@article{campo008,

title = {Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks},

author = {Isabel Vara and Celeste Campo-Vázquez},

url = {http://hdl.handle.net/10016/28110},

doi = {https://doi.org/10.3390/s150717621},

issn = {1424-8220},

year  = {2015},

date = {2015-07-20},

urldate = {2015-07-20},

journal = {Sensors },

volume = {15},

issue = {7},

pages = {17621-17648},

abstract = {Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead.},

keywords = {inrisco, manet, olsrv2, service discovery},

pubstate = {published},

tppubtype = {article}

}

@article{campo009,

title = {Entropy-based privacy against profiling of user mobility},

author = {Alicia Rodriguez-Carrion and David Rebollo-Monedero and Jordi Forne and Celeste Campo-Vázquez and Carlos García-Rubio and Javier Parra-Arnau and Sajal Das},

url = {http://hdl.handle.net/10016/27924},

doi = {https://doi.org/10.3390/e17063913},

issn = {1099-4300},

year  = {2015},

date = {2015-06-10},

urldate = {2015-06-10},

journal = {Entropy},

volume = {17},

issue = {6},

pages = {3913-3946},

abstract = {Location-based services (LBSs) flood mobile phones nowadays, but their use poses an evident privacy risk. The locations accompanying the LBS queries can be exploited by the LBS provider to build the user profile of visited locations, which might disclose sensitive data, such as work or home locations. The classic concept of entropy is widely used to evaluate privacy in these scenarios, where the information is represented as a sequence of independent samples of categorized data. However, since the LBS queries might be sent very frequently, location profiles can be improved by adding temporal dependencies, thus becoming mobility profiles, where location samples are not independent anymore and might disclose the user's mobility patterns. Since the time dimension is factored in, the classic entropy concept falls short of evaluating the real privacy level, which depends also on the time component. Therefore, we propose to extend the entropy-based privacy metric to the use of the entropy rate to evaluate mobility profiles. Then, two perturbative mechanisms are considered to preserve locations and mobility profiles under gradual utility constraints. We further use the proposed privacy metric and compare it to classic ones to evaluate both synthetic and real mobility profiles when the perturbative methods proposed are applied. The results prove the usefulness of the proposed metric for mobility profiles and the need for tailoring the perturbative methods to the features of mobility profiles in order to improve privacy without completely loosing utility.},

keywords = {emrisco, entropy, location history, location-based services, perturbative methods, privacy},

pubstate = {published},

tppubtype = {article}

}

@article{ariascabarcos002,

title = {Blended Identity: Pervasive IdM for Continuous Authentication},

author = {Patricia Arias-Cabarcos and Florina Almenárez and Rubén Trapero and Daniel Díaz-Sánchez and Andrés Marín},

url = {https://ieeexplore.ieee.org/document/7118079},

doi = {https://doi.org/10.1109/MSP.2015.62},

issn = {1540-7993},

year  = {2015},

date = {2015-06-04},

urldate = {2015-06-04},

journal = {IEEE Xplore},

volume = {13},

issue = {3},

pages = {32-39},

abstract = {A proper identity management approach is necessary for pervasive computing to be invisible to users. Federated identity management is key to achieving efficient identity blending and natural integration in the physical and online layers where users, devices, and services are present.},

keywords = {blended identity, emrisco, identity management, IdM, Pervasive computing, Protocols, risk assessment, Security},

pubstate = {published},

tppubtype = {article}

}

@article{diazsanchez002,

title = {A distributed transcoding and content protection system: Enabling pay per quality using the cloud},

author = {Daniel Díaz-Sánchez and Rosa Sánchez-Guerrero and Patricia Arias and Florina Almenarez and Andrés Marín },

url = {https://link.springer.com/article/10.1007/s11235-014-9952-x},

doi = {https://doi.org/10.1007/s11235-014-9952-x},

issn = {1572-9451},

year  = {2015},

date = {2015-01-01},

urldate = {2015-01-01},

journal = {Telecommunication Systems},

volume = {61},

issue = {1},

pages = {59 - 76},

abstract = {Video coding is a process for adapting media content to the constraints of transmission networks delivery and terminal device visualization. Moreover, content protection is also necessary. Nowadays the heterogeneity of client devices is increasing leading to different resolutions, qualities and form factors. Due to this, transcoding and protection are essential processes to be conducted in modern video distribution networks to adapt video to devices and network constraints and to enable pay per quality schemas enforcing content licenses. Unfortunately, transcoding and protection can be no longer considered linear since every single content should be transcoded in several formats and sometimes protected, so it would require a long time to finish. Modern scalable coding techniques, as H264 SVC, can help to save processing power and bandwidth providing in a single stream several video versions. However, if the enhancements of a SVC encoded content are protected separately, it would possible to enable pay-per-quality providing an additional degree of freedom to content delivery industry. Unfortunatelly, transcoding and protection entail huge doses of processing power at provider side and should be distributed. Moreover, processing key streams to decrypt enhancements that were encrypted separately can increase the complexity at receiver side. Cloud computing emerges as a potential solution for coping with large population of users with heterogeneous visualization devices. The elastic nature of cloud computing can be an advantage given the difficulty to predict the computing resources video content would require to be distributed during the entire content life. This article describes a system that distributes and parallelizes the video transcoding process as well as the content encryption, following the SaaS approach in cloud computing. Moreover, the article describes an experimental approach for generating and processing a flexible key stream that would help to simplify key management at receiver side and would allow legacy receivers to consume SVC content with separate enhancement protection.},

keywords = {Cloud computing, content protection keyword, raudo2, transcoding},

pubstate = {published},

tppubtype = {article}

}

@article{garciarubio006,

title = {Service architecting and dynamic composition in pervasive smart ecosystems for the internet of things based on sensor network technology},

author = {Miguel Familiar and Jose Martínez and Carlos García-Rubio },

doi = {https://doi.org/10.3233/ais-140262},

isbn = {1876-1364},

year  = {2014},

date = {2014-05-05},

urldate = {2014-05-05},

journal = {Journal of Ambient Intelligence and Smart Environments },

volume = {6},

issue = {3},

pages = {331-333},

publisher = {Journal of Ambient Intelligence and Smart Environments},

abstract = {The present article summarizes the doctoral dissertation of Miguel S. Familiar.},

keywords = {IoT, pervasive smart ecosystems},

pubstate = {published},

tppubtype = {article}

}

@article{diazsanchez001,

title = {Media Gateway: bringing privacy to Private Multimedia Clouds connections},

author = {Daniel Díaz-Sánchez and Florina Almenarez and Andrés Marín and Rosa Sánchez-Guerrero and Patricia Arias },

url = {https://link.springer.com/article/10.1007/s11235-013-9783-1},

doi = {https://doi.org/10.1007/s11235-013-9783-1},

issn = {1572-9451},

year  = {2014},

date = {2014-02-01},

urldate = {2014-02-01},

journal = {Telecommunication Systems},

volume = {55},

issue = {2},

pages = {315-330},

abstract = {The growing interest in media sharing combined with the explosion of social applications have opened an opportunity window for cloud based applications for media management as Media Cloud, described in this article, that has brought the concept of Cloud Computing to home environments. Media Cloud provides a comprehensive and efficient solution for managing content among federated home environments. As part of the purpose of empowering the user role as well as to improve user experience, we placed significant efforts on interoperability and privacy protection when it comes to accessing cloud resources from other networks. This article describes a solution that enables limited devices to access contents located in private clouds, as Media Cloud, with the cooperation of network providers.},

keywords = {Cloud computing, multimedia, privacy, streaming},

pubstate = {published},

tppubtype = {article}

}

@article{almenarez010,

title = {To Federate or Not To Federate: A Reputation-Based Mechanism to Dynamize Cooperation in Identity Management },

author = {Patricia Arias-Cabarcos and Florina Almenares-Mendoza and Felix Gómez-Mármol and Andrés Marín- López },

doi = {https://doi.org/10.1007/s11277-013-1338-y},

issn = {0929-6212},

year  = {2013},

date = {2013-08-01},

urldate = {2013-08-01},

journal = {Wireless Personal Communications},

volume = {75},

issue = {3},

pages = {1769-1786},

abstract = {Identity Management systems cannot be centralized anymore. Nowadays, users have multiple accounts, profiles and personal data distributed throughout the web and hosted by different providers. However, the online world is currently divided into identity silos forcing users to deal with repetitive authentication and registration processes and hindering a faster development of large scale e-business. Federation has been proposed as a technology to bridge different trust domains, allowing user identity information to be shared in order to improve usability. But further research is required to shift from the current static model, where manual bilateral agreements must be pre-configured to enable cooperation between unknown parties, to a more dynamic one, where trust relationships are established on demand in a fully automated fashion. This paper presents IdMRep, the first completely decentralized reputation-based mechanism which makes dynamic federation a reality. Initial experiments demonstrate its accuracy as well as an assumable overhead in scenarios with and without malicious nodes.},

keywords = {cooperative systems, identity federation, identity management, trust and reputation management},

pubstate = {published},

tppubtype = {article}

}

@article{campo014,

title = {A Bandwidth-Efficient Service for Local Information Dissemination in Sparse to Dense Roadways},

author = {Estrella García-Lozano and Celeste Campo-Vázquez and Carlos García-Rubio and Alberto Cortés and Alicia Rodriguez-Carrion and Patricia Noriega-Vivas},

url = {http://hdl.handle.net/10016/27912},

doi = {https://doi.org/10.3390/s130708612},

issn = {1424-3210},

year  = {2013},

date = {2013-07-05},

urldate = {2013-07-05},

journal = {Sensors },

volume = {13},

issue = {7},

pages = {8612-8639},

abstract = {Thanks to the research on Vehicular Ad Hoc Networks (VANETs), we will be able to deploy applications on roadways that will contribute to energy efficiency through a better planning of long trips. With this goal in mind, we have designed a gas/charging station advertising system, which takes advantage of the broadcast nature of the network. We have found that reducing the number of total sent packets is important, as it allows for a better use of the available bandwidth. We have designed improvements for a distance-based flooding scheme, so that it can support the advertising application with good results in sparse to dense roadway scenarios.},

keywords = {bandwidth efficiency, multi-hop broadcast, service discovery, store-carry-forward, VANETs},

pubstate = {published},

tppubtype = {article}

}

@article{almenarez004,

title = {Overhead of using Secure Wireless Communications in Mobile Computing},

author = {Florina Almenares and Patricia Arias and Andrés Marín and Daniel Díaz-Sánchez and Rosa Sánchez

},

url = {https://ieeexplore.ieee.org/document/6531115

https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6531115},

doi = {https://doi.org/10.1109/TCE.2013.6531115},

issn = {0098-3063},

year  = {2013},

date = {2013-05-06},

urldate = {2013-05-06},

journal = {IEEE TRANSACTIONS ON CONSUMER ELECTRONICS},

volume = {59},

issue = {2},

pages = {335-342},

abstract = {Secure wireless communications are fundamental in any interaction in order to avoid security and privacy breaches, especially from mobile devices. The use of this kind of communications is far more frequent and the number of users increases day after day. This paper shows and analyzes the support, performance and consumption of cryptographic algorithms and cipher suites in terms of time and energy when secure communications (i.e., using SSL) are established according to different security levels. This study has been performed in distinct operating systems, and using different browsers and libraries.},

keywords = {Browsers, Ciphers, Energy and time performance, Energy consumption, Handheld devices, Secure wireless communications, servicioseguridad, SSL/TLS, Wireless communication},

pubstate = {published},

tppubtype = {article}

}

@article{ariascabarcos004,

title = {SuSSo: Seamless and Ubiquitous Single Sign-on for Cloud Service Continuity across devices},

author = {Patricia Arias-Cabarcos and Florina Almenárez-Mendoza and Rosa Sánchez-Guerrero and Andrés Marín-López and Daniel Díaz-Sánchez},

url = {https://ieeexplore.ieee.org/document/6415016

https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6415016},

doi = {https://doi.org/10.1109/TCE.2012.6415016},

issn = {0098-3063},

year  = {2012},

date = {2012-11-01},

urldate = {2012-11-01},

journal = {IEEE TRANSACTIONS ON CONSUMER ELECTRONICS},

volume = {58},

issue = {4},

pages = {1425-1433},

abstract = {The great variety of consumer electronic devices with support of wireless communications combined with the emerging Cloud Computing paradigm is paving the way to real anytime/anywhere computing. In this context, many services, such as music or video streaming, are delivered to the clients using Cloud-based providers. However, service continuity when moving across different terminals is still a major challenge. This paper proposes SuSSo, a novel middleware architecture that allows sessions initiated from one device to be seamlessly transferred to a second one, as might be desirable in the enjoyment of long running media.},

keywords = {Cloud computing, Computer architecture, context, middleware, Performance evaluation, personal multimedia devices, raudo2, Security, service continuity, sessionhandoff, xml},

pubstate = {published},

tppubtype = {article}

}