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Blockchain Hybrid-model Scheme for Scalable Cross-domain Authorisation

Blockchain: Research and Applications 2025年

作者： Munkenyi Mukhandi Jorge Granjal João P. Vilela CISUC Dep. of Informatics Engineering University of Coimbra Portugal CISUC Dep. of Informatics Engineering & CRACS / INESCTEC & Dep. of Computer Science Faculty of Sciences University of Porto Portugal

We introduce a novel blockchain-based inter-ledger authorization scheme, a unique solution designed to support delegated authorization management in cross-domain cloud environments. This innovative approach enables client applications, acting on behalf of a user, to request access to specific resources owned by a different organization. It benefits cross-domain multi-cloud applications, such as large-scale collaboration projects involving multiple cloud service providers. Multi-cloud presents authorization challenges because of complex access control operations in multiple distinct domains. OAuth2 is the state-of-the-art choice for delegated authorization. However, it falls short in handling such complex interactions with multiple authorization servers and resource servers, and this is our motivation. Compared to OAuth2, our approach overcomes the limitations of a centralized model and achieves coordinated distinct delegations among multiple entities without a third-party trusted component. Authorization servers are blockchain participants and designated access token issuers, ensuring minimum client data collection and promoting client privacy. Multiple smart contracts are deployed in our multi-ledger blockchain environment to guarantee the provenance of the authorization operations and facilitate scalable cross-domain authorization. Our ‘hybrid inter-ledger model’, combines security techniques such as blockchain-based device authentication, hashed-time locks (HTCLs), and service discovery. The blockchain-based device authentication ensures secure and trusted interactions, HTCLs enable time-bound transactions, and service discovery simplifies finding and connecting to the required cloud services. Our experimental evaluation provides insights into the scalability of our approach, which achieves decentralized authorization in a multi-cloud environment with acceptable latencies compared to related works and shows stable throughput against concurrent authorization reque

关键词： OAuth2 multi-cloud decentralised coordinated authorisation multi-ledgers blockchain security smart contracts

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Evaluating flexibility degrees in optical networks

Evaluating flexibility degrees in optical networks

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Optical Fiber Communication Conference, OFC 2015

作者： Christodoulopoulos, Konstantinos Varvarigos, Emmanouel Manos Computer Engineering and Informatics Dep. University of Patras Computer Technology Institute and Press -Diophantus Patra Greece

We consider an IP over flexgrid network and present a joint IP routing, distance-adaptive routing and spectrum allocation formulation. We evaluate the performance of fixed- and flex-grid switches, fixed transponders, ... 详细信息

ISBN: (纸本)9781557529374

关键词： Optical fibers

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Gamification of in-classroom diagram design for science students

Gamification of in-classroom diagram design for science stud...

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International Conference on e-Learning 2019, EL 2019

作者： Mallas, Andreas Xenos, Michalis Computer Engineering and Informatics Dep. University of Patras Rio Campus University Building B Patras Greece

ISBN: (纸本)9789898533883

Merging the content of learning with the motivation of games can be a successful combination, if done properly and supported by the appropriate tool. Towards this goal, we developed Diagramatic an environment used to gamify the in-classroom activity of designing diagrams during a lecture. Using Diagramatic the professor, instead of lecturing about diagrams or showing examples of such diagrams, can design short games where the students could play by competing during the lecture. Diagramatic is a complete environment offering to the professor a design application to create games and a management application. The management application is used for monitoring the games while students play, as well as to present the results to the students after the end of each game, or to evaluate these results after classroom time. The students may use the mobile application on their mobiles to practice by designing diagrams outside of the classroom, as well as to play a game during classroom time, but only after the professor starts this game. The environment handles the communication from students' mobiles to the professor's applications and vice versa, while the students submit their diagrams or receive the correct ones, so to proceed to follow up games. The current version of Diagramatic is tailored for designing flow graphs used for path testing into a higher education software engineering course, but the environment can be used in any similar case requiring the design of diagrams (e.g. math, physics, chemistry). © Copyright 2019 IADIS Press All rights reserved.

关键词： Students

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Orchestrating feedback for hybrid rateless codes 21

Orchestrating feedback for hybrid rateless codes

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21st European Wireless Conference, European Wireless 2015

作者： Faneca, Carlos Vieira, José Zúquete, André Cano, Julio Moreira, André Almeida, Luís Department of Electronics Telecommunications and Informatics IEETA University of Aveiro Portugal Dep. Electrical and Computer Engineering IT Portugal

ISBN: (纸本)9783800739769

In several scenarios, such as in training and education, it is frequently important to distribute large files to many clients, e.g., operating system boot images or raw data files. To carry out such distribution efficiently, we use wireless broadcast and Fountain Codes with low density random encoding to tolerate network packet losses. In particular, we use a hybrid coding technique that combines forward coding using weak LT Codes with a feedback phase at the end, which allows concluding the process faster with lower computing cost than traditional LT codes and without the precoding of Raptor Codes. The novelty of our approach consists of using a scheduler to orchestrate the clients' feedback. The scheduler is scalable in the number of clients and allows the server to know which clients are active and in which phase, and control the coding process adequately. We show early experimental results from simulation and from a practical testbed that confirm the effectiveness of our proposed approach. With a feedback phase triggered when just 2% symbols are missing, we reduced the codewords overhead by 2.5% with respect to traditional LT Codes. We also achieved a high reduction in computational overhead associated to weak LT Codes. Moreover, this approach gives the server full control over the transfer, avoiding producing codewords beyond those strictly needed. Using 802.11g in ad-hoc mode and exploiting TXOPs, we transferred a 100MB file in 21.77s with up to 10% losses. © VDE Verlag GMBH, Berlin, Offenbach, Germany.

关键词： Network coding

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Speaker Diarization for Low-Resource Languages Through Wav2vec Fine-Tuning

arXiv

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arXiv 2025年

作者： Abdullah, Abdulhady Abas Taher Karim, Sarkhel H. Ahmed, Sara Azad Tariq, Kanar R. Rashid, Tarik A. Artificial Intelligence and Innovation Centre University of Kurdistan Hewler Erbil Iraq Computer Science Department College of Science University of Halabja Kurdistan Region Iraq Computer Engineering Dep Komar University of Science and Technology Iraq Information Technology Department Technical College of Informatics Sulaimani Polytechnic University Sulaymaniyah Iraq

Speaker diarization, a core problem in speech processing, entails partitioning a given audio stream according to the speakers. Even though progress has been made in the development of the models for high-resource languages, there is still a set of specific difficulties in going through a similar process for low-resource languages such as Kurdish: there are very few annotated datasets available;the language has dialects;speakers use code-switching a lot. These challenges are met in this study by training the Wav2Vec 2.0 SSL model on a Kurdish dataset prepared for this purpose. Thanks to transfer learning, it was possible to transfer multilingual representations learnt in other languages to the phonetic and acoustic features of Kurdish speech. The general Diarization Error Rate (DER) was reduced by 7.2%, and the cluster purity increased by 13% when compared to the baseline algorithm. They show that making improvements in any state-of-the-art model can help in enhancing the performance of under-resourced languages. Implications of this work include transcription services for Kurdish-language media programs, as well as speaker segmentation in multilingual call centers, teleconferencing, and videoconferencing systems. Therefore, this work demonstrates that self-supervised and transfer techniques can improve speaker diarization for Kurdish and other low-resource languages with diverse features. The approach provides a base for building effective diarization systems in other understudied languages, which remains essential for speech technology’s equity. © 2025, CC BY.

关键词： Speech enhancement

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Assessment of Defect Type influence in Complex and Integrated Space Systems: Analysis Based on ODC and ISVV Issues 45

Assessment of Defect Type influence in Complex and Integrate...

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45th Annual IEEE/IFIP International Conference on dependable Systems and Networks Workshops, DSN-W 2015

作者： Silva, Nuno Vieira, Marco Ricci, Dario Cotroneo, Domenico CISUC Department of Informatics Engineering University of Coimbra Coimbra Portugal CINI Dep. of Computer and Control Engineering Federico II University of Naples Naples Italy

ISBN: (纸本)9781467380447

Safety or mission critical systems are those where failures should be avoided at all costs. engineering processes, techniques and tools are, however, not perfect, and lead to software and systems with flaws. This paper presents an analysis of the impact of late found issues versus the fault types for critical aerospace systems. These issues are the independently detected faults that remain once the engineering processes that are required by European space standards have been applied and the engineering teams have performed their verification and validation activities. This study presents the analysis of the fault impact versus fault type distribution according to the detection phases and to the issues severity/type and presents recommendations to improve space systems engineering. © 2015 IEEE.

关键词： Quality control

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Blockchain-based scalable authentication for IoT: Poster abstract 20

Blockchain-based scalable authentication for IoT: Poster abs...

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18th ACM Conference on Embedded Networked Sensor Systems, SenSys 2020

作者： Mukhandi, Munkenyi Andrade, Eduardo Damião, Francisco Granjal, Jorge Vilela, João P. Cisuc Dep. of Informatics Engineering University of Coimbra Portugal Pdmfc Lisbon Portugal CRACS/INESCTEC Cisuc Dep. of Computer Science Faculty of Sciences University of Porto Portugal

ISBN: (纸本)9781450375900

Device identity management and authentication are one of the critical and primary security challenges in IoT. In order to decrease the IoT attack surface and provide protection from security threats such as introduction of fake IoT nodes and identity theft, IoT requires scalable device identity management systems and resilient device authentication mechanisms. Existing mechanisms for device identity management and device authentication were not designed for huge number of devices and therefore are not suitable for IoT environments. This work presents results of a blockchain-based identity management approach with consensus authentication, as a scalable solution for IoT device authentication management. Our identity management approach relies on having a blockchain secure tamper proof registry and lightweight consensus-based identity authentication. © 2020 Owner/Author.

关键词： Blockchain

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Dynamic secure aspect modeling with UML: From models to code 05

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8th International Conference on Model Driven engineering Languages and Systems, MoDELS 2005

作者： Jürjens, Jan Houmb, Siv Hilde Software and Systems Engineering Dep. of Informatics TU Munich Germany Department of Computer and Information Science Norwegian University of Science and Technology Norway

ISBN: (纸本)3540290109

Security engineering deals with modeling, analysis, and implementation of complex security mechanisms. The dynamic nature of such mechanisms makes it difficult to anticipate undesirable emergent behavior. In this work, we propose an approach to develop and analyze security-critical specifications and implementations using aspect-oriented modeling. Since we focus on the dynamic views of a system, our work is complementary to existing approaches to security aspects mostly concerned with static views. Our approach includes a link to implementations in so far as the code which is constructed from the models can be analyzed automatically for satisfaction of the security requirements stated in the UML diagrams. We present tool support for our approach. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Security of data

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Multi-RAT Fiber-Wireless Technologies towards 6G Networks 23

Multi-RAT Fiber-Wireless Technologies towards 6G Networks

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23rd International Conference on Transparent Optical Networks, ICTON 2023

作者： Vagionas, Chris Maximidis, Ronis Kanta, Konstantina Toumasis, Panagiotis Giannoulis, Giannis Apostolopoulos, Dimitris Kalfas, George Gatzianas, Marios Mesodiakaki, Agapi Avramopoulos, Hercules Miliou, Amalia Pleros, Nikos Aristotle University of Thessaloniki CIRI Dep. of Informatics 54636 Greece National Technical University of Athens School of Electrical and Computer Engineering Greece

ISBN: (纸本)9798350303032

At the dawning of the beyond 5G era, broadband last mile connectivity is stimulating rapid developments in optical and wireless technologies that will efficiently handle the traffic generated by mobile users and demanding network applications. To this end, multiple Radio Access (multi-RAT) technologies operating at various millimeter wave (mmWave) frequency bands, e.g., V-/E-/D-band are being actively pursued, in parallel with the investigation of efficient fiber wireless fronthaul schemes, e.g. Analog Radio over Fiber (aRoF) or Intermediate Frequency over Fiber (IFoF), to deliver low-complexity, broadband, last-mile connectivity. However, integration of such novel technologies in an actual mobile network infrastructure remains a challenge, as it needs to support compatibility with the network operators' equipment. The current talk aims to present a holistic Fiber Wireless (FiWi) connectivity, demonstrating the co-existence of Analog and Digital RoF traffic along with flexible, reconfigurable point-to-multipoint connectivity to multi-RAT antenna units. Experimental results on high capacity FiWi fronthaul links operating in the V- (60 GHz) and D- (145 GHz) will be presented. Moreover, end-to-end, integrated real-time traffic and network operation will also be discussed and experimentally presented, indicating a possible technology roadmap towards multi-RAT 6G networks. © 2023 IEEE.

关键词： Radio-over-fiber

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A mechanism for multicast multimedia data with adaptive QoS characteristics 6

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6th International Conference on Protocols for Multimedia Systems, PROMS 2001

作者： Bouras, Christos Gkamas, A. Computer Engineering and Informatics Dep. Univ. Of Patras PatrasGR26500 Greece Computer Technology Institute Riga Feraiou 61 PatrasGR 26221 Greece

ISBN: (纸本)9783540427087

In this paper, we describe a mechanism for adaptive transmission of multimedia data, which is based on real time protocols. The proposed mechanism can be used for multicast multimedia data over heterogeneous networks, like the Internet, and has the capability to adapt the transmission of the multimedia data to network changes. In addition, the adaptive multicast transmission mechanism uses an inter-receiver fairness function in order to treat the group of receivers with fairness in a heterogeneous environment. The proposed mechanism uses a "friendly" to the network users congestion control policy to control the transmission of the data. We evaluate the adaptive multicast transmission mechanism through a number of simulations in order to examine its fairness to the group of receivers and its behavior against TCP and UDP data streams. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Heterogeneous networks

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