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Bahri, Leila
Publications (6 of 6) Show all publications
Bahri, L. & Girdzijauskas, S. (2019). Blockchain technology: Practical P2P computing (Tutorial). In: Proceedings - 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems, FAS*W 2019: . Paper presented at June 2019, Article number 8791982, Pages 249-2504th IEEE International Workshops on Foundations and Applications of Self* Systems, FAS*W 2019; Umea; Sweden; 16 June 2019 through 20 June 2019 (pp. 249-250). Institute of Electrical and Electronics Engineers (IEEE), Article ID 8791982.
Open this publication in new window or tab >>Blockchain technology: Practical P2P computing (Tutorial)
2019 (English)In: Proceedings - 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems, FAS*W 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, p. 249-250, article id 8791982Conference paper, Published paper (Refereed)
Abstract [en]

Blockchain technology comes with the promise to revolutionize the way current IT systems are organized as well as to revise how trust is perceived in the wider society. In spite of the wide attention that cyrpto-currencies (such as Bitcoin) have attracted, Blockchain technology is more likely to make an impact beyond ongoing speculations on cyrpto-currencies. Decentralized identity management, transparent supply-chain systems, and IoT governance and security are only few examples of research challenges for which this technology may hold substantial potential. Blockchain technology has emerged at the intersection of two well established research areas: peer-to-peer (P2P) computing and cryptography. In this tutorial, we provide a general overview of the main components behind this technology, we present the difference between the types of Blockchain available today, and we make a high level discussion on its potentials and limitations as well as possible research challenges.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
Blockchain, Consensus in Blockchain, DLT, PoW
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-262644 (URN)10.1109/FAS-W.2019.00066 (DOI)2-s2.0-85071419745 (Scopus ID)9781728124063 (ISBN)
Conference
June 2019, Article number 8791982, Pages 249-2504th IEEE International Workshops on Foundations and Applications of Self* Systems, FAS*W 2019; Umea; Sweden; 16 June 2019 through 20 June 2019
Note

QC 20191017

Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17Bibliographically approved
Bahri, L. & Girdzijauskas, S. (2019). Trust Mends Blockchains: Living up to Expectations. In: IEEE 39th International Conference on Distributed Computing Systems (ICDCS), Dallas, July 7-10 2019: . Paper presented at IEEE 39th International Conference on Distributed Computing Systems - ICDCS 2019.
Open this publication in new window or tab >>Trust Mends Blockchains: Living up to Expectations
2019 (English)In: IEEE 39th International Conference on Distributed Computing Systems (ICDCS), Dallas, July 7-10 2019, 2019Conference paper, Published paper (Refereed)
Abstract [en]

At the heart of Blockchains is the trustless leader election mechanism for achieving consensus among pseudoanonymous peers, without the need of oversight from any third party or authority whatsoever. So far, two main mechanisms are being discussed: proof-of-work (PoW) and proof-of-stake (PoS). PoW relies on demonstration of computational power, and comes with the markup of huge energy wastage in return of the stake in cyrpto-currency. PoS tries to address this by relying on owned stake (i.e., amount of crypto-currency) in the system. In both cases, Blockchains are limited to systems with financial basis. This forces non-crypto-currency Blockchain applications to resort to “permissioned” setting only, effectively centralizing the system. However, non-crypto-currency permisionless blockhains could enable secure and self-governed peer-to-peer structures for numerous emerging application domains, such as education and health, where some trust exists among peers. This creates a new possibility for valuing trust among peers and capitalizing it as the basis (stake) for reaching consensus. In this paper we show that there is a viable way for permisionless non-financial Blockhains to operate in completely decentralized environments and achieve leader election through proof-of-trust (PoT). In our PoT construction, peer trust is extracted from a trust network that emerges in a decentralized manner and is used as a waiver for the effort to be spent for PoW, thus dramatically reducing total energy expenditure of the system. Furthermore, our PoT construction is resilient to the risk of small cartels monopolizing the network (as it happens with the mining-pool phenomena in PoW) and is not vulnerable to sybils. We evluate security guarantees, and perform experimental evaluation of our construction, demonstrating up to 10-fold energy savings compared to PoW without trading off any of the decentralization characteristics, with further guarantees against risks of monopolization.

Keywords
Proof-of-Trust Blockchain, Blockchain, PoW, PoT
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:kth:diva-251639 (URN)
Conference
IEEE 39th International Conference on Distributed Computing Systems - ICDCS 2019
Note

QC 20190521

Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-21Bibliographically approved
Tran, N. H., Phung, C. V., Nguyen, B. Q. & Bahri, L. (2018). An effective privacy-preserving data coding in peer-to-peer network. International Journal of Computer Networks & Communications, 10(3), 55-74
Open this publication in new window or tab >>An effective privacy-preserving data coding in peer-to-peer network
2018 (English)In: International Journal of Computer Networks & Communications, ISSN 0975-2293, E-ISSN 0974-9322, Vol. 10, no 3, p. 55-74Article in journal (Refereed) Published
Abstract [en]

Coding Opportunistically (COPE) is a simple but very effective data coding mechanism in the wireless network. However, COPE leaves risks for attackers easily getting the private information saved in the packets, when they move through the network to their destination nodes. Hence, a lightweight cryptographic approach, namely SCOPE, was proposed to consolidate COPE against the honest-but-curious and malicious attacks. Honest-but-curious attack serves adversaries who accurately obey the protocol but try to learn as much private information as possible for their curiosity. Additionally, this kind of attack is not destructive consequently. However, it may leave the backdoor for the more dangerous attacks carrying catastrophes to the system. Malicious attack tries to learn not only the private information but also modifies the packet on harmful purposes. To cope with this issue, in this work, a lightweight cryptographic approach improves COPE, namely SCOPE, that is defensive to the both attacks. The private information in the COPE packet are encrypted by Elliptic Curve Cryptography (ECC), and an additional information is inserted into SCOPE packets served for the authentication process using the lightweight hash Elliptic Curve Digital Signature Algorithm (ECDSA). We then prove our new protocol is still guaranteed to be a secure method of data coding, and to be light to effectively operate in the peer-to-peer wireless network.

Place, publisher, year, edition, pages
Academy and Industry Research Collaboration Center (AIRCC), 2018
Keywords
Elliptic Curve Cryptography (ECC), Elliptic Curve Digital Signature Algorithm (ECDSA), Homomorphic encryption, Honest-But-Curious Attack, Malicious attac, Network coding, Peer-to-Peer
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-247404 (URN)10.5121/IJCNC.2018.10305 (DOI)2-s2.0-85062328652 (Scopus ID)
Note

QC20190502

Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-05-03Bibliographically approved
Kefato, Z., Sheikh, N., Bahri, L., Soliman, A., Girdzijauskas, S. & Montresor, A. (2018). CAS2VEC: Network-Agnostic Cascade Prediction in Online Social Networks. In: The 5th International Symposium on Social Networks Analysis, Management and Security (SNAMS-2018): . Paper presented at The 5th International Symposium on Social Networks Analysis, Management and Security (SNAMS-2018). IEEE
Open this publication in new window or tab >>CAS2VEC: Network-Agnostic Cascade Prediction in Online Social Networks
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2018 (English)In: The 5th International Symposium on Social Networks Analysis, Management and Security (SNAMS-2018), IEEE, 2018Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
IEEE, 2018
National Category
Computer Systems
Identifiers
urn:nbn:se:kth:diva-239542 (URN)2-s2.0-85060045802 (Scopus ID)
Conference
The 5th International Symposium on Social Networks Analysis, Management and Security (SNAMS-2018)
Note

QC 20181130

Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2019-06-26Bibliographically approved
Kefato, Z. T., Sheikh, N., Bahri, L., Soliman, A., Montresor, A. & Girdzijauskas, S. (2018). CAS2VEC: Network-Agnostic Cascade Prediction in Online Social Networks. In: : . Paper presented at 2018 FIFTH INTERNATIONAL CONFERENCE ON SOCIAL NETWORKS ANALYSIS, MANAGEMENT AND SECURITY (SNAMS) (pp. 72-79). IEEE
Open this publication in new window or tab >>CAS2VEC: Network-Agnostic Cascade Prediction in Online Social Networks
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2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Effectively predicting whether a given post or tweet is going to become viral in online social networks is of paramount importance for several applications, such as trend and break-out forecasting. While several attempts towards this end exist, most of the current approaches rely on features extracted from the underlying network structure over which the content spreads. Recent studies have shown, however, that prediction can be effectively performed with very little structural information about the network, or even with no structural information at all. In this study we propose a novel network-agnostic approach called CAS2VEC, that models information cascades as time series and discretizes them using time slices. For the actual prediction task we have adopted a technique from the natural language processing community. The particular choice of the technique is mainly inspired by an empirical observation on the strong similarity between the distribution of discretized values occurrence in cascades and words occurrence in natural language documents. Thus, thanks to such a technique for sentence classification using convolutional neural networks, CAS2VEC can predict whether a cascade is going to become viral or not. We have performed extensive experiments on two widely used real-world datasets for cascade prediction, that demonstrate the effectiveness of our algorithm against strong baselines.

Place, publisher, year, edition, pages
IEEE, 2018
National Category
Software Engineering
Identifiers
urn:nbn:se:kth:diva-252430 (URN)10.1109/SNAMS.2018.8554730 (DOI)000466979100012 ()2-s2.0-85060045802 (Scopus ID)
Conference
2018 FIFTH INTERNATIONAL CONFERENCE ON SOCIAL NETWORKS ANALYSIS, MANAGEMENT AND SECURITY (SNAMS)
Note

QC 20190715

Available from: 2019-07-15 Created: 2019-07-15 Last updated: 2019-07-15Bibliographically approved
Kefato, Z., Sheikh, N., Bahri, L., Soliman, A., Girdzijauskas, S. & Montresor, A. (2018). CaTS: Network-Agnostic Virality Prediction Model to Aid Rumour Detection. In: : . Paper presented at International Workshop on Rumours and Deception in Social Media (RDSM 2018).
Open this publication in new window or tab >>CaTS: Network-Agnostic Virality Prediction Model to Aid Rumour Detection
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2018 (English)Conference paper, Published paper (Refereed)
National Category
Computer Systems
Identifiers
urn:nbn:se:kth:diva-239543 (URN)
Conference
International Workshop on Rumours and Deception in Social Media (RDSM 2018)
Note

QC 20181130

Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-30Bibliographically approved
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