{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,2]],"date-time":"2026-01-02T07:47:27Z","timestamp":1767340047964,"version":"build-2065373602"},"reference-count":27,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2021,11,26]],"date-time":"2021-11-26T00:00:00Z","timestamp":1637884800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000780","name":"European Commission","doi-asserted-by":"publisher","award":["871536"],"award-info":[{"award-number":["871536"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Computers"],"abstract":"<jats:p>Cloud Infrastructure as a Service (IaaS) Service Level Agreements (SLAs) assessment constitutes the de facto area of interest and applications in the public cloud infrastructure. However, the domination of colossal corporations tends to monopolize the way metrics and Key Performance Indicators (KPIs) are measured and determined, leading to governed environments where the clientele is unable to obtain accurate and unbiased assessment of SLAs. Leaning toward SLA self-assessment, this paper provides a fair SLA consensus approach with innate transparency and privacy by leveraging permissioned blockchains that are equipped with Trusted Execution Environments (TEEs). The SLA assessment intelligence is performed inside enclaved smart contracts isolated from the on-chain entities views. The result constitutes a permissioned blockchain ecosystem where the IaaS and their clientele commonly agree on all the respective SLA monitoring and computation rules beforehand, as defined in any SLA assessment process, while the SLA consensus scheme constantly audits the SLA metrics based on these pre-approved regulations.<\/jats:p>","DOI":"10.3390\/computers10120159","type":"journal-article","created":{"date-parts":[[2021,11,28]],"date-time":"2021-11-28T22:19:16Z","timestamp":1638137956000},"page":"159","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Reinforcing SLA Consensus on Blockchain"],"prefix":"10.3390","volume":"10","author":[{"given":"Nikolaos","family":"Kapsoulis","sequence":"first","affiliation":[{"name":"Innov-Acts Ltd., Nicosia 1101, Cyprus"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alexandros","family":"Psychas","sequence":"additional","affiliation":[{"name":"Electrical and Computer Engineering School, National Technical University of Athens, 157 80 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7658-2559","authenticated-orcid":false,"given":"Antonios","family":"Litke","sequence":"additional","affiliation":[{"name":"Electrical and Computer Engineering School, National Technical University of Athens, 157 80 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Theodora","family":"Varvarigou","sequence":"additional","affiliation":[{"name":"Electrical and Computer Engineering School, National Technical University of Athens, 157 80 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,26]]},"reference":[{"unstructured":"Columbus, L. (2021, November 11). Roundup of Cloud Computing Forecasts And Market Estimates, 2016. Forbes. [Online]. Available online: https:\/\/www.forbes.com\/sites\/louiscolumbus\/2016\/03\/13\/roundup-of-cloud-computing-forecasts-and-market-estimates-2016\/.","key":"ref_1"},{"unstructured":"(2021, November 11). Amazon Cloudwatch. Available online: https:\/\/aws.amazon.com\/cloudwatch\/.","key":"ref_2"},{"unstructured":"(2021, November 11). Microsoft Monitor. Available online: https:\/\/azure.microsoft.com\/en-us\/services\/monitor\/.","key":"ref_3"},{"unstructured":"(2021, November 11). Google Monitoring. Available online: https:\/\/cloud.google.com\/monitoring\/.","key":"ref_4"},{"doi-asserted-by":"crossref","unstructured":"Sabt, M., Achemlal, M., and Bouabdallah, A. (2015, January 20\u201322). Trusted Execution Environment: What It is, and What It is Not. Proceedings of the 2015 IEEE Trustcom\/BigDataSE\/ISPA, Helsinki, Finland.","key":"ref_5","DOI":"10.1109\/Trustcom.2015.357"},{"doi-asserted-by":"crossref","unstructured":"Nguyen, T.-V., L\u00ea, T.-V., Dao, B., and Nguyen-An, K. (2019, January 26\u201328). Leveraging Blockchain in Monitoring SLA-Oriented Tourism Service Provisioning. Proceedings of the International Conference on Advanced Computing and Applications (ACOMP), Nha Trang, Vietnam.","key":"ref_6","DOI":"10.1109\/ACOMP.2019.00014"},{"doi-asserted-by":"crossref","unstructured":"Ranchal, R., and Choudhury, O. (2020, January 21\u201322). SLAM: A Framework for SLA Management in Multicloud ecosystem using Blockchain. Proceedings of the IEEE Cloud Summit, Harrisburg, PA, USA.","key":"ref_7","DOI":"10.1109\/IEEECloudSummit48914.2020.00011"},{"doi-asserted-by":"crossref","unstructured":"Alowayed, Y., Canini, M., Marcos, P., Chiesa, M., and Barcellos, M. (2018). Picking a Partner: A Fair Blockchain Based Scoring Protocol for Autonomous Systems. Proc. Appl. Netw. Res. Workshop, 33\u201339.","key":"ref_8","DOI":"10.1145\/3232755.3232785"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e5800","DOI":"10.1002\/cpe.5800","article-title":"Distributed service-level agreement management with smart contracts and blockchain","volume":"33","author":"Uriarte","year":"2021","journal-title":"Concurr. Comput. Pract. Exper"},{"doi-asserted-by":"crossref","unstructured":"Alzubaidi, A., Mitra, K., Patel, P., and Solaiman, E. (2020, January 14\u201316). A Blockchain-based Approach for Assessing Compliance with SLA-guaranteed IoT Services. Proceedings of the IEEE International Conference on Smart Internet of Things (SmartIoT), Beijing, China.","key":"ref_10","DOI":"10.1109\/SmartIoT49966.2020.00039"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1109\/MITP.2019.2909216","article-title":"Blockchain-Based SLA Management in the Context of IoT","volume":"21","author":"Alzubaidi","year":"2019","journal-title":"IT Prof."},{"doi-asserted-by":"crossref","unstructured":"D\u2019Angelo, G., Ferretti, S., and Marzolla, M. (2018, January 15). A Blockchain-based Flight Data Recorder for Cloud Accountability. Proceedings of the 1st Workshop on Cryptocurrencies and Blockchains for Distributed Systems, Munich, Germany.","key":"ref_12","DOI":"10.1145\/3211933.3211950"},{"doi-asserted-by":"crossref","unstructured":"Tan, W., Zhu, H., Tan, J., Zhao, Y., Xu, L.D., and Guo, K. (2021). A novel service level agreement model using blockchain and smart contract for cloud manufacturing in industry 4.0. Enterp. Inf. Syst., 1\u201326.","key":"ref_13","DOI":"10.1080\/17517575.2021.1939426"},{"unstructured":"(2021, November 11). Hyperledger Fabric. Available online: https:\/\/www.hyperledger.org\/use\/fabric.","key":"ref_14"},{"unstructured":"(2021, November 11). Fabric Private Chaincode. Available online: https:\/\/github.com\/hyperledger-labs\/fabric-private-chaincode.","key":"ref_15"},{"unstructured":"(2021, November 11). ISO\/IEC 19086-2:2018 Cloud Computing\u2014Service Level Agreement (SLA) Framework\u2014Part 2: Metric Model. Available online: https:\/\/www.iso.org\/standard\/67546.html.","key":"ref_16"},{"unstructured":"(2021, November 11). Amazon Compute Service Level Agreement. Available online: https:\/\/aws.amazon.com\/compute\/sla\/.","key":"ref_17"},{"unstructured":"(2021, November 11). SLALOM SLA Specification and Reference Model. Available online: http:\/\/slalom-project.eu\/content\/final-version-slalom-sla-technical-specification-and-reference-model.","key":"ref_18"},{"doi-asserted-by":"crossref","unstructured":"Androulaki, E., Barger, A., Bortnikov, V., Cachin, C., Christidis, K., De Caro, A., Enyeart, D., Ferris, C., Laventman, G., and Manevich, Y. (2018, January 23\u201326). Hyperledger fabric: A distributed operating system for permissioned blockchains. Proceedings of the thirteenth EuroSys conference (EuroSys\u201918), Porto, Portugal.","key":"ref_19","DOI":"10.1145\/3190508.3190538"},{"unstructured":"Benet, J. (2021, November 11). IPFS\u2013Content Addressed, Versioned, P2P File System. Available online: https:\/\/ipfs.io\/.","key":"ref_20"},{"unstructured":"Diego, O., and John, O. (2014, January 19\u201320). In search of an understandable consensus algorithm. Proceedings of the 2014 USENIX Conference on USENIX Annual Technical Conference (USENIX ATC\u201914), Philadelphia, PA, USA.","key":"ref_21"},{"unstructured":"(2021, November 11). Amazon AWS General Purpose Instance t2.nano. Available online: https:\/\/aws.amazon.com\/ec2\/instance-types\/.","key":"ref_22"},{"unstructured":"(2021, November 11). Go Chaincode Contract API. Available online: https:\/\/github.com\/hyperledger\/fabric-contract-api-go\/tree\/main\/contractapi.","key":"ref_23"},{"key":"ref_24","first-page":"260","article-title":"RSA-OAEP Is Secure under the RSA Assumption","volume":"2139","author":"Fujisaki","year":"2018","journal-title":"Adv. Cryptol."},{"unstructured":"(2021, November 11). Standards for Efficient Cryptography. Available online: http:\/\/www.secg.org\/sec2-v2.pdf.","key":"ref_25"},{"unstructured":"Nguyen, M., Loghin, D., and Dinh, T.T. (2021). Understanding the Scalability of Hyperledger Fabric. arXiv.","key":"ref_26"},{"doi-asserted-by":"crossref","unstructured":"Dreyer, J., Fischer, M., and T\u00f6njes, R. (2020). Performance analysis of hyperledger fabric 2.0 blockchain platform. Proceedings of the Workshop on Cloud Continuum Services for Smart IoT Systems (CCIoT \u201920), Association for Computing Machinery.","key":"ref_27","DOI":"10.1145\/3417310.3431398"}],"container-title":["Computers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-431X\/10\/12\/159\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:36:04Z","timestamp":1760168164000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-431X\/10\/12\/159"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,11,26]]},"references-count":27,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2021,12]]}},"alternative-id":["computers10120159"],"URL":"https:\/\/doi.org\/10.3390\/computers10120159","relation":{},"ISSN":["2073-431X"],"issn-type":[{"type":"electronic","value":"2073-431X"}],"subject":[],"published":{"date-parts":[[2021,11,26]]}}}