{"id":405,"date":"2019-03-22T14:02:40","date_gmt":"2019-03-22T14:02:40","guid":{"rendered":"https:\/\/website.prod.unilu.spikeseed.cloud\/fr\/news\/first-reputation-based-system-improves-blockchain-security\/"},"modified":"2019-03-22T14:02:40","modified_gmt":"2019-03-22T14:02:40","slug":"first-reputation-based-system-improves-blockchain-security","status":"publish","type":"news","link":"https:\/\/www.uni.lu\/fr\/news\/first-reputation-based-system-improves-blockchain-security\/","title":{"rendered":"First Reputation-based system improves Blockchain security"},"content":{"rendered":"<section class=\"wp-block-unilux-blocks-free-section section\"><div class=\"container xl:max-w-screen-xl\"><p>In June 2014 Bitcoin users were confronted with the unthinkable. A Bitcoin mining pool called Ghash.io had attained control over 51% of the network&rsquo;s total mining power. Bitcoin users, miners and developers responded with shock, panic and denial, but could do nothing about the fact that Ghash.io now had the ability to manipulate the network at will.<\/p><p>Researchers at the University of Luxembourg are now the first to propose a blockchain system that mitigates this risk, guaranteeing proper performance even when more than 51% of the system\u2019s computing power is controlled by an attacker. Their system, <strong>RepuCoin<\/strong>, makes it thousands of times more expensive to attack than Bitcoin. It was developed at the University\u2019s <a href=\"https:\/\/wwwfr.uni.lu\/snt\" target=\"_self\" title=\"\" rel=\"noopener\">Interdisciplinary Centre for Security, Reliability and Trust<\/a>, and has the potential to be applied in a number of global sectors including fintech, energy, food supply chains, health care and future 5G telecommunications networks.<\/p><p>At their heart, cryptocurrencies such as Bitcoin, which use blockchain technology, are distributed ledgers. Each block in a blockchain is a record of transactions, like a page in a ledger. When the page is full, we open a new page. In the case of a cryptocurrency we gain a new block in the blockchain. And they are distributed because the whole network sees and approves new blocks through democratic consensus. Users therefore don\u2019t have to place their trust \u2013 and money \u2013 in the hands of a single central authority.<\/p><p>The challenge here is that if new blocks are created too quickly and without regulation, then this can result in conflicting blocks. To prevent this, so-called \u2018miners\u2019 \u2013 this can be anyone with access to specialised hardware \u2013 perform an arbitrary but time-consuming cryptographic computing task to create and verify a new block.<\/p><p>Despite this safety mechanism, the Bitcoin system suffers from a known weakness. If a given miner owns a majority of the total mining power in the system it ceases to be distributed. That miner can add blocks faster than the rest of the network, reject blocks proposed by competing miners, target users with exorbitant transaction fees and reject selected transactions. \u201cThis vulnerability can be exploited through a flash attack, where someone briefly hires computing power and can therefore carry out such 51% attacks,\u201d explains lead researcher Dr. Jiangshan Yu \u2013 previously at the University\u2019s Interdisciplinary Centre for Security, Reliability and Trust and now a Lecturer at <a href=\"https:\/\/www.monash.edu\/\" target=\"_blank\" title=\"\" rel=\"noopener\">Monash University<\/a>, Australia.<\/p><p>To prevent such flash attacks from influencing the validity of a blockchain transfer, Yu and his colleagues have developed a solution that takes the long-term performance and reliability of a miner into account. Their system \u2013 RepuCoin \u2013 is the first to provide guarantees even when an attacker temporarily dominates more than 50 per cent of the system\u2019s computing power.<\/p><p>\u201cRather than simply using computer processing power to dictate how much of the system a miner controls, the RepuCoin algorithm uses what we call reputation,\u201d says Yu. Unlike social reputation, this is a strictly mathematical quality which accumulates through consistent and honest mining over long periods, like charging a battery before it can be used. It makes RepuCoin the first such system to be resilient against miners holding 51% or more of the network\u2019s computing resources.<\/p><p>A happy consequence of their method is that it also accelerates transaction processing. Bitcoin users currently have to wait hours or days for a transaction to be verified because fewer than 20 transactions can be performed worldwide per second. \u201cThe algorithm we propose brings it up to 10,000 transactions per second,\u201d says Yu, who hopes that one or more cryptocurrencies will opt to use it in the near future.<\/p><p>Co-author Prof. Paulo Esteves-Ver\u00edssimo, who leads SnT\u2019s work in critical and extreme security and dependability, says: \u201cIt\u2019s an elegant solution to a problem that many thought was insoluble. Existing systems always linked computational power to voting power. We separated them, and now someone could join RepuCoin with 99% of the total computing power and they still wouldn\u2019t be able to attack it.\u201d<\/p><p>For reference:\u00a0<a href=\"http:\/\/hdl.handle.net\/10993\/38630\" target=\"_blank\" title=\"\" rel=\"noopener\">RepuCoin: Your Reputation is Your Power<\/a>\u00a0(\u00a9\u00a0IEEE Transactions on Computers 2019)\u00a0Jiangshan Yu, David Kozhaya, J\u00e9r\u00e9mie Decouchant, Paulo Verissimo<\/p><figure class=\"wp-block-dev4-reusable-blocks-image  object-fit--contain\">\n    \n<img decoding=\"async\" class=\"wp-block-image unilux-custom-image-block\"\n                alt=\"\"\n            src=\"https:\/\/www.uni.lu\/wp-content\/uploads\/sites\/11\/2023\/07\/snt_10th_anniversary-2.png\"\n                    style=\"object-position: 50.00% 50.00%; font-family: &quot;object-fit: contain; object-position: 50.00% 50.00%;&quot;; aspect-ratio: 1\/1; object-fit: contain; width: 100%;\"\n        loading=\"lazy\"\n\/>    <\/figure><p>\u00a0 \u00a0\u00a0<\/p><p><strong>SnT is turning 10!<\/strong> We\u2019ve come a long way since launching our activities in 2009. Stay tuned for a year full of celebrations, cutting-edge research, and new milestones.<\/p><p>OVER 40 INDUSTRY PARTNERS | MORE THAN 70 EUROPEAN PROJECTS | 103 GRADUATED PHDS | 4 SPIN-OFFS<\/p><p>Photo: \u00a9 iStock \/ University of Luxembourg<\/p><\/div><\/section>","protected":false},"excerpt":{"rendered":"<p>In June 2014 Bitcoin users were confronted with the unthinkable. A Bitcoin mining pool called Ghash.io had attained control over 51% of the network&rsquo;s total mining power. Bitcoin users, miners and developers responded with shock, panic and denial, but could do nothing about the fact that Ghash.io now had the ability to manipulate the network at will.<\/p>\n","protected":false},"author":0,"featured_media":0,"template":"","format":"standard","meta":{"featured_image_focal_point":[],"show_featured_caption":false,"ulux_newsletter_groups":"","uluxPostTitle":"","uluxPrePostTitle":"","_trash_the_other_posts":false,"_price":"","_stock":"","_tribe_ticket_header":"","_tribe_default_ticket_provider":"","_tribe_ticket_capacity":"0","_ticket_start_date":"","_ticket_end_date":"","_tribe_ticket_show_description":"","_tribe_ticket_show_not_going":false,"_tribe_ticket_use_global_stock":"","_tribe_ticket_global_stock_level":"","_global_stock_mode":"","_global_stock_cap":"","_tribe_rsvp_for_event":"","_tribe_ticket_going_count":"","_tribe_ticket_not_going_count":"","_tribe_tickets_list":"[]","_tribe_ticket_has_attendee_info_fields":false},"news-category":[4,3],"news-topic":[],"organisation":[184,226],"authorship":[],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v22.3 (Yoast SEO v22.3) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>First Reputation-based system improves Blockchain security - Universit\u00e9 du Luxembourg<\/title>\n<meta name=\"description\" content=\"In June 2014 Bitcoin users were confronted with the unthinkable. A Bitcoin mining pool called Ghash.io had attained control over 51% of the network&#039;s total mining power. Bitcoin users, miners and developers responded with shock, panic and denial, but could do nothing about the fact that Ghash.io now had the ability to manipulate the network at will.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.uni.lu\/fr\/news\/first-reputation-based-system-improves-blockchain-security\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"First Reputation-based system improves Blockchain security\" \/>\n<meta property=\"og:description\" content=\"In June 2014 Bitcoin users were confronted with the unthinkable. A Bitcoin mining pool called Ghash.io had attained control over 51% of the network&#039;s total mining power. 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