first_imgPool revenue using the Selfsh-Mine strategy for different propagation factors, compared to the honest Bitcoin protocol. Simulation matches the theoretical analysis, and both show that Selfsh-Mine results in higher revenues than the honest protocol above a threshold. Credit: arXiv:1311.0243 [cs.CR] . Explore further (Phys.org) —Bitcoin is a digital currency that has, well, gained currency, as a medium of exchange. Now two computer science researchers from Cornell find that this extensive ecosystem can be undermined and they outline how in a paper that they have posted on arXiv. More information: Majority is not Enough: Bitcoin Mining is Vulnerable, arXiv:1311.0243 [cs.CR]: arxiv.org/abs/1311.0243hackingdistributed.com/2013/11 … /faq-selfish-mining/www.newscientist.com/article/d … irtual-currency.html New fund launched for bitcoin investors The paper, “Majority is not Enough: Bitcoin Mining is Vulnerable,” is by Ittay Eyal, a postdoc member of the Computer Sciences department at Cornell and Emin Gun Sirer, associate professor at Cornell. According to the two researchers, “Empirical evidence shows that Bitcoin miners behave strategically and form pools. Specifically, because rewards are distributed at infrequent, random intervals miners form mining pools in order to decrease the variance of their income rate. Within such pools, all members contribute to the solution of each cryptopuzzle, and share the rewards proportionally to their contributions. To the best of our knowledge, so far such pools have been benign and followed the protocol.” Nonetheless, they describe a strategy that could be used by a minority pool to obtain more revenue than the pool’s fair share, that is, more than its ratio of the total mining power. “The key idea behind this strategy, called Selfish Mining, is for a pool to keep its discovered blocks private, thereby intentionally forking the chain,” they wrote. This selfishness can come out of people getting together to siphon off more money than a fair share for mining activities.The authors wrote that central to Bitcoin operations is a public log called the blockchain where all transactions are recorded. The security of the blockchain is established by a chain of cryptographic puzzles solved by a loosely organized network of participants called miners. The two researchers present an attack with which colluding miners obtain a revenue larger than their fair share. “This attack can have significant consequences for Bitcoin,” they warned, where rational miners join selfish miners and the colluding group increases increase in size until it becomes a majority. At this point, they said, the Bitcoin system ceases to be a decentralized currency. A Scientific American report on their findings further explained how damage might occur: Instead of releasing solutions to solved cryptopuzzles. The selfish crew can mine a branch in secret, hiding it from honest miners. The group would then get a higher share of coins than is fair for the resources they have contributed because they have forced other miners to waste computing power on the original chain. The problem gets worse as the selfish group recruits extra members.Elsewhere, the two were asked if they were trying to take Bitcoin down with their sober warning. “We’re Bitcoin supporters,” they blogged, ” and are working to make the currency stronger against a broader set of possible misbehaviors than what has been considered so far.” They proposed in their paper a practical modification to the Bitcoin protocol that protects against selfish mining pools. Can Bitcoin remain a viable currency? Sirer said, “Probably. We have shown that as long as selfish miners are below a certain threshold, they will not succeed.” Citation: Cornell researchers teach Bitcoin attack lesson in selfish mining (2013, November 6) retrieved 18 August 2019 from https://phys.org/news/2013-11-cornell-bitcoin-lesson-selfish.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2013 Phys.orglast_img read more

first_imgCheap flights carrier Ryanair is basing new aircraft in Bristol and Liverpool ahead of launching more routes from the airports.From March 28th, the airline will launch flights to Faro, Gdansk, Palma de Mallorca, Venice Treviso and Valencia from the south-west airport, with its number of Bristol-based aircraft increasing to five.Two new aircraft will be based in Liverpool in order to accommodate flights to Lodz, Rimini and Trapani, while further new routes will be introduced from Edinburgh and Glasgow Prestwick.In addition, Ryanair will also increase frequencies on two Bristol and four Liverpool flights.Ryanair’s Stephen McNamara said that Ryanair routes at regional airports deliver “millions of passengers” each year.”Ryanair is delighted to announce three new aircraft and ten new routes for Bristol, Edinburgh, Glasgow Prestwick and Liverpool airports which will deliver 400,000 additional passengers and sustain 400 new jobs while ensuring increased competition and choice for consumers,” he commented.The airline announced earlier this month that the number of passengers travelling on its routes during October increased by 15 percent compared to the same month last year.ReturnOne wayMulti-cityFromAdd nearby airports ToAdd nearby airportsDepart14/08/2019Return21/08/2019Cabin Class & Travellers1 adult, EconomyDirect flights onlySearch flights Map RelatedRyanair to launch five new flights from Liverpool in OctoberCheap flights carrier Ryanair will launch five new routes from Liverpool John Lennon Airport this autumn.Flights to Ibiza, Nantes and Pisa on offer by RyanairFlights to Ibiza, Nantes and Pisa on offer by RyanairRyanair announces expansion from three of its basesRyanair has announced that it will expand the number of aircraft at its Alicante, Bristol and Edinburgh baseslast_img read more