stressing out: bitcoin “stress tes2ng”yuxingh/static/stress-slides.pdf · khaled baqer, danny...
TRANSCRIPT
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StressingOut:Bitcoin“StressTes2ng”
KhaledBaqer,DannyYuxingHuang,DamonMcCoyandNickWeaver
(givenbyRossAnderson)
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Overview
• SpamaNackonBitcoin(July2015)• Importance:blocksizedebate!AtpresentyoucanbringdownBitcoinfor$50k
• Goalhere:highlightspammo2fs,inves2gateimpact,analysesecurityeconomics(feeincomeincrease,costofspamcampaign)
• Usedaclusteringmethodtogrouptransac2onsandfindpaNerns
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Bitcoinspam
• Fan-in:Transac2onsthatabsorbalotofinputsreducetheunspenttransac2onoutput(UTXO)setbuts2lloccupysubstan2alspaceintheblocks
• Fan-out:Transac2onsthatsplitafewinputsintomanyoutputsoccupyspaceinblocksandalsoincreasetheUTXOset(Mempoolimpact)
• Dustoutput:“Dust”outputsconveyatrivialamountofvaluebutoccupythesameamountofresourcesintheBitcoinnetwork
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Spamcampaign(July2015)
• Someonesaid,‘stresstes2ngBitcoinnetwork’• Mo2va2on(?):showBitcoinisvulnerabletoDoS,andgetsupporttoraisetheblocksize
• DoS:sendtransac2onswithhigherfeestodepletespaceinblocks
• Spamalsousesmanysimilartransac2onstohaveasignificantimpactonthenetwork
• Butwhatdoesspamlooklike?
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k-meansClustering
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k-meansClustering(II)
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ImpactonBitcoin:Thenumberoftransac2onsperdayintheblockchain
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ImpactonBitcoin(II):Theaveragenumberofunconfirmedtransac2ons
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ImpactonBitcoin(III):Thetotalamountoftransac2onfeeseveryday
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ImpactonBitcoin(IV):Averagetransac2ondelay
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ImpactonBitcoin(V):Averagetransac2onfeespertransac2onperday(normalized)
![Page 12: Stressing Out: Bitcoin “Stress Tes2ng”yuxingh/static/stress-slides.pdf · Khaled Baqer, Danny Yuxing Huang, Damon McCoy and Nick Weaver (given by Ross Anderson) Overview • Spam](https://reader035.vdocument.in/reader035/viewer/2022062607/6051728229bdfc659454c31c/html5/thumbnails/12.jpg)
Summaryofresults(10-dayspamcampaign)
• 385,256(23.41%)outof1,645,667totalBitcointransac2onswerespam
• Spamincreasedaveragefeesby51%(from45to68Satoshis/byte)
• Spamincreasedprocessingdelayby72mes(from0.33to2.67hours)
• CostofthisaNackonBitcoin:$49K,abouthalfbeingtopayhigherfees
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Ques2ons?
• Ifskypedoesn’twork,[email protected](whocouldnotgetavisaprocessedin2me)
• Furtherpossiblediscussionsforthebarbecue:sovereignriskandotheremergentproblemsofgovernance