?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Tampering+with+the+Delivery+of+Blocks+and+Transactions+in+Bitcoin&rft.creator=Gervais%2C+Arthur&rft.creator=Ritzdorf%2C+Hubert&rft.creator=Karame%2C+Ghassan+O&rft.creator=Capkun%2C+Srdjan&rft.description=Given+the+increasing+adoption+of+Bitcoin%2C+the+number+of+transactions+and+the+block+sizes+within+the+system+are+only+expected+to+increase.+To+sustain+its+correct+operation+in+spite+of+its+ever-increasing%0D%0Ause%2C+Bitcoin+implements+a+number+of+necessary+optimizations+and%0D%0Ascalability+measures.+These+measures+limit+the+amount+of+information+broadcast+in+the+system+to+the+minimum+necessary.%0D%0AIn+this+paper%2C+we+show+that+current+scalability+measures+adopted%0D%0Aby+Bitcoin+come+at+odds+with+the+security+of+the+system.+More%0D%0Aspecifically%2C+we+show+that+an+adversary+can+exploit+these+measures%0D%0Ain+order+to+effectively+delay+the+propagation+of+transactions+and%0D%0Ablocks+to+specific+nodes%E2%80%94without+causing+a+network+partitioning%0D%0Ain+the+system.+We+show+that+this+allows+the+adversary+to+easily%0D%0Amount+Denial-of-Service+attacks%2C+considerably+increase+its+mining%0D%0Aadvantage+in+the+network%2C+and+double-spend+transactions+in+spite+of%0D%0Athe+current+countermeasures+adopted+by+Bitcoin.+Based+on+our+results%2C+we+propose+a+number+of+countermeasures+in+order+to+enhance%0D%0Athe+security+of+Bitcoin+without+deteriorating+its+scalability.&rft.publisher=Association+for+Computing+Machinery+(ACM)&rft.date=2015-10-12&rft.type=Proceedings+paper&rft.language=eng&rft.source=+++++In%3A++Proceedings+of+the+22nd+ACM+SIGSAC+Conference+on+Computer+and+Communications+Security.++(pp.+pp.+692-705).++Association+for+Computing+Machinery+(ACM)%3A+Denver%2C+CO%2C+USA.+(2015)+++++&rft.format=text&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F10182349%2F1%2F2015-578.pdf&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F10182349%2F&rft.rights=open