Improving the Security and Efficiency of Blockchain-based Cryptocurrencies

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.advisorPaverd, Andrew
dc.contributor.authorGopinath Nirmala, Rakesh
dc.contributor.schoolPerustieteiden korkeakoulufi
dc.contributor.supervisorN, Asokan
dc.date.accessioned2017-09-04T10:33:30Z
dc.date.available2017-09-04T10:33:30Z
dc.date.issued2017-08-28
dc.description.abstractIn recent years, the desire for financial privacy and anonymity spurred the growth of electronic cash and cryptocurrencies. The introduction of decentralized cryptocurrencies, such as Bitcoin, accelerated their adoption in society. Since digital information is easier to reproduce, digital currencies are vulnerable to be spent more than once – this is called a double-spending attack. In order to prevent double-spending, Bitcoin records transactions in a tamper-resilient shared ledger called the blockchain. However, the time required to generate new blocks in the blockchain causes a delay in the transaction confirmation. This delay, typically around one hour in Bitcoin, is impractical for real world trade and limits the wide-spread use of blockchain-based cryptocurrencies. In this thesis, we propose a solution to prevent double-spending attacks and thus enable fast transaction confirmations using the security guarantees of Trusted Execution Environments (TEEs). We achieve this by enforcing sign-once semantics that prevent the payer from reusing designated signing keys to sign more than one transaction. We also provide a way for the payee to verify whether a specific signing key is subject to sign-once semantics. The payee, however still receives the funds later, once the transaction is verified similarly to existing credit card payments. In this way, our solution reduces transaction confirmation times of blockchain-based cryptocurrencies and is also compatible with existing deployments since it does not require any modifications to the base protocol, peers, or miners. We designed and implemented a proof-of-concept of our solution using Intel SGX technology and integrated it with Copay, a popular Bitcoin wallet from BitPay. This thesis also presents the security evaluation of our system along with other possible extensions and enhancements.en
dc.format.extent77
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/27919
dc.identifier.urnURN:NBN:fi:aalto-201709046818
dc.language.isoenen
dc.programmeMaster's Degree Programme in Security and Mobile Computing (NordSecMob)fi
dc.programme.majorSecurity and Mobile Computingfi
dc.programme.mcodeT3011fi
dc.subject.keywordcryptocurrencyen
dc.subject.keywordbitcoinen
dc.subject.keywordblockchainen
dc.subject.keyworddouble-spendingen
dc.subject.keywordtrusted hardwareen
dc.subject.keywordSGXen
dc.titleImproving the Security and Efficiency of Blockchain-based Cryptocurrenciesen
dc.typeG2 Pro gradu, diplomityöfi
dc.type.ontasotMaster's thesisen
dc.type.ontasotDiplomityöfi
local.aalto.electroniconlyyes
local.aalto.openaccessyes
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