• 정보보호학회논문지
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• 제28권3호
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• pp.717-727
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• 2018

비트코인으로 불법거래를 할 경우 해당 거래에 사용된 모든 비트코인을 추적하여 압수하기는 쉽지 않다. 특히, 범죄자가 여러 비트코인 주소에 분산하여 불법거래를 한다면, 일부 비트코인을 압수하더라도 압수한 비트코인 이외에 추적되지 않고 감춰진 비트코인을 파악하기가 어렵다. 본 논문은 불법거래로 의심되는 비트코인 거래를 추적하고 모니터링하는 방법을 제안한다. 이 방법을 통해 범죄혐의가 있는 비트코인 주소 리스트를 기반으로 해당 주소와 거래한 모든 비트코인 주소 중에서 범죄와 관련성이 높은 비트코인 주소를 추정하고, 이 주소와 관련된 거래를 지속적으로 추적하여 불법 비트코인 거래 수사에 도움을 준다.

• 정보보호학회논문지
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• 제28권4호
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• pp.1009-1019
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• 2018

Bitcoin은 블록체인을 활용한 최초의 어플리케이션으로 새로운 지불 수단으로 각광받고 있지만, 확장성에 있어서 한계점을 갖는다. Lightning Network의 개념은 최근 Bitcoin의 확장성 문제를 다루기 위해 소개되었다. 본 논문에서는 실제 Bitcoin Lightning Network가 scale-free 특성을 갖는다는 것을 밝혔다. 따라서 임의 노드 실패에 강건한 반면, 네트워크의 특정 노드를 목표로 하는 공격에 대해 취약할 수 있다. 네트워크 공격 모델의 시뮬레이션을 통해 Bitcoin Lightning Network의 강건성을 실험적으로 분석했으며, 시뮬레이션 결과는 실제로 Lightning Network가 높은 차수를 갖는 소수의 노드를 파괴하는 공격에 취약하다는 것을 보여 준다.

• Journal of Information Processing Systems
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• 제20권1호
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• pp.85-92
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• 2024

In recent years, Bitcoin and Ethereum have witnessed a surge in trading activity, driven by venture capital investment and funding through initial coin offerings (ICOs) and initial exchange offerings (IEOs). This heightened interest has led to kickstarting a vibrant ecosystem for blockchain development. The total number of cryptocurrencies listed on CoinMarketCap.com has reached 2,274 highlights how dynamic and wide blockchain development landscape has grown. In blockchain development, new blockchain projects are being created by forking blockchains inspired by major cryptocurrencies such as Bitcoin and Ethereum. These projects aim to address the perceived shortcomings and improve existing technologies. Altcoins, representing these alternative cryptocurrencies, are an ongoing industry effort to improve performance and security with enhancement proposals such as Bitcoin Improvement Proposals (BIP), Ethereum Improvement Proposals (EIP), and EOSIO Enhancement Proposals (EEP). With competitive attempts to improve blockchain performance and security, an ongoing performance race between various blockchains has taken shape, each claiming its own performance advantages. In this paper, we describe the transactions contained in the blocks of each representative blockchain, and find the factors that affect the transactions per second (TPS) through transaction processing and block generation processes, and suggest their relationship with scalability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권3호
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• pp.861-876
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• 2022

Cryptoassets such as Bitcoin and Ethereum are widely traded around the world. Cryptocurrencies are also transferred between investors. Cryptocurrency has become a new and attractive means of remittance. Thus, blockchain-based smart contracts also attract attention when central banks design digital currencies. However, it has been discovered that a significant amount of cryptoassets on blockchain are lost or stranded for a variety of reasons, including the loss of the private key or the owner's death. To address this issue, we propose a method for recoverable transactions that would replace the traditional transaction by allowing cryptoassets to be sent to a backup account address after a deadline has passed. We provide the computational workload required for our method by analyzing the prototype. The method proposed in this paper can be considered as a good model for digital currency design, including central bank digital currency (CBDC).

• ETRI Journal
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• 제43권2호
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• pp.357-370
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• 2021

The evolution of blockchain-based systems has enabled researchers to develop nextgeneration e-voting systems. However, the classical consensus method of blockchain, that is, Proof-of-Work, as implemented in Bitcoin, has a significant impact on energy consumption and compromises the scalability, efficiency, and latency of the system. In this paper, we propose a hybrid consensus model (PSC-Bchain) composed of Proof of Credibility and Proof of Stake that work mutually to address the aforementioned problems to secure e-voting systems. Smart contracts are used to provide a trustworthy public bulletin board and a secure computing environment to ensure the accuracy of the ballot outcome. We combine a sharding mechanism with the PSC-Bchain hybrid approach to emphasize security, thus enhancing the scalability and performance of the blockchain-based e-voting system. Furthermore, we compare and discuss the execution of attacks on the classical blockchain and our proposed hybrid blockchain, and analyze the security. Our experiments yielded new observations on the overall security, performance, and scalability of blockchain-based e-voting systems.