1.
블록체인. 저도 많은 관심을 가지고 있습니다. 아주 개인적인 생각일 수 있지만 블록체인을 바라보는 한국의 관점은 너무 사업적인 측면만을 강조한 듯 합니다. 아마도 비즈니스만 무성한 이유는 비트코인과 블록체인과 관련한 기술이 오픈소스이고 이를 둘러싼 기술적 토론이 바탕을 이루지 못한 탓인 듯 합니다. 기술적 토대가 없는 복수 및 붙이기 사업방식(Copy and Paste)은 국내에서 먹힐 수 있지만 세계에서 성공할 수 없습니다.
금융이 관심을 가지고 바라보는 블록체인, 정확히 표현하면 사적블록체인(Private Blockchain)도 한 예입니다. 해외의 글을 보면 Publick vs Private를 둘러싼 다양한 토론이 이루어졌고 지금도 이루어지고 있습니다. 물론 바탕에는 기술적 관점이 있습니다. 소개하고자 하는 책을 쓴 저자중 한명인 Arvind Narayana 교수가 Private blockchain을 비판적으로 분석한 “Private blockchain” is just a confusing name for a shared database도 한 예입니다.
Banks and financial institutions seem to be all over the blockchain. It seems they agree with the Bitcoin community that the technology behind Bitcoin can provide an efficient platform for settlement and for issuing digital assets. Curiously, though, they seem to shy away from Bitcoin itself. Instead, they want something they have more control over and doesn’t require exposing transactions publicly. Besides, Bitcoin has too much of an association in the media with theft, crime, and smut — no place for serious, upstanding bankers. As a result, the buzz in the financial industry is about “private blockchains.”
But here’s the thing — “private blockchain” is just a confusing name for a shared database.
The key to Bitcoin’s security (and success) is its decentralization which comes from its innovative use of proof-of-work mining. However, if you have a blockchain where only a few companies are allowed to participate, proof-of-work doesn’t make sense any more. You’re left with a system where a set of identified (rather than pseudonymous) parties maintain a shared ledger, keeping tabs on each other so that no single party controls the database. What is it about a blockchain that makes this any better than using a regular replicated database?
Supporters argue that the blockchain’s crypto, including signatures and hash pointers, is what distinguishes a private blockchain from a vanilla shared database. The crypto makes the system harder to tamper with and easier to audit. But these aspects of the blockchain weren’t Bitcoin’s innovation! In fact, Satoshi tweaked them only slightly from the earlier research that he cites in his whitepaper — research by Haber and Stornetta going all the way back to 1991!
Here’s my take on what’s going on:
It is true that adding signatures and hash pointers makes a shared database a bit more secure. However, it’s qualitatively different from the level of security, irreversibility, and censorship-resistance you get with the public blockchain.
The use of these crypto techniques for building a tamper-resistant database has been known for 25 years. At first there wasn’t much impetus for Wall Street to pay attention, but gradually there has arisen a great opportunity in moving some types of financial infrastructure to an automated, cryptographically secured model.
For banks to go this route, they must learn about the technology, get everyone to the same table, and develop and deploy a standard. The blockchain conveniently solves these problems due to the hype around it. In my view, it’s not the novelty of blockchain technology but rather its mindshare that has gotten Wall Street to converge on it, driven by the fear of missing out. It’s acted as a focal point for standardization.
To build these private blockchains, banks start with the Bitcoin Core code and rip out all the parts they don’t need. It’s a bit like hammering in a thumb tack, but if a hammer is readily available and no one’s told you that thumb tacks can be pushed in by hand, there’s nothing particularly wrong with it.
2.
본론입니다. 위에서 언급한 Arvind Narayanan외 Joseph Bonneau, Edward Felten, Andrew Miller등이 공동으로 참여한 온라인 강의가 있습니다. 프린스턴대학이 제공하는 Bitcoin and Cryptocurrency Technologies입니다. Narayanan 교수가 The Princeton Bitcoin textbook is now freely available에서 공개하였습니다. 정식으로 출간한 책이라고 합니다. 혹 관련한 정보를 원하면 아래에 연락처를 남기라고 합니다.
비트코인과 블록체인을 공부하려고 책을 조사한 적이 있었습니다. 이 때 찾았던 책이 Blockchain: Blueprint for a New Economy입니다. 이 책과 비교하면 소프트웨어기술에 더 집중한 책이 Princeton Bitcoin textbook입니다. 개인적으로 두 책이 같이 공부할까 합니다.
3.
앞서 Narayanan 교수가 책을 공개하면서 쓴 블로그중에 이런 문장이 있습니다.
The Coursera course accompanying this book had 30,000 students in its first version, and it was a success based on engagement and end-of-course feedback.
30,000명. 블록체인과 비트코인에 관심을 가진 최소의 숫자입니다. 한국의 비트코인과 블록체인 개발자들이 모아도 이 숫자를 넘치못하겠죠?
