區塊鏈如何運作?

Whiteboard Session: How Does Blockchain Work?
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分散式分類帳的力量。

卡林.拉哈尼:今天我要花點時間和大家談談區塊鏈。區塊鏈的基本元素是分類帳。分類帳基本上留存了各方的交易紀錄。分類帳有很多分錄。關於分類帳,首先它不只存在一家公司裡,或一個人手裡,而是同時存在非常、非常多地方,在世界各地都有複本。你想要多少份,就可以複製多少份。

第二,這些分類帳全都互相連結,存在一個點對點的網路中。因此,連結是在各個點之間。因此區塊鏈中有交易紀錄。然後,它們之間有點對點的連結。這樣就不存在單一瓶頸。交易發生時,發生這項交易的證據,會複製到所有人手中持有的分類帳。

第三,我們所謂的假名或匿名,含有一種透明的概念。就像電子郵件一樣,你可以用karim@hbs.edu作為你的電郵地址,或用secretpeson@hbs.edu或secretperson@gmail.com。同樣地,你在這裡也可以用假名。你可以在區塊鏈上隱藏自己的身分。

但karim和secretperson之間發生的交易,會被記錄下來。交易會被記錄下來,但在這種機制下,你可以維持匿名。接著是「不可逆轉」的概念,這表示交易一旦發生,並被記錄到分類帳之後,就很難回去更改那項交易(所以我會把它加上引號)。

假設我透過區塊鏈匯一百元給你,兩天後我改變主意,想把錢拿回來。如果交易並非不可逆轉的,我就可以回去嘗試修改分類帳裡的交易。而這就是區塊鏈的一個神奇之處,我們進行了運算證明,以確保交易被鎖定。

為了更改此處的任何一筆交易,你必須回去逆轉所有其他交易。這是龐大的運算任務。因此區塊鏈的不可逆性很重要。最後,區塊鏈實際上是可程式化的。我們可以把軟體邏輯內建到交易之中。

例如,假設你是物流公司,要把某個東西從A點運送到B點。當貨車的GPS坐標與倉庫位置相符時,交易就會發生,根據的基礎就是貨車抵達倉庫時就會付錢。你可以把這種可程式性,建立在現有的分類帳技術中。這五件事讓我們了解區塊鏈如何運作。

但在很多方面,這與電郵的運作方式相同。電郵沒有中央節點。我們的電郵穿越網際網路,透過點對點連結傳給我們。我們設法從地址A前往地址C,然後交易可以去到那裡,讓一切順利運作。那麼,你為什麼要關心這件事?

首先,網路上充斥大量媒體報導,對吧?如果你搜尋區塊鏈,會出現一大堆新聞報導。這才剛開始爆炸式成長。比特幣的價值有點像底層的力量,區塊鏈的應用則是來自頂層。商業媒體中總是不乏區塊鏈的故事。媒體實在瘋狂。

其次,區塊鏈新創公司吸引到大量投資。過去四、五年中,已投資了超過10億美元,投注在約三百家試圖運用區塊鏈的公司。我們看到創投界對此很感興趣。雖然創投常有一窩蜂的傾向,但他們在尋求標的時,還是會展現一些智慧。然後,你看到這種興趣擴及整個創投界,你應該開始關注這個議題。

第三,世界上最保守的機構之一就是銀行,銀行正全力投入區塊鏈。如果你看一下投資組合,銀行的科技投資組合,就會發現各家銀行目前都在投資區塊鏈,以促進它們必須達到的營運效能,以及他們認為區塊鏈有潛力的地方。

最後,我們看到了新應用的爆炸式成長。人們在夢想一些事情,以前我們認為不可能做到的事情,現在可透過這個叫分類帳的枯燥科技來實現。若要開始思考這件事,你可以想像所有的應用,想像紀錄的所有用途,想像它們在哪裡進行,然後從那裡開始思考,哪裡有協調工作的重擔。

如果突然之間,你可以與其他方共享分類帳,那麼突然之間你可以開始想像,這將會開始為你帶來一些價值。首先,要找出你認為不費力就可以嘗試的應用。然後就是建立原型。現在網路上提供許多工具,擅長資訊科技的人可用來打造第一批原型。

第三就是找出組織的變化。一旦你更改分類帳的邏輯,一旦你更改紀錄如何保存和由誰保存的邏輯,你就會遭遇組織變革的工作。最後,應擴展到你所屬組織之外,因為我真的認為,這是區塊鏈真正的利益所在之處。當你採取分類帳的概念,把它當成開放式分類帳,讓自己生態系統中的重要參與者使用,如此你就可以開始建立彼此間的信任,因為你們共享一套開放式分類帳系統。

但這並不表示你將進入公共網路,對吧?就像你有一個區域網路,就擁有虛擬私人網路,區塊鏈也有一樣的特性。你可以有私有鏈,只把某些人和某些組織連結起來。這也可能發生。把分類帳視為全球分散式超級分類帳,是革命性的觀點,因為自有商業活動以來,自從我們開始記錄各項交易以來,交易紀錄始終是私有的。

現在,我們要讓分類帳公開。這削減了交易成本,而且這項技術本質上就是數位技術,因此我們可以在這項技術裡,內建高度的可程式性。區塊鏈是交易的基礎技術,用以維持大多數組織的命脈。祕訣在於,我們應找出現在可以用這項技術去建立的應用。

(劉純佑譯)


Karim Lakhani: Today I’m going to spend some time with you to talk about blockchain. The basic element of the blockchain is a ledger. A ledger basically keeps track of transactions between parties. The ledger has a bunch of entries. Now, the thing about this ledger is that it's not just sitting in one company or with one person, but the ledger is in many, many places itself. And it's duplicated across the world. You can have as many copies of the ledger as you want.

The second thing is that these are all connected in a peer-to-peer network. Ok? So the connections go between the peers. So there is a transaction record in blockchain. Then there is a peer-to-peer connectivity amongst them. And what this does is that there's no single bottleneck that exists, that as transactions take place, the evidence of that transaction taking place is replicated across all the holders of the ledger.

Thirdly, there is a notion of sort of transparency with what we call pseudonymity. Just as in email, you can have karim@hbs.edu as your email address, or secretpeson@hbs.edu, or secretperson@gmail.com as your address. Similarly, you could be pseudonymous here. You can hide your identity on the blockchain.

But the transactions that take place between Karim and Secret Person are actually recorded. So the transaction recording takes place, but you can remain anonymous on this setup. Then there's a notion of irreversibility, which means that, as transactions take place, and they are committed to the ledger, it's very difficult—so I’ll put that under quotations—It's very difficult to go back and change the transaction.

Let’s say I sent you $100 through the blockchain, and then two days later I changed my mind and I wanted this money back. I could come back and try to refix the transactions in the ledger if the transactions were not irreversible. And so this is where some of the magic of the blockchain happens, where we do a computational proof to ensure that the transactions are locked in.

So in order for you to change any one transaction up here, you'd have to go back and reverse all the other transactions as well. And it's a massive computational task. And that's why the irreversibility of the blockchain matters. And then finally, there is the fact that the blockchain is programmable. We can build in software logic into our transactions.

Say for instance, you are a shipper, and you're shipping something from point A to point B. And when the GPS coordinates of the truck match with the location of the warehouse, there's a transaction that takes place based on the location of that truck arriving at the warehouse to release the money. You can create that kind of a programmability into the ledger technology that exists. So these five things help us understand how blockchain works.

But in many ways, this is the same way as email works. There's no central node in emails. Our email traffic traverses the internet and find its way to us through peer-to-peer connections. We're looking for address A to address C, and then transactions can go there and make it work. Now, why should you care?

Well, first of all, look, there's a tremendous amount of press, right ? If you did a search on blockchain, there’s a ton of press. So this is just going up exponentially. The value of Bitcoin, which is sort of like the underlying force, application of blockchain, that’s through the roof. There's always some story about the blockchain in the business press. So the press is going crazy.

Secondly, there is a ton of investment in blockchain startups. So over the past four years, five years, there’s been over a billion dollars invested, $1 billion invested, in about 300 companies that are trying to do something with the blockchain. All right? So we're seeing a lot of interest from the VC community. And although VCs tend to move in herds, there is some wisdom to the things they're going after.

And then you see this much interest across the board in the VC community, you want to start to pay attention to this. The third thing is that some of the most conservative institutions in the world, banks, banks are going fully into this. So if you look at the portfolio, the technology portfolios of banks, what you see is a whole range of them are now investing in blockchain in terms of operational effectiveness that they need to do, and what they see as the potential for the blockchain.

And finally, what we see is an explosion of new applications. People are dreaming up things that we didn't think we're possible before in terms of boring technology called ledgers. Now, the way to start thinking about it is can you imagine, you know, all the applications, all the uses of recordkeeping, and where they're being done, and then from there start to think about where is there coordination burden.

If all of a sudden you could share the ledger with other parties, then all of a sudden you can start to imagine that this is going to have –beginning to have some value for you. First, identify the applications that you think are low-hanging fruit for you to try. Then, there is build the prototype. There are so many tools now available online where a competent person in technology, in IT could starts to build the first set of prototypes.

The third thing is identify organization change. As soon as you change the logic of the ledger, as soon as you change the logic of how records are being kept and who keeps them, you're going to run into organizational change efforts. And then finally, scale to outside of your organization, because I really think that this is where the real benefits of blockchain will come, when you can take this notion of the ledger and apply it as an open ledger available to important parties in your ecosystem that you can start to build trust with each other by having a shared open ledger system take place.

Now, that doesn't mean you're going to be out in the public internet, right? Because just as you have a local area network, you have a VPN, you have the same thing with blockchain. You can have private chains that are only connecting certain people, certain organizations together. And that can also take place. This view of the ledger, of a distributed hyperledger in the world is revolutionary in the sense that, since the days of commerce, since the days that we started keeping track of transactions, the transaction records were always private.

Now, we're going to make them open and public. That reduces the cost of transactions that take place, and because the technology is inherently digital, we can build in a whole lot of programmability into the technology itself. Blockchain is a foundational technology for transactions, for the lifeblood of most organizations. And the trick is going to be for us to figure out the applications that we can now start to build on top of this technology.



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