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Centralization vs. Decentralization

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比特币和数字货币技术

普林斯顿大学

4.7（2,020 個評分） | 340K 名學生已註冊

To really understand what is special about Bitcoin, we need to understand how it works at a technical level. We’ll address the important questions about Bitcoin, such as: How does Bitcoin work? What makes Bitcoin different? How secure are your Bitcoins? How anonymous are Bitcoin users? What determines the price of Bitcoins? Can cryptocurrencies be regulated? What might the future hold? After this course, you’ll know everything you need to be able to separate fact from fiction when reading claims about Bitcoin and other cryptocurrencies. You’ll have the conceptual foundations you need to engineer secure software that interacts with the Bitcoin network. And you’ll be able to integrate ideas from Bitcoin in your own projects. Course Lecturers: Arvind Narayanan, Princeton University All the features of this course are available for free. It does not offer a certificate upon completion.

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您將學習的技能

Bitcoin Network, Blockchains, Cryptocurrency, Bitcoin

審閱

4.7（2,020 個評分）

5 stars
1,533 ratings
4 stars
383 ratings
3 stars
73 ratings
2 stars
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1 star
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LB

Jan 15, 2017

I find this course prepared very well. There are many perspectives and this course does not concentrate on the technology only. I find this course very helpful. The level is more then just beginner.

AG

Feb 08, 2017

Loved this course! It was very thorough. However I think assignments could have been made more clearer as it was often hard to figure out what needed to be done without checking discussion forums.

從本節課中

How Bitcoin Achieves Decentralization

Learn Bitcoin's consensus mechanism and reason about its security. Appreciate how security comes from a combination of technical methods and clever incentive engineering.

Centralization vs. Decentralization4:47

Distributed Consensus13:07

Consensus without Identity: the Block Chain17:55

Incentives and Proof of Work19:47

Putting It All Together18:05

教學方

Arvind Narayanan
Associate Professor

腳本

[MUSIC]

Hello, and welcome to the second lecture,

which is going to be all about decentralization in Bitcoin.

Now, in the first lecture you saw a lot of the crypto basics that underlie Bitcoin

and we ended with a simple currency that we called Scrooge coin.

That seems to achieve a lot of what we want in a ledger based crypto currency,

except for one big glaring problem,

which is that it relies upon the centralized authority called Scrooge.

And we end it with the question of, how do we de-scroogify this currency?

How do we go to a decentralized version of this?

That's what we're gonna see today.

What I find cool about this is that the way in which Bitcoin achieves

decentralization is not purely technical but

it's a combination of technical and clever incentive engineering.

And, at the end of this lecture, you should have a really good appreciation for

how this happens asnd a lot of the magic or mystery of Bitcoin should

become clear to you and how it works and why it's secure, and what makes it tick.

So it turns out that decentralization is an important concept, not just for

Bitcoin but in fact, this notion of competing paradigms of centralization

versus decentralization plays out in a variety of different digital technologies.

To understand Bitcoin's decentralization, I want to start with the caveat

that decentralization almost always is not all or nothing.

Almost no system is purely decentralized or purely centralized and a good example

of this is email, which is a decentralized system, fundamentally, I would say.

It's based on a standard spaced protocol, SMTP.

But, what has happened, especially in the last decade or

so, is that we see a dominance of a few different web mail providers,

which are sort of centralized service providers.

And this might be a good model for

understanding what might be happening to Bitcoin.

So with that,

let's delve into some the technical aspects of Bitcoin's decentralization and

I would break this down into at least five different questions.

Questions like, who maintains this ledger of transactions?

Who has authority over which transactions are valid?

Who creates new Bitcoins?

And in fact, other questions like,

who determines how the rules of the system change?

And how do Bitcoins acquire exchange value?

So these are all components of decentralization of the Bitcoin protocol,

more or less.

And the first three of these are going to be

questions that we will consider in this lecture.

And when I say how is Bitcoin decentralized,

what I mean encompasses the first three of these meanings.

And I want to emphasize that there are aspects to decentralization

beyond the protocol that includes things like Bitcoin exchanges,

where you can convert Bitcoin into other currencies.

It includes things like wallet software and

a variety of other service providers and

so, even though the underlying protocol is decentralized, these services that

develop on top of it may be centralized or decentralized, to varying degrees.

And just to drive home this point, let me show you three different aspects

of Bitcoin and where they fall on the centralization, decentralization spectrum.

First, there's the peer to peer network and this aspect of Bitcoin,

I would say, is the closest thing to purely decentralized.

Why is that?

Because anybody can run a Bitcoin node, and there's a fairly low barrier to entry.

You can go online, you can download a Bitcoin client yourself.

It requires a lot of disconsumption on your computer, but

basically you can run that on your laptop or your PC yourself and

currently there are several thousand Bitcoin nodes.

And so this really resembles a peer to peer decentralized system.

But that's not the only component of Bitcoin.

There's also Bitcoin mining, which we'll study later in this lecture and

Bitcoin mining is technically also open to anyone.

But it turns out that it requires a very high capital cost.

It's a consequence of how the system happens to have evolved.

And because of this, there has been a high centralization or

a concentration of power in the Bitcoin mining ecosystem, and

the community frequently sees this as quite undesirable.

So this aspect of Bitcoin is not quite as decentralized as one might want it to be.

And, here's a third aspect, updates to the software.

And this really gets to how and when rules of the system change.

And once again here, one can conceptually imagine that everybody running a Bitcoin

node will look at the Bitcoin specification, and maybe even create their

own software and again, you have a purely decentralized system.

But of course, that's not how it works in practice.

The core developers are really trusted by the community,

and they have a lot of power when it comes to determining what

Bitcoin software each of these nodes will run on their computer.

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