(28DW-S8-Day7) 比特币原始文献略读

有了前面的简单基础，今天来过下比特币的原始文献。

比特币白皮书

中本聪在 2008 年 11 月 1 日发表的文章《Bitcoin: A Peer-to-Peer Electronic Cash System》被认为是比特币的最初提出文献，后来称为比特币白皮书。

白皮书中的主要部分

电子货币即数字签名链

We define an electronic coin as a chain of digital signatures. Each owner transfers the coin to the next by digitally signing a hash of the previous transaction and the public key of the next owner and adding these to the end of the coin. A payee can verify the signatures to verify the chain of ownership.

定义每个数字货币就是一条数字签名链。

这个电子货币的每个拥有者都将按照自己拥有的顺序，把自己的签名加到这个链里面。

收款人可以通过验证数字签名来证实其为该链的所有者。

双重支付的问题 (double-spending)

传统货币的做法是依靠引入一个可信任的中央机构或铸币厂，只有铸币厂直接发行的会比才能被确认没有被双重支付。

to accomplish this without a trusted party, transactions must be publicly announced, and we need a system for participants to agree on a single history of the order in which they were received. The payee needs proof that at the time of each transaction, the majority of nodes agreed it was the first received.

如果不引入可信任机构来解决这个问题，交易必须公开发布，而且需要一个让参与者认可的系统，这个系统能刻画一个单一历史顺序，这个顺序就是大家交易收到的顺序。而且这个系统能保证多数节点认同此交易是谁最先收到的证据。

工作量证明(Proof-of-work)

Proof-of-work is essentially one-CPU-one-vote. 工作量证明本质是一个 CPU 投票机制。

这规避了按照 IP 地址投票的隐患(有人可能有很多 IP 地址)。

The majority decision is represented by the longest chain, which has the greatest proof-of-work effort invested in it. If a majority of CPU power is controlled by honest nodes, the honest chain will grow the fastest and outpace any competing chains.

最长链代表了多数决策，因为有最大的工作量证明投在这里。如果大多数 CPU 资源被诚实节点控制，那最诚实的链就是增长最快的能超越其他所有的竞争链。

To modify a past block, an attacker would have to redo the proof-of-work of the block and all blocks after it and then catch up with and surpass the work of the honest nodes. We will show later that the probability of a slower attacker catching up diminishes exponentially as subsequent blocks are added.

要修改已有区块，攻击者需要重做这个区块以及其后所有区块对应的工作量证明。而且还得能赶超哦。 可以证明，一个较慢速攻击者要赶上诚实节点们速度的可能性随着后续区块的增加，这个概率呈指数下降趋势。

BTC 网络运行机制

• 新交易向所有节点广播

• 每个节点将新交易收集到一个区块

• 每个节点挖矿：为它的区块寻找工作量证明

• 当一个节点找到了工作量证明，就像所有节点广播这个区块

• 节点只有在节点只有在区块内所有交易都是有效的且之前没有被支付的情况下接收这个区块。

• Nodes express their acceptance of the block by working on creating the next block in the chain, using the hash of the accepted block as the previous hash. 节点通过使用这个区块的哈希值作为上一个哈希值在链中创建下一个区块的方式 表示对这个区块的接受。

激励 Incentive

By convention, the first transaction in a block is a special transaction that starts a new coin owned by the creator of the block. This adds an incentive for nodes to support the network, and provides a way to initially distribute coins into circulation, since there is no central authority to issue them. The steady addition of a constant of amount of new coins is analogous to gold miners expending resources to add gold to circulation. In our case, it is CPU time and electricity that is expended.

约定，每个区块中的第一笔交易是特殊的交易，它开启了一枚属于区块创建者的新货币。

这增加了对支持网络的节点的激励，并提供了一种发行货币的方法。

比特币里没有中央机构来发行货币。所有产生新区块就是发行新货币。

新货币按固定量稳定地增加就像金矿矿工消耗资源并增加黄金到流通领域一样。对我们而言，消耗的是 CPU 时间和电力.

more...

时间仓促，先摘录到这里。和前面几篇小文对照看，都好理解。

参考文献

• 中本聪：《比特币：一种点对点的电子现金系统》

• https://bitcoin.org/