比特币白皮书（导言译稿）

翻译  杨怀玉

一、导言

互联网商业，逐渐发展成为几乎完全借助作为被信任第三方的金融机构来处理电子支付业务。然而，该系统即使目前运转良好，足以应付大多数交易业务，但它还是受困于其固有的“基于信任模式”缺陷的问题。（互联网商业中，）“完全不可逆交易” 并非真正可行，原因是会导致金融机构不能避免地卷入争端的调解。这种调解成本导致的交易成本增加，限制了可实现交易的最小规模，同时断绝了日常小额交易的可能性，而且还有一种更为广义的成本，即为不可逆服务而设计出来的不可逆支付能力将会减弱。伴随着（交易）撤销可能性的是信任需求扩张。（由于交易可能单方面撤销，）商人们必须对他们的顾客保持戒备，由此，为了获取更多的信息不断烦扰顾客，（即使该信息量）远超他们所需。甚至无可奈何地接受一定程度上的欺诈。（现实中），人们使用物理货币时，这些成本与支付的不确定能够避免，但（在互联网商业中），没有商家会通过一种没有信任方的信息渠道进行支付。

因此，一种以建立在密码学基础上的证明来替代信任的电子支付系统，就很有必要，该系统允许任何有交易意愿的双方直接相互交易，而不需要一个被信任的第三方。在计算上不可能撤销的交易将保护卖方不被诈骗，常规的第三方中间商亦能够轻松地实现对买方的保护。这篇论文里，我们提出一种双重支付问题解决方案，就是使用一种点对点分布式时间戳服务器，以生成可计算的、按时间的前后顺序排列的交易序列证明。只要诚实的节点共同控制的CPU算力，比协同操作的攻击者节点集团更多，这个系统就是安全的。

Introduction

Commerce on the Internet has come to rely almost exclusively on financial institutions serving as trusted third parties to process electronic payments.  While the system works well enough for most transactions, it still suffers from the inherent weaknesses of the trust based model. Completely non-reversible transactions are not really possible, since financial institutions cannot avoid mediating disputes.  The cost of mediation increases transaction costs, limiting the minimum practical transaction size and cutting off the possibility for small casual transactions, and there is a broader cost in the loss of ability to make non-reversible payments for nonreversible services.  With the possibility of reversal, the need for trust spreads.  Merchants must be wary of their customers, hassling them for more information than they would otherwise need. A certain percentage of fraud is accepted as unavoidable.  These costs and payment uncertainties can be avoided in person by using physical currency, but no mechanism exists to make payments over a communications channel without a trusted party.

What is needed is an electronic payment system based on cryptographic proof instead of trust, allowing any two willing parties to transact directly with each other without the need for a trusted third party.  Transactions that are computationally impractical to reverse would protect sellers from fraud, and routine escrow mechanisms could easily be implemented to protect buyers.  In this paper, we propose a solution to the double-spending problem using a peer-to-peer distributed timestamp server to generate computational proof of the chronological order of transactions.  The system is secure as long as honest nodes collectively control more CPU power than any cooperating group of attacker nodes.