SN-10006 附来源、原文与上下文。
引用的来信James A. Donald来源 ↗Satoshi Nakamoto 写道：
Satoshi Nakamoto wrote:
引用的中本聪旧文中本聪来源 ↗我一直在开发一种新的电子现金系统，它完全采用点对点方式，无需可信第三方。
I've been working on a new electronic cash system that's fully peer-to-peer, with no trusted third party.
The paper is available at: http://www.bitcoin.org/bitcoin.pdf
我们非常、非常需要这样的系统，但按我对你的方案的理解，它似乎无法扩展到所需的规模。
We very, very much need such a system, but the way I understand your proposal, it does not seem to scale to the required size.
可转让的工作量证明代币要有价值，就必须具有货币价值。要有货币价值，就必须在一个非常大的网络中转让—— 例如类似 bittorrent 的文件交换网络。
For transferable proof of work tokens to have value, they must have monetary value. To have monetary value, they must be transferred within a very large network - for example a file trading network akin to bittorrent.
要及时发现并拒绝一次双重支付，就必须掌握交易中那些币的大部分过往交易；如果直接实现，就要求每个对等节点掌握大部分过往交易，或者最近发生的大部分过往交易。如果数亿人都在交易，就需要很大的带宽——每个人都必须知道全部交易，或其中相当大的一部分。
To detect and reject a double spending event in a timely manner, one must have most past transactions of the coins in the transaction, which, naively implemented, requires each peer to have most past transactions, or most past transactions that occurred recently. If hundreds of millions of people are doing transactions, that is a lot of bandwidth - each must know all, or a substantial part thereof.
早在网络接近这么大的规模之前，用户就可以安全地使用简化支付验证（第 8 节）检查双重支付，这只需要保存区块头链，大约每天 12KB。只有尝试生成新币的人才需要运行网络节点。起初，大多数用户都会运行网络节点，但随着网络增长到一定程度，这项工作会越来越多地交给拥有专用硬件服务器群的专业人员。一个服务器群只需要在网络中运行一个节点，局域网里的其他机器都连接这个节点。
Long before the network gets anywhere near as large as that, it would be safe for users to use Simplified Payment Verification (section 8) to check for double spending, which only requires having the chain of block headers, or about 12KB per day. Only people trying to create new coins would need to run network nodes. At first, most users would run network nodes, but as the network grows beyond a certain point, it would be left more and more to specialists with server farms of specialized hardware. A server farm would only need to have one node on the network and the rest of the LAN connects with that one node.
带宽要求可能没有你想的那么难以承受。一笔典型交易大约是 400 字节（ECC 非常紧凑）。每笔交易需要广播两次，所以我们按每笔交易 1KB 算。Visa 在 2008 财年处理了 370 亿笔交易，平均每天 1 亿笔。这么多交易需要 100GB 的带宽，相当于 12 张 DVD 或 2 部高清电影的大小，按当前价格计算，带宽费用约为 $18。
The bandwidth might not be as prohibitive as you think. A typical transaction would be about 400 bytes (ECC is nicely compact). Each transaction has to be broadcast twice, so lets say 1KB per transaction. Visa processed 37 billion transactions in FY2008, or an average of 100 million transactions per day. That many transactions would take 100GB of bandwidth, or the size of 12 DVD or 2 HD quality movies, or about $18 worth of bandwidth at current prices.
如果网络达到那么大的规模，也需要好几年，到那时，在互联网上传送 2 部高清电影大概就不算什么大事了。
If the network were to get that big, it would take several years, and by then, sending 2 HD movies over the Internet would probably not seem like a big deal.
Satoshi Nakamoto
Satoshi Nakamoto
