SN-2245 已核对来源，附原文与上下文。
这是个非常有趣的话题。如果找到了解法，就能实现一种好得多、更容易、更方便的 Bitcoin。
This is a very interesting topic. If a solution was found, a much better, easier, more convenient implementation of Bitcoin would be possible.
最初，一枚币可以只是一串签名。有了时间戳服务，旧的可以在回溯扇出过大之前逐步丢弃，或者比特币可以单独或按面额保存。需要检查不存在双重支出，才是需要全网知晓所有交易的原因。
Originally, a coin can be just a chain of signatures. With a timestamp service, the old ones could be dropped eventually before there's too much backtrace fan-out, or coins could be kept individually or in denominations. It's the need to check for the absence of double-spends that requires global knowledge of all transactions.
挑战在于：如何证明不存在其他花费？看来节点必须知道所有交易才能验证这一点。如果它只知道 in/outpoint 的哈希，它就无法检查签名以确认某个 outpoint 是否被花过。对此你有什么想法？
The challenge is, how do you prove that no other spends exist? It seems a node must know about all transactions to be able to verify that. If it only knows the hash of the in/outpoints, it can't check the signatures to see if an outpoint has been spent before. Do you have any ideas on this?
很难想出如何在这种情况下应用零知识证明。
It's hard to think of how to apply zero-knowledge-proofs in this case.
我们要证明的是某种东西*不存在*，而这似乎要求知道全部、并检查那个东西不在其中。
We're trying to prove the absence of something, which seems to require knowing about all and checking that the something isn't included.
