SN-0755 已核对来源，附原文与上下文。
SHA-256 非常强。它不像 MD5 到 SHA1 那种渐进的一步。除非出现某种重大的突破性攻击，它可以用上几十年。
SHA-256 is very strong. It's not like the incremental step from MD5 to SHA1. It can last several decades unless there's some massive breakthrough attack.
如果 SHA-256 被彻底攻破，我想我们可以就"麻烦开始之前哪条是诚实的区块链"达成共识，把它锁定，然后用新的哈希函数从那里继续。
If SHA-256 became completely broken, I think we could come to some agreement about what the honest block chain was before the trouble started, lock that in and continue from there with a new hash function.
如果哈希是逐渐失效的，我们可以有序地过渡到新哈希。软件可以被设定为在某个区块号之后开始使用新哈希。所有人都必须在那时之前升级。软件可以保存所有旧区块的新哈希，确保无法使用一个与旧哈希相同的不同区块。
If the hash breakdown came gradually, we could transition to a new hash in an orderly way. The software would be programmed to start using a new hash after a certain block number. Everyone would have to upgrade by that time. The software could save the new hash of all the old blocks to make sure a different block with the same old hash can't be used.
