That's why I mentioned git, not just putting it in a text file. Every git commit contains a hash of all the previous commits, and is itself referred to by a ha

That's why I mentioned git, not just putting it in a text file. Every git commit contains a hash of all the previous commits, and is itself referred to by a hash. So if you change an old commit, all commits descending from that get a new hash, and so a new identity. If you publish the latest hash in the newspaper, you've locked down all the previous commits also.