[Cryptography] Does Bitcoin have unaddressed design flaws?

[John Levine]

In article <pZg2lwQKDCtATfsxeJvk9hNPul9c7RIVYvYDOcKa-M5KqtHUuq65hjpqxRF4qUDvGmRE-zXEBmsULS1RwuI6uar-g0Fk2QRQkxg6gZxDXws=@protonmail.ch> you write:
>The essence of a blockchain was I think proposed, or at least extensively discussed on this list long ago, as an immutable append only data
>structure that determines the current state of a database - the intended purpose being that people could not retroactively adjust the
>association between cryptographic and human readable identifiers.
>
>If it is an immutable append only data structure with a hash that can used to prove facts about its current state, and summarizes a sequence of
>hashes that summarize all its past states, it is a blockchain.

Right. It's important to keep in mind the distinction between a
permissioned blockchain, where there is a known set of entities that
can add blocks, and an unpermissioned one where there isn't.

Permissioned blockchains were invented in 1990 (maybe earlier,
depending on how you interpret some old references) and have all sorts
of uses.  Unpermissioned are newer and the jury is still out.

R's,
John