[rdiddly]

Well, all you need is an immutable write-only (edit: append-only) database. Which is the one thing a blockchain actually is.

[TomSwirly]

But a very very very slow such database, one that uses insane quantities of memory and energy.

[delaaxe]

I think you mean append only. Blockchains are immutable thus not writeable

[rdiddly]

Whoops, yes