
The Libra Blockchain White Paper [pdf] - Anon84
https://developers.libra.org/docs/assets/papers/the-libra-blockchain.pdf
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andrewla
There's really one big question that any sort of cryptocurrency design has to
answer, and that's the state precedence system. If a new client comes up and
sees two different states both advertised as genuine, which one does it
choose?

This has to be an unambiguous decision to prevent any disagreement about
consensus or state evolution.

Bitcoin, for example, is just the accumulated proof of work -- an unbiased
estimator of the amount of SHA256 hashes that were computed to produce the
chain. Ethereum has a similar design currently, but wants to switch to proof
of stake; the algorithm here is more complicated, but basically the longest
chain that has no attestations against it on a competing chain.

I can't quite tell what Libra is offering here -- I think they create a group
of validators (section 9.2), and the state is the one that the most validators
have cumulatively agreed upon is the current state. How validators are
unambiguously identified is unclear at this point; presumably the public keys
will be shipped with the client so that they are effectively public knowledge,
and eventually will be proof-of-stake based, so that key pairs that hold large
amounts of LibraCoin will use their key to sign the state. There seems to be
very little specificity here, though.

