Re: [Ilc] Clarifications and thoughts purpose of ILC list

[Tony Arcieri <[e-mail]>]

On Wed, Feb 22, 2017 at 10:25 AM, David Mazieres <
[e-mail]> wrote:

> Well, there are a bunch of different variants of Satoshi consensus.
> Some of them, like peercoin and tendermint, look more like traditional
> BFT, only where participants are elected based on some other criterion
> such as stake in a cryptocurrency.


Like many things in this space, "Satoshi consensus" is an ill-defined
buzzword. In part I think it means incorporating programs into the
consensus decision, which seems like fairly novel and interesting work to
me (and somewhat similar to e.g. Trillian's "personalities"). In this
space, yes incorporating consensus programs into (P)BFT-like schemes such
as Tendermint is interesting.

However, above I was using it specifically to refer to the proof-of-work
scheme for consensus. "CP" versus "AP" of course both assume "P", a
property Bitcoin (and systems using a similar proof-of-work consensus
model) do not have. Under a network partition in Bitcoin, the system will
both make progress and be available for reading (where CP systems will fail
closed if they can't reach a quorum). When the partition is healed,
acknowledge writes are lost and data is clobbered. Systems which truly
uphold "CP" or "AP" semantics do not clobber data this way.

This sort of split-brain behavior can be exploited by attackers who are
able to arbitrarily create network partitions. Eclipse attacks are a common
example.

-- 
Tony Arcieri