Date: Thu, 04 Apr 2019 23:52:20 +0000
To: Aymeric Vitte <vitteaymeric@gmail.com>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Smart Contracts Unchained
Precedence: list

Good morning Aymeric,


> What if the smart contract platform(s) disappear?
>

It is still possible to recover the funds, *if* you can convince all partic=
ipants of some "fair" distribution of the funds.
You do this by all participants simply signing with their participant keys =
and taking the first branch of the script.
This branch does not require the participation of the smart contract platfo=
rm, at all.
If all participants can agree to the result of the smart contract without d=
ispute, then they can exit the platform even after the platform disappears.

Now of course there will be participants who will not cooperate in such a c=
ase, for example if they were doing some betting game and "lost".
But at least it gives the possibility of doing so, and it will not be as ma=
ssive a loss.

Indeed, if the smart contract platform code is open source, it may be possi=
ble to set up another implementation of the smart contract platform.
And it would be possible to at least try to convince all participants to sw=
itch to that new platform (again, via the "as long as everybody agrees" esc=
ape hatch).
Again, this is not possible with current federated sidechains, or Ethereum =
(if Ethereum fails, all ETH becomes valueless).

> The proposal induces a very centralized system, to my knowledge all of
> existing sidechains whether on bitcoin or ethereum are centralized,
> except lightning (if we forget that someone must watch what others are
> doing when you are on a trek in Nepal)

I would not lump together Lightning with sidechains.
Indeed, this design moves things closer to true offchain techniques (as in =
Lightning) than to sidechain techniques.

So while centralized, it is less centralized than a federated sidechains.

> Now I don't get why a sidechain should be a blockchain on top on another
> one (given also that we can't consider bitcoin or ethereum as
> decentralized today, so the path might be long for the sidechains...),
> the latest is used to store the final state, the former does not have to
> store forever the intermediate states, then it could just use a
> decentralized system (not necessarilly blockchain-like) to store the
> intermediate states and maybe be a distributed escrow
>
> I know, easy to say, please do it (why not), now the fact that
> sidechains claim to be decentralized or that they will be is just
> misleading people (that's not the case of your proposal but it does not
> say what happens if the platforms go down)

Perhaps it can be a next step.

Regards,
ZmnSCPxj