Date: Tue, 14 Jan 2020 04:12:56 +0000
To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
From: Robin Linus <robinlinus@protonmail.com>
Reply-To: Robin Linus <robinlinus@protonmail.com>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Coins: A trustless sidechain protocol
Precedence: list

Good morning ZmnSCPxj,

> > > because all users must process all transactions within the blockchain
> >
> > Reality shows, that's wrong. Bitcoin's security doesn't require verific=
ation to scale quadratically with users. Since the whitepaper, Satoshi was =
explicit about that phenomena. We can discuss nuances, yet it's overall pla=
usible and empirically it's true: Only a tiny minority of users ever verifi=
es the blockchain, still bitcoin works perfectly well. An honest economic m=
ajority is sufficient.
> > Yes, if you can, run your own node. Let's lower the barriers and let's =
help others to run their own nodes. Let's keep the blocks small and bitcoin=
's UTXOs set verifiable with consumer hardware. That's the core of decentra=
lized security.
> > But let's face it: most people on this planet will never run a bitcoin =
full node. And it is not required.
> > Bitcoin-backed PoS-sidechains scale in terms of verification and storag=
e just like any other blockchain. However, security is strictly better beca=
use double-spends are impossible. A single honest validating user guarantee=
s that attackers cannot do more harm than halting a sidechain. Thus, enduse=
rs won't have to validate all of each others' transactions at all.
> > For most endusers such sidechains' security is strictly superior to tod=
ay's LN experience.
> > Let's face it: The most popular LN apps are fully custodial.
> > They have to be custodial because there is no way to make LN usable for=
 regular users on unreliable phones.
> > Any payment channel which requires you to be always online excludes 99%=
 of the world's population.
> > Any payment channel which potentially requires you to be able to pay hi=
gh on-chain fees excludes most people, too. And on-chain fees keep rising.
> > Thus, no matter what Channel Factory constructions we build, they will =
not match most people's requirements. We will keep falling back to custodia=
l solutions.
> > Excel tables connected to the LN. The LN is awesome as a settlement lay=
er. In particular for anything like bitcoin banks that have been discussed =
since the beginning.
> > But why 1000 trusted Excel tables if we can have 1000 trustless sidecha=
ins?
>
> First:
>
> > A single honest validating user guarantees that attackers cannot do mor=
e harm than halting a sidechain.
>
> Is not compatible with:
>
> > 1000 trustless sidechains
>
> You are *tr\sting that there exists at least one honest user per sidechai=
n.
> Thus it is not a trustless solution, but a tr\*sted one.
> Replacing 1000 tr\*sted Excel tables with 1000 tr\*sted blockchains is th=
e same class of error as replacing the banking system with centralized larg=
e-scale blockchains: you gain the drawbacks of blockchains without gaining =
its benefits.

Agreed. Still, let's discuss a solution that meets the requirements of bill=
ions of average users with unreliable mobile devices.

Endusers payment experience should be insanely simple.

The LN currently offers regular users mostly custodial services. Is there a=
 foreseeable roadmap to meet endusers' simplicity requirements with non-cus=
todial constructions?

Bitcoin-backed PoS sidechains are strictly superior to custodial hubs. They=
 provide all hub features such as being able to pay merchants in BTC, plus =
many clear advantages such as better security including public auditability=
 and decentralized data storage. And they do not require any consensus chan=
ges.


> The security, integrity, and censorship-resistance of Bitcoin is dependen=
t on there existing some sophisticated actors ("persons") who are willing t=
o take on the risk of running fullnodes and providing hashpower.
> This is the Risk-Sharing principle, by which the risk of keeping Bitcoin =
running is spread out among many persons who are willing to keep Bitcoin al=
ive.
> The existence of such actors cannot be assured, but it seems to me that f=
ragmenting the entire community of such limited number of actors would not =
give good risk-sharing within a sidechain.

Indeed, a highly fragmented market would be inefficient and insecure. Howev=
er, I'd assume a free market of sidechains is intelligent enough to use its=
 resources efficiently.


Thanks again for your detailed feedback,
-Robin