原文： http://0rz.tw/3eN5b
So-called lightning network “watchtowers” — a much-anticipated next step for
securing the network — are coming soon.
Watchtowers have long been considered a missing piece of bitcoin’s lightning la
yer, as they’re crucial for squashing fraud on the experimental, off-chain netw
ork that could make bitcoin payments faster and more scalable. With version 0.7
of the LND software release coming at an undisclosed date in June, Lightning La
bs is launching the most complete build of a network watchtower to date.
When someone uses lightning, it’s necessary for someone using it to remain onli
ne to make sure their “counterparty” isn’t trying to steal those funds. But t
his is obviously a UX nightmare; for example, customers don’t have to monitor t
heir Wells Fargo accounts every day to ensure that they’re not being defrauded.
The watchtower “watches” for old “states” to be broadcast. In other words, i
f a bad actor tries to broadcast an old transaction — giving themselves extra m
oney — the watchtower responds by punishing that bad actor.
Thus, watchtowers outsource this anti-fraud functionality so users don’t have t
o do perform this kind of monitoring themselves.
Lightning Labs head of cryptographic engineering Conner Fromknecht has been the
driving force behind this implementation, even giving a talk on the design decis
ions (like how they made decisions to preserve privacy) of the implementations
at a virtual lightning conference in April. Lightning Labs CTO Olaoluwa Osuntok
un and others on the team have collaborated with him design decisions over the p
ast year.
As Osuntokun explained to CoinDesk:
“A big factor also [in my opinion] is that now we have a direct deterrence in p
lace against any possible breach attempts, now that the tower code is out there
in the open, an attacker now has a very strong disincentive against attempting a
n attack since it’s very possible that the potential victim has a tower watchin
g their back.”
The concept for watchtowers aren’t new, as it was first proposed in the origina
l 2015 lightning network whitepaper as a way to prevent fraud.
Indeed, Lightning Labs has been working on an implementation since at least the
beginning of last year, as CoinDesk reported. But what’s set to be released is
, perhaps, the most-advanced implementation intended for real-world use so far.
Running a ‘tower’
Since inception, there have been some technological tests for watchtowers, inclu
ding MIT’s Lit, an open-source project led by lightning white paper co-author T
adge Dyja, and Lightning Peach from blockchain services firm BitFury.
But with LND’s forthcoming release, one notable aspect will be that users will
be able to tap the watchtowers to watch real-world participants who are testing
lightning today.
Then there’s Bitcoin Lightning Wallet, which implements watchtowers in what’s
known as the “Olympus Server.” But, Osuntokun notes, LND’s watchtower code ca
n be run by anyone.
“The importance of this release is that once deployed, any routing node can run
their own tower to protect their infrastructure, also any business using [light
ning network] today can also start to run towers to protect their nodes,” Osunt
okun told CoinDesk.
But not everyone will want to run their own watchtower, especially as they will
eat up a lot of data. So people can start connecting to outside towers to protec
t their money.
As more of these towers crop up, users can connect to as many of the towers as t
hey want to make sure they’re not trusting just one tower to make sure their mo
ney is safe. That said, this state of affairs might not happen right away.
“We’ll also likely see instances of people running towers in the open for thei
r friends to connect to for themselves,” Osuntokun added.
Osuntokun expects that the introduction of watchtowers will lead to a “safer ne
twork,” paving the way for users to be able to make payments on the network tha
t weren’t considered safe before. That includes allowing users to put more mone
y into lightning channels via a technology named after Spongebob, he said.
‘Ecash’ token and beyond
This coming release is a big step for the long-awaited technology, but Osuntokun
and the Lightning Labs team still have future plans for improving the watchtowe
r software.
For example, those users set to run watchtowers will be doing so for free. But L
ightning Labs is planning an upgrade to allow people to pay small fees to watcht
owers so there’s “financial incentive” to run them as well.
Interestingly, though, there’s a bit of a debate going on about the necessity o
f this approach.
Lightning co-creator Dryja has argued that if lightning works, watchtowers shoul
dn’t actually be used very much. That’s because, if the watchtowers work, bad
actors shouldn’t try to broadcast old channels states because the watchtowers w
ill ensure the bad actor loses money if they try.
And if there are watchtowers at work, such an arrangement should, in theory, ser
ve as a barrier to keep people from trying to commit fraud. Therefore, they’ll
rarely be used and get paid for it. But it’s hard to predict such outcomes unti
l the watchtowers have been deployed and start attracting user attention.
As they’re trying to keep watchtowers as privacy-preserving as possible, the te
am is looking into a way for making these payments to watchtowers more private.
To that end, they’re looking into creating a “sort of ecash token.” Ecash is
the anonymous currency created by cryptographer David Chaum in the 80s, and is c
onsidered to be one of the precursors to bitcoin.
The idea is to allow lightning users to pay for watchtowers in a way that isn’t
“linkable.”
Then, there’s one other big step. Right now, LND is the only main lightning net
work implementation following the official specifications to have an up-and-ru
nning watchtower so far. As such, other implementations will need to implement t
heir own watchtowers as well.
中文:
閃電網絡實驗室（Lightning Labs）即將推出重大更新——瞭望塔（watchtowers）。其早
在2015年的閃電網白皮書中就曾提出，用以防止欺詐。
為啥不讓我改標題qq