Validating Lightning Signer - AMA
11k sats \ 10k boost \ 33 comments \ @devrandom 13 Jul 2023 bitcoin
Hello fellow stackers! 👋
We are the team working on the Validating Lightning Signer (VLS) FOSS project: @devrandom, @ken6, @JackRonaldi
VLS is a nifty piece of software that helps boost the security of the Bitcoin Lightning Network. 🛡️
Here's how it works: usually, your private keys are stored on your Lightning node, but if a hacker gets into your node, they could snatch your funds. To avoid this, VLS keeps your private keys separate from your node. So, even if the bad guys compromise your node, your funds are safu.
VLS doesn't stop there, though.
When you're making transactions, instead of your lightning node signing the transactions internally, they are forwarded to VLS running on a secure signing device. VLS double-checks everything and confirms that the transaction does not steal or lose funds before it signs. This extra layer of security significantly reduces the attack surface for a lightning network user. It's a real game-changer.
Plus, VLS opens the door to using multi-signature setups in the Lightning Network, much like the multi-signature wallets you might know from Bitcoin L1. The idea here is that, just like a bank vault needing two keys to open, a transaction would need more than one signature to go through. This makes it even harder for anyone with bad intentions to get their hands on your funds.
Topics to ask us about:
  • What is VLS?
  • Why is VLS important?
  • How does VLS work?
  • How can I try VLS?
  • How do we work with you?
  • What does our roadmap look like?
  • Wen multi-sig?
  • What is the airspeed velocity of an unladen swallow?
  • What is the answer to the ultimate question of the life, the universe and everything?
We'll do our best to answer questions for the rest of the day.
Let's go! ⚡️
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202 sats \ 2 replies \ @pillar 13 Jul 2023
Will VLS allow "shared-ownership" of a Lightning node? As in:
  • Alice, Bob and Charlie share TheNode.
  • TheNode can only open a channel, close a channel or send onchain funds from the node wallet if Alice, Bob and Charlie sign with each individual's key.
  • There is no way for these actions to take place unless all three agree by signing.
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93 sats \ 1 reply \ @jackronaldi 13 Jul 2023
This seems like a 3-of-3 multi-sig setup where each person holds 1 key.
While LN multi-sig is not yet ready, we are following work being done by Lightning core devs on multi-sig protocols which should allow for this to happen.
As a side note, 3-of-3 setups are dangerous if you don't properly backup your keys, as one lost key means you lose your funds.
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0 sats \ 0 replies \ @devrandom OP 14 Jul 2023
To follow up, a 2-of-3 or 3-of-5 multisig setup is safer. These kind of setups are common for L1 multisig wallets.
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177 sats \ 2 replies \ @ek 13 Jul 2023
Is your target group businesses which run lightning nodes or are you also targeting plebs?
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248 sats \ 1 reply \ @ken6 13 Jul 2023
Both! VLS encapsulates the minimum amount of state required to maintain custody, so it's useful for both high end operations using a HSM and individuals using a personal signing device
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138 sats \ 0 replies \ @jackronaldi 13 Jul 2023
To add to what Ken said, VLS is focused on building a library and reference implementation which can be used by LN companies and developers to build into their solutions. VLS will be capable of running on cheap personal signing devices that plebs can use, but if the pleb is not a dev the solution they use will need to be built by one of these LN companies/devs
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169 sats \ 1 reply \ @k00b 13 Jul 2023
On a podcast I heard that VLS requires the signer implement a lot of the lightning protocol. Can you elaborate on that? Is that expected to change with time?
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20 sats \ 0 replies \ @devrandom OP 13 Jul 2023
We keep track of the Lightning state machine, but we don't need to keep track of the protocol.
As far as state, we keep track of L2 state and L1 state - about 10 pieces of data each.
We don't keep track of things like gossip and we don't need a network stack, so the complexity and attack surface is much smaller than an actual node.
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160 sats \ 2 replies \ @beorange 13 Jul 2023
Looks like an awesome project, the space is really maturing nicely. Here are my questions:
How hard will it be for a regular user (not an expert) to use VLS? Assuming he knows the minimum to run his own lightning node.
How much overhead will it impose? over regular usage.
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10 sats \ 1 reply \ @ken6 13 Jul 2023
We have some instructions on how to set up basic configurations: https://gitlab.com/lightning-signer/validating-lightning-signer/-/blob/main/contrib/howto/README.md
These are for early adopters, folks who are already comfortable with unix CLI and lightning node setup and operation.
Making an umbrel (or similar) version will make it even easier ...
There shouldn't be much overhead, you will be asked to confirm spends to unknown destinations, for example
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0 sats \ 0 replies \ @jackronaldi 13 Jul 2023
Also, it should get easier from here as LN companies like Stakwork build user facing solutions that integrate VLS with an UI
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20 sats \ 1 reply \ @kr 13 Jul 2023
really curious to hear about your roadmap, what are you most excited about?
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203 sats \ 0 replies \ @jackronaldi 13 Jul 2023
We’re very excited about our next release, which is focused on enabling low resource signers. For example, the Stakwork and Sphinx team is working on running VLS on an ESP32, which costs only $10!
Looking forward, we’re excited to get VLS running in the secure area of mobile phones, and also to figure out Lightning multi-sig.
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10 sats \ 2 replies \ @2bithits 14 Jul 2023
Any wallets signaling adoption of VLS at the moment?
I like the idea. A little extra inconvenience for A LOT more security
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21 sats \ 1 reply \ @jackronaldi 14 Jul 2023
Breez is using Greenlight, who are using VLS to separate LN keys from the node
Maybe @roy can provide more details, as I'm not sure on what it will look like
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21 sats \ 0 replies \ @roy 14 Jul 2023 freebie
Yep! Works great! It seamless to end users, so not sure what to add...
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60 sats \ 3 replies \ @0368d36190 13 Jul 2023 freebie
if attacker gets access to the node, why can it just run required queries to VLS to sign transactions he needs? Everything he needs for this should be on the node in one form or another
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0 sats \ 2 replies \ @jackronaldi 13 Jul 2023
VLS normally asks the user to approve transactions, so it will refuse to sign if the user didn't initiate the action. And since the device running VLS holds the LN keys, the node will not be able to independently sign the transactions (unlike a blind signer which would be open to the exploit you describe)
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50 sats \ 1 reply \ @0368d36190 13 Jul 2023 freebie
Thank you for answer! Follow up about scaling, afaik in a typical ln node quite a lot going on, that require sig ops - htlc, commitments, etc. Is user input required for all of this?
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0 sats \ 0 replies \ @jackronaldi 13 Jul 2023
The devs building VLS into their Lightning apps will be able to configure which actions do/don’t require user input.
They may also provide optional velocity controls which will allow routine payments to known destinations up to a limit (per hour/day/week/etc) defined by the user
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110 sats \ 3 replies \ @k00b 13 Jul 2023
In setups where VLS is used with a hosted node solution like with Blockstream’s greenlight, what kind of privacy might signers lose?
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144 sats \ 2 replies \ @devrandom OP 13 Jul 2023
Currently, with a hosted node such as Greenlight, the node constructs routes, so you lose privacy related to your payees. We are considering syncing the routing table from the node and constructing routes and onions on our side. If this is something people are interested in, we would love to hear.
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110 sats \ 1 reply \ @moneyball 13 Jul 2023
Can RGS be used for this? https://github.com/lightningdevkit/rust-lightning/tree/main/lightning-rapid-gossip-sync
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10 sats \ 0 replies \ @devrandom OP 13 Jul 2023
yes, RGS seems like the ideal solution, especially for mobile, since it optimizes for network bandwidth.
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10 sats \ 3 replies \ @k00b 13 Jul 2023
Why might someone choose to not use VLS?
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300 sats \ 2 replies \ @jackronaldi 13 Jul 2023
This is a great question and I think this depends on their preferred LN setup and security needs/budget. A lot of plebs I’ve talked to have asked why do I need VLS if I have my Lightning node on an Umbrel or why do I need VLS if I’m keeping small amounts on my node?
Those are good questions to ask. From an individual’s perspective, given their specific circumstances, the cost to setup VLS or the time required to manage it may not be worth it. Or they may prefer to have full control over the node from one device, rather than splitting the keys from the node. This may even apply to small merchants depending on their risk tolerance and security needs/budget.
When we’re talking about larger merchants/enterprises, with more significant volumes flowing through their node, I find it hard to imagine a case where they are using the Lightning network and not using VLS or something like it.
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100 sats \ 1 reply \ @k00b 13 Jul 2023
That makes sense. There might be cases where the security benefit does not outweigh the convenience of omitting it.
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0 sats \ 0 replies \ @jackronaldi 13 Jul 2023
That being said, we recommend everyone practice safe transactions, use VLS (whenever possible) 😉
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10 sats \ 1 reply \ @kr 13 Jul 2023
how popular do you think multi-sig setups will be on Bitcoin’s base layer over time? how popular will they be on Lightning?
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213 sats \ 0 replies \ @jackronaldi 13 Jul 2023
Imo, multi-sig setups will likely be the standard for enterprises, institutions, large merchants, etc which are using either L1/L2, because they have a need for increased security and also to segregate duties so there's not too much power in the hands of one individual.
Whether or not multi-sig becomes widespread among individuals I think really depends on the UX that can be built around it. Right now, multi-sig for L1 is daunting for many users, especially the less tech-savvy. If the difficulty can be abstracted away easily, without sacrificing too much in security or becoming too expensive, I could see it catching on more widely.
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0 sats \ 2 replies \ @lpop4254 13 Jul 2023
Vls can violate our privacy , if it double check everythink
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0 sats \ 0 replies \ @devrandom OP 14 Jul 2023
To clarify, VLS is a code library. It is used by developers to create applications which self-custody bitcoin Lightning funds. The applications would run on end-user controlled devices. We have no access to any end-user information.
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0 sats \ 0 replies \ @jackronaldi 13 Jul 2023
Do you mind elaborating how you think VLS might violate privacy? We will address your concern, but just want to make sure we understand first
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