Thread by @joostjgr

1/ Lightning is great, but can't say it is battle-tested. If script kids would be interested, they could take down those shiny new 5 BTC #wumbo channels with negligible cost and no effort at all.

2/ The underlying issue is that a channel cannot hold more than 483 htlcs at a time, regardless of the channel capacity. Sending 483 micro-payments to yourself and holding on to the htlcs is enough to incapacitate a channel for up to two weeks.

3/ By utilizing the max route length to add loops, each payment can consume up to 9 htlc slots on the target channel. If the script kid is lucky, they only need to send 54 payments to get it done. A single tiny channel takes double-digit amounts of #bitcoin out of business.

4/ Here you see me locking up ~5800000 sat with a refundable 18 sat payment looping five times through three mainnet channels owned by @bitfinex and @OpenNodeCo. For basically as long as I want. This happened today.

5/ Wanting to become the world's payment system sounds good, but then we can't have trivially exploitable vulnerabilities like this. Walk the talk.

6/ Therefore I started a new project called Circuit Breaker: a firewall for Lightning nodes. The primary goal is to encourage thinking about this problem, with the potential to grow into a full-fledged Lightning protection system.
github.com/lightningequip…