mirror of https://github.com/lightninglabs/loop
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
68 lines
4.3 KiB
Markdown
68 lines
4.3 KiB
Markdown
5 years ago
|
# Loop Architecture
|
||
|
|
|
||
|
|
Lightning Loop's architecture for orchestrating submarine swaps is based on a
|
||
|
|
client/server concept.
|
||
|
|
|
||
|
|
The client has a swap execution daemon `loopd` controlled by a CLI application
|
||
|
|
`loop` which uses a gRPC API. The client daemon initiates swaps and handles
|
||
|
|
their progress through swap phases. To manage keys and the connection to the
|
||
|
|
LN/BTC network layers the client daemon connects to a local lnd wallet.
|
||
|
|
|
||
|
|
Client daemons communicate with the Loop server daemon, which is opaque but
|
||
|
|
operates in a similar way. The server is not a trusted component in this
|
||
|
|
architecture; the client daemon validates that the terms of the swap are
|
||
|
|
acceptable and the server cannot access the swap funds unless the swap enters
|
||
|
|
the "complete" phase.
|
||
|
|
|
||
|
|
## Loop Out Swap (off -> on-chain)
|
||
|
|
|
||
|
|
Phases:
|
||
|
|
|
||
|
|
1. Initiation: Client queries for terms of a swap
|
||
|
|
2. Fee: Client sends a small fee HTLC that is unrestricted
|
||
|
|
3. Funding: Client sends a funding HTLC locked to a preimage they generate
|
||
|
|
4. Payment: Server sends the funds on-chain locked to the funding preimage hash
|
||
|
|
5. Complete: Client uses the preimage to take the on-chain funds.
|
||
|
|
6. Final: The server uses the on-chain-revealed preimage to claim funding HTLC
|
||
|
|
|
||
|
|
```
|
||
|
|
loop out 500
|
||
|
|
|
|
||
|
|
|
|
||
|
|
v
|
||
|
|
.-----------------------------.
|
||
|
|
| Loop CLI |
|
||
|
|
| ./cmd/loop |
|
||
|
|
| |
|
||
|
|
| |
|
||
|
|
| .-------------------. | .--------------. .---------------.
|
||
|
|
| | Loop Client (lib) | | | LND node | | Bitcoin node |
|
||
|
|
| | ./ |<-------------| |-------------------| |
|
||
|
|
| | | | | | on-chain | |
|
||
|
|
| | |------------->| | htlc | |
|
||
|
|
| | | | off-chain | | | |
|
||
|
|
| '-------------------' | htlc '--------------' '---------------'
|
||
|
|
'-----------------|-----------' | ^
|
||
|
|
| | |
|
||
|
|
| v |
|
||
|
|
| .--. .--.
|
||
|
|
| _ -( )- _ _ -( )- _
|
||
|
|
| .--,( ),--. .--,( ),--.
|
||
|
|
initiate| _.-( )-._ _.-( )-._
|
||
|
|
swap | ( LIGHTNING NETWORK ) ( BITCOIN NETWORK )
|
||
|
|
| '-._( )_.-' '-._( )_.-'
|
||
|
|
| '__,( ),__' '__,( ),__'
|
||
|
|
| - ._(__)_. - - ._(__)_. -
|
||
|
|
| | ^
|
||
|
|
| | |
|
||
|
|
v v |
|
||
|
|
.--------------------. off-chain .--------------. .---------------.
|
||
|
|
| Loop Server | htlc | LND node | | Bitcoin node |
|
||
|
|
| |<-------------| | | |
|
||
|
|
| | | | on-chain | |
|
||
|
|
| | | | htlc | |
|
||
|
|
| |--------------| |----------------->| |
|
||
|
|
| | | | | |
|
||
|
|
'--------------------' '--------------' '---------------'
|
||
|
|
```
|