lit - a lightning node you can run on your pwn

Under development, not for use with real money.

Installing on Linux

1. Start by installing Go

• Check this tutorial out: https://www.digitalocean.com/community/tutorials/how-to-install-go-1-6-on-ubuntu-14-04

2. Make sure your Go paths are set correctly: the .../go/bin path is in $PATH, $GOROOT is set to .../go/, and $GOPATH is the location of where you want lit to be.

3. Download the lit project: go get github.com/mit-dci/lit

4. The go get will fail.

• Lit uses btcd libraries, and btcd does not yet have segwit support in master. This will hopefully be merged soon, before segwit activates on mainnet.
• I have a fork of btcd from roasbeef/segwit, and could make it go-gettable by changing all the imports, but hopefully it will be merged in soon.
• To make it work, switch to the adiabat/btcd libraries:

# github.com/mit-dci/lit/uspv
uspv/eight333.go:406: undefined: wire.InvTypeWitnessBlock
... other errors.

user@host:~/go/src/github.com/mit-dci/lit$ cd ../../btcsuite/btcd/

user@host:~/go/src/github.com/btcsuite/btcd$ git remote add adiabat https://github.com/adiabat/btcd
user@host:~/go/src/github.com/btcsuite/btcd$ git fetch adiabat
user@host:~/go/src/github.com/btcsuite/btcd$ git checkout adiabat/bc2

user@host:~/go/src/github.com/btcsuite/btcd$ cd ../btcutil

user@host:~/go/src/github.com/btcsuite/btcutil$ git remote add adiabat https://github.com/adiabat/btcutil
user@host:~/go/src/github.com/btcsuite/btcutil$ git fetch adiabat
user@host:~/go/src/github.com/btcsuite/btcutil$ git checkout adiabat/master

5. compile lit, then run it:

user@host:~/go/src/github.com/btcsuite/btcutil$ cd ../../mit-dci/lit
user@host:~/go/src/github.com/mit-dci/lit$ go build -v
user@host:~/go/src/github.com/mit-dci/lit$ ./lit -spv my.testnet.node.tld

Folders:

cmd

has some rpc client code to interact with the lit node. Not much there yet

elkrem

a hash-tree for storing log(n) items instead of n

lndc

lightning network data connection -- send encrypted / authenticated messages between nodes

lnutil

some widely used utility functions

portxo

portable utxo format, exchangable between node and base wallet (or between wallets). Should make this into a BIP once it's more stable.

qln

A quick, channel implementation with databases. Doesn't do multihop yet.

sig64

Library to make signatures 64 bytes instead of 71 or 72 or something

watchtower

Unlinkable outsourcing of channel monitoring

uspv

An spv wallet library

Heirarchy of packages

One instance of lit has one litNode (package qln).

LitNodes manage lndc connections to other litnodes, manage all channels, rpc listener, and the ln.db. Litnodes then initialize and contol wallits.

wallit

A litNode can have multiple wallits; each must have different params. For example, there can be a testnet3 wallit, and a regtest wallit. Eventually it might make sense to support a root key per wallit, but right now the litNode gives a rootPrivkey to each wallet on startup. Wallits each have a db file which tracks utxos, addresses, and outpoints to watch for the upper litNode. Wallits do not directly do any network communication. Instead, wallits have one or more chainhooks; a chainhook is an interface that talks to the blockchain.

uspv

One package that implements the chainhook interface is uspv. Uspv deals with headers, wire messages to fullnodes, filters, and all the other mess that is contemporary SPV.

(in theory it shouldn't be too hard to write a package that implements the chainhook interface and talks to some block explorer. Maybe if you ran your own explorer and authed and stuff that'd be OK.)