lit

README

lit - a lightning node you can run on your own

Under development, not for use with real money.

Setup

Prerequisites

• Git

Installing

1. Start by installing Go

• Go Installation

1. Set your Go variables to match your installed paths are set correctly:

• .../go/bin (your install location) is in $PATH (Windows: Add the install location into your PATH System Variable)
• $GOPATH is set the location of where you want lit (and other projects) to be
• optional: If you want to have packages download in a separate location than your installation add $GOROOT set to another location (Windows: Add )

1. Download the lit project with go get github.com/mit-dci/lit

Building

1. Go to the location of your lit installation with your defined gopath variable ($GOPATH on Linux and %GOPATH% Windows) to the lit location

cd [gopath]/src/github.com/mit-dci/lit

1. If you try to build now with go build you will receive several errors such as

cannot find package "golang.org/x/crypto/nacl/secretbox"
...
cannot find package "golang.org/x/crypto/scrypt"
...
cannot find package [packageName]
...

1. In order to download all missing packages, do go get ./... or go get .

2. Go back to location of the lit folder if you are not already there (Step 1) and try to rebuild the project.

3. You may now want to build lit-af, the text based client which controls the lit node using

cd cmd/lit-af
go build

1. To run lit use: (Note : Windows users can take off ./ but may need to change lit to lit.exe in the second line.)

cd GOPATH/src/github.com/mit-dci/lit
./lit --tn3 my.testnet.node.tld

Using Lightning

Great! Now that you are all done setting up lit, you can

• read about the arguments for starting lit here
• read about the folders for the code and what does what here
• head over to the Walkthrough to create some lit nodes or
• check out how to Contribute.

Command line arguments

(a lit.conf file is not yet implemented but is on the TODO list)

When starting lit, the following command line arguments are available

connecting to networks:

Arguments	Details	Default Port
--tn3 <nodeHostName>	connect to nodeHostName, which is a bitcoin testnet3 node.	18333
--reg <nodeHostName>	connect to nodeHostName, which is a bitcoin regtest node.	18444
--lt4 <nodeHostName>	connect to nodeHostName, which is a litecoin testnet4 node.	19335

other settings:

Arguments	Details
-v or --verbose	Verbose; log everything to stdout as well as the lit.log file. Lots of text.
--dir <folderPath>	use folderPath as the directory. By default, saves to ~/.lit/
-p or --rpcport <portNumber>	listen for RPC clients on port portNumber. Defaults to 8001. Useful when you want to run multiple lit nodes on the same computer (also need the --dir option)
-r or --reSync	try to re-sync to the blockchain from the height given -tip

Folders

Folder Name	Details
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
litbamf	Lightning Network Browser Actuated Multi-Functionality -- web gui for lit
litrpc	Websocket based RPC connection
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.
powless	Introduces a web API chainhook in addition to the uspv one
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
test	Integration tests
uspv	Deals with the network layer, sending network messages and filtering what to hand over to wallit
wallit	Deals with storing and retreiving utxos, creating and signing transactions
watchtower	Unlinkable outsourcing of channel monitoring

Hierarchy 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.

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.

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.)

License

MIT