LNDK

LNDK is a standalone daemon that connects to LND (via its grpc API) that aims to implement bolt 12 functionality externally to LND. LNDK leverages the lightning development kit to provide functionality, acting as a thin "shim" between LND's APIs and LDK's lightning library.

Project Milestones:

• v0.1.0: Onion message forwarding for LND.
• v0.2.0: Payment to offers with blinded paths.

Please note that this project is still experimental.

Resources

• Contributor guidelines
• Code of Conduct
• Architecture

Setting up LNDK

Compiling LND

To run LNDK, LND is assumed to be running. You'll need to make some adjustments when compiling and running LND to make it compatible with LNDK.

First, you'll need to run a particular branch of LND to allow the advertising of onion_message feature bits. To do so, follow these steps:

git clone https://github.com/lightningnetwork/lnd
cd lnd
git checkout v0.16.2-patch-customfeatures

While on this branch, compile LND. Make sure that the peersrpc and signerrpc services and dev tag are enabled, like this:

make install --tags="peersrpc signerrpc dev"

Note that this guide assumes some familiarity with setting up LND. If you're looking to get up to speed, try this guide.

Running LND

Once you're ready to run LND, the binary must be run with --protocol.custom-message=513 to allow it to report onion messages to LNDK as well as --protocol.custom-nodeann=39 --protocol.custom-init=39 for advertising the onion message feature bits.

There are two ways you can do this:

1. Pass these options directly to LND when running it:

lnd --protocol.custom-message=513 --protocol.custom-nodeann=39 --protocol.custom-init=39

2. Adding these to the config file lnd.conf:

[protocol]
protocol.custom-message=513
protocol.custom-nodeann=39
protocol.custom-init=39

Running LNDK

Now we need to set up LNDK. To start:

git clone https://github.com/lndk-org/lndk
cd lndk

In order for LNDK successfully connect to LND, we need to pass in the grpc address and authentication credentials. There are two ways to do this:

1. These values can be passed in via the command line when running the LNDK program, like this:

cargo run -- --address=<ADDRESS> --cert=<TLSPATH> --macaroon=<MACAROONPATH>

Or in a more concrete example:

cargo run -- --address=https://localhost:10009 --cert=/home/<USERNAME>/.lnd/tls.cert --macaroon=/home/<USERNAME>/.lnd/data/chain/bitcoin/regtest/admin.macaroon

Remember that the grpc address must start with https:// for the program to work.

2. Alternatively, you can use a configuration file to add the required arguments.

• In the lndk directory, create file named lndk.conf.
• Add the following lines to the file:
  • address="<ADDRESS"
  • cert="<TLSPATH>"
  • macaroon="<MACAROONPATH>"
• Run cargo run -- --conf lndk.conf

• Use any of the commands with the --help option for more information about each argument.

Custom macaroon

Rather than use the admin.macaroon with unrestricted permission to an LND node, we can bake a macaroon using lncli with much more specific permissions for better security. With this command, generate a macaroon which will give LNDK only the specific grpc endpoints it's designed to hit:

lncli --save_to=<FILEPATH>/lndk.macaroon uri:/lnrpc.Lightning/GetInfo uri:/lnrpc.Lightning/ListPeers uri:/lnrpc.Lightning/SubscribePeerEvents uri:/lnrpc.Lightning/SendCustomMessage uri:/lnrpc.Lightning/SubscribeCustomMessages uri:/peersrpc.Peers/UpdateNodeAnnouncement uri:/signrpc.Signer/DeriveSharedKey

Security

NOTE: It is recommended to always use cargo-crev to verify the trustworthiness of each of your dependencies, including this one.