ln-verifymessagejs

A simple library to recover Lightning Network node ids from signed messages. No need to run a Lightning Network node. Everything is done in js. Also supports signing.

Tested implementations:

• lnd
• core-lightning
• eclair
• LDK (react-native)

Basically, all implementations that follow the specinatweet and output zbase or hex are supported.

Install

npm i ln-verifymessagejs

Usage

Verify Message

Check if a signature and message has been signed by a specific node.

import { verifyMessage } from "ln-verifymessagejs";

const messageThatHasBeenSigned = "helloWorld"
const zbaseSignature = "ry13r8phfdyt3yukuft4m8s5tq4kgbfmpnn9a54akrar7waxjooi1h1nsp8uzsf5t6fcctupzhhte1y388d19jwobz5bwh5rybs5wrb7"
const expectedNodeId = "02fbbee488a01cc8a9b429b6c4567e0ce7a43a2778d60729d5c4c67dcb9a34a898"

const isValid = verifyMessage(zbaseSignature, messageThatHasBeenSigned, expectedNodeId);

• signature: string Signature to verify.
• message: string Plain text message that has been signed.
• nodePubkey: string Node id of the node that signed the message.
• options Optional arguments.
  • options.prefix: string Message prefix. Default is Lightning Signed Message:.

Derive Node Id

Recover a node id from a signature and message.

import { deriveNodeId } from "ln-verifymessagejs";

const messageThatHasBeenSigned = "ln-verifymessagejs";
const zbaseSignature = "rynmoqhhadjsttaracxgo9nhkoioi6peib8k18dekrih4hxpp36zcbgc6ntyrggc11uhjcb9prcx5py6qo16bk89i458r4n51ghggnxc";

const derivedNodeId = deriveNodeId(zbaseSignature, messageThatHasBeenSigned);
console.log("Message has been signed by", derivedNodeId);

• signature: string Signature to verify.
• message: string Plain text message that has been signed.
• prefix?: string Message prefix. Default is Lightning Signed Message:.

Be aware: deriveNodeId does it check if the node exists.

Sign Message

Sign a message with a private key.

import { signMessage, utils } from "ln-verifymessagejs";

const {privateKey, publicKey} = utils.generateKeyPair(); // Generate a keypair or use your own private key.

const messageToSign = "helloWorld"
const signature = await signMessage(messageToSign, privateKey.hex);

• message: string Plain text message to sign.
• privateKey: Uint8Array | string Private key either as bytes array or hex string.
• options Optional arguments.
  • options.signatureFormat: "hex" | "zbase" Output encoding. Default is zbase.
  • options.prefix: string Message prefix. Default is Lightning Signed Message:.

Derive shared secret

Derive a shared secret between a private key and a public key. Two parties deriving a secret with their respective private key and the partners public key generate the same shared secret.

import { generateSharedSecret } from "ln-verifymessagejs";

const myKeys = utils.generateKeyPair(); // Generate a keypair or use your own key.
const partnerNodeId = '0200000000a3eff613189ca6c4070c89206ad658e286751eca1f29262948247a5f';

const secret = generateSharedSecret(myKeys.privateKey.hex, partnerNodeId)

• privateKey: Uint8Array | string Private key either as bytes array or hex string.
• nodePubkey: string Node id of the partner node.
• derivationName?: string Optional derivation name to create a unique secret. Double sha256(baseSecret + derivationName).

Sign with a Lightning Network node

Node operators can sign messages with Thunderhub or Ride the Lightning. If a user has access to a terminal messages can be signed directly with the cli.

lnd signmessage

lncli signmessage --msg MyMessageToSign
# {
#     "signature": "rynmoqhhadjsttaracxgo9nhkoioi6peib8k18dekrih4hxpp36zcbgc6ntyrggc11uhjcb9prcx5py6qo16bk89i458r4n51ghggnxc"
# }

core-ightning signmessage

lightning-cli signmessage MyMessageToSign
# {
#    "signature": "ddd47bc1398327e98775b27cc575fce1df2464c382549eacebc7233c1cbc4b430f8ee4d654719a1bc281f51b030ba9fa8bf95032c26abfe6e56bb282a9065332",
#    "recid": "01",
#    "zbase": "rdq7e66b8gb1x4c8qs383tmi9uo76jdraqbfj8ic7xd1gxyhztfwgdhqhumfehc4dxbed7e5ycf4u6wm9fedfoukz9uqk471okwocw31"
# }

# Use the zbase field

eclair signmessage

eclair-cli signmessage --msg=$(echo -n 'MyMessageToSign' | base64)
# {
#   "nodeId": "02ca7361934233f6d4defd4d792fb2ce2cd0b50c7605e6c5cd16006bcd5be2bf70",
#   "message": "aGVsbG8gd29ybGQK",
#   "signature": "1f730dce842c31b692dc041c2d0f00423d2a2a67b0c63c1a905d500f09652a5b1a036763a1603333fa589ae92d1f7963428ff170e976d0966a113f4b9f9d0efc7f"
# }

# Use the signature field. It's hex

react-native-ldk signmessage

const res = await ldk.nodeSign({
  message: 'MyMessageToSign',
  messagePrefix: 'Lightning Signed Message:' //Optional with default
});
if (res.isErr()) {
  console.error(res.error);
  return;
}

console.log(res.value);