Test LUD-13

index.cjs

const { mnemonicToSeed } = require("@scure/bip39");
const ecc = require("tiny-secp256k1");
const { BIP32Factory } = require("bip32");
const bip32 = BIP32Factory(ecc);
const { HMAC, Hash } = require("fast-sha256");
const secp256k1 = require("secp256k1");
const lnurl = require("@zerologin/lnurl");
const { CipherSeed } = require("aezeed");
const axios = require("axios");
const ZBase32 = require("@darkwolf/zbase32");

const stringToUint8Array = (str) => {
  return Uint8Array.from(str, (x) => x.charCodeAt(0));
};

const seedFromWords = async (mnemonic) => {
  const seed = await mnemonicToSeed(mnemonic);
  return Buffer.from(seed);
};

const hexToUint8Array = (hexString) => {
  return new Uint8Array(
    hexString.match(/.{1,2}/g).map((byte) => parseInt(byte, 16))
  );
};

const bytesToHexString = (bytes) => {
  return bytes.reduce(function (memo, i) {
    return memo + ("0" + i.toString(16)).slice(-2); //padd with leading 0 if <16
  }, "");
};

const sha256Hash = (buff) => {
  return new Hash().update(buff).digest();
};

const SIGN_PREFIX = "Lightning Signed Message:";
const CANONICAL_MESSAGE =
  "DO NOT EVER SIGN THIS TEXT WITH YOUR PRIVATE KEYS! IT IS ONLY USED FOR DERIVATION OF LNURL-AUTH HASHING-KEY, DISCLOSING ITS SIGNATURE WILL COMPROMISE YOUR LNURL-AUTH IDENTITY AND MAY LEAD TO LOSS OF FUNDS!";

const go2 = async () => {
  const lnurlObject = lnurl.decode(
    "LNURL1DP68GURN8GHJ7MR0VA5KUTNYDAK82TNYV4MZ7CTSDYHHVVF0D3H82UNV8A6XZEEAD3HKW6TWYE4NZ0FSXQCK2D3HXSCRGDP5VYMN2WPK8P3KZEFKXUMRYD3HXUEN2EFHV3JNSVRPXVEXGCNYXY6NXWP4X56NZWPEVYMRGEFHX93RGCTZXE3XZFNSW43XC6TRF9JR6EP48Y6KZCTYX5KNGDFEXVKNGCFNXCKNJWPSV5KNGVN9XPJNSCF5XSMKXVG30RYSY"
  );
  const domain = lnurlObject.domain;
  const k1 = lnurlObject.k1;
  const lnurlDecoded = lnurlObject.decoded;

  const mnemonic3 =
    "my 24 words from blixt";
  const cipherSeed1 = CipherSeed.fromMnemonic(mnemonic3);
  const root = bip32.fromSeed(cipherSeed1.entropy);

  let digest = sha256Hash([
    ...Buffer.from(SIGN_PREFIX),
    ...Buffer.from(CANONICAL_MESSAGE),
  ]);
  digest = sha256Hash(digest);

  const signatureBuffer = root.sign(digest);
  const signature = ZBase32.encode(signatureBuffer);
  console.log({ signature: Buffer.from(signature) });

  // HERE, SIGNATURE RESULT IS NOT THE SAME AS MY BLIXT WALLET SIGNATURE USING THE SAME SEED
  
  const hashingKey2 = sha256Hash(signature);

  // 4. SERVICE domain name is extracted from auth LNURL and then service-specific linkingPrivKey is defined as PrivateKey(hmacSha256(hashingKey, service domain name)).
  const linkingKeyPriv = new HMAC(hashingKey2)
    .update(stringToUint8Array(domain))
    .digest();

  // Obtain the public key
  const linkingKeyPub = secp256k1.publicKeyCreate(linkingKeyPriv, true);

  // Sign the message
  const signedMessage = secp256k1.ecdsaSign(
    hexToUint8Array(k1),
    linkingKeyPriv
  );
  const signedMessageDER = secp256k1.signatureExport(signedMessage.signature);

  const url =
    lnurlDecoded +
    `&sig=${bytesToHexString(signedMessageDER)}` +
    `&key=${bytesToHexString(linkingKeyPub)}`;

  const result = await axios.get(url);
  console.log(result.data);
};

go2();