signer.js

var grpc = require('grpc')
var ByteBuffer = require('bytebuffer')
var LND = require('./lightning')

const env = process.env.NODE_ENV || 'production'
const config = require(__dirname + '/config.json')[env]

var signerClient;

const loadSigner = () => {
  if (signerClient) {
    return signerClient
  } else {
    try {
      var credentials = LND.loadCredentials('signer.macaroon')
      var lnrpcDescriptor = grpc.load("proto/signer.proto");
      var signer = lnrpcDescriptor.signrpc
      signerClient = new signer.Signer(config.node_ip + ':' + config.lnd_port, credentials);
      return signerClient
    } catch (e) {
      throw e
    }
  }
}

const signMessage = (msg) => {
  return new Promise(async (resolve, reject) => {
    let signer = await loadSigner()
    try {
      const options = {
        msg: ByteBuffer.fromHex(msg),
        key_loc: { key_family: 6, key_index: 0 },
      }
      signer.signMessage(options, function (err, sig) {
        if (err || !sig.signature) {
          reject(err)
        } else {
          const buf = ByteBuffer.wrap(sig.signature);
          resolve(buf.toBase64())
        }
      })
    } catch (e) {
      reject(e)
    }
  })
}

async function signAscii(ascii) {
  try {
    const sig = await signMessage(ascii_to_hexa(ascii))
    return sig
  } catch (e) {
    throw e
  }
}

function ascii_to_hexa(str) {
  var arr1 = [];
  for (var n = 0, l = str.length; n < l; n++) {
    var hex = Number(str.charCodeAt(n)).toString(16);
    arr1.push(hex);
  }
  return arr1.join('');
}


async function verifyAscii(ascii,sig,pubkey) {
  try {
    const r = await verifyMessage(ascii_to_hexa(ascii),sig,pubkey)
    return r
  } catch(e) {
    throw e
  }
}
function verifyMessage(msg,sig,pubkey) {
  return new Promise(async(resolve, reject)=> {
    let signer = await loadSigner()
    if(msg.length===0) {
      return reject('invalid msg')
    }
    if(sig.length!==96) {
      return reject('invalid sig')
    }
    if(pubkey.length!==66) {
      return reject('invalid pubkey')
    }
    try {
      const options = {
        msg:ByteBuffer.fromHex(msg),
        signature:ByteBuffer.fromBase64(sig),
        pubkey:ByteBuffer.fromHex(pubkey),
      }
      signer.verifyMessage(options, function(err,res){
        if(err) {
          reject(err)
        } else {
          resolve(res)
        }
      })
    } catch(e) {
      reject(e)
    }
  })
}

module.exports={
  signAscii, verifyAscii
}