metamask_ethereum_signing.js

metamask_ethereum_signing.js

// For eth_sign, we need to sign arbitrary data:
signMessage (withAccount, data) {
  const wallet = this._getWalletForAccount(withAccount)
  const message = ethUtil.stripHexPrefix(data)
  var privKey = wallet.getPrivateKey()
  var msgSig = ethUtil.ecsign(new Buffer(message, 'hex'), privKey)
  var rawMsgSig = ethUtil.bufferToHex(sigUtil.concatSig(msgSig.v, msgSig.r, msgSig.s))
  return Promise.resolve(rawMsgSig)
}

personalSign: function (privateKey, msgParams) {
  var message = ethUtil.toBuffer(msgParams.data)
  var msgHash = ethUtil.hashPersonalMessage(message)
  var sig = ethUtil.ecsign(msgHash, privateKey)
  var serialized = ethUtil.bufferToHex(this.concatSig(sig.v, sig.r, sig.s))
  return serialized
},

/**
 * Returns the keccak-256 hash of `message`, prefixed with the header used by the `eth_sign` RPC call.
 * The output of this function can be fed into `ecsign` to produce the same signature as the `eth_sign`
 * call for a given `message`, or fed to `ecrecover` along with a signature to recover the public key
 * used to produce the signature.
 * @param message
 * @returns {Buffer} hash
 */
exports.hashPersonalMessage = function (message) {
  const prefix = exports.toBuffer('\u0019Ethereum Signed Message:\n' + message.length.toString())
  return exports.sha3(Buffer.concat([prefix, message]))
}

/**
 * ECDSA sign
 * @param {Buffer} msgHash
 * @param {Buffer} privateKey
 * @return {Object}
 */
exports.ecsign = function (msgHash, privateKey) {
  const sig = secp256k1.sign(msgHash, privateKey)

  const ret = {}
  ret.r = sig.signature.slice(0, 32)
  ret.s = sig.signature.slice(32, 64)
  ret.v = sig.recovery + 27
  return ret
}