metamask-extension/app/scripts/keyring-controller.js

const async = require('async')
const ethUtil = require('ethereumjs-util')
const EthQuery = require('eth-query')
const bip39 = require('bip39')
const Transaction = require('ethereumjs-tx')
const EventEmitter = require('events').EventEmitter
const filter = require('promise-filter')
const encryptor = require('browser-passworder')

const normalize = require('./lib/sig-util').normalize
const messageManager = require('./lib/message-manager')
const IdStoreMigrator = require('./lib/idStore-migrator')
const BN = ethUtil.BN

// Keyrings:
const SimpleKeyring = require('./keyrings/simple')
const HdKeyring = require('./keyrings/hd')
const keyringTypes = [
  SimpleKeyring,
  HdKeyring,
]

const createId = require('./lib/random-id')

module.exports = class KeyringController extends EventEmitter {

  // PUBLIC METHODS
  //
  // THE FIRST SECTION OF METHODS ARE PUBLIC-FACING,
  // MEANING THEY ARE USED BY CONSUMERS OF THIS CLASS.
  //
  // THEIR SURFACE AREA SHOULD BE CHANGED WITH GREAT CARE.

  constructor (opts) {
    super()
    this.configManager = opts.configManager
    this.ethStore = opts.ethStore
    this.encryptor = encryptor
    this.keyringTypes = keyringTypes

    this.keyrings = []
    this.identities = {} // Essentially a name hash

    this._unconfTxCbs = {}
    this._unconfMsgCbs = {}

    this.getNetwork = opts.getNetwork

    // TEMPORARY UNTIL FULL DEPRECATION:
    this.idStoreMigrator = new IdStoreMigrator({
      configManager: this.configManager,
    })
  }

  // Set Store
  //
  // Allows setting the ethStore after the constructor.
  // This is currently required because of the initialization order
  // of the ethStore and this class.
  //
  // Eventually would be nice to be able to add this in the constructor.
  setStore (ethStore) {
    this.ethStore = ethStore
  }

  // Full Update
  // returns Promise( @object state )
  //
  // Emits the `update` event and
  // returns a Promise that resolves to the current state.
  //
  // Frequently used to end asynchronous chains in this class,
  // indicating consumers can often either listen for updates,
  // or accept a state-resolving promise to consume their results.
  //
  // Not all methods end with this, that might be a nice refactor.
  fullUpdate () {
    this.emit('update')
    return Promise.resolve(this.getState())
  }

  // Get State
  // returns @object state
  //
  // This method returns a hash representing the current state
  // that the keyringController manages.
  //
  // It is extended in the MetamaskController along with the EthStore
  // state, and its own state, to create the metamask state branch
  // that is passed to the UI.
  //
  // This is currently a rare example of a synchronously resolving method
  // in this class, but will need to be Promisified when we move our
  // persistence to an async model.
  getState () {
    const configManager = this.configManager
    const address = configManager.getSelectedAccount()
    const wallet = configManager.getWallet() // old style vault
    const vault = configManager.getVault() // new style vault

    return {
      seedWords: this.configManager.getSeedWords(),
      isInitialized: (!!wallet || !!vault),
      isUnlocked: Boolean(this.password),
      isDisclaimerConfirmed: this.configManager.getConfirmedDisclaimer(), // AUDIT this.configManager.getConfirmedDisclaimer(),
      unconfTxs: this.configManager.unconfirmedTxs(),
      transactions: this.configManager.getTxList(),
      unconfMsgs: messageManager.unconfirmedMsgs(),
      messages: messageManager.getMsgList(),
      selectedAccount: address,
      shapeShiftTxList: this.configManager.getShapeShiftTxList(),
      currentFiat: this.configManager.getCurrentFiat(),
      conversionRate: this.configManager.getConversionRate(),
      conversionDate: this.configManager.getConversionDate(),
      keyringTypes: this.keyringTypes.map(krt => krt.type),
      identities: this.identities,
    }
  }

  // Create New Vault And Keychain
  // @string password - The password to encrypt the vault with
  //
  // returns Promise( @object state )
  //
  // Destroys any old encrypted storage,
  // creates a new encrypted store with the given password,
  // randomly creates a new HD wallet with 1 account,
  // faucets that account on the testnet.
  createNewVaultAndKeychain (password) {
    return this.persistAllKeyrings(password)
    .then(this.createFirstKeyTree.bind(this))
    .then(this.fullUpdate.bind(this))
  }

  // CreateNewVaultAndRestore
  // @string password - The password to encrypt the vault with
  // @string seed - The BIP44-compliant seed phrase.
  //
  // returns Promise( @object state )
  //
  // Destroys any old encrypted storage,
  // creates a new encrypted store with the given password,
  // creates a new HD wallet from the given seed with 1 account.
  createNewVaultAndRestore (password, seed) {
    if (typeof password !== 'string') {
      return Promise.reject('Password must be text.')
    }

    if (!bip39.validateMnemonic(seed)) {
      return Promise.reject('Seed phrase is invalid.')
    }

    this.clearKeyrings()

    return this.persistAllKeyrings(password)
    .then(() => {
      return this.addNewKeyring('HD Key Tree', {
        mnemonic: seed,
        numberOfAccounts: 1,
      })
    }).then(() => {
      const firstKeyring = this.keyrings[0]
      return firstKeyring.getAccounts()
    })
    .then((accounts) => {
      const firstAccount = accounts[0]
      const hexAccount = normalize(firstAccount)
      this.configManager.setSelectedAccount(hexAccount)
      return this.setupAccounts(accounts)
    })
    .then(this.persistAllKeyrings.bind(this, password))
    .then(this.fullUpdate.bind(this))
  }

  // PlaceSeedWords
  // returns Promise( @object state )
  //
  // Adds the current vault's seed words to the UI's state tree.
  //
  // Used when creating a first vault, to allow confirmation.
  // Also used when revealing the seed words in the confirmation view.
  placeSeedWords () {
    const firstKeyring = this.keyrings[0]
    return firstKeyring.serialize()
    .then((serialized) => {
      const seedWords = serialized.mnemonic
      this.configManager.setSeedWords(seedWords)
      return this.fullUpdate()
    })
  }

  // ClearSeedWordCache
  //
  // returns Promise( @string currentSelectedAccount )
  //
  // Removes the current vault's seed words from the UI's state tree,
  // ensuring they are only ever available in the background process.
  clearSeedWordCache () {
    this.configManager.setSeedWords(null)
    return Promise.resolve(this.configManager.getSelectedAccount())
  }

  // Set Locked
  // returns Promise( @object state )
  //
  // This method deallocates all secrets, and effectively locks metamask.
  setLocked () {
    this.password = null
    this.keyrings = []
    return this.fullUpdate()
  }

  // Submit Password
  // @string password
  //
  // returns Promise( @object state )
  //
  // Attempts to decrypt the current vault and load its keyrings
  // into memory.
  //
  // Temporarily also migrates any old-style vaults first, as well.
  // (Pre MetaMask 3.0.0)
  submitPassword (password) {
    return this.migrateOldVaultIfAny(password)
    .then(() => {
      return this.unlockKeyrings(password)
    })
    .then((keyrings) => {
      this.keyrings = keyrings
      return this.fullUpdate()
    })
  }

  // Add New Keyring
  // @string type
  // @object opts
  //
  // returns Promise( @Keyring keyring )
  //
  // Adds a new Keyring of the given `type` to the vault
  // and the current decrypted Keyrings array.
  //
  // All Keyring classes implement a unique `type` string,
  // and this is used to retrieve them from the keyringTypes array.
  addNewKeyring (type, opts) {
    const Keyring = this.getKeyringClassForType(type)
    const keyring = new Keyring(opts)
    return keyring.getAccounts()
    .then((accounts) => {
      this.keyrings.push(keyring)
      return this.setupAccounts(accounts)
    })
    .then(() => { return this.password })
    .then(this.persistAllKeyrings.bind(this))
    .then(() => {
      return keyring
    })
  }

  // Add New Account
  // @number keyRingNum
  //
  // returns Promise( @object state )
  //
  // Calls the `addAccounts` method on the Keyring
  // in the kryings array at index `keyringNum`,
  // and then saves those changes.
  addNewAccount (keyRingNum = 0) {
    const ring = this.keyrings[keyRingNum]
    return ring.addAccounts(1)
    .then(this.setupAccounts.bind(this))
    .then(this.persistAllKeyrings.bind(this))
    .then(this.fullUpdate.bind(this))
  }

  // Set Selected Account
  // @string address
  //
  // returns Promise( @string address )
  //
  // Sets the state's `selectedAccount` value
  // to the specified address.
  setSelectedAccount (address) {
    var addr = normalize(address)
    this.configManager.setSelectedAccount(addr)
    return Promise.resolve(addr)
  }

  // Save Account Label
  // @string account
  // @string label
  //
  // returns Promise( @string label )
  //
  // Persists a nickname equal to `label` for the specified account.
  saveAccountLabel (account, label) {
    const address = normalize(account)
    const configManager = this.configManager
    configManager.setNicknameForWallet(address, label)
    this.identities[address].name = label
    return Promise.resolve(label)
  }

  // Export Account
  // @string address
  //
  // returns Promise( @string privateKey )
  //
  // Requests the private key from the keyring controlling
  // the specified address.
  //
  // Returns a Promise that may resolve with the private key string.
  exportAccount (address) {
    try {
      return this.getKeyringForAccount(address)
      .then((keyring) => {
        return keyring.exportAccount(normalize(address))
      })
    } catch (e) {
      return Promise.reject(e)
    }
  }


  // SIGNING RELATED METHODS
  //
  // SIGN, SUBMIT TX, CANCEL, AND APPROVE.
  // THIS SECTION INVOLVES THE REQUEST, STORING, AND SIGNING OF DATA
  // WITH THE KEYS STORED IN THIS CONTROLLER.


  // Add Unconfirmed Transaction
  // @object txParams
  // @function onTxDoneCb
  // @function cb
  //
  // Calls back `cb` with @object txData = { txParams }
  // Calls back `onTxDoneCb` with `true` or an `error` depending on result.
  //
  // Prepares the given `txParams` for final confirmation and approval.
  // Estimates gas and other preparatory steps.
  // Caches the requesting Dapp's callback, `onTxDoneCb`, for resolution later.
  addUnconfirmedTransaction (txParams, onTxDoneCb, cb) {
    const configManager = this.configManager

    // create txData obj with parameters and meta data
    var time = (new Date()).getTime()
    var txId = createId()
    txParams.metamaskId = txId
    txParams.metamaskNetworkId = this.getNetwork()
    var txData = {
      id: txId,
      txParams: txParams,
      time: time,
      status: 'unconfirmed',
      gasMultiplier: configManager.getGasMultiplier() || 1,
      metamaskNetworkId: this.getNetwork(),
    }

    // keep the onTxDoneCb around for after approval/denial (requires user interaction)
    // This onTxDoneCb fires completion to the Dapp's write operation.
    this._unconfTxCbs[txId] = onTxDoneCb

    var provider = this.ethStore._query.currentProvider
    var query = new EthQuery(provider)

    // calculate metadata for tx
    this.analyzeTxGasUsage(query, txData, this.txDidComplete.bind(this, txData, cb))
  }

  estimateTxGas (query, txData, blockGasLimitHex, cb) {
    const txParams = txData.txParams
    // check if gasLimit is already specified
    txData.gasLimitSpecified = Boolean(txParams.gas)
    // if not, fallback to block gasLimit
    if (!txData.gasLimitSpecified) {
      txParams.gas = blockGasLimitHex
    }
    // run tx, see if it will OOG
    query.estimateGas(txParams, cb)
  }

  checkForTxGasError (txData, estimatedGasHex, cb) {
    txData.estimatedGas = estimatedGasHex
    // all gas used - must be an error
    if (estimatedGasHex === txData.txParams.gas) {
      txData.simulationFails = true
    }
    cb()
  }

  setTxGas (txData, blockGasLimitHex, cb) {
    const txParams = txData.txParams
    // if OOG, nothing more to do
    if (txData.simulationFails) {
      cb()
      return
    }
    // if gasLimit was specified and doesnt OOG,
    // use original specified amount
    if (txData.gasLimitSpecified) {
      txData.estimatedGas = txParams.gas
      cb()
      return
    }
    // if gasLimit not originally specified,
    // try adding an additional gas buffer to our estimation for safety
    const estimatedGasBn = new BN(ethUtil.stripHexPrefix(txData.estimatedGas), 16)
    const blockGasLimitBn = new BN(ethUtil.stripHexPrefix(blockGasLimitHex), 16)
    const estimationWithBuffer = new BN(this.addGasBuffer(estimatedGasBn), 16)
    // added gas buffer is too high
    if (estimationWithBuffer.gt(blockGasLimitBn)) {
      txParams.gas = txData.estimatedGas
    // added gas buffer is safe
    } else {
      const gasWithBufferHex = ethUtil.intToHex(estimationWithBuffer)
      txParams.gas = gasWithBufferHex
    }
    cb()
    return
  }

  txDidComplete (txData, cb, err) {
    if (err) return cb(err)
    const configManager = this.configManager
    configManager.addTx(txData)
    // signal update
    this.emit('update')
    // signal completion of add tx
    cb(null, txData)
  }

  analyzeTxGasUsage (query, txData, cb) {
    query.getBlockByNumber('latest', true, (err, block) => {
      if (err) return cb(err)
      async.waterfall([
        this.estimateTxGas.bind(this, query, txData, block.gasLimit),
        this.checkForTxGasError.bind(this, txData),
        this.setTxGas.bind(this, txData, block.gasLimit),
      ], cb)
    })
  }

  // Cancel Transaction
  // @string txId
  // @function cb
  //
  // Calls back `cb` with no error if provided.
  //
  // Forgets any tx matching `txId`.
  cancelTransaction (txId, cb) {
    const configManager = this.configManager
    var approvalCb = this._unconfTxCbs[txId] || noop

    // reject tx
    approvalCb(null, false)
    // clean up
    configManager.rejectTx(txId)
    delete this._unconfTxCbs[txId]

    if (cb && typeof cb === 'function') {
      cb()
    }
  }

  // Approve Transaction
  // @string txId
  // @function cb
  //
  // Calls back `cb` with no error always.
  //
  // Attempts to sign a Transaction with `txId`
  // and submit it to the blockchain.
  //
  // Calls back the cached Dapp's confirmation callback, also.
  approveTransaction (txId, cb) {
    const configManager = this.configManager
    var approvalCb = this._unconfTxCbs[txId] || noop

    // accept tx
    cb()
    approvalCb(null, true)
    // clean up
    configManager.confirmTx(txId)
    delete this._unconfTxCbs[txId]
    this.emit('update')
  }

  signTransaction (txParams, cb) {
    try {
      const address = normalize(txParams.from)
      return this.getKeyringForAccount(address)
      .then((keyring) => {
        // Handle gas pricing
        var gasMultiplier = this.configManager.getGasMultiplier() || 1
        var gasPrice = new BN(ethUtil.stripHexPrefix(txParams.gasPrice), 16)
        gasPrice = gasPrice.mul(new BN(gasMultiplier * 100, 10)).div(new BN(100, 10))
        txParams.gasPrice = ethUtil.intToHex(gasPrice.toNumber())

        // normalize values
        txParams.to = normalize(txParams.to)
        txParams.from = normalize(txParams.from)
        txParams.value = normalize(txParams.value)
        txParams.data = normalize(txParams.data)
        txParams.gasLimit = normalize(txParams.gasLimit || txParams.gas)
        txParams.nonce = normalize(txParams.nonce)

        const tx = new Transaction(txParams)
        return keyring.signTransaction(address, tx)
      })
      .then((tx) => {
        // Add the tx hash to the persisted meta-tx object
        var txHash = ethUtil.bufferToHex(tx.hash())
        var metaTx = this.configManager.getTx(txParams.metamaskId)
        metaTx.hash = txHash
        this.configManager.updateTx(metaTx)

        // return raw serialized tx
        var rawTx = ethUtil.bufferToHex(tx.serialize())
        cb(null, rawTx)
      })
    } catch (e) {
      cb(e)
    }
  }

  // Add Unconfirmed Message
  // @object msgParams
  // @function cb
  //
  // Does not call back, only emits an `update` event.
  //
  // Adds the given `msgParams` and `cb` to a local cache,
  // for displaying to a user for approval before signing or canceling.
  addUnconfirmedMessage (msgParams, cb) {
    // create txData obj with parameters and meta data
    var time = (new Date()).getTime()
    var msgId = createId()
    var msgData = {
      id: msgId,
      msgParams: msgParams,
      time: time,
      status: 'unconfirmed',
    }
    messageManager.addMsg(msgData)
    console.log('addUnconfirmedMessage:', msgData)

    // keep the cb around for after approval (requires user interaction)
    // This cb fires completion to the Dapp's write operation.
    this._unconfMsgCbs[msgId] = cb

    // signal update
    this.emit('update')
    return msgId
  }

  // Cancel Message
  // @string msgId
  // @function cb (optional)
  //
  // Calls back to cached `unconfMsgCb`.
  // Calls back to `cb` if provided.
  //
  // Forgets any messages matching `msgId`.
  cancelMessage (msgId, cb) {
    var approvalCb = this._unconfMsgCbs[msgId] || noop

    // reject tx
    approvalCb(null, false)
    // clean up
    messageManager.rejectMsg(msgId)
    delete this._unconfTxCbs[msgId]

    if (cb && typeof cb === 'function') {
      cb()
    }
  }

  // Sign Message
  // @object msgParams
  // @function cb
  //
  // returns Promise(@buffer rawSig)
  // calls back @function cb with @buffer rawSig
  // calls back cached Dapp's @function unconfMsgCb.
  //
  // Attempts to sign the provided @object msgParams.
  signMessage (msgParams, cb) {
    try {
      const msgId = msgParams.metamaskId
      delete msgParams.metamaskId
      const approvalCb = this._unconfMsgCbs[msgId] || noop

      const address = normalize(msgParams.from)
      return this.getKeyringForAccount(address)
      .then((keyring) => {
        return keyring.signMessage(address, msgParams.data)
      }).then((rawSig) => {
        cb(null, rawSig)
        approvalCb(null, true)
        return rawSig
      })
    } catch (e) {
      cb(e)
    }
  }

  // PRIVATE METHODS
  //
  // THESE METHODS ARE ONLY USED INTERNALLY TO THE KEYRING-CONTROLLER
  // AND SO MAY BE CHANGED MORE LIBERALLY THAN THE ABOVE METHODS.

  // Migrate Old Vault If Any
  // @string password
  //
  // returns Promise()
  //
  // Temporary step used when logging in.
  // Checks if old style (pre-3.0.0) Metamask Vault exists.
  // If so, persists that vault in the new vault format
  // with the provided password, so the other unlock steps
  // may be completed without interruption.
  migrateOldVaultIfAny (password) {
    const shouldMigrate = !!this.configManager.getWallet() && !this.configManager.getVault()
    if (!shouldMigrate) {
      return Promise.resolve()
    }

    return this.idStoreMigrator.migratedVaultForPassword(password)
    .then((result) => {
      this.password = password

      if (result && shouldMigrate) {
        const { serialized, lostAccounts } = result
        this.configManager.setLostAccounts(lostAccounts)
        return this.restoreKeyring(serialized)
        .then(keyring => keyring.getAccounts())
        .then((accounts) => {
          this.configManager.setSelectedAccount(accounts[0])
          return this.persistAllKeyrings()
        })
      } else {
        return Promise.resolve()
      }
    })
  }

  // Create First Key Tree
  // returns @Promise
  //
  // Clears the vault,
  // creates a new one,
  // creates a random new HD Keyring with 1 account,
  // makes that account the selected account,
  // faucets that account on testnet,
  // puts the current seed words into the state tree.
  createFirstKeyTree () {
    this.clearKeyrings()
    return this.addNewKeyring('HD Key Tree', {numberOfAccounts: 1})
    .then(() => {
      return this.keyrings[0].getAccounts()
    })
    .then((accounts) => {
      const firstAccount = accounts[0]
      const hexAccount = normalize(firstAccount)
      this.configManager.setSelectedAccount(hexAccount)
      this.emit('newAccount', hexAccount)
      return this.setupAccounts(accounts)
    }).then(() => {
      return this.placeSeedWords()
    })
    .then(this.persistAllKeyrings.bind(this))
  }

  // Setup Accounts
  // @array accounts
  //
  // returns @Promise(@object account)
  //
  // Initializes the provided account array
  // Gives them numerically incremented nicknames,
  // and adds them to the ethStore for regular balance checking.
  setupAccounts (accounts) {
    return this.getAccounts()
    .then((loadedAccounts) => {
      const arr = accounts || loadedAccounts
      return Promise.all(arr.map((account) => {
        return this.getBalanceAndNickname(account)
      }))
    })
  }

  // Get Balance And Nickname
  // @string account
  //
  // returns Promise( @string label )
  //
  // Takes an account address and an iterator representing
  // the current number of named accounts.
  getBalanceAndNickname (account) {
    if (!account) {
      throw new Error('Problem loading account.')
    }
    const address = normalize(account)
    this.ethStore.addAccount(address)
    return this.createNickname(address)
  }

  // Create Nickname
  // @string address
  //
  // returns Promise( @string label )
  //
  // Takes an address, and assigns it an incremented nickname, persisting it.
  createNickname (address) {
    const hexAddress = normalize(address)
    var i = Object.keys(this.identities).length
    const oldNickname = this.configManager.nicknameForWallet(address)
    const name = oldNickname || `Account ${++i}`
    this.identities[hexAddress] = {
      address: hexAddress,
      name,
    }
    return this.saveAccountLabel(hexAddress, name)
  }

  // Persist All Keyrings
  // @password string
  //
  // returns Promise
  //
  // Iterates the current `keyrings` array,
  // serializes each one into a serialized array,
  // encrypts that array with the provided `password`,
  // and persists that encrypted string to storage.
  persistAllKeyrings (password = this.password) {
    if (typeof password === 'string') {
      this.password = password
    }
    return Promise.all(this.keyrings.map((keyring) => {
      return Promise.all([keyring.type, keyring.serialize()])
      .then((serializedKeyringArray) => {
        // Label the output values on each serialized Keyring:
        return {
          type: serializedKeyringArray[0],
          data: serializedKeyringArray[1],
        }
      })
    }))
    .then((serializedKeyrings) => {
      return this.encryptor.encrypt(this.password, serializedKeyrings)
    })
    .then((encryptedString) => {
      this.configManager.setVault(encryptedString)
      return true
    })
  }

  // Unlock Keyrings
  // @string password
  //
  // returns Promise( @array keyrings )
  //
  // Attempts to unlock the persisted encrypted storage,
  // initializing the persisted keyrings to RAM.
  unlockKeyrings (password) {
    const encryptedVault = this.configManager.getVault()
    return this.encryptor.decrypt(password, encryptedVault)
    .then((vault) => {
      this.password = password
      vault.forEach(this.restoreKeyring.bind(this))
      return this.keyrings
    })
  }

  // Restore Keyring
  // @object serialized
  //
  // returns Promise( @Keyring deserialized )
  //
  // Attempts to initialize a new keyring from the provided
  // serialized payload.
  //
  // On success, returns the resulting @Keyring instance.
  restoreKeyring (serialized) {
    const { type, data } = serialized
    const Keyring = this.getKeyringClassForType(type)
    const keyring = new Keyring()
    return keyring.deserialize(data)
    .then(() => {
      return keyring.getAccounts()
    })
    .then((accounts) => {
      return this.setupAccounts(accounts)
    })
    .then(() => {
      this.keyrings.push(keyring)
      return keyring
    })
  }

  // Get Keyring Class For Type
  // @string type
  //
  // Returns @class Keyring
  //
  // Searches the current `keyringTypes` array
  // for a Keyring class whose unique `type` property
  // matches the provided `type`,
  // returning it if it exists.
  getKeyringClassForType (type) {
    return this.keyringTypes.find(kr => kr.type === type)
  }

  // Get Accounts
  // returns Promise( @Array[ @string accounts ] )
  //
  // Returns the public addresses of all current accounts
  // managed by all currently unlocked keyrings.
  getAccounts () {
    const keyrings = this.keyrings || []
    return Promise.all(keyrings.map(kr => kr.getAccounts()))
    .then((keyringArrays) => {
      return keyringArrays.reduce((res, arr) => {
        return res.concat(arr)
      }, [])
    })
  }

  // Get Keyring For Account
  // @string address
  //
  // returns Promise(@Keyring keyring)
  //
  // Returns the currently initialized keyring that manages
  // the specified `address` if one exists.
  getKeyringForAccount (address) {
    const hexed = normalize(address)

    return Promise.all(this.keyrings.map((keyring) => {
      return Promise.all([
        keyring,
        keyring.getAccounts(),
      ])
    }))
    .then(filter((candidate) => {
      const accounts = candidate[1].map(normalize)
      return accounts.includes(hexed)
    }))
    .then((winners) => {
      if (winners && winners.length > 0) {
        return winners[0][0]
      } else {
        throw new Error('No keyring found for the requested account.')
      }
    })
  }

  // Add Gas Buffer
  // @string gas (as hexadecimal value)
  //
  // returns @string bufferedGas (as hexadecimal value)
  //
  // Adds a healthy buffer of gas to an initial gas estimate.
  addGasBuffer (gas) {
    const gasBuffer = new BN('100000', 10)
    const bnGas = new BN(ethUtil.stripHexPrefix(gas), 16)
    const correct = bnGas.add(gasBuffer)
    return ethUtil.addHexPrefix(correct.toString(16))
  }

  // Clear Keyrings
  //
  // Deallocates all currently managed keyrings and accounts.
  // Used before initializing a new vault.
  clearKeyrings () {
    let accounts
    try {
      accounts = Object.keys(this.ethStore._currentState.accounts)
    } catch (e) {
      accounts = []
    }
    accounts.forEach((address) => {
      this.ethStore.removeAccount(address)
    })

    this.keyrings = []
    this.identities = {}
    this.configManager.setSelectedAccount()
  }

}


function noop () {}