electrum/plugins/trustedcoin.py

#!/usr/bin/env python
#
# Electrum - Lightweight Bitcoin Client
# Copyright (C) 2015 Thomas Voegtlin
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

import threading
import socket
import os
import re
import requests
import json
from hashlib import sha256
from urlparse import urljoin
from urllib import quote

from PyQt4.QtGui import *
from PyQt4.QtCore import *

import electrum
from electrum import bitcoin
from electrum.bitcoin import *
from electrum.mnemonic import Mnemonic
from electrum import version
from electrum.wallet import Wallet_2of3
from electrum.i18n import _
from electrum.plugins import BasePlugin, run_hook, hook

from electrum_gui.qt.util import text_dialog, EnterButton, WaitingDialog
from electrum_gui.qt.qrcodewidget import QRCodeWidget
from electrum_gui.qt import ok_cancel_buttons, ok_cancel_buttons2, close_button
from electrum_gui.qt.amountedit import AmountEdit
from electrum_gui.qt.main_window import StatusBarButton

from decimal import Decimal

# signing_xpub is hardcoded so that the wallet can be restored from seed, without TrustedCoin's server
signing_xpub = "xpub661MyMwAqRbcGnMkaTx2594P9EDuiEqMq25PM2aeG6UmwzaohgA6uDmNsvSUV8ubqwA3Wpste1hg69XHgjUuCD5HLcEp2QPzyV1HMrPppsL"
billing_xpub = "xpub6DTBdtBB8qUmH5c77v8qVGVoYk7WjJNpGvutqjLasNG1mbux6KsojaLrYf2sRhXAVU4NaFuHhbD9SvVPRt1MB1MaMooRuhHcAZH1yhQ1qDU"

SEED_PREFIX = version.SEED_PREFIX_2FA


class TrustedCoinException(Exception):
    def __init__(self, message, status_code=0):
        Exception.__init__(self, message)
        self.status_code = status_code

class TrustedCoinCosignerClient(object):
    def __init__(self, user_agent=None, base_url='https://api.trustedcoin.com/2/', debug=False):
        self.base_url = base_url
        self.debug = debug
        self.user_agent = user_agent
        
    def send_request(self, method, relative_url, data=None):
        kwargs = {'headers': {}}
        if self.user_agent:
            kwargs['headers']['user-agent'] = self.user_agent
        if method == 'get' and data:
            kwargs['params'] = data
        elif method == 'post' and data:
            kwargs['data'] = json.dumps(data)
            kwargs['headers']['content-type'] = 'application/json'
        url = urljoin(self.base_url, relative_url)
        if self.debug:
            print '%s %s %s' % (method, url, data)
        response = requests.request(method, url, **kwargs)
        if self.debug:
            print response.text
            print
        if response.status_code != 200:
            message = str(response.text)
            if response.headers.get('content-type') == 'application/json':
                r = response.json()
                if 'message' in r:
                    message = r['message']
            raise TrustedCoinException(message, response.status_code)        
        if response.headers.get('content-type') == 'application/json':
            return response.json()
        else:
            return response.text
        
    def get_terms_of_service(self, billing_plan='electrum-per-tx-otp'):
        """
        Returns the TOS for the given billing plan as a plain/text unicode string.
        :param billing_plan: the plan to return the terms for
        """
        payload = {'billing_plan': billing_plan}
        return self.send_request('get', 'tos', payload)
        
    def create(self, xpubkey1, xpubkey2, email, billing_plan='electrum-per-tx-otp'):
        """
        Creates a new cosigner resource.
        :param xpubkey1: a bip32 extended public key (customarily the hot key)
        :param xpubkey2: a bip32 extended public key (customarily the cold key)
        :param email: a contact email 
        :param billing_plan: the billing plan for the cosigner
        """
        payload = {
            'email': email,
            'xpubkey1': xpubkey1,
            'xpubkey2': xpubkey2,
            'billing_plan': billing_plan,
        }
        return self.send_request('post', 'cosigner', payload)
        
    def auth(self, id, otp):
        """
        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param otp: the one time password
        """
        payload = {'otp': otp}
        return self.send_request('post', 'cosigner/%s/auth' % quote(id), payload)
        
    def get(self, id):
        """
        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param otp: the one time password
        """
        return self.send_request('get', 'cosigner/%s' % quote(id))
        
    def sign(self, id, transaction, otp):
        """
        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param transaction: the hex encoded [partially signed] compact transaction to sign
        :param otp: the one time password
        """
        payload = {
            'otp': otp,
            'transaction': transaction
        }
        return self.send_request('post', 'cosigner/%s/sign' % quote(id), payload)

    def transfer_credit(self, id, recipient, otp, signature_callback):
        """
        Tranfer a cosigner's credits to another cosigner.
        :param id: the id of the sending cosigner
        :param recipient: the id of the recipient cosigner
        :param otp: the one time password (of the sender)
        :param signature_callback: a callback that signs a text message using xpubkey1/0/0 returning a compact sig
        """
        payload = {
            'otp': otp,
            'recipient': recipient,
            'timestamp': int(time.time()),
            
        }
        relative_url = 'cosigner/%s/transfer' % quote(id)
        full_url = urljoin(self.base_url, relative_url)
        headers = {
            'x-signature': signature_callback(full_url + '\n' + json.dumps(payload))
        }
        return self.send_request('post', relative_url, payload, headers)


server = TrustedCoinCosignerClient(user_agent="Electrum/" + version.ELECTRUM_VERSION)


class Wallet_2fa(Wallet_2of3):

    wallet_type = '2fa'

    def get_action(self):
        xpub1 = self.master_public_keys.get("x1/")
        xpub2 = self.master_public_keys.get("x2/")
        xpub3 = self.master_public_keys.get("x3/")
        if xpub2 is None and not self.storage.get('use_trustedcoin'):
            return 'show_disclaimer'
        if xpub2 is None:
            return 'create_extended_seed'
        if xpub3 is None:
            return 'create_remote_key'
        if not self.accounts:
            return 'create_accounts'

    def make_seed(self):
        return Mnemonic('english').make_seed(num_bits=256, prefix=SEED_PREFIX)

    def estimated_fee(self, tx):
        fee = Wallet_2of3.estimated_fee(self, tx)
        x = run_hook('extra_fee', tx)
        if x: fee += x
        return fee

    def get_tx_fee(self, tx):
        fee = Wallet_2of3.get_tx_fee(self, tx)
        x = run_hook('extra_fee', tx)
        if x: fee += x
        return fee



class Plugin(BasePlugin):

    wallet = None

    def __init__(self, x, y):
        BasePlugin.__init__(self, x, y)
        electrum.wallet.wallet_types.append(('twofactor', '2fa', _("Wallet with two-factor authentication"), Wallet_2fa))
        self.seed_func = lambda x: bitcoin.is_new_seed(x, SEED_PREFIX)
        self.billing_info = None
        self.is_billing = False

    def fullname(self):
        return 'Two Factor Authentication'

    def description(self):
        return _("This plugin adds two-factor authentication to your wallet.") + '<br/>'\
            + _("For more information, visit") + " <a href=\"https://api.trustedcoin.com/#/electrum-help\">https://api.trustedcoin.com/#/electrum-help</a>"

    def is_available(self):
        if not self.wallet:
            return False
        if self.wallet.storage.get('wallet_type') == '2fa':
            return True
        return False

    def requires_settings(self):
        return True

    def set_enabled(self, enabled):
        self.wallet.storage.put('use_' + self.name, enabled)

    def is_enabled(self):
        if not self.is_available():
            return False
        if self.wallet.master_private_keys.get('x2/'):
            return False
        return True

    def make_long_id(self, xpub_hot, xpub_cold):
        return bitcoin.sha256(''.join(sorted([xpub_hot, xpub_cold])))

    def get_user_id(self):
        xpub_hot = self.wallet.master_public_keys["x1/"]
        xpub_cold = self.wallet.master_public_keys["x2/"]
        long_id = self.make_long_id(xpub_hot, xpub_cold)
        short_id = hashlib.sha256(long_id).hexdigest()
        return long_id, short_id

    def make_xpub(self, xpub, s):
        _, _, _, c, cK = deserialize_xkey(xpub)
        cK2, c2 = bitcoin._CKD_pub(cK, c, s)
        xpub2 = ("0488B21E" + "00" + "00000000" + "00000000").decode("hex") + c2 + cK2
        return EncodeBase58Check(xpub2)

    def make_billing_address(self, num):
        long_id, short_id = self.get_user_id()
        xpub = self.make_xpub(billing_xpub, long_id)
        _, _, _, c, cK = deserialize_xkey(xpub)
        cK, c = bitcoin.CKD_pub(cK, c, num)
        address = public_key_to_bc_address( cK )
        return address

    def enable(self):
        if self.is_enabled():
            self.window.show_message('Error: Two-factor authentication is already activated on this wallet')
            return
        self.set_enabled(True)
        self.window.show_message('Two-factor authentication is enabled.')

    def create_extended_seed(self, wallet, window):
        seed = wallet.make_seed()
        if not window.show_seed(seed, None):
            return

        if not window.verify_seed(seed, None, self.seed_func):
            return

        password = window.password_dialog()
        wallet.storage.put('seed_version', wallet.seed_version, True)
        wallet.storage.put('use_encryption', password is not None, True)

        words = seed.split()
        n = len(words)/2
        wallet.add_cosigner_seed(' '.join(words[0:n]), 'x1/', password)
        wallet.add_cosigner_xpub(' '.join(words[n:]), 'x2/')

        msg = [ 
            _('Your wallet file is:') + " %s"%os.path.abspath(wallet.storage.path),
            _('You need to be online in order to complete the creation of your wallet.'),
            _('If you generated your seed on an offline computer, click on "%s" to close this window, move your wallet file to an online computer and reopen it with Electrum.') % _('Close'),
            _('If you are online, click on "%s" to continue.') % _('Next')
        ]
        return window.question('\n\n'.join(msg), no_label=_('Close'), yes_label=_('Next'))


    def show_disclaimer(self, wallet, window):
        msg = [
            _("Two-factor authentication is a service provided by TrustedCoin.") + ' ',
            _("It uses a multi-signature wallet, where you own 2 of 3 keys.") + ' ',
            _("The third key is stored on a remote server that signs transactions on your behalf.") + ' ',
            _("To use this service, you will need a smartphone with Google Authenticator.") + '\n\n',

            _("A small fee will be charged on each transaction that uses the remote server.") + ' ',
            _("You may check and modify your billing preferences once the installation is complete.") + '\n\n',

            _("Note that your coins are not locked in this service.") + ' ',
            _("You may withdraw your funds at any time and at no cost, without the remote server, by using the 'restore wallet' option with your wallet seed.") + '\n\n',

            _('The next step will generate the seed of your wallet.') + ' ',
            _('This seed will NOT be saved in your computer, and it must be stored on paper.') + ' ',
            _('To be safe from malware, you may want to do this on an offline computer, and move your wallet later to an online computer.')
        ]
        icon = QPixmap(':icons/trustedcoin.png')
        if not window.question(''.join(msg), icon=icon):
            return False
        self.wallet = wallet
        self.set_enabled(True)
        return True


    def restore_third_key(self, wallet):
        long_user_id, short_id = self.get_user_id()
        xpub3 = self.make_xpub(signing_xpub, long_user_id)
        wallet.add_master_public_key('x3/', xpub3)

    @hook
    def init_qt(self, gui):
        self.window = gui.main_window

    @hook
    def do_clear(self):
        self.is_billing = False

    @hook
    def load_wallet(self, wallet):
        self.trustedcoin_button = StatusBarButton( QIcon(":icons/trustedcoin.png"), _("Network"), self.settings_dialog)
        self.window.statusBar().addPermanentWidget(self.trustedcoin_button)
        self.xpub = self.wallet.master_public_keys.get('x1/')
        self.user_id = self.get_user_id()[1]
        t = threading.Thread(target=self.request_billing_info)
        t.setDaemon(True)
        t.start()

    @hook
    def close_wallet(self):
        self.window.statusBar().removeWidget(self.trustedcoin_button)

    @hook
    def get_wizard_action(self, window, wallet, action):
        if hasattr(self, action):
            return getattr(self, action)
            
    @hook
    def installwizard_restore(self, window, storage):
        if storage.get('wallet_type') != '2fa': 
            return

        seed = window.enter_seed_dialog("Enter your seed", None, func=self.seed_func)
        if not seed: 
            return
        wallet = Wallet_2fa(storage)
        self.wallet = wallet
        password = window.password_dialog()

        wallet.add_seed(seed, password)
        words = seed.split()
        n = len(words)/2
        wallet.add_cosigner_seed(' '.join(words[0:n]), 'x1/', password)
        wallet.add_cosigner_seed(' '.join(words[n:]), 'x2/', password)

        self.restore_third_key(wallet)
        wallet.create_main_account(password)
        # disable plugin
        self.set_enabled(False)
        return wallet


    def create_remote_key(self, wallet, window):
        self.wallet = wallet
        self.window = window

        if wallet.storage.get('wallet_type') != '2fa': 
            raise
            return

        email = self.accept_terms_of_use(window)
        if not email:
            return

        xpub_hot = wallet.master_public_keys["x1/"]
        xpub_cold = wallet.master_public_keys["x2/"]

        # Generate third key deterministically.
        long_user_id, self.user_id = self.get_user_id()
        xpub3 = self.make_xpub(signing_xpub, long_user_id)

        # secret must be sent by the server
        try:
            r = server.create(xpub_hot, xpub_cold, email)
        except socket.error:
            self.window.show_message('Server not reachable, aborting')
            return

        otp_secret = r.get('otp_secret')
        if not otp_secret:
            self.window.show_message(_('Error'))
            return

        _xpub3 = r['xpubkey_cosigner']
        _id = r['id']
        try:
            assert _id == self.user_id, ("user id error", _id, self.user_id)
            assert xpub3 == _xpub3, ("xpub3 error", xpub3, _xpub3)
        except Exception as e:
            self.window.show_message(str(e))
            return
            
        if not self.setup_google_auth(self.window, _id, otp_secret):
            return

        self.wallet.add_master_public_key('x3/', xpub3)
        return True



    def need_server(self, tx):
        from electrum.account import BIP32_Account
        # Detect if the server is needed
        long_id, short_id = self.get_user_id()
        xpub3 = self.wallet.master_public_keys['x3/']
        for x in tx.inputs_to_sign():
            if x[0:2] == 'ff':
                xpub, sequence = BIP32_Account.parse_xpubkey(x)
                if xpub == xpub3:
                    return True
        return False

    @hook
    def send_tx(self, tx):
        print_error("twofactor:send_tx")
        if self.wallet.storage.get('wallet_type') != '2fa':
            return

        if not self.need_server(tx):
            print_error("twofactor: xpub3 not needed")
            self.auth_code = None
            return

        self.auth_code = self.auth_dialog()

    @hook
    def before_send(self):
        # request billing info before forming the transaction
        self.billing_info = None
        self.waiting_dialog = WaitingDialog(self.window, 'please wait...', self.request_billing_info)
        self.waiting_dialog.start()
        self.waiting_dialog.wait()
        if self.billing_info is None:
            self.window.show_message('Could not contact server')
            return True
        return False

    @hook
    def extra_fee(self, tx):
        if self.billing_info.get('tx_remaining'):
            return 0
        if self.is_billing:
            return 0
        # trustedcoin won't charge if the total inputs is lower than their fee
        price = int(self.price_per_tx.get(1))
        assert price <= 100000
        if tx.input_value() < price:
            print_error("not charging for this tx")
            return 0
        return price

    @hook
    def make_unsigned_transaction(self, tx):
        price = self.extra_fee(tx)
        if not price:
            return
        tx.outputs.append(('address', self.billing_info['billing_address'], price))

    @hook
    def sign_transaction(self, tx, password):
        print_error("twofactor:sign")
        if self.wallet.storage.get('wallet_type') != '2fa':
            print_error("twofactor: aborting")
            return

        self.long_user_id, self.user_id = self.get_user_id()

        if not self.auth_code:
            return

        if tx.is_complete():
            return

        tx_dict = tx.as_dict()
        raw_tx = tx_dict["hex"]
        try:
            r = server.sign(self.user_id, raw_tx, self.auth_code)
        except Exception as e:
            tx.error = str(e)
            return

        print_error( "received answer", r)
        if not r:
            return 

        raw_tx = r.get('transaction')
        tx.update(raw_tx)
        print_error("twofactor: is complete", tx.is_complete())


    def auth_dialog(self ):
        d = QDialog(self.window)
        d.setModal(1)
        vbox = QVBoxLayout(d)
        pw = AmountEdit(None, is_int = True)
        msg = _('Please enter your Google Authenticator code')
        vbox.addWidget(QLabel(msg))
        grid = QGridLayout()
        grid.setSpacing(8)
        grid.addWidget(QLabel(_('Code')), 1, 0)
        grid.addWidget(pw, 1, 1)
        vbox.addLayout(grid)
        vbox.addLayout(ok_cancel_buttons(d))
        if not d.exec_(): 
            return
        return pw.get_amount()

    def settings_widget(self, window):
        return EnterButton(_('Settings'), self.settings_dialog)

    def settings_dialog(self):
        self.waiting_dialog = WaitingDialog(self.window, 'please wait...', self.request_billing_info, self.show_settings_dialog)
        self.waiting_dialog.start()

    def show_settings_dialog(self, success):
        if not success:
            self.window.show_message(_('Server not reachable.'))
            return

        d = QDialog(self.window)
        d.setWindowTitle("TrustedCoin Information")
        d.setMinimumSize(500, 200)
        vbox = QVBoxLayout(d)
        hbox = QHBoxLayout()

        logo = QLabel()
        logo.setPixmap(QPixmap(":icons/trustedcoin.png"))
        msg = _('This wallet is protected by TrustedCoin\'s two-factor authentication.') + '<br/>'\
              + _("For more information, visit") + " <a href=\"https://api.trustedcoin.com/#/electrum-help\">https://api.trustedcoin.com/#/electrum-help</a>"
        label = QLabel(msg)
        label.setOpenExternalLinks(1)
        
        hbox.addStretch(10)
        hbox.addWidget(logo)
        hbox.addStretch(10)
        hbox.addWidget(label)
        hbox.addStretch(10)

        vbox.addLayout(hbox)
        vbox.addStretch(10)

        msg = _('TrustedCoin charges a fee per co-signed transaction. You may pay on each transaction (an extra output will be added to your transaction), or you may purchase prepaid transaction using this dialog.') + '<br/>'
        label = QLabel(msg)
        label.setWordWrap(1)
        vbox.addWidget(label)

        vbox.addStretch(10)
        grid = QGridLayout()
        vbox.addLayout(grid)

        v = self.price_per_tx.get(1)
        grid.addWidget(QLabel(_("Price per transaction (not prepaid):")), 0, 0)
        grid.addWidget(QLabel(self.window.format_amount(v) + ' ' + self.window.base_unit()), 0, 1)

        i = 1
        for k, v in sorted(self.price_per_tx.items()):
            if k!=1:
                grid.addWidget(QLabel("Price for %d prepaid transactions:"%k), i, 0)
                grid.addWidget(QLabel(self.window.format_amount(v) + ' ' + self.window.base_unit()), i, 1)
                b = QPushButton(_("Buy"))
                grid.addWidget(b, i, 2)
                def on_buy():
                    d.close()
                    if self.window.pluginsdialog:
                        self.window.pluginsdialog.close()
                    uri = "bitcoin:" + self.billing_info['billing_address'] + "?message=TrustedCoin Prepaid Transactions&amount="+str(Decimal(v)/100000000)
                    self.is_billing = True
                    self.window.pay_from_URI(uri)
                    self.window.payto_e.setFrozen(True)
                    self.window.message_e.setFrozen(True)
                    self.window.amount_e.setFrozen(True)
                b.clicked.connect(on_buy)
                i += 1

        n = self.billing_info.get('tx_remaining', 0)
        grid.addWidget(QLabel(_("Your wallet has %d prepaid transactions.")%n), i, 0)

        # tranfer button
        #def on_transfer():
        #    server.transfer_credit(self.user_id, recipient, otp, signature_callback)
        #    pass
        #b = QPushButton(_("Transfer"))
        #b.clicked.connect(on_transfer)
        #grid.addWidget(b, 1, 2)

        #grid.addWidget(QLabel(_("Next Billing Address:")), i, 0)
        #grid.addWidget(QLabel(self.billing_info['billing_address']), i, 1)
        vbox.addLayout(close_button(d))
        d.exec_()


    def request_billing_info(self):
        billing_info = server.get(self.user_id)
        billing_address = self.make_billing_address(billing_info['billing_index'])
        assert billing_address == billing_info['billing_address']
        self.billing_info = billing_info
        self.price_per_tx = dict(self.billing_info['price_per_tx'])
        return True

    def accept_terms_of_use(self, window):
        vbox = QVBoxLayout()
        window.set_layout(vbox)
        vbox.addWidget(QLabel(_("Terms of Service")))

        tos_e = QTextEdit()
        tos_e.setReadOnly(True)
        vbox.addWidget(tos_e)

        vbox.addWidget(QLabel(_("Please enter your e-mail address")))
        email_e = QLineEdit()
        vbox.addWidget(email_e)
        vbox.addStretch()
        hbox, accept_button = ok_cancel_buttons2(window, _('Accept'))
        accept_button.setEnabled(False)
        vbox.addLayout(hbox)

        def request_TOS():
            tos = server.get_terms_of_service()
            self.TOS = tos
            window.emit(SIGNAL('twofactor:TOS'))
            
        def on_result():
            tos_e.setText(self.TOS)

        window.connect(window, SIGNAL('twofactor:TOS'), on_result)
        t = threading.Thread(target=request_TOS)
        t.setDaemon(True)
        t.start()

        regexp = r"[^@]+@[^@]+\.[^@]+"
        email_e.textChanged.connect(lambda: accept_button.setEnabled(re.match(regexp,email_e.text()) is not None))
        email_e.setFocus(True)

        if not window.exec_(): 
            return

        email = str(email_e.text())
        return email


    def setup_google_auth(self, window, _id, otp_secret):
        uri = "otpauth://totp/%s?secret=%s"%('trustedcoin.com', otp_secret)
        vbox = QVBoxLayout()
        window.set_layout(vbox)
        vbox.addWidget(QLabel("Please scan this QR code in Google Authenticator."))
        qrw = QRCodeWidget(uri)
        vbox.addWidget(qrw, 1)
        #vbox.addWidget(QLabel(data), 0, Qt.AlignHCenter)

        hbox = QHBoxLayout()
        msg = _('Then, enter your Google Authenticator code:')
        hbox.addWidget(QLabel(msg))
        pw = AmountEdit(None, is_int = True)
        pw.setFocus(True)
        hbox.addWidget(pw)
        hbox.addStretch(1)
        vbox.addLayout(hbox)

        hbox, b = ok_cancel_buttons2(window, _('Next'))
        b.setEnabled(False)
        vbox.addLayout(hbox)
        pw.textChanged.connect(lambda: b.setEnabled(len(pw.text())==6))

        window.exec_()
        otp = pw.get_amount()
        try:
            server.auth(_id, otp)
        except:
            self.window.show_message('Incorrect password, aborting')
            return

        return True