initial import

.gitignore

@@ -0,0 +1,108 @@
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+env/
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# dotenv
+.env
+
+# virtualenv
+.venv
+venv/
+ENV/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+
+
+# pycharm configuration
+.idea/
+
+bin/
+data/

.travis.yml

@@ -0,0 +1,19 @@
+sudo: false
+language: python
+
+python:
+  - "2.7"
+  - "3.6"
+
+install: pip install tox-travis coverage
+
+script:
+  - tox
+
+after_success:
+  - coverage combine tests/
+  - bash <(curl -s https://codecov.io/bash)
+
+branches:
+  only: 
+    - master

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018 LBRY Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

MANIFEST.in

@@ -0,0 +1,4 @@
+include README.md
+include CHANGELOG.md
+include LICENSE
+recursive-include torba *.txt *.py

setup.cfg

@@ -0,0 +1,7 @@
+[coverage:run]
+branch = True
+
+[coverage:paths]
+source =
+  torba
+  .tox/*/lib/python*/site-packages/torba

setup.py

@@ -0,0 +1,45 @@
+import os
+import re
+from setuptools import setup, find_packages
+
+init_file = open(os.path.join(os.path.dirname(__path__), 'torba', '__init__.py')).read()
+version = re.search('\d+\.\d+\.\d+', init_file).group()
+
+setup(
+    name='torba',
+    version=version,
+    url='https://github.com/lbryio/torba',
+    license='MIT',
+    author='LBRY Inc.',
+    author_email='hello@lbry.io',
+    description='Wallet library for bitcoin based currencies.',
+    keywords='wallet,crypto,currency,money,bitcoin,lbry',
+    classifiers=(
+        'Framework :: Twisted',
+        'Intended Audience :: Developers',
+        'Intended Audience :: System Administrators',
+        'License :: OSI Approved :: MIT License',
+        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3',
+        'Operating System :: OS Independent',
+        'Topic :: Internet',
+        'Topic :: Software Development :: Libraries :: Python Modules',
+        'Topic :: System :: Distributed Computing',
+        'Topic :: Utilities',
+    ),
+    packages=find_packages(exclude=('tests',)),
+    include_package_data=True,
+    python_requires='>=2.7,>=3.6',
+    install_requires=(
+        'twisted',
+        'ecdsa',
+        'pbkdf2',
+        'cryptography',
+        'typing'
+    ),
+    extras_require={
+        'test': (
+            'mock',
+        )
+    }
+)

tests/unit/ftc.py

@@ -0,0 +1,43 @@
+from six import int2byte
+from binascii import unhexlify
+from torba.baseledger import BaseLedger
+from torba.basenetwork import BaseNetwork
+from torba.basescript import BaseInputScript, BaseOutputScript
+from torba.basetransaction import BaseTransaction, BaseInput, BaseOutput
+from torba.basecoin import BaseCoin
+
+
+class Ledger(BaseLedger):
+    network_class = BaseNetwork
+
+
+class Input(BaseInput):
+    script_class = BaseInputScript
+
+
+class Output(BaseOutput):
+    script_class = BaseOutputScript
+
+
+class Transaction(BaseTransaction):
+    input_class = Input
+    output_class = Output
+
+
+class FTC(BaseCoin):
+    name = 'Fakecoin'
+    symbol = 'FTC'
+    network = 'mainnet'
+
+    ledger_class = Ledger
+    transaction_class = Transaction
+
+    pubkey_address_prefix = int2byte(0x00)
+    script_address_prefix = int2byte(0x05)
+    extended_public_key_prefix = unhexlify('0488b21e')
+    extended_private_key_prefix = unhexlify('0488ade4')
+
+    default_fee_per_byte = 50
+
+    def __init__(self, ledger, fee_per_byte=default_fee_per_byte):
+        super(FTC, self).__init__(ledger, fee_per_byte)

tests/unit/test_account.py

@@ -0,0 +1,105 @@
+from binascii import hexlify
+from twisted.trial import unittest
+
+from torba.coin.btc import BTC
+from torba.manager import WalletManager
+from torba.wallet import Account
+
+
+class TestAccount(unittest.TestCase):
+
+    def setUp(self):
+        ledger = WalletManager().get_or_create_ledger(BTC.get_id())
+        self.coin = BTC(ledger)
+
+    def test_generate_account(self):
+        account = Account.generate(self.coin, u"torba")
+        self.assertEqual(account.coin, self.coin)
+        self.assertIsNotNone(account.seed)
+        self.assertEqual(account.public_key.coin, self.coin)
+        self.assertEqual(account.private_key.public_key, account.public_key)
+
+        self.assertEqual(len(account.receiving_keys.child_keys), 0)
+        self.assertEqual(len(account.receiving_keys.addresses), 0)
+        self.assertEqual(len(account.change_keys.child_keys), 0)
+        self.assertEqual(len(account.change_keys.addresses), 0)
+
+        account.ensure_enough_addresses()
+        self.assertEqual(len(account.receiving_keys.child_keys), 20)
+        self.assertEqual(len(account.receiving_keys.addresses), 20)
+        self.assertEqual(len(account.change_keys.child_keys), 6)
+        self.assertEqual(len(account.change_keys.addresses), 6)
+
+    def test_generate_account_from_seed(self):
+        account = Account.from_seed(
+            self.coin,
+            u"carbon smart garage balance margin twelve chest sword toast envelope bottom stomach ab"
+            u"sent",
+            u"torba"
+        )
+        self.assertEqual(
+            account.private_key.extended_key_string(),
+            'xprv9s21ZrQH143K2dyhK7SevfRG72bYDRNv25yKPWWm6dqApNxm1Zb1m5gGcBWYfbsPjTr2v5joit8Af2Zp5P'
+            '6yz3jMbycrLrRMpeAJxR8qDg8'
+        )
+        self.assertEqual(
+            account.public_key.extended_key_string(),
+            'xpub661MyMwAqRbcF84AR8yfHoMzf4S2ct6mPJtvBtvNeyN9hBHuZ6uGJszkTSn5fQUCdz3XU17eBzFeAUwV6f'
+            'iW44g14WF52fYC5J483wqQ5ZP'
+        )
+        self.assertEqual(
+            account.receiving_keys.generate_next_address(),
+            '1PmX9T3sCiDysNtWszJa44SkKcpGc2NaXP'
+        )
+        private_key = account.get_private_key_for_address('1PmX9T3sCiDysNtWszJa44SkKcpGc2NaXP')
+        self.assertEqual(
+            private_key.extended_key_string(),
+            'xprv9xNEfQ296VTRaEUDZ8oKq74xw2U6kpj486vFUB4K1wT9U25GX4UwuzFgJN1YuRrqkQ5TTwCpkYnjNpSoHS'
+            'BaEigNHPkoeYbuPMRo6mRUjxg'
+        )
+        self.assertIsNone(account.get_private_key_for_address('BcQjRlhDOIrQez1WHfz3whnB33Bp34sUgX'))
+
+        self.assertEqual(
+            hexlify(private_key.wif()),
+            b'1cc27be89ad47ef932562af80e95085eb0ab2ae3e5c019b1369b8b05ff2e94512f01'
+        )
+
+    def test_load_and_save_account(self):
+        account_data = {
+            'seed':
+                "carbon smart garage balance margin twelve chest sword toast envelope bottom stomac"
+                "h absent",
+            'encrypted': False,
+            'private_key':
+                'xprv9s21ZrQH143K2dyhK7SevfRG72bYDRNv25yKPWWm6dqApNxm1Zb1m5gGcBWYfbsPjTr2v5joit8Af2Zp5P'
+                '6yz3jMbycrLrRMpeAJxR8qDg8',
+            'public_key':
+                'xpub661MyMwAqRbcF84AR8yfHoMzf4S2ct6mPJtvBtvNeyN9hBHuZ6uGJszkTSn5fQUCdz3XU17eBzFeAUwV6f'
+                'iW44g14WF52fYC5J483wqQ5ZP',
+            'receiving_gap': 10,
+            'receiving_keys': [
+                '0222345947a59dca4a3363ffa81ac87dd907d2b2feff57383eaeddbab266ca5f2d',
+                '03fdc9826d5d00a484188cba8eb7dba5877c0323acb77905b7bcbbab35d94be9f6'
+            ],
+            'change_gap': 10,
+            'change_keys': [
+                '038836be4147836ed6b4df6a89e0d9f1b1c11cec529b7ff5407de57f2e5b032c83'
+            ]
+        }
+
+        account = Account.from_dict(self.coin, account_data)
+
+        self.assertEqual(len(account.receiving_keys.addresses), 2)
+        self.assertEqual(
+            account.receiving_keys.addresses[0],
+            '1PmX9T3sCiDysNtWszJa44SkKcpGc2NaXP'
+        )
+        self.assertEqual(len(account.change_keys.addresses), 1)
+        self.assertEqual(
+            account.change_keys.addresses[0],
+            '1PUbu1D1f3c244JPRSJKBCxRqui5NT6geR'
+        )
+
+        self.maxDiff = None
+        account_data['coin'] = 'btc_mainnet'
+        self.assertDictEqual(account_data, account.to_dict())

tests/unit/test_coinselection.py

@@ -0,0 +1,157 @@
+import unittest
+
+from torba.coin.btc import BTC
+from torba.coinselection import CoinSelector, MAXIMUM_TRIES
+from torba.constants import CENT
+from torba.manager import WalletManager
+
+from .test_transaction import Output, get_output as utxo
+
+
+NULL_HASH = b'\x00'*32
+
+
+def search(*args, **kwargs):
+    selection = CoinSelector(*args, **kwargs).branch_and_bound()
+    return [o.output.amount for o in selection] if selection else selection
+
+
+class BaseSelectionTestCase(unittest.TestCase):
+
+    def setUp(self):
+        ledger = WalletManager().get_or_create_ledger(BTC.get_id())
+        self.coin = BTC(ledger)
+
+    def estimates(self, *args):
+        txos = args if isinstance(args[0], Output) else args[0]
+        return [txo.get_estimator(self.coin) for txo in txos]
+
+
+class TestCoinSelectionTests(BaseSelectionTestCase):
+
+    def test_empty_coins(self):
+        self.assertIsNone(CoinSelector([], 0, 0).select())
+
+    def test_skip_binary_search_if_total_not_enough(self):
+        fee = utxo(CENT).get_estimator(self.coin).fee
+        big_pool = self.estimates(utxo(CENT+fee) for _ in range(100))
+        selector = CoinSelector(big_pool, 101 * CENT, 0)
+        self.assertIsNone(selector.select())
+        self.assertEqual(selector.tries, 0)  # Never tried.
+        # check happy path
+        selector = CoinSelector(big_pool, 100 * CENT, 0)
+        self.assertEqual(len(selector.select()), 100)
+        self.assertEqual(selector.tries, 201)
+
+    def test_exact_match(self):
+        fee = utxo(CENT).get_estimator(self.coin).fee
+        utxo_pool = self.estimates(
+            utxo(CENT + fee),
+            utxo(CENT),
+            utxo(CENT - fee)
+        )
+        selector = CoinSelector(utxo_pool, CENT, 0)
+        match = selector.select()
+        self.assertEqual([CENT + fee], [c.output.amount for c in match])
+        self.assertTrue(selector.exact_match)
+
+    def test_random_draw(self):
+        utxo_pool = self.estimates(
+            utxo(2 * CENT),
+            utxo(3 * CENT),
+            utxo(4 * CENT)
+        )
+        selector = CoinSelector(utxo_pool, CENT, 0, '\x00')
+        match = selector.select()
+        self.assertEqual([2 * CENT], [c.output.amount for c in match])
+        self.assertFalse(selector.exact_match)
+
+
+class TestOfficialBitcoinCoinSelectionTests(BaseSelectionTestCase):
+
+    #       Bitcoin implementation:
+    #       https://github.com/bitcoin/bitcoin/blob/master/src/wallet/coinselection.cpp
+    #
+    #       Bitcoin implementation tests:
+    #       https://github.com/bitcoin/bitcoin/blob/master/src/wallet/test/coinselector_tests.cpp
+    #
+    #       Branch and Bound coin selection white paper:
+    #       https://murch.one/wp-content/uploads/2016/11/erhardt2016coinselection.pdf
+
+    def setUp(self):
+        ledger = WalletManager().get_or_create_ledger(BTC.get_id())
+        self.coin = BTC(ledger, 0)
+
+    def make_hard_case(self, utxos):
+        target = 0
+        utxo_pool = []
+        for i in range(utxos):
+            amount = 1 << (utxos+i)
+            target += amount
+            utxo_pool.append(utxo(amount))
+            utxo_pool.append(utxo(amount + (1 << (utxos-1-i))))
+        return self.estimates(utxo_pool), target
+
+    def test_branch_and_bound_coin_selection(self):
+        utxo_pool = self.estimates(
+            utxo(1 * CENT),
+            utxo(2 * CENT),
+            utxo(3 * CENT),
+            utxo(4 * CENT)
+        )
+
+        # Select 1 Cent
+        self.assertEqual([1 * CENT], search(utxo_pool, 1 * CENT, 0.5 * CENT))
+
+        # Select 2 Cent
+        self.assertEqual([2 * CENT], search(utxo_pool, 2 * CENT, 0.5 * CENT))
+
+        # Select 5 Cent
+        self.assertEqual([3 * CENT, 2 * CENT], search(utxo_pool, 5 * CENT, 0.5 * CENT))
+
+        # Select 11 Cent, not possible
+        self.assertIsNone(search(utxo_pool, 11 * CENT, 0.5 * CENT))
+
+        # Select 10 Cent
+        utxo_pool += self.estimates(utxo(5 * CENT))
+        self.assertEqual(
+            [4 * CENT, 3 * CENT, 2 * CENT, 1 * CENT],
+            search(utxo_pool, 10 * CENT, 0.5 * CENT)
+        )
+
+        # Negative effective value
+        # Select 10 Cent but have 1 Cent not be possible because too small
+        # TODO: bitcoin has [5, 3, 2]
+        self.assertEqual(
+            [4 * CENT, 3 * CENT, 2 * CENT, 1 * CENT],
+            search(utxo_pool, 10 * CENT, 5000)
+        )
+
+        # Select 0.25 Cent, not possible
+        self.assertIsNone(search(utxo_pool, 0.25 * CENT, 0.5 * CENT))
+
+        # Iteration exhaustion test
+        utxo_pool, target = self.make_hard_case(17)
+        selector = CoinSelector(utxo_pool, target, 0)
+        self.assertIsNone(selector.branch_and_bound())
+        self.assertEqual(selector.tries, MAXIMUM_TRIES)  # Should exhaust
+        utxo_pool, target = self.make_hard_case(14)
+        self.assertIsNotNone(search(utxo_pool, target, 0))  # Should not exhaust
+
+        # Test same value early bailout optimization
+        utxo_pool = self.estimates([
+            utxo(7 * CENT),
+            utxo(7 * CENT),
+            utxo(7 * CENT),
+            utxo(7 * CENT),
+            utxo(2 * CENT)
+        ] + [utxo(5 * CENT)]*50000)
+        self.assertEqual(
+            [7 * CENT, 7 * CENT, 7 * CENT, 7 * CENT, 2 * CENT],
+            search(utxo_pool, 30 * CENT, 5000)
+        )
+
+        # Select 1 Cent with pool of only greater than 5 Cent
+        utxo_pool = self.estimates(utxo(i * CENT) for i in range(5, 21))
+        for _ in range(100):
+            self.assertIsNone(search(utxo_pool, 1 * CENT, 2 * CENT))

tests/unit/test_hash.py

@@ -0,0 +1,21 @@
+import mock
+from unittest import TestCase
+from torba.hash import aes_decrypt, aes_encrypt
+
+
+class TestAESEncryptDecrypt(TestCase):
+
+    @mock.patch('os.urandom', side_effect=lambda i: b'f'*i)
+    def test_encrypt(self, _):
+        self.assertEqual(aes_encrypt(
+            b'bubblegum', b'The Times 03/Jan/2009 Chancellor on brink of second bailout for banks'),
+            b'OWsqm2goP4wXAPFyDde0IP2rPxRaESGr9NUlPn4y2nZrywQJo7pZCPt9ixYa7Ye9tzSpirF03Qd5OyI75xlGjd'
+            b'4khKCvcX6tcViLmhIGUPY='
+        )
+
+    def test_decrypt(self):
+        self.assertEqual(aes_decrypt(
+            b'bubblegum', b'WeW99mQgRExAEzPjJOAC/MdTJaHgz3hT+kazFbvVQqF/KFva48ulVMOewU7JWD0ufWJIxtAIQ'
+            b'bGtlbvbq5w74bsCCJLrtNTHBhenkms8XccJXTr/UF/ZYTF1Prz8b0AQ'),
+            b'The Times 03/Jan/2009 Chancellor on brink of second bailout for banks'
+        )

tests/unit/test_mnemonic.py

@@ -0,0 +1,23 @@
+import unittest
+from binascii import hexlify
+
+from torba.mnemonic import Mnemonic
+
+
+class TestMnemonic(unittest.TestCase):
+
+    def test_mnemonic_to_seed(self):
+        seed = Mnemonic.mnemonic_to_seed(mnemonic=u'foobar', passphrase=u'torba')
+        self.assertEqual(
+            hexlify(seed),
+            b'475a419db4e991cab14f08bde2d357e52b3e7241f72c6d8a2f92782367feeee9f403dc6a37c26a3f02ab9'
+            b'dec7f5063161eb139cea00da64cd77fba2f07c49ddc'
+        )
+
+    def test_make_seed_decode_encode(self):
+        iters = 10
+        m = Mnemonic('en')
+        for _ in range(iters):
+            seed = m.make_seed()
+            i = m.mnemonic_decode(seed)
+            self.assertEqual(m.mnemonic_encode(i), seed)

tests/unit/test_script.py

@@ -0,0 +1,218 @@
+from binascii import hexlify, unhexlify
+from twisted.trial import unittest
+
+from torba.bcd_data_stream import BCDataStream
+from torba.basescript import Template, ParseError, tokenize, push_data
+from torba.basescript import PUSH_SINGLE, PUSH_MANY, OP_HASH160, OP_EQUAL
+from torba.basescript import BaseInputScript, BaseOutputScript
+
+
+def parse(opcodes, source):
+    template = Template('test', opcodes)
+    s = BCDataStream()
+    for t in source:
+        if isinstance(t, bytes):
+            s.write_many(push_data(t))
+        elif isinstance(t, int):
+            s.write_uint8(t)
+        else:
+            raise ValueError()
+    s.reset()
+    return template.parse(tokenize(s))
+
+
+class TestScriptTemplates(unittest.TestCase):
+
+    def test_push_data(self):
+        self.assertEqual(parse(
+                (PUSH_SINGLE('script_hash'),),
+                (b'abcdef',)
+            ), {
+                'script_hash': b'abcdef'
+            }
+        )
+        self.assertEqual(parse(
+                (PUSH_SINGLE('first'), PUSH_SINGLE('last')),
+                (b'Satoshi', b'Nakamoto')
+            ), {
+                'first': b'Satoshi',
+                'last': b'Nakamoto'
+            }
+        )
+        self.assertEqual(parse(
+                (OP_HASH160, PUSH_SINGLE('script_hash'), OP_EQUAL),
+                (OP_HASH160, b'abcdef', OP_EQUAL)
+            ), {
+                'script_hash': b'abcdef'
+            }
+        )
+
+    def test_push_data_many(self):
+        self.assertEqual(parse(
+                (PUSH_MANY('names'),),
+                (b'amit',)
+            ), {
+                'names': [b'amit']
+            }
+        )
+        self.assertEqual(parse(
+                (PUSH_MANY('names'),),
+                (b'jeremy', b'amit', b'victor')
+            ), {
+                'names': [b'jeremy', b'amit', b'victor']
+            }
+        )
+        self.assertEqual(parse(
+                (OP_HASH160, PUSH_MANY('names'), OP_EQUAL),
+                (OP_HASH160, b'grin', b'jack', OP_EQUAL)
+            ), {
+                'names': [b'grin', b'jack']
+            }
+        )
+
+    def test_push_data_mixed(self):
+        self.assertEqual(parse(
+                (PUSH_SINGLE('CEO'), PUSH_MANY('Devs'), PUSH_SINGLE('CTO'), PUSH_SINGLE('State')),
+                (b'jeremy', b'lex', b'amit', b'victor', b'jack', b'grin', b'NH')
+            ), {
+                'CEO': b'jeremy',
+                'CTO': b'grin',
+                'Devs': [b'lex', b'amit', b'victor', b'jack'],
+                'State': b'NH'
+            }
+        )
+
+    def test_push_data_many_separated(self):
+        self.assertEqual(parse(
+                (PUSH_MANY('Chiefs'), OP_HASH160, PUSH_MANY('Devs')),
+                (b'jeremy', b'grin', OP_HASH160, b'lex', b'jack')
+            ), {
+                'Chiefs': [b'jeremy', b'grin'],
+                'Devs': [b'lex', b'jack']
+            }
+        )
+
+    def test_push_data_many_not_separated(self):
+        with self.assertRaisesRegexp(ParseError, 'consecutive PUSH_MANY'):
+            parse((PUSH_MANY('Chiefs'), PUSH_MANY('Devs')), (b'jeremy', b'grin', b'lex', b'jack'))
+
+
+class TestRedeemPubKeyHash(unittest.TestCase):
+
+    def redeem_pubkey_hash(self, sig, pubkey):
+        # this checks that factory function correctly sets up the script
+        src1 = BaseInputScript.redeem_pubkey_hash(unhexlify(sig), unhexlify(pubkey))
+        self.assertEqual(src1.template.name, 'pubkey_hash')
+        self.assertEqual(hexlify(src1.values['signature']), sig)
+        self.assertEqual(hexlify(src1.values['pubkey']), pubkey)
+        # now we test that it will round trip
+        src2 = BaseInputScript(src1.source)
+        self.assertEqual(src2.template.name, 'pubkey_hash')
+        self.assertEqual(hexlify(src2.values['signature']), sig)
+        self.assertEqual(hexlify(src2.values['pubkey']), pubkey)
+        return hexlify(src1.source)
+
+    def test_redeem_pubkey_hash_1(self):
+        self.assertEqual(
+            self.redeem_pubkey_hash(
+                b'30450221009dc93f25184a8d483745cd3eceff49727a317c9bfd8be8d3d04517e9cdaf8dd502200e'
+                b'02dc5939cad9562d2b1f303f185957581c4851c98d497af281118825e18a8301',
+                b'025415a06514230521bff3aaface31f6db9d9bbc39bf1ca60a189e78731cfd4e1b'
+            ),
+            b'4830450221009dc93f25184a8d483745cd3eceff49727a317c9bfd8be8d3d04517e9cdaf8dd502200e02d'
+            b'c5939cad9562d2b1f303f185957581c4851c98d497af281118825e18a830121025415a06514230521bff3'
+            b'aaface31f6db9d9bbc39bf1ca60a189e78731cfd4e1b'
+        )
+
+
+class TestRedeemScriptHash(unittest.TestCase):
+
+    def redeem_script_hash(self, sigs, pubkeys):
+        # this checks that factory function correctly sets up the script
+        src1 = BaseInputScript.redeem_script_hash(
+            [unhexlify(sig) for sig in sigs],
+            [unhexlify(pubkey) for pubkey in pubkeys]
+        )
+        subscript1 = src1.values['script']
+        self.assertEqual(src1.template.name, 'script_hash')
+        self.assertEqual([hexlify(v) for v in src1.values['signatures']], sigs)
+        self.assertEqual([hexlify(p) for p in subscript1.values['pubkeys']], pubkeys)
+        self.assertEqual(subscript1.values['signatures_count'], len(sigs))
+        self.assertEqual(subscript1.values['pubkeys_count'], len(pubkeys))
+        # now we test that it will round trip
+        src2 = BaseInputScript(src1.source)
+        subscript2 = src2.values['script']
+        self.assertEqual(src2.template.name, 'script_hash')
+        self.assertEqual([hexlify(v) for v in src2.values['signatures']], sigs)
+        self.assertEqual([hexlify(p) for p in subscript2.values['pubkeys']], pubkeys)
+        self.assertEqual(subscript2.values['signatures_count'], len(sigs))
+        self.assertEqual(subscript2.values['pubkeys_count'], len(pubkeys))
+        return hexlify(src1.source)
+
+    def test_redeem_script_hash_1(self):
+        self.assertEqual(
+            self.redeem_script_hash([
+                b'3045022100fec82ed82687874f2a29cbdc8334e114af645c45298e85bb1efe69fcf15c617a0220575'
+                b'e40399f9ada388d8e522899f4ec3b7256896dd9b02742f6567d960b613f0401',
+                b'3044022024890462f731bd1a42a4716797bad94761fc4112e359117e591c07b8520ea33b02201ac68'
+                b'9e35c4648e6beff1d42490207ba14027a638a62663b2ee40153299141eb01',
+                b'30450221009910823e0142967a73c2d16c1560054d71c0625a385904ba2f1f53e0bc1daa8d02205cd'
+                b'70a89c6cf031a8b07d1d5eb0d65d108c4d49c2d403f84fb03ad3dc318777a01'
+            ], [
+                b'0372ba1fd35e5f1b1437cba0c4ebfc4025b7349366f9f9c7c8c4b03a47bd3f68a4',
+                b'03061d250182b2db1ba144167fd8b0ef3fe0fc3a2fa046958f835ffaf0dfdb7692',
+                b'02463bfbc1eaec74b5c21c09239ae18dbf6fc07833917df10d0b43e322810cee0c',
+                b'02fa6a6455c26fb516cfa85ea8de81dd623a893ffd579ee2a00deb6cdf3633d6bb',
+                b'0382910eae483ce4213d79d107bfc78f3d77e2a31ea597be45256171ad0abeaa89'
+            ]),
+            b'00483045022100fec82ed82687874f2a29cbdc8334e114af645c45298e85bb1efe69fcf15c617a0220575e'
+            b'40399f9ada388d8e522899f4ec3b7256896dd9b02742f6567d960b613f0401473044022024890462f731bd'
+            b'1a42a4716797bad94761fc4112e359117e591c07b8520ea33b02201ac689e35c4648e6beff1d42490207ba'
+            b'14027a638a62663b2ee40153299141eb014830450221009910823e0142967a73c2d16c1560054d71c0625a'
+            b'385904ba2f1f53e0bc1daa8d02205cd70a89c6cf031a8b07d1d5eb0d65d108c4d49c2d403f84fb03ad3dc3'
+            b'18777a014cad53210372ba1fd35e5f1b1437cba0c4ebfc4025b7349366f9f9c7c8c4b03a47bd3f68a42103'
+            b'061d250182b2db1ba144167fd8b0ef3fe0fc3a2fa046958f835ffaf0dfdb76922102463bfbc1eaec74b5c2'
+            b'1c09239ae18dbf6fc07833917df10d0b43e322810cee0c2102fa6a6455c26fb516cfa85ea8de81dd623a89'
+            b'3ffd579ee2a00deb6cdf3633d6bb210382910eae483ce4213d79d107bfc78f3d77e2a31ea597be45256171'
+            b'ad0abeaa8955ae'
+        )
+
+
+class TestPayPubKeyHash(unittest.TestCase):
+
+    def pay_pubkey_hash(self, pubkey_hash):
+        # this checks that factory function correctly sets up the script
+        src1 = BaseOutputScript.pay_pubkey_hash(unhexlify(pubkey_hash))
+        self.assertEqual(src1.template.name, 'pay_pubkey_hash')
+        self.assertEqual(hexlify(src1.values['pubkey_hash']), pubkey_hash)
+        # now we test that it will round trip
+        src2 = BaseOutputScript(src1.source)
+        self.assertEqual(src2.template.name, 'pay_pubkey_hash')
+        self.assertEqual(hexlify(src2.values['pubkey_hash']), pubkey_hash)
+        return hexlify(src1.source)
+
+    def test_pay_pubkey_hash_1(self):
+        self.assertEqual(
+            self.pay_pubkey_hash(b'64d74d12acc93ba1ad495e8d2d0523252d664f4d'),
+            b'76a91464d74d12acc93ba1ad495e8d2d0523252d664f4d88ac'
+        )
+
+
+class TestPayScriptHash(unittest.TestCase):
+
+    def pay_script_hash(self, script_hash):
+        # this checks that factory function correctly sets up the script
+        src1 = BaseOutputScript.pay_script_hash(unhexlify(script_hash))
+        self.assertEqual(src1.template.name, 'pay_script_hash')
+        self.assertEqual(hexlify(src1.values['script_hash']), script_hash)
+        # now we test that it will round trip
+        src2 = BaseOutputScript(src1.source)
+        self.assertEqual(src2.template.name, 'pay_script_hash')
+        self.assertEqual(hexlify(src2.values['script_hash']), script_hash)
+        return hexlify(src1.source)
+
+    def test_pay_pubkey_hash_1(self):
+        self.assertEqual(
+            self.pay_script_hash(b'63d65a2ee8c44426d06050cfd71c0f0ff3fc41ac'),
+            b'a91463d65a2ee8c44426d06050cfd71c0f0ff3fc41ac87'
+        )

tests/unit/test_transaction.py

@@ -0,0 +1,174 @@
+from binascii import hexlify, unhexlify
+from twisted.trial import unittest
+
+from torba.account import Account
+from torba.coin.btc import BTC, Transaction, Output, Input
+from torba.constants import CENT, COIN
+from torba.manager import WalletManager
+from torba.wallet import Wallet
+
+
+NULL_HASH = b'\x00'*32
+FEE_PER_BYTE = 50
+FEE_PER_CHAR = 200000
+
+
+def get_output(amount=CENT, pubkey_hash=NULL_HASH):
+    return Transaction() \
+        .add_outputs([Output.pay_pubkey_hash(amount, pubkey_hash)]) \
+        .outputs[0]
+
+
+def get_input():
+    return Input.spend(get_output())
+
+
+def get_transaction(txo=None):
+    return Transaction() \
+        .add_inputs([get_input()]) \
+        .add_outputs([txo or Output.pay_pubkey_hash(CENT, NULL_HASH)])
+
+
+def get_wallet_and_coin():
+    ledger = WalletManager().get_or_create_ledger(BTC.get_id())
+    coin = BTC(ledger)
+    return Wallet('Main', [coin], [Account.generate(coin, u'torba')]), coin
+
+
+class TestSizeAndFeeEstimation(unittest.TestCase):
+
+    def setUp(self):
+        self.wallet, self.coin = get_wallet_and_coin()
+
+    def io_fee(self, io):
+        return self.coin.get_input_output_fee(io)
+
+    def test_output_size_and_fee(self):
+        txo = get_output()
+        self.assertEqual(txo.size, 46)
+        self.assertEqual(self.io_fee(txo), 46 * FEE_PER_BYTE)
+
+    def test_input_size_and_fee(self):
+        txi = get_input()
+        self.assertEqual(txi.size, 148)
+        self.assertEqual(self.io_fee(txi), 148 * FEE_PER_BYTE)
+
+    def test_transaction_size_and_fee(self):
+        tx = get_transaction()
+        base_size = tx.size - 1 - tx.inputs[0].size
+        self.assertEqual(tx.size, 204)
+        self.assertEqual(tx.base_size, base_size)
+        self.assertEqual(self.coin.get_transaction_base_fee(tx), FEE_PER_BYTE * base_size)
+
+
+class TestTransactionSerialization(unittest.TestCase):
+
+    def test_genesis_transaction(self):
+        raw = unhexlify(
+            '01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff4d04'
+            'ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e20'
+            '6272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73ffffffff0100f2052a01'
+            '000000434104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4c'
+            'ef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac00000000'
+        )
+        tx = Transaction(raw)
+        self.assertEqual(tx.version, 1)
+        self.assertEqual(tx.locktime, 0)
+        self.assertEqual(len(tx.inputs), 1)
+        self.assertEqual(len(tx.outputs), 1)
+
+        coinbase = tx.inputs[0]
+        self.assertEqual(coinbase.output_txid, NULL_HASH)
+        self.assertEqual(coinbase.output_index, 0xFFFFFFFF)
+        self.assertEqual(coinbase.sequence, 4294967295)
+        self.assertTrue(coinbase.is_coinbase)
+        self.assertEqual(coinbase.script, None)
+        self.assertEqual(
+            coinbase.coinbase[8:],
+            b'The Times 03/Jan/2009 Chancellor on brink of second bailout for banks'
+        )
+
+        out = tx.outputs[0]
+        self.assertEqual(out.amount, 5000000000)
+        self.assertEqual(out.index, 0)
+        self.assertTrue(out.script.is_pay_pubkey)
+        self.assertFalse(out.script.is_pay_pubkey_hash)
+        self.assertFalse(out.script.is_pay_script_hash)
+
+        tx._reset()
+        self.assertEqual(tx.raw, raw)
+
+    def test_coinbase_transaction(self):
+        raw = unhexlify(
+            '01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff4e03'
+            '1f5a070473319e592f4254432e434f4d2f4e59412ffabe6d6dcceb2a9d0444c51cabc4ee97a1a000036ca0'
+            'cb48d25b94b78c8367d8b868454b0100000000000000c0309b21000008c5f8f80000ffffffff0291920b5d'
+            '0000000017a914e083685a1097ce1ea9e91987ab9e94eae33d8a13870000000000000000266a24aa21a9ed'
+            'e6c99265a6b9e1d36c962fda0516b35709c49dc3b8176fa7e5d5f1f6197884b400000000'
+        )
+        tx = Transaction(raw)
+        self.assertEqual(tx.version, 1)
+        self.assertEqual(tx.locktime, 0)
+        self.assertEqual(len(tx.inputs), 1)
+        self.assertEqual(len(tx.outputs), 2)
+
+        coinbase = tx.inputs[0]
+        self.assertEqual(coinbase.output_txid, NULL_HASH)
+        self.assertEqual(coinbase.output_index, 0xFFFFFFFF)
+        self.assertEqual(coinbase.sequence, 4294967295)
+        self.assertTrue(coinbase.is_coinbase)
+        self.assertEqual(coinbase.script, None)
+        self.assertEqual(
+            coinbase.coinbase[9:22],
+            b'/BTC.COM/NYA/'
+        )
+
+        out = tx.outputs[0]
+        self.assertEqual(out.amount, 1561039505)
+        self.assertEqual(out.index, 0)
+        self.assertFalse(out.script.is_pay_pubkey)
+        self.assertFalse(out.script.is_pay_pubkey_hash)
+        self.assertTrue(out.script.is_pay_script_hash)
+        self.assertFalse(out.script.is_return_data)
+
+        out1 = tx.outputs[1]
+        self.assertEqual(out1.amount, 0)
+        self.assertEqual(out1.index, 1)
+        self.assertEqual(
+            hexlify(out1.script.values['data']),
+            b'aa21a9ede6c99265a6b9e1d36c962fda0516b35709c49dc3b8176fa7e5d5f1f6197884b4'
+        )
+        self.assertTrue(out1.script.is_return_data)
+        self.assertFalse(out1.script.is_pay_pubkey)
+        self.assertFalse(out1.script.is_pay_pubkey_hash)
+        self.assertFalse(out1.script.is_pay_script_hash)
+
+        tx._reset()
+        self.assertEqual(tx.raw, raw)
+
+
+class TestTransactionSigning(unittest.TestCase):
+
+    def test_sign(self):
+        ledger = WalletManager().get_or_create_ledger(BTC.get_id())
+        coin = BTC(ledger)
+        wallet = Wallet('Main', [coin], [Account.from_seed(
+            coin, u'carbon smart garage balance margin twelve chest sword toast envelope bottom stom'
+                  u'ach absent', u'torba'
+        )])
+        account = wallet.default_account
+
+        address1 = account.receiving_keys.generate_next_address()
+        address2 = account.receiving_keys.generate_next_address()
+        pubkey_hash1 = account.coin.address_to_hash160(address1)
+        pubkey_hash2 = account.coin.address_to_hash160(address2)
+
+        tx = Transaction() \
+            .add_inputs([Input.spend(get_output(2*COIN, pubkey_hash1))]) \
+            .add_outputs([Output.pay_pubkey_hash(int(1.9*COIN), pubkey_hash2)]) \
+            .sign(account)
+
+        self.assertEqual(
+            hexlify(tx.inputs[0].script.values['signature']),
+            b'304402203d463519290d06891e461ea5256c56097ccdad53379b1bb4e51ec5abc6e9fd02022034ed15b9d7c678716c4aa7c0fd26c688e8f9db8075838f2839ab55d551b62c0a01'
+        )

tests/unit/test_wallet.py

@@ -0,0 +1,97 @@
+from twisted.trial import unittest
+
+from torba.coin.btc import BTC
+from torba.manager import WalletManager
+from torba.wallet import Account, Wallet, WalletStorage
+
+from .ftc import FTC
+
+
+class TestWalletCreation(unittest.TestCase):
+
+    def setUp(self):
+        self.manager = WalletManager()
+        self.btc_ledger = self.manager.get_or_create_ledger(BTC.get_id())
+        self.ftc_ledger = self.manager.get_or_create_ledger(FTC.get_id())
+
+    def test_create_wallet_and_accounts(self):
+        wallet = Wallet()
+        self.assertEqual(wallet.name, 'Wallet')
+        self.assertEqual(wallet.coins, [])
+        self.assertEqual(wallet.accounts, [])
+
+        account1 = wallet.generate_account(self.btc_ledger)
+        account2 = wallet.generate_account(self.btc_ledger)
+        account3 = wallet.generate_account(self.ftc_ledger)
+        self.assertEqual(wallet.default_account, account1)
+        self.assertEqual(len(wallet.coins), 2)
+        self.assertEqual(len(wallet.accounts), 3)
+        self.assertIsInstance(wallet.coins[0], BTC)
+        self.assertIsInstance(wallet.coins[1], FTC)
+
+        self.assertEqual(len(account1.receiving_keys.addresses), 0)
+        self.assertEqual(len(account1.change_keys.addresses), 0)
+        self.assertEqual(len(account2.receiving_keys.addresses), 0)
+        self.assertEqual(len(account2.change_keys.addresses), 0)
+        self.assertEqual(len(account3.receiving_keys.addresses), 0)
+        self.assertEqual(len(account3.change_keys.addresses), 0)
+        account1.ensure_enough_addresses()
+        account2.ensure_enough_addresses()
+        account3.ensure_enough_addresses()
+        self.assertEqual(len(account1.receiving_keys.addresses), 20)
+        self.assertEqual(len(account1.change_keys.addresses), 6)
+        self.assertEqual(len(account2.receiving_keys.addresses), 20)
+        self.assertEqual(len(account2.change_keys.addresses), 6)
+        self.assertEqual(len(account3.receiving_keys.addresses), 20)
+        self.assertEqual(len(account3.change_keys.addresses), 6)
+
+    def test_load_and_save_wallet(self):
+        wallet_dict = {
+            'name': 'Main Wallet',
+            'accounts': [
+                {
+                    'coin': 'btc_mainnet',
+                    'seed':
+                        "carbon smart garage balance margin twelve chest sword toast envelope bottom stomac"
+                        "h absent",
+                    'encrypted': False,
+                    'private_key':
+                        'xprv9s21ZrQH143K2dyhK7SevfRG72bYDRNv25yKPWWm6dqApNxm1Zb1m5gGcBWYfbsPjTr2v5joit8Af2Zp5P'
+                        '6yz3jMbycrLrRMpeAJxR8qDg8',
+                    'public_key':
+                        'xpub661MyMwAqRbcF84AR8yfHoMzf4S2ct6mPJtvBtvNeyN9hBHuZ6uGJszkTSn5fQUCdz3XU17eBzFeAUwV6f'
+                        'iW44g14WF52fYC5J483wqQ5ZP',
+                    'receiving_gap': 10,
+                    'receiving_keys': [
+                        '0222345947a59dca4a3363ffa81ac87dd907d2b2feff57383eaeddbab266ca5f2d',
+                        '03fdc9826d5d00a484188cba8eb7dba5877c0323acb77905b7bcbbab35d94be9f6'
+                    ],
+                    'change_gap': 10,
+                    'change_keys': [
+                        '038836be4147836ed6b4df6a89e0d9f1b1c11cec529b7ff5407de57f2e5b032c83'
+                    ]
+                }
+            ]
+        }
+
+        storage = WalletStorage(default=wallet_dict)
+        wallet = Wallet.from_storage(storage, self.manager)
+        self.assertEqual(wallet.name, 'Main Wallet')
+        self.assertEqual(len(wallet.coins), 1)
+        self.assertIsInstance(wallet.coins[0], BTC)
+        self.assertEqual(len(wallet.accounts), 1)
+        account = wallet.default_account
+        self.assertIsInstance(account, Account)
+
+        self.assertEqual(len(account.receiving_keys.addresses), 2)
+        self.assertEqual(
+            account.receiving_keys.addresses[0],
+            '1PmX9T3sCiDysNtWszJa44SkKcpGc2NaXP'
+        )
+        self.assertEqual(len(account.change_keys.addresses), 1)
+        self.assertEqual(
+            account.change_keys.addresses[0],
+            '1PUbu1D1f3c244JPRSJKBCxRqui5NT6geR'
+        )
+        wallet_dict['coins'] = {'btc_mainnet': {'fee_per_byte': 50}}
+        self.assertDictEqual(wallet_dict, wallet.to_dict())

torba/__init__.py

@@ -0,0 +1,2 @@
+__path__ = __import__('pkgutil').extend_path(__path__, __name__)
+__version__ = '0.0.1'

torba/account.py

@@ -0,0 +1,190 @@
+import itertools
+from typing import Dict, Generator
+from binascii import hexlify, unhexlify
+
+from torba.basecoin import BaseCoin
+from torba.mnemonic import Mnemonic
+from torba.bip32 import PrivateKey, PubKey, from_extended_key_string
+from torba.hash import double_sha256, aes_encrypt, aes_decrypt
+
+
+class KeyChain:
+
+    def __init__(self, parent_key, child_keys, gap):
+        self.coin = parent_key.coin
+        self.parent_key = parent_key  # type: PubKey
+        self.child_keys = child_keys
+        self.minimum_gap = gap
+        self.addresses = [
+            self.coin.public_key_to_address(key)
+            for key in child_keys
+        ]
+
+    @property
+    def has_gap(self):
+        if len(self.addresses) < self.minimum_gap:
+            return False
+        for address in self.addresses[-self.minimum_gap:]:
+            if self.coin.ledger.is_address_old(address):
+                return False
+        return True
+
+    def generate_next_address(self):
+        child_key = self.parent_key.child(len(self.child_keys))
+        self.child_keys.append(child_key.pubkey_bytes)
+        self.addresses.append(child_key.address)
+        return child_key.address
+
+    def ensure_enough_addresses(self):
+        starting_length = len(self.addresses)
+        while not self.has_gap:
+            self.generate_next_address()
+        return self.addresses[starting_length:]
+
+
+class Account:
+
+    def __init__(self, coin, seed, encrypted, private_key, public_key,
+                 receiving_keys=None, receiving_gap=20,
+                 change_keys=None, change_gap=6):
+        self.coin = coin  # type: BaseCoin
+        self.seed = seed  # type: str
+        self.encrypted = encrypted  # type: bool
+        self.private_key = private_key  # type: PrivateKey
+        self.public_key = public_key  # type: PubKey
+        self.keychains = (
+            KeyChain(public_key.child(0), receiving_keys or [], receiving_gap),
+            KeyChain(public_key.child(1), change_keys or [], change_gap)
+        )
+        self.receiving_keys, self.change_keys = self.keychains
+
+    @classmethod
+    def generate(cls, coin, password):  # type: (BaseCoin, unicode) -> Account
+        seed = Mnemonic().make_seed()
+        return cls.from_seed(coin, seed, password)
+
+    @classmethod
+    def from_seed(cls, coin, seed, password):  # type: (BaseCoin, unicode, unicode) -> Account
+        private_key = cls.get_private_key_from_seed(coin, seed, password)
+        return cls(
+            coin=coin, seed=seed, encrypted=False,
+            private_key=private_key,
+            public_key=private_key.public_key
+        )
+
+    @staticmethod
+    def get_private_key_from_seed(coin, seed, password):  # type: (BaseCoin, unicode, unicode) -> PrivateKey
+        return PrivateKey.from_seed(coin, Mnemonic.mnemonic_to_seed(seed, password))
+
+    @classmethod
+    def from_dict(cls, coin, d):  # type: (BaseCoin, Dict) -> Account
+        if not d['encrypted']:
+            private_key = from_extended_key_string(coin, d['private_key'])
+            public_key = private_key.public_key
+        else:
+            private_key = d['private_key']
+            public_key = from_extended_key_string(coin, d['public_key'])
+        return cls(
+            coin=coin,
+            seed=d['seed'],
+            encrypted=d['encrypted'],
+            private_key=private_key,
+            public_key=public_key,
+            receiving_keys=[unhexlify(k) for k in d['receiving_keys']],
+            receiving_gap=d['receiving_gap'],
+            change_keys=[unhexlify(k) for k in d['change_keys']],
+            change_gap=d['change_gap']
+        )
+
+    def to_dict(self):
+        return {
+            'coin': self.coin.get_id(),
+            'seed': self.seed,
+            'encrypted': self.encrypted,
+            'private_key': self.private_key if self.encrypted else
+                           self.private_key.extended_key_string(),
+            'public_key': self.public_key.extended_key_string(),
+            'receiving_keys': [hexlify(k).decode('iso-8859-1') for k in self.receiving_keys.child_keys],
+            'receiving_gap': self.receiving_keys.minimum_gap,
+            'change_keys': [hexlify(k).decode('iso-8859-1') for k in self.change_keys.child_keys],
+            'change_gap': self.change_keys.minimum_gap
+        }
+
+    def decrypt(self, password):
+        assert self.encrypted, "Key is not encrypted."
+        secret = double_sha256(password)
+        self.seed = aes_decrypt(secret, self.seed)
+        self.private_key = from_extended_key_string(self.coin, aes_decrypt(secret, self.private_key))
+        self.encrypted = False
+
+    def encrypt(self, password):
+        assert not self.encrypted, "Key is already encrypted."
+        secret = double_sha256(password)
+        self.seed = aes_encrypt(secret, self.seed)
+        self.private_key = aes_encrypt(secret, self.private_key.extended_key_string())
+        self.encrypted = True
+
+    @property
+    def addresses(self):
+        return itertools.chain(self.receiving_keys.addresses, self.change_keys.addresses)
+
+    def get_private_key_for_address(self, address):
+        assert not self.encrypted, "Cannot get private key on encrypted wallet account."
+        for a, keychain in enumerate(self.keychains):
+            for b, match in enumerate(keychain.addresses):
+                if address == match:
+                    return self.private_key.child(a).child(b)
+
+    def ensure_enough_addresses(self):
+        return [
+            address
+            for keychain in self.keychains
+            for address in keychain.ensure_enough_addresses()
+        ]
+
+    def addresses_without_history(self):
+        for address in self.addresses:
+            if not self.coin.ledger.has_address(address):
+                yield address
+
+    def get_least_used_receiving_address(self, max_transactions=1000):
+        return self._get_least_used_address(
+            self.receiving_keys.addresses,
+            self.receiving_keys,
+            max_transactions
+        )
+
+    def get_least_used_change_address(self, max_transactions=100):
+        return self._get_least_used_address(
+            self.change_keys.addresses,
+            self.change_keys,
+            max_transactions
+        )
+
+    def _get_least_used_address(self, addresses, keychain, max_transactions):
+        ledger = self.coin.ledger
+        address = ledger.get_least_used_address(addresses, max_transactions)
+        if address:
+            return address
+        address = keychain.generate_next_address()
+        ledger.subscribe_history(address)
+        return address
+
+    def get_unspent_utxos(self):
+        return [
+            utxo
+            for address in self.addresses
+            for utxo in self.coin.ledger.get_unspent_outputs(address)
+        ]
+
+    def get_balance(self):
+        return sum(utxo.amount for utxo in self.get_unspent_utxos())
+
+
+class AccountsView:
+
+    def __init__(self, accounts):
+        self._accounts_generator = accounts
+
+    def __iter__(self):  # type: () -> Generator[Account]
+        return self._accounts_generator()

torba/basecoin.py

@@ -0,0 +1,79 @@
+import six
+from typing import Dict, Type
+from torba.hash import hash160, double_sha256, Base58
+
+
+class CoinRegistry(type):
+    coins = {}  # type: Dict[str, Type[BaseCoin]]
+
+    def __new__(mcs, name, bases, attrs):
+        cls = super(CoinRegistry, mcs).__new__(mcs, name, bases, attrs)  # type: Type[BaseCoin]
+        if not (name == 'BaseCoin' and not bases):
+            coin_id = cls.get_id()
+            assert coin_id not in mcs.coins, 'Coin with id "{}" already registered.'.format(coin_id)
+            mcs.coins[coin_id] = cls
+            assert cls.ledger_class.coin_class is None, (
+                "Ledger ({}) which this coin ({}) references is already referenced by another "
+                "coin ({}). One to one relationship between a coin and a ledger is strictly and "
+                "automatically enforced. Make sure that coin_class=None in the ledger and that "
+                "another Coin isn't already referencing this Ledger."
+            ).format(cls.ledger_class.__name__, name, cls.ledger_class.coin_class.__name__)
+            # create back reference from ledger to the coin
+            cls.ledger_class.coin_class = cls
+        return cls
+
+    @classmethod
+    def get_coin_class(mcs, coin_id):  # type: (str) -> Type[BaseCoin]
+        return mcs.coins[coin_id]
+
+
+class BaseCoin(six.with_metaclass(CoinRegistry)):
+
+    name = None
+    symbol = None
+    network = None
+
+    ledger_class = None  # type: Type[BaseLedger]
+    transaction_class = None  # type: Type[BaseTransaction]
+
+    secret_prefix = None
+    pubkey_address_prefix = None
+    script_address_prefix = None
+    extended_public_key_prefix = None
+    extended_private_key_prefix = None
+
+    def __init__(self, ledger, fee_per_byte):
+        self.ledger = ledger
+        self.fee_per_byte = fee_per_byte
+
+    @classmethod
+    def get_id(cls):
+        return '{}_{}'.format(cls.symbol.lower(), cls.network.lower())
+
+    def to_dict(self):
+        return {'fee_per_byte': self.fee_per_byte}
+
+    def get_input_output_fee(self, io):
+        """ Fee based on size of the input / output. """
+        return self.fee_per_byte * io.size
+
+    def get_transaction_base_fee(self, tx):
+        """ Fee for the transaction header and all outputs; without inputs. """
+        return self.fee_per_byte * tx.base_size
+
+    def hash160_to_address(self, h160):
+        raw_address = self.pubkey_address_prefix + h160
+        return Base58.encode(bytearray(raw_address + double_sha256(raw_address)[0:4]))
+
+    @staticmethod
+    def address_to_hash160(address):
+        bytes = Base58.decode(address)
+        prefix, pubkey_bytes, addr_checksum = bytes[0], bytes[1:21], bytes[21:]
+        return pubkey_bytes
+
+    def public_key_to_address(self, public_key):
+        return self.hash160_to_address(hash160(public_key))
+
+    @staticmethod
+    def private_key_to_wif(private_key):
+        return b'\x1c' + private_key + b'\x01'

torba/baseledger.py

@@ -0,0 +1,469 @@
+import os
+import hashlib
+from binascii import hexlify, unhexlify
+from typing import List, Dict, Type
+from operator import itemgetter
+
+from twisted.internet import threads, defer, task, reactor
+
+from torba.account import Account, AccountsView
+from torba.basecoin import BaseCoin
+from torba.basetransaction import BaseTransaction
+from torba.basenetwork import BaseNetwork
+from torba.stream import StreamController, execute_serially
+from torba.util import hex_to_int, int_to_hex, rev_hex, hash_encode
+from torba.hash import double_sha256, pow_hash
+
+
+class Address:
+
+    def __init__(self, pubkey_hash):
+        self.pubkey_hash = pubkey_hash
+        self.transactions = []  # type: List[BaseTransaction]
+
+    def __iter__(self):
+        return iter(self.transactions)
+
+    def __len__(self):
+        return len(self.transactions)
+
+    def add_transaction(self, transaction):
+        self.transactions.append(transaction)
+
+    def get_unspent_utxos(self):
+        inputs, outputs, utxos = [], [], []
+        for tx in self:
+            for txi in tx.inputs:
+                inputs.append((txi.output_txid, txi.output_index))
+            for txo in tx.outputs:
+                if txo.script.is_pay_pubkey_hash and txo.script.values['pubkey_hash'] == self.pubkey_hash:
+                    outputs.append((txo, txo.transaction.hash, txo.index))
+        for output in set(outputs):
+            if output[1:] not in inputs:
+                yield output[0]
+
+
+class BaseLedger:
+
+    # coin_class is automatically set by BaseCoin metaclass
+    # when it creates the Coin classes, there is a 1..1 relationship
+    # between a coin and a ledger (at the class level) but a 1..* relationship
+    # at instance level. Only one Ledger instance should exist per coin class,
+    # but many coin instances can exist linking back to the single Ledger instance.
+    coin_class = None  # type: Type[BaseCoin]
+    network_class = None  # type: Type[BaseNetwork]
+
+    verify_bits_to_target = True
+
+    def __init__(self, accounts, config=None, network=None, db=None):
+        self.accounts = accounts  # type: AccountsView
+        self.config = config or {}
+        self.db = db
+        self.addresses = {}  # type: Dict[str, Address]
+        self.transactions = {}  # type: Dict[str, BaseTransaction]
+        self.headers = Headers(self)
+        self._on_transaction_controller = StreamController()
+        self.on_transaction = self._on_transaction_controller.stream
+        self.network = network or self.network_class(self.config)
+        self.network.on_header.listen(self.process_header)
+        self.network.on_status.listen(self.process_status)
+
+    @property
+    def transaction_class(self):
+        return self.coin_class.transaction_class
+
+    @classmethod
+    def from_json(cls, json_dict):
+        return cls(json_dict)
+
+    @defer.inlineCallbacks
+    def load(self):
+        txs = yield self.db.get_transactions()
+        for tx_hash, raw, height in txs:
+            self.transactions[tx_hash] = self.transaction_class(raw, height)
+        txios = yield self.db.get_transaction_inputs_and_outputs()
+        for tx_hash, address_hash, input_output, amount, height in txios:
+            tx = self.transactions[tx_hash]
+            address = self.addresses.get(address_hash)
+            if address is None:
+                address = self.addresses[address_hash] = Address(self.coin_class.address_to_hash160(address_hash))
+            tx.add_txio(address, input_output, amount)
+            address.add_transaction(tx)
+
+    def is_address_old(self, address, age_limit=2):
+        age = -1
+        for tx in self.get_transactions(address, []):
+            if tx.height == 0:
+                tx_age = 0
+            else:
+                tx_age = self.headers.height - tx.height + 1
+            if tx_age > age:
+                age = tx_age
+        return age > age_limit
+
+    def add_transaction(self, address, transaction):  # type: (str, BaseTransaction) -> None
+        if address not in self.addresses:
+            self.addresses[address] = Address(self.coin_class.address_to_hash160(address))
+        self.addresses[address].add_transaction(transaction)
+        self.transactions.setdefault(hexlify(transaction.id), transaction)
+        self._on_transaction_controller.add(transaction)
+
+    def has_address(self, address):
+        return address in self.addresses
+
+    def get_transaction(self, tx_hash, *args):
+        return self.transactions.get(tx_hash, *args)
+
+    def get_transactions(self, address, *args):
+        return self.addresses.get(address, *args)
+
+    def get_status(self, address):
+        hashes = [
+            '{}:{}:'.format(hexlify(tx.hash), tx.height).encode()
+            for tx in self.get_transactions(address, []) if tx.height is not None
+        ]
+        if hashes:
+            return hexlify(hashlib.sha256(b''.join(hashes)).digest())
+
+    def has_transaction(self, tx_hash):
+        return tx_hash in self.transactions
+
+    def get_least_used_address(self, addresses, max_transactions=100):
+        transaction_counts = []
+        for address in addresses:
+            transactions = self.get_transactions(address, [])
+            tx_count = len(transactions)
+            if tx_count == 0:
+                return address
+            elif tx_count >= max_transactions:
+                continue
+            else:
+                transaction_counts.append((address, tx_count))
+        if transaction_counts:
+            transaction_counts.sort(key=itemgetter(1))
+            return transaction_counts[0]
+
+    def get_unspent_outputs(self, address):
+        if address in self.addresses:
+            return list(self.addresses[address].get_unspent_utxos())
+        return []
+
+    @defer.inlineCallbacks
+    def start(self):
+        first_connection = self.network.on_connected.first
+        self.network.start()
+        yield first_connection
+        self.headers.touch()
+        yield self.update_headers()
+        yield self.network.subscribe_headers()
+        yield self.update_accounts()
+
+    def stop(self):
+        return self.network.stop()
+
+    @execute_serially
+    @defer.inlineCallbacks
+    def update_headers(self):
+        while True:
+            height_sought = len(self.headers)
+            headers = yield self.network.get_headers(height_sought)
+            print("received {} headers starting at {} height".format(headers['count'], height_sought))
+            #log.info("received {} headers starting at {} height".format(headers['count'], height_sought))
+            if headers['count'] <= 0:
+                break
+            yield self.headers.connect(height_sought, unhexlify(headers['hex']))
+
+    @defer.inlineCallbacks
+    def process_header(self, response):
+        header = response[0]
+        if self.update_headers.is_running:
+            return
+        if header['height'] == len(self.headers):
+            # New header from network directly connects after the last local header.
+            yield self.headers.connect(len(self.headers), unhexlify(header['hex']))
+        elif header['height'] > len(self.headers):
+            # New header is several heights ahead of local, do download instead.
+            yield self.update_headers()
+
+    @execute_serially
+    def update_accounts(self):
+        return defer.DeferredList([
+            self.update_account(a) for a in self.accounts
+        ])
+
+    @defer.inlineCallbacks
+    def update_account(self, account):  # type: (Account) -> defer.Defferred
+        # Before subscribing, download history for any addresses that don't have any,
+        # this avoids situation where we're getting status updates to addresses we know
+        # need to update anyways. Continue to get history and create more addresses until
+        # all missing addresses are created and history for them is fully restored.
+        account.ensure_enough_addresses()
+        addresses = list(account.addresses_without_history())
+        while addresses:
+            yield defer.DeferredList([
+                self.update_history(a) for a in addresses
+            ])
+            addresses = account.ensure_enough_addresses()
+
+        # By this point all of the addresses should be restored and we
+        # can now subscribe all of them to receive updates.
+        yield defer.DeferredList([
+            self.subscribe_history(address)
+            for address in account.addresses
+        ])
+
+    @defer.inlineCallbacks
+    def update_history(self, address):
+        history = yield self.network.get_history(address)
+        for hash in map(itemgetter('tx_hash'), history):
+            transaction = self.get_transaction(hash)
+            if not transaction:
+                raw = yield self.network.get_transaction(hash)
+                transaction = self.transaction_class(unhexlify(raw))
+            self.add_transaction(address, transaction)
+
+    @defer.inlineCallbacks
+    def subscribe_history(self, address):
+        status = yield self.network.subscribe_address(address)
+        if status != self.get_status(address):
+            yield self.update_history(address)
+
+    def process_status(self, response):
+        address, status = response
+        if status != self.get_status(address):
+            task.deferLater(reactor, 0, self.update_history, address)
+
+    def broadcast(self, tx):
+        return self.network.broadcast(hexlify(tx.raw))
+
+
+class Headers:
+
+    def __init__(self, ledger):
+        self.ledger = ledger
+        self._size = None
+        self._on_change_controller = StreamController()
+        self.on_changed = self._on_change_controller.stream
+
+    @property
+    def path(self):
+        wallet_path = self.ledger.config.get('wallet_path', '')
+        filename = '{}_headers'.format(self.ledger.coin_class.get_id())
+        return os.path.join(wallet_path, filename)
+
+    def touch(self):
+        if not os.path.exists(self.path):
+            with open(self.path, 'wb'):
+                pass
+
+    @property
+    def height(self):
+        return len(self) - 1
+
+    def sync_read_length(self):
+        return os.path.getsize(self.path) // self.ledger.header_size
+
+    def sync_read_header(self, height):
+        if 0 <= height < len(self):
+            with open(self.path, 'rb') as f:
+                f.seek(height * self.ledger.header_size)
+                return f.read(self.ledger.header_size)
+
+    def __len__(self):
+        if self._size is None:
+            self._size = self.sync_read_length()
+        return self._size
+
+    def __getitem__(self, height):
+        assert not isinstance(height, slice),\
+            "Slicing of header chain has not been implemented yet."
+        header = self.sync_read_header(height)
+        return self._deserialize(height, header)
+
+    @execute_serially
+    @defer.inlineCallbacks
+    def connect(self, start, headers):
+        yield threads.deferToThread(self._sync_connect, start, headers)
+
+    def _sync_connect(self, start, headers):
+        previous_header = None
+        for header in self._iterate_headers(start, headers):
+            height = header['block_height']
+            if previous_header is None and height > 0:
+                previous_header = self[height-1]
+            self._verify_header(height, header, previous_header)
+            previous_header = header
+
+        with open(self.path, 'r+b') as f:
+            f.seek(start * self.ledger.header_size)
+            f.write(headers)
+            f.truncate()
+
+        _old_size = self._size
+        self._size = self.sync_read_length()
+        change = self._size - _old_size
+        #log.info('saved {} header blocks'.format(change))
+        self._on_change_controller.add(change)
+
+    def _iterate_headers(self, height, headers):
+        assert len(headers) % self.ledger.header_size == 0
+        for idx in range(len(headers) // self.ledger.header_size):
+            start, end = idx * self.ledger.header_size, (idx + 1) * self.ledger.header_size
+            header = headers[start:end]
+            yield self._deserialize(height+idx, header)
+
+    def _verify_header(self, height, header, previous_header):
+        previous_hash = self._hash_header(previous_header)
+        assert previous_hash == header['prev_block_hash'], \
+            "prev hash mismatch: {} vs {}".format(previous_hash, header['prev_block_hash'])
+
+        bits, target = self._calculate_lbry_next_work_required(height, previous_header, header)
+        assert bits == header['bits'], \
+            "bits mismatch: {} vs {} (hash: {})".format(
+            bits, header['bits'], self._hash_header(header))
+
+        _pow_hash = self._pow_hash_header(header)
+        assert int(b'0x' + _pow_hash, 16) <= target, \
+            "insufficient proof of work: {} vs target {}".format(
+            int(b'0x' + _pow_hash, 16), target)
+
+    @staticmethod
+    def _serialize(header):
+        return b''.join([
+            int_to_hex(header['version'], 4),
+            rev_hex(header['prev_block_hash']),
+            rev_hex(header['merkle_root']),
+            rev_hex(header['claim_trie_root']),
+            int_to_hex(int(header['timestamp']), 4),
+            int_to_hex(int(header['bits']), 4),
+            int_to_hex(int(header['nonce']), 4)
+        ])
+
+    @staticmethod
+    def _deserialize(height, header):
+        return {
+            'version': hex_to_int(header[0:4]),
+            'prev_block_hash': hash_encode(header[4:36]),
+            'merkle_root': hash_encode(header[36:68]),
+            'claim_trie_root': hash_encode(header[68:100]),
+            'timestamp': hex_to_int(header[100:104]),
+            'bits': hex_to_int(header[104:108]),
+            'nonce': hex_to_int(header[108:112]),
+            'block_height': height
+        }
+
+    def _hash_header(self, header):
+        if header is None:
+            return b'0' * 64
+        return hash_encode(double_sha256(unhexlify(self._serialize(header))))
+
+    def _pow_hash_header(self, header):
+        if header is None:
+            return b'0' * 64
+        return hash_encode(pow_hash(unhexlify(self._serialize(header))))
+
+    def _calculate_lbry_next_work_required(self, height, first, last):
+        """ See: lbrycrd/src/lbry.cpp """
+
+        if height == 0:
+            return self.ledger.genesis_bits, self.ledger.max_target
+
+        if self.ledger.verify_bits_to_target:
+            bits = last['bits']
+            bitsN = (bits >> 24) & 0xff
+            assert 0x03 <= bitsN <= 0x1f, \
+                "First part of bits should be in [0x03, 0x1d], but it was {}".format(hex(bitsN))
+            bitsBase = bits & 0xffffff
+            assert 0x8000 <= bitsBase <= 0x7fffff, \
+                "Second part of bits should be in [0x8000, 0x7fffff] but it was {}".format(bitsBase)
+
+        # new target
+        retargetTimespan = self.ledger.target_timespan
+        nActualTimespan = last['timestamp'] - first['timestamp']
+
+        nModulatedTimespan = retargetTimespan + (nActualTimespan - retargetTimespan) // 8
+
+        nMinTimespan = retargetTimespan - (retargetTimespan // 8)
+        nMaxTimespan = retargetTimespan + (retargetTimespan // 2)
+
+        # Limit adjustment step
+        if nModulatedTimespan < nMinTimespan:
+            nModulatedTimespan = nMinTimespan
+        elif nModulatedTimespan > nMaxTimespan:
+            nModulatedTimespan = nMaxTimespan
+
+        # Retarget
+        bnPowLimit = _ArithUint256(self.ledger.max_target)
+        bnNew = _ArithUint256.SetCompact(last['bits'])
+        bnNew *= nModulatedTimespan
+        bnNew //= nModulatedTimespan
+        if bnNew > bnPowLimit:
+            bnNew = bnPowLimit
+
+        return bnNew.GetCompact(), bnNew._value
+
+
+class _ArithUint256:
+    """ See: lbrycrd/src/arith_uint256.cpp """
+
+    def __init__(self, value):
+        self._value = value
+
+    def __str__(self):
+        return hex(self._value)
+
+    @staticmethod
+    def fromCompact(nCompact):
+        """Convert a compact representation into its value"""
+        nSize = nCompact >> 24
+        # the lower 23 bits
+        nWord = nCompact & 0x007fffff
+        if nSize <= 3:
+            return nWord >> 8 * (3 - nSize)
+        else:
+            return nWord << 8 * (nSize - 3)
+
+    @classmethod
+    def SetCompact(cls, nCompact):
+        return cls(cls.fromCompact(nCompact))
+
+    def bits(self):
+        """Returns the position of the highest bit set plus one."""
+        bn = bin(self._value)[2:]
+        for i, d in enumerate(bn):
+            if d:
+                return (len(bn) - i) + 1
+        return 0
+
+    def GetLow64(self):
+        return self._value & 0xffffffffffffffff
+
+    def GetCompact(self):
+        """Convert a value into its compact representation"""
+        nSize = (self.bits() + 7) // 8
+        nCompact = 0
+        if nSize <= 3:
+            nCompact = self.GetLow64() << 8 * (3 - nSize)
+        else:
+            bn = _ArithUint256(self._value >> 8 * (nSize - 3))
+            nCompact = bn.GetLow64()
+        # The 0x00800000 bit denotes the sign.
+        # Thus, if it is already set, divide the mantissa by 256 and increase the exponent.
+        if nCompact & 0x00800000:
+            nCompact >>= 8
+            nSize += 1
+        assert (nCompact & ~0x007fffff) == 0
+        assert nSize < 256
+        nCompact |= nSize << 24
+        return nCompact
+
+    def __mul__(self, x):
+        # Take the mod because we are limited to an unsigned 256 bit number
+        return _ArithUint256((self._value * x) % 2 ** 256)
+
+    def __ifloordiv__(self, x):
+        self._value = (self._value // x)
+        return self
+
+    def __gt__(self, x):
+        return self._value > x._value

torba/basenetwork.py

@@ -0,0 +1,221 @@
+import six
+import json
+import socket
+import logging
+from itertools import cycle
+from twisted.internet import defer, reactor, protocol
+from twisted.application.internet import ClientService, CancelledError
+from twisted.internet.endpoints import clientFromString
+from twisted.protocols.basic import LineOnlyReceiver
+
+from torba import __version__
+from torba.stream import StreamController
+
+log = logging.getLogger()
+
+
+def unicode2bytes(string):
+    if isinstance(string, six.text_type):
+        return string.encode('iso-8859-1')
+    elif isinstance(string, list):
+        return [unicode2bytes(s) for s in string]
+    return string
+
+
+def bytes2unicode(maybe_bytes):
+    if isinstance(maybe_bytes, bytes):
+        return maybe_bytes.decode()
+    elif isinstance(maybe_bytes, list):
+        return [bytes2unicode(b) for b in maybe_bytes]
+    return maybe_bytes
+
+
+class StratumClientProtocol(LineOnlyReceiver):
+    delimiter = b'\n'
+    MAX_LENGTH = 100000
+
+    def __init__(self):
+        self.request_id = 0
+        self.lookup_table = {}
+        self.session = {}
+
+        self.on_disconnected_controller = StreamController()
+        self.on_disconnected = self.on_disconnected_controller.stream
+
+    def _get_id(self):
+        self.request_id += 1
+        return self.request_id
+
+    @property
+    def _ip(self):
+        return self.transport.getPeer().host
+
+    def get_session(self):
+        return self.session
+
+    def connectionMade(self):
+        try:
+            self.transport.setTcpNoDelay(True)
+            self.transport.setTcpKeepAlive(True)
+            self.transport.socket.setsockopt(
+                socket.SOL_TCP, socket.TCP_KEEPIDLE, 120
+                # Seconds before sending keepalive probes
+            )
+            self.transport.socket.setsockopt(
+                socket.SOL_TCP, socket.TCP_KEEPINTVL, 1
+                # Interval in seconds between keepalive probes
+            )
+            self.transport.socket.setsockopt(
+                socket.SOL_TCP, socket.TCP_KEEPCNT, 5
+                # Failed keepalive probles before declaring other end dead
+            )
+        except Exception as err:
+            # Supported only by the socket transport,
+            # but there's really no better place in code to trigger this.
+            log.warning("Error setting up socket: %s", err)
+
+    def connectionLost(self, reason=None):
+        self.on_disconnected_controller.add(True)
+
+    def lineReceived(self, line):
+
+        try:
+            # `line` comes in as a byte string but `json.loads` automatically converts everything to
+            # unicode. For keys it's not a big deal but for values there is an expectation
+            # everywhere else in wallet code that most values are byte strings.
+            message = json.loads(
+                line, object_hook=lambda obj: {
+                    k: unicode2bytes(v) for k, v in obj.items()
+                }
+            )
+        except (ValueError, TypeError):
+            raise ValueError("Cannot decode message '{}'".format(line.strip()))
+
+        if message.get('id'):
+            try:
+                d = self.lookup_table.pop(message['id'])
+                if message.get('error'):
+                    d.errback(RuntimeError(*message['error']))
+                else:
+                    d.callback(message.get('result'))
+            except KeyError:
+                raise LookupError(
+                    "Lookup for deferred object for message ID '{}' failed.".format(message['id']))
+        elif message.get('method') in self.network.subscription_controllers:
+            controller = self.network.subscription_controllers[message['method']]
+            controller.add(message.get('params'))
+        else:
+            log.warning("Cannot handle message '%s'" % line)
+
+    def rpc(self, method, *args):
+        message_id = self._get_id()
+        message = json.dumps({
+            'id': message_id,
+            'method': method,
+            'params': [bytes2unicode(arg) for arg in args]
+        })
+        self.sendLine(message.encode('latin-1'))
+        d = self.lookup_table[message_id] = defer.Deferred()
+        return d
+
+
+class StratumClientFactory(protocol.ClientFactory):
+
+    protocol = StratumClientProtocol
+
+    def __init__(self, network):
+        self.network = network
+        self.client = None
+
+    def buildProtocol(self, addr):
+        client = self.protocol()
+        client.factory = self
+        client.network = self.network
+        self.client = client
+        return client
+
+
+class BaseNetwork:
+
+    def __init__(self, config):
+        self.config = config
+        self.client = None
+        self.service = None
+        self.running = False
+
+        self._on_connected_controller = StreamController()
+        self.on_connected = self._on_connected_controller.stream
+
+        self._on_header_controller = StreamController()
+        self.on_header = self._on_header_controller.stream
+
+        self._on_status_controller = StreamController()
+        self.on_status = self._on_status_controller.stream
+
+        self.subscription_controllers = {
+            b'blockchain.headers.subscribe': self._on_header_controller,
+            b'blockchain.address.subscribe': self._on_status_controller,
+        }
+
+    @defer.inlineCallbacks
+    def start(self):
+        for server in cycle(self.config['default_servers']):
+            endpoint = clientFromString(reactor, 'tcp:{}:{}'.format(*server))
+            self.service = ClientService(endpoint, StratumClientFactory(self))
+            self.service.startService()
+            try:
+                self.client = yield self.service.whenConnected(failAfterFailures=2)
+                yield self.ensure_server_version()
+                self._on_connected_controller.add(True)
+                yield self.client.on_disconnected.first
+            except CancelledError:
+                return
+            except Exception as e:
+                pass
+            finally:
+                self.client = None
+            if not self.running:
+                return
+
+    def stop(self):
+        self.running = False
+        if self.service is not None:
+            self.service.stopService()
+        if self.is_connected:
+            return self.client.on_disconnected.first
+        else:
+            return defer.succeed(True)
+
+    @property
+    def is_connected(self):
+        return self.client is not None and self.client.connected
+
+    def rpc(self, list_or_method, *args):
+        if self.is_connected:
+            return self.client.rpc(list_or_method, *args)
+        else:
+            raise ConnectionError("Attempting to send rpc request when connection is not available.")
+
+    def ensure_server_version(self, required='1.2'):
+        return self.rpc('server.version', __version__, required)
+
+    def broadcast(self, raw_transaction):
+        return self.rpc('blockchain.transaction.broadcast', raw_transaction)
+
+    def get_history(self, address):
+        return self.rpc('blockchain.address.get_history', address)
+
+    def get_transaction(self, tx_hash):
+        return self.rpc('blockchain.transaction.get', tx_hash)
+
+    def get_merkle(self, tx_hash, height):
+        return self.rpc('blockchain.transaction.get_merkle', tx_hash, height)
+
+    def get_headers(self, height, count=10000):
+        return self.rpc('blockchain.block.headers', height, count)
+
+    def subscribe_headers(self):
+        return self.rpc('blockchain.headers.subscribe', True)
+
+    def subscribe_address(self, address):
+        return self.rpc('blockchain.address.subscribe', address)

torba/basescript.py

@@ -0,0 +1,407 @@
+from itertools import chain
+from binascii import hexlify
+from collections import namedtuple
+
+from torba.bcd_data_stream import BCDataStream
+from torba.util import subclass_tuple
+
+# bitcoin opcodes
+OP_0 = 0x00
+OP_1 = 0x51
+OP_16 = 0x60
+OP_DUP = 0x76
+OP_HASH160 = 0xa9
+OP_EQUALVERIFY = 0x88
+OP_CHECKSIG = 0xac
+OP_CHECKMULTISIG = 0xae
+OP_EQUAL = 0x87
+OP_PUSHDATA1 = 0x4c
+OP_PUSHDATA2 = 0x4d
+OP_PUSHDATA4 = 0x4e
+OP_RETURN = 0x6a
+OP_2DROP = 0x6d
+OP_DROP = 0x75
+
+
+# template matching opcodes (not real opcodes)
+# base class for PUSH_DATA related opcodes
+PUSH_DATA_OP = namedtuple('PUSH_DATA_OP', 'name')
+# opcode for variable length strings
+PUSH_SINGLE = subclass_tuple('PUSH_SINGLE', PUSH_DATA_OP)
+# opcode for variable number of variable length strings
+PUSH_MANY = subclass_tuple('PUSH_MANY', PUSH_DATA_OP)
+# opcode with embedded subscript parsing
+PUSH_SUBSCRIPT = namedtuple('PUSH_SUBSCRIPT', 'name template')
+
+
+def is_push_data_opcode(opcode):
+    return isinstance(opcode, PUSH_DATA_OP) or isinstance(opcode, PUSH_SUBSCRIPT)
+
+
+def is_push_data_token(token):
+    return 1 <= token <= OP_PUSHDATA4
+
+
+def push_data(data):
+    size = len(data)
+    if size < OP_PUSHDATA1:
+        yield BCDataStream.uint8.pack(size)
+    elif size <= 0xFF:
+        yield BCDataStream.uint8.pack(OP_PUSHDATA1)
+        yield BCDataStream.uint8.pack(size)
+    elif size <= 0xFFFF:
+        yield BCDataStream.uint8.pack(OP_PUSHDATA2)
+        yield BCDataStream.uint16.pack(size)
+    else:
+        yield BCDataStream.uint8.pack(OP_PUSHDATA4)
+        yield BCDataStream.uint32.pack(size)
+    yield data
+
+
+def read_data(token, stream):
+    if token < OP_PUSHDATA1:
+        return stream.read(token)
+    elif token == OP_PUSHDATA1:
+        return stream.read(stream.read_uint8())
+    elif token == OP_PUSHDATA2:
+        return stream.read(stream.read_uint16())
+    else:
+        return stream.read(stream.read_uint32())
+
+
+# opcode for OP_1 - OP_16
+SMALL_INTEGER = namedtuple('SMALL_INTEGER', 'name')
+
+
+def is_small_integer(token):
+    return OP_1 <= token <= OP_16
+
+
+def push_small_integer(num):
+    assert 1 <= num <= 16
+    yield BCDataStream.uint8.pack(OP_1 + (num - 1))
+
+
+def read_small_integer(token):
+    return (token - OP_1) + 1
+
+
+class Token(namedtuple('Token', 'value')):
+    __slots__ = ()
+
+    def __repr__(self):
+        name = None
+        for var_name, var_value in globals().items():
+            if var_name.startswith('OP_') and var_value == self.value:
+                name = var_name
+                break
+        return name or self.value
+
+
+class DataToken(Token):
+    __slots__ = ()
+
+    def __repr__(self):
+        return '"{}"'.format(hexlify(self.value))
+
+
+class SmallIntegerToken(Token):
+    __slots__ = ()
+
+    def __repr__(self):
+        return 'SmallIntegerToken({})'.format(self.value)
+
+
+def token_producer(source):
+    token = source.read_uint8()
+    while token is not None:
+        if is_push_data_token(token):
+            yield DataToken(read_data(token, source))
+        elif is_small_integer(token):
+            yield SmallIntegerToken(read_small_integer(token))
+        else:
+            yield Token(token)
+        token = source.read_uint8()
+
+
+def tokenize(source):
+    return list(token_producer(source))
+
+
+class ScriptError(Exception):
+    """ General script handling error. """
+
+
+class ParseError(ScriptError):
+    """ Script parsing error. """
+
+
+class Parser:
+
+    def __init__(self, opcodes, tokens):
+        self.opcodes = opcodes
+        self.tokens = tokens
+        self.values = {}
+        self.token_index = 0
+        self.opcode_index = 0
+
+    def parse(self):
+        while self.token_index < len(self.tokens) and self.opcode_index < len(self.opcodes):
+            token = self.tokens[self.token_index]
+            opcode = self.opcodes[self.opcode_index]
+            if isinstance(token, DataToken):
+                if isinstance(opcode, (PUSH_SINGLE, PUSH_SUBSCRIPT)):
+                    self.push_single(opcode, token.value)
+                elif isinstance(opcode, PUSH_MANY):
+                    self.consume_many_non_greedy()
+                else:
+                    raise ParseError("DataToken found but opcode was '{}'.".format(opcode))
+            elif isinstance(token, SmallIntegerToken):
+                if isinstance(opcode, SMALL_INTEGER):
+                    self.values[opcode.name] = token.value
+                else:
+                    raise ParseError("SmallIntegerToken found but opcode was '{}'.".format(opcode))
+            elif token.value == opcode:
+                pass
+            else:
+                raise ParseError("Token is '{}' and opcode is '{}'.".format(token.value, opcode))
+            self.token_index += 1
+            self.opcode_index += 1
+
+        if self.token_index < len(self.tokens):
+            raise ParseError("Parse completed without all tokens being consumed.")
+
+        if self.opcode_index < len(self.opcodes):
+            raise ParseError("Parse completed without all opcodes being consumed.")
+
+        return self
+
+    def consume_many_non_greedy(self):
+        """ Allows PUSH_MANY to consume data without being greedy
+            in cases when one or more PUSH_SINGLEs follow a PUSH_MANY. This will
+            prioritize giving all PUSH_SINGLEs some data and only after that
+            subsume the rest into PUSH_MANY.
+        """
+
+        token_values = []
+        while self.token_index < len(self.tokens):
+            token = self.tokens[self.token_index]
+            if not isinstance(token, DataToken):
+                self.token_index -= 1
+                break
+            token_values.append(token.value)
+            self.token_index += 1
+
+        push_opcodes = []
+        push_many_count = 0
+        while self.opcode_index < len(self.opcodes):
+            opcode = self.opcodes[self.opcode_index]
+            if not is_push_data_opcode(opcode):
+                self.opcode_index -= 1
+                break
+            if isinstance(opcode, PUSH_MANY):
+                push_many_count += 1
+            push_opcodes.append(opcode)
+            self.opcode_index += 1
+
+        if push_many_count > 1:
+            raise ParseError(
+                "Cannot have more than one consecutive PUSH_MANY, as there is no way to tell which"
+                " token value should go into which PUSH_MANY."
+            )
+
+        if len(push_opcodes) > len(token_values):
+            raise ParseError(
+                "Not enough token values to match all of the PUSH_MANY and PUSH_SINGLE opcodes."
+            )
+
+        many_opcode = push_opcodes.pop(0)
+
+        # consume data into PUSH_SINGLE opcodes, working backwards
+        for opcode in reversed(push_opcodes):
+            self.push_single(opcode, token_values.pop())
+
+        # finally PUSH_MANY gets everything that's left
+        self.values[many_opcode.name] = token_values
+
+    def push_single(self, opcode, value):
+        if isinstance(opcode, PUSH_SINGLE):
+            self.values[opcode.name] = value
+        elif isinstance(opcode, PUSH_SUBSCRIPT):
+            self.values[opcode.name] = Script.from_source_with_template(value, opcode.template)
+        else:
+            raise ParseError("Not a push single or subscript: {}".format(opcode))
+
+
+class Template(object):
+
+    __slots__ = 'name', 'opcodes'
+
+    def __init__(self, name, opcodes):
+        self.name = name
+        self.opcodes = opcodes
+
+    def parse(self, tokens):
+        return Parser(self.opcodes, tokens).parse().values
+
+    def generate(self, values):
+        source = BCDataStream()
+        for opcode in self.opcodes:
+            if isinstance(opcode, PUSH_SINGLE):
+                data = values[opcode.name]
+                source.write_many(push_data(data))
+            elif isinstance(opcode, PUSH_SUBSCRIPT):
+                data = values[opcode.name]
+                source.write_many(push_data(data.source))
+            elif isinstance(opcode, PUSH_MANY):
+                for data in values[opcode.name]:
+                    source.write_many(push_data(data))
+            elif isinstance(opcode, SMALL_INTEGER):
+                data = values[opcode.name]
+                source.write_many(push_small_integer(data))
+            else:
+                source.write_uint8(opcode)
+        return source.get_bytes()
+
+
+class Script(object):
+
+    __slots__ = 'source', 'template', 'values'
+
+    templates = []
+
+    def __init__(self, source=None, template=None, values=None, template_hint=None):
+        self.source = source
+        self.template = template
+        self.values = values
+        if source:
+            self.parse(template_hint)
+        elif template and values:
+            self.generate()
+
+    @property
+    def tokens(self):
+        return tokenize(BCDataStream(self.source))
+
+    @classmethod
+    def from_source_with_template(cls, source, template):
+        return cls(source, template_hint=template)
+
+    def parse(self, template_hint=None):
+        tokens = self.tokens
+        for template in chain((template_hint,), self.templates):
+            if not template:
+                continue
+            try:
+                self.values = template.parse(tokens)
+                self.template = template
+                return
+            except ParseError:
+                continue
+        raise ValueError('No matching templates for source: {}'.format(hexlify(self.source)))
+
+    def generate(self):
+        self.source = self.template.generate(self.values)
+
+
+class BaseInputScript(Script):
+    """ Input / redeem script templates (aka scriptSig) """
+
+    __slots__ = ()
+
+    REDEEM_PUBKEY = Template('pubkey', (
+        PUSH_SINGLE('signature'),
+    ))
+    REDEEM_PUBKEY_HASH = Template('pubkey_hash', (
+        PUSH_SINGLE('signature'), PUSH_SINGLE('pubkey')
+    ))
+    REDEEM_SCRIPT = Template('script', (
+        SMALL_INTEGER('signatures_count'), PUSH_MANY('pubkeys'), SMALL_INTEGER('pubkeys_count'),
+        OP_CHECKMULTISIG
+    ))
+    REDEEM_SCRIPT_HASH = Template('script_hash', (
+        OP_0, PUSH_MANY('signatures'), PUSH_SUBSCRIPT('script', REDEEM_SCRIPT)
+    ))
+
+    templates = [
+        REDEEM_PUBKEY,
+        REDEEM_PUBKEY_HASH,
+        REDEEM_SCRIPT_HASH,
+        REDEEM_SCRIPT
+    ]
+
+    @classmethod
+    def redeem_pubkey_hash(cls, signature, pubkey):
+        return cls(template=cls.REDEEM_PUBKEY_HASH, values={
+            'signature': signature,
+            'pubkey': pubkey
+        })
+
+    @classmethod
+    def redeem_script_hash(cls, signatures, pubkeys):
+        return cls(template=cls.REDEEM_SCRIPT_HASH, values={
+            'signatures': signatures,
+            'script': cls.redeem_script(signatures, pubkeys)
+        })
+
+    @classmethod
+    def redeem_script(cls, signatures, pubkeys):
+        return cls(template=cls.REDEEM_SCRIPT, values={
+            'signatures_count': len(signatures),
+            'pubkeys': pubkeys,
+            'pubkeys_count': len(pubkeys)
+        })
+
+
+class BaseOutputScript(Script):
+
+    __slots__ = ()
+
+    # output / payment script templates (aka scriptPubKey)
+    PAY_PUBKEY_FULL = Template('pay_pubkey_full', (
+        PUSH_SINGLE('pubkey'), OP_CHECKSIG
+    ))
+    PAY_PUBKEY_HASH = Template('pay_pubkey_hash', (
+        OP_DUP, OP_HASH160, PUSH_SINGLE('pubkey_hash'), OP_EQUALVERIFY, OP_CHECKSIG
+    ))
+    PAY_SCRIPT_HASH = Template('pay_script_hash', (
+        OP_HASH160, PUSH_SINGLE('script_hash'), OP_EQUAL
+    ))
+    RETURN_DATA = Template('return_data', (
+        OP_RETURN, PUSH_SINGLE('data')
+    ))
+
+    templates = [
+        PAY_PUBKEY_FULL,
+        PAY_PUBKEY_HASH,
+        PAY_SCRIPT_HASH,
+        RETURN_DATA
+    ]
+
+    @classmethod
+    def pay_pubkey_hash(cls, pubkey_hash):
+        return cls(template=cls.PAY_PUBKEY_HASH, values={
+            'pubkey_hash': pubkey_hash
+        })
+
+    @classmethod
+    def pay_script_hash(cls, script_hash):
+        return cls(template=cls.PAY_SCRIPT_HASH, values={
+            'script_hash': script_hash
+        })
+
+    @property
+    def is_pay_pubkey(self):
+        return self.template.name.endswith('pay_pubkey_full')
+
+    @property
+    def is_pay_pubkey_hash(self):
+        return self.template.name.endswith('pay_pubkey_hash')
+
+    @property
+    def is_pay_script_hash(self):
+        return self.template.name.endswith('pay_script_hash')
+
+    @property
+    def is_return_data(self):
+        return self.template.name.endswith('return_data')

torba/basetransaction.py

@@ -0,0 +1,287 @@
+import six
+import logging
+from typing import List
+from collections import namedtuple
+
+from torba.basecoin import BaseCoin
+from torba.basescript import BaseInputScript, BaseOutputScript
+from torba.bcd_data_stream import BCDataStream
+from torba.hash import sha256
+from torba.account import Account
+from torba.util import ReadOnlyList
+
+
+log = logging.getLogger()
+
+
+NULL_HASH = b'\x00'*32
+
+
+class InputOutput(object):
+
+    @property
+    def size(self):
+        """ Size of this input / output in bytes. """
+        stream = BCDataStream()
+        self.serialize_to(stream)
+        return len(stream.get_bytes())
+
+    def serialize_to(self, stream):
+        raise NotImplemented
+
+
+class BaseInput(InputOutput):
+
+    script_class = None
+
+    NULL_SIGNATURE = b'\x00'*72
+    NULL_PUBLIC_KEY = b'\x00'*33
+
+    def __init__(self, output_or_txid_index, script, sequence=0xFFFFFFFF):
+        if isinstance(output_or_txid_index, BaseOutput):
+            self.output = output_or_txid_index  # type: BaseOutput
+            self.output_txid = self.output.transaction.hash
+            self.output_index = self.output.index
+        else:
+            self.output = None  # type: BaseOutput
+            self.output_txid, self.output_index = output_or_txid_index
+        self.sequence = sequence
+        self.is_coinbase = self.output_txid == NULL_HASH
+        self.coinbase = script if self.is_coinbase else None
+        self.script = script if not self.is_coinbase else None  # type: BaseInputScript
+
+    def link_output(self, output):
+        assert self.output is None
+        assert self.output_txid == output.transaction.hash
+        assert self.output_index == output.index
+        self.output = output
+
+    @classmethod
+    def spend(cls, output):
+        """ Create an input to spend the output."""
+        assert output.script.is_pay_pubkey_hash, 'Attempting to spend unsupported output.'
+        script = cls.script_class.redeem_pubkey_hash(cls.NULL_SIGNATURE, cls.NULL_PUBLIC_KEY)
+        return cls(output, script)
+
+    @property
+    def amount(self):
+        """ Amount this input adds to the transaction. """
+        if self.output is None:
+            raise ValueError('Cannot get input value without referenced output.')
+        return self.output.amount
+
+    @classmethod
+    def deserialize_from(cls, stream):
+        txid = stream.read(32)
+        index = stream.read_uint32()
+        script = stream.read_string()
+        sequence = stream.read_uint32()
+        return cls(
+            (txid, index),
+            cls.script_class(script) if not txid == NULL_HASH else script,
+            sequence
+        )
+
+    def serialize_to(self, stream, alternate_script=None):
+        stream.write(self.output_txid)
+        stream.write_uint32(self.output_index)
+        if alternate_script is not None:
+            stream.write_string(alternate_script)
+        else:
+            if self.is_coinbase:
+                stream.write_string(self.coinbase)
+            else:
+                stream.write_string(self.script.source)
+        stream.write_uint32(self.sequence)
+
+
+class BaseOutputAmountEstimator(object):
+
+    __slots__ = 'coin', 'output', 'fee', 'effective_amount'
+
+    def __init__(self, coin, txo):  # type: (BaseCoin, BaseOutput) -> None
+        self.coin = coin
+        self.output = txo
+        txi = coin.transaction_class.input_class.spend(txo)
+        self.fee = coin.get_input_output_fee(txi)
+        self.effective_amount = txo.amount - self.fee
+
+    def __lt__(self, other):
+        return self.effective_amount < other.effective_amount
+
+
+class BaseOutput(InputOutput):
+
+    script_class = None
+    estimator_class = BaseOutputAmountEstimator
+
+    def __init__(self, amount, script):
+        self.amount = amount  # type: int
+        self.script = script  # type: BaseOutputScript
+        self.transaction = None  # type: BaseTransaction
+        self.index = None  # type: int
+
+    def get_estimator(self, coin):
+        return self.estimator_class(coin, self)
+
+    @classmethod
+    def pay_pubkey_hash(cls, amount, pubkey_hash):
+        return cls(amount, cls.script_class.pay_pubkey_hash(pubkey_hash))
+
+    @classmethod
+    def deserialize_from(cls, stream):
+        return cls(
+            amount=stream.read_uint64(),
+            script=cls.script_class(stream.read_string())
+        )
+
+    def serialize_to(self, stream):
+        stream.write_uint64(self.amount)
+        stream.write_string(self.script.source)
+
+
+class BaseTransaction:
+
+    input_class = None
+    output_class = None
+
+    def __init__(self, raw=None, version=1, locktime=0, height=None, is_saved=False):
+        self._raw = raw
+        self._hash = None
+        self._id = None
+        self.version = version  # type: int
+        self.locktime = locktime  # type: int
+        self.height = height  # type: int
+        self._inputs = []  # type: List[BaseInput]
+        self._outputs = []  # type: List[BaseOutput]
+        self.is_saved = is_saved  # type: bool
+        if raw is not None:
+            self._deserialize()
+
+    @property
+    def id(self):
+        if self._id is None:
+            self._id = self.hash[::-1]
+        return self._id
+
+    @property
+    def hash(self):
+        if self._hash is None:
+            self._hash = sha256(sha256(self.raw))
+        return self._hash
+
+    @property
+    def raw(self):
+        if self._raw is None:
+            self._raw = self._serialize()
+        return self._raw
+
+    def _reset(self):
+        self._id = None
+        self._hash = None
+        self._raw = None
+
+    @property
+    def inputs(self):  # type: () -> ReadOnlyList[BaseInput]
+        return ReadOnlyList(self._inputs)
+
+    @property
+    def outputs(self):  # type: () -> ReadOnlyList[BaseOutput]
+        return ReadOnlyList(self._outputs)
+
+    def add_inputs(self, inputs):
+        self._inputs.extend(inputs)
+        self._reset()
+        return self
+
+    def add_outputs(self, outputs):
+        for txo in outputs:
+            txo.transaction = self
+            txo.index = len(self._outputs)
+            self._outputs.append(txo)
+        self._reset()
+        return self
+
+    @property
+    def fee(self):
+        """ Fee that will actually be paid."""
+        return self.input_sum - self.output_sum
+
+    @property
+    def size(self):
+        """ Size in bytes of the entire transaction. """
+        return len(self.raw)
+
+    @property
+    def base_size(self):
+        """ Size in bytes of transaction meta data and all outputs; without inputs. """
+        return len(self._serialize(with_inputs=False))
+
+    def _serialize(self, with_inputs=True):
+        stream = BCDataStream()
+        stream.write_uint32(self.version)
+        if with_inputs:
+            stream.write_compact_size(len(self._inputs))
+            for txin in self._inputs:
+                txin.serialize_to(stream)
+        stream.write_compact_size(len(self._outputs))
+        for txout in self._outputs:
+            txout.serialize_to(stream)
+        stream.write_uint32(self.locktime)
+        return stream.get_bytes()
+
+    def _serialize_for_signature(self, signing_input):
+        stream = BCDataStream()
+        stream.write_uint32(self.version)
+        stream.write_compact_size(len(self._inputs))
+        for i, txin in enumerate(self._inputs):
+            if signing_input == i:
+                txin.serialize_to(stream, txin.output.script.source)
+            else:
+                txin.serialize_to(stream, b'')
+        stream.write_compact_size(len(self._outputs))
+        for txout in self._outputs:
+            txout.serialize_to(stream)
+        stream.write_uint32(self.locktime)
+        stream.write_uint32(1)  # signature hash type: SIGHASH_ALL
+        return stream.get_bytes()
+
+    def _deserialize(self):
+        if self._raw is not None:
+            stream = BCDataStream(self._raw)
+            self.version = stream.read_uint32()
+            input_count = stream.read_compact_size()
+            self.add_inputs([
+                self.input_class.deserialize_from(stream) for _ in range(input_count)
+            ])
+            output_count = stream.read_compact_size()
+            self.add_outputs([
+                self.output_class.deserialize_from(stream) for _ in range(output_count)
+            ])
+            self.locktime = stream.read_uint32()
+
+    def sign(self, account):  # type: (Account) -> BaseTransaction
+        for i, txi in enumerate(self._inputs):
+            txo_script = txi.output.script
+            if txo_script.is_pay_pubkey_hash:
+                address = account.coin.hash160_to_address(txo_script.values['pubkey_hash'])
+                private_key = account.get_private_key_for_address(address)
+                tx = self._serialize_for_signature(i)
+                txi.script.values['signature'] = private_key.sign(tx)+six.int2byte(1)
+                txi.script.values['pubkey'] = private_key.public_key.pubkey_bytes
+                txi.script.generate()
+        self._reset()
+        return self
+
+    def sort(self):
+        # See https://github.com/kristovatlas/rfc/blob/master/bips/bip-li01.mediawiki
+        self._inputs.sort(key=lambda i: (i['prevout_hash'], i['prevout_n']))
+        self._outputs.sort(key=lambda o: (o[2], pay_script(o[0], o[1])))
+
+    @property
+    def input_sum(self):
+        return sum(i.amount for i in self._inputs)
+
+    @property
+    def output_sum(self):
+        return sum(o.amount for o in self._outputs)

torba/bcd_data_stream.py

@@ -0,0 +1,126 @@
+import struct
+from io import BytesIO
+
+
+class BCDataStream:
+
+    def __init__(self, data=None):
+        self.data = BytesIO(data)
+
+    @property
+    def is_at_beginning(self):
+        return self.data.tell() == 0
+
+    def reset(self):
+        self.data.seek(0)
+
+    def get_bytes(self):
+        return self.data.getvalue()
+
+    def read(self, size):
+        return self.data.read(size)
+
+    def write(self, data):
+        self.data.write(data)
+
+    def write_many(self, many):
+        self.data.writelines(many)
+
+    def read_string(self):
+        return self.read(self.read_compact_size())
+
+    def write_string(self, s):
+        self.write_compact_size(len(s))
+        self.write(s)
+
+    def read_compact_size(self):
+        size = self.read_uint8()
+        if size < 253:
+            return size
+        if size == 253:
+            return self.read_uint16()
+        elif size == 254:
+            return self.read_uint32()
+        elif size == 255:
+            return self.read_uint64()
+
+    def write_compact_size(self, size):
+        if size < 253:
+            self.write_uint8(size)
+        elif size <= 0xFFFF:
+            self.write_uint8(253)
+            self.write_uint16(size)
+        elif size <= 0xFFFFFFFF:
+            self.write_uint8(254)
+            self.write_uint32(size)
+        else:
+            self.write_uint8(255)
+            self.write_uint64(size)
+
+    def read_boolean(self):
+        return self.read_uint8() != 0
+
+    def write_boolean(self, val):
+        return self.write_uint8(1 if val else 0)
+
+    int8 = struct.Struct('b')
+    uint8 = struct.Struct('B')
+    int16 = struct.Struct('<h')
+    uint16 = struct.Struct('<H')
+    int32 = struct.Struct('<i')
+    uint32 = struct.Struct('<I')
+    int64 = struct.Struct('<q')
+    uint64 = struct.Struct('<Q')
+
+    def _read_struct(self, fmt):
+        value = self.read(fmt.size)
+        if len(value) > 0:
+            return fmt.unpack(value)[0]
+
+    def read_int8(self):
+        return self._read_struct(self.int8)
+
+    def read_uint8(self):
+        return self._read_struct(self.uint8)
+
+    def read_int16(self):
+        return self._read_struct(self.int16)
+
+    def read_uint16(self):
+        return self._read_struct(self.uint16)
+
+    def read_int32(self):
+        return self._read_struct(self.int32)
+
+    def read_uint32(self):
+        return self._read_struct(self.uint32)
+
+    def read_int64(self):
+        return self._read_struct(self.int64)
+
+    def read_uint64(self):
+        return self._read_struct(self.uint64)
+
+    def write_int8(self, val):
+        self.write(self.int8.pack(val))
+
+    def write_uint8(self, val):
+        self.write(self.uint8.pack(val))
+
+    def write_int16(self, val):
+        self.write(self.int16.pack(val))
+
+    def write_uint16(self, val):
+        self.write(self.uint16.pack(val))
+
+    def write_int32(self, val):
+        self.write(self.int32.pack(val))
+
+    def write_uint32(self, val):
+        self.write(self.uint32.pack(val))
+
+    def write_int64(self, val):
+        self.write(self.int64.pack(val))
+
+    def write_uint64(self, val):
+        self.write(self.uint64.pack(val))

torba/bip32.py

@@ -0,0 +1,329 @@
+# Copyright (c) 2017, Neil Booth
+# Copyright (c) 2018, LBRY Inc.
+#
+# All rights reserved.
+#
+# See the file "LICENCE" for information about the copyright
+# and warranty status of this software.
+
+""" Logic for BIP32 Hierarchical Key Derivation. """
+
+import struct
+import hashlib
+from six import int2byte, byte2int, indexbytes
+
+import ecdsa
+import ecdsa.ellipticcurve as EC
+import ecdsa.numbertheory as NT
+
+from torba.basecoin import BaseCoin
+from torba.hash import Base58, hmac_sha512, hash160, double_sha256
+from torba.util import cachedproperty, bytes_to_int, int_to_bytes
+
+
+class DerivationError(Exception):
+    """ Raised when an invalid derivation occurs. """
+
+
+class _KeyBase(object):
+    """ A BIP32 Key, public or private. """
+
+    CURVE = ecdsa.SECP256k1
+
+    def __init__(self, coin, chain_code, n, depth, parent):
+        if not isinstance(coin, BaseCoin):
+            raise TypeError('invalid coin')
+        if not isinstance(chain_code, (bytes, bytearray)):
+            raise TypeError('chain code must be raw bytes')
+        if len(chain_code) != 32:
+            raise ValueError('invalid chain code')
+        if not 0 <= n < 1 << 32:
+            raise ValueError('invalid child number')
+        if not 0 <= depth < 256:
+            raise ValueError('invalid depth')
+        if parent is not None:
+            if not isinstance(parent, type(self)):
+                raise TypeError('parent key has bad type')
+        self.coin = coin
+        self.chain_code = chain_code
+        self.n = n
+        self.depth = depth
+        self.parent = parent
+
+    def _hmac_sha512(self, msg):
+        """ Use SHA-512 to provide an HMAC, returned as a pair of 32-byte objects. """
+        hmac = hmac_sha512(self.chain_code, msg)
+        return hmac[:32], hmac[32:]
+
+    def _extended_key(self, ver_bytes, raw_serkey):
+        """ Return the 78-byte extended key given prefix version bytes and serialized key bytes. """
+        if not isinstance(ver_bytes, (bytes, bytearray)):
+            raise TypeError('ver_bytes must be raw bytes')
+        if len(ver_bytes) != 4:
+            raise ValueError('ver_bytes must have length 4')
+        if not isinstance(raw_serkey, (bytes, bytearray)):
+            raise TypeError('raw_serkey must be raw bytes')
+        if len(raw_serkey) != 33:
+            raise ValueError('raw_serkey must have length 33')
+
+        return (ver_bytes + int2byte(self.depth)
+                + self.parent_fingerprint() + struct.pack('>I', self.n)
+                + self.chain_code + raw_serkey)
+
+    def fingerprint(self):
+        """ Return the key's fingerprint as 4 bytes. """
+        return self.identifier()[:4]
+
+    def parent_fingerprint(self):
+        """ Return the parent key's fingerprint as 4 bytes. """
+        return self.parent.fingerprint() if self.parent else int2byte(0)*4
+
+    def extended_key_string(self):
+        """ Return an extended key as a base58 string. """
+        return Base58.encode_check(self.extended_key())
+
+
+class PubKey(_KeyBase):
+    """ A BIP32 public key. """
+
+    def __init__(self, coin, pubkey, chain_code, n, depth, parent=None):
+        super(PubKey, self).__init__(coin, chain_code, n, depth, parent)
+        if isinstance(pubkey, ecdsa.VerifyingKey):
+            self.verifying_key = pubkey
+        else:
+            self.verifying_key = self._verifying_key_from_pubkey(pubkey)
+
+    @classmethod
+    def _verifying_key_from_pubkey(cls, pubkey):
+        """ Converts a 33-byte compressed pubkey into an ecdsa.VerifyingKey object. """
+        if not isinstance(pubkey, (bytes, bytearray)):
+            raise TypeError('pubkey must be raw bytes')
+        if len(pubkey) != 33:
+            raise ValueError('pubkey must be 33 bytes')
+        if byte2int(pubkey[0]) not in (2, 3):
+            raise ValueError('invalid pubkey prefix byte')
+        curve = cls.CURVE.curve
+
+        is_odd = byte2int(pubkey[0]) == 3
+        x = bytes_to_int(pubkey[1:])
+
+        # p is the finite field order
+        a, b, p = curve.a(), curve.b(), curve.p()
+        y2 = pow(x, 3, p) + b
+        assert a == 0  # Otherwise y2 += a * pow(x, 2, p)
+        y = NT.square_root_mod_prime(y2 % p, p)
+        if bool(y & 1) != is_odd:
+            y = p - y
+        point = EC.Point(curve, x, y)
+
+        return ecdsa.VerifyingKey.from_public_point(point, curve=cls.CURVE)
+
+    @cachedproperty
+    def pubkey_bytes(self):
+        """ Return the compressed public key as 33 bytes. """
+        point = self.verifying_key.pubkey.point
+        prefix = int2byte(2 + (point.y() & 1))
+        padded_bytes = _exponent_to_bytes(point.x())
+        return prefix + padded_bytes
+
+    @cachedproperty
+    def address(self):
+        """ The public key as a P2PKH address. """
+        return self.coin.public_key_to_address(self.pubkey_bytes)
+
+    def ec_point(self):
+        return self.verifying_key.pubkey.point
+
+    def child(self, n):
+        """ Return the derived child extended pubkey at index N. """
+        if not 0 <= n < (1 << 31):
+            raise ValueError('invalid BIP32 public key child number')
+
+        msg = self.pubkey_bytes + struct.pack('>I', n)
+        L, R = self._hmac_sha512(msg)
+
+        curve = self.CURVE
+        L = bytes_to_int(L)
+        if L >= curve.order:
+            raise DerivationError
+
+        point = curve.generator * L + self.ec_point()
+        if point == EC.INFINITY:
+            raise DerivationError
+
+        verkey = ecdsa.VerifyingKey.from_public_point(point, curve=curve)
+
+        return PubKey(self.coin, verkey, R, n, self.depth + 1, self)
+
+    def identifier(self):
+        """ Return the key's identifier as 20 bytes. """
+        return hash160(self.pubkey_bytes)
+
+    def extended_key(self):
+        """ Return a raw extended public key. """
+        return self._extended_key(
+            self.coin.extended_public_key_prefix,
+            self.pubkey_bytes
+        )
+
+
+class LowSValueSigningKey(ecdsa.SigningKey):
+    """
+    Enforce low S values in signatures
+    BIP-0062: https://github.com/bitcoin/bips/blob/master/bip-0062.mediawiki#low-s-values-in-signatures
+    """
+
+    def sign_number(self, number, entropy=None, k=None):
+        order = self.privkey.order
+        r, s = ecdsa.SigningKey.sign_number(self, number, entropy, k)
+        if s > order / 2:
+            s = order - s
+        return r, s
+
+
+class PrivateKey(_KeyBase):
+    """A BIP32 private key."""
+
+    HARDENED = 1 << 31
+
+    def __init__(self, coin, privkey, chain_code, n, depth, parent=None):
+        super(PrivateKey, self).__init__(coin, chain_code, n, depth, parent)
+        if isinstance(privkey, ecdsa.SigningKey):
+            self.signing_key = privkey
+        else:
+            self.signing_key = self._signing_key_from_privkey(privkey)
+
+    @classmethod
+    def _signing_key_from_privkey(cls, private_key):
+        """ Converts a 32-byte private key into an ecdsa.SigningKey object. """
+        exponent = cls._private_key_secret_exponent(private_key)
+        return LowSValueSigningKey.from_secret_exponent(exponent, curve=cls.CURVE)
+
+    @classmethod
+    def _private_key_secret_exponent(cls, private_key):
+        """ Return the private key as a secret exponent if it is a valid private key. """
+        if not isinstance(private_key, (bytes, bytearray)):
+            raise TypeError('private key must be raw bytes')
+        if len(private_key) != 32:
+            raise ValueError('private key must be 32 bytes')
+        exponent = bytes_to_int(private_key)
+        if not 1 <= exponent < cls.CURVE.order:
+            raise ValueError('private key represents an invalid exponent')
+        return exponent
+
+    @classmethod
+    def from_seed(cls, coin, seed):
+        # This hard-coded message string seems to be coin-independent...
+        hmac = hmac_sha512(b'Bitcoin seed', seed)
+        privkey, chain_code = hmac[:32], hmac[32:]
+        return cls(coin, privkey, chain_code, 0, 0)
+
+    @cachedproperty
+    def private_key_bytes(self):
+        """ Return the serialized private key (no leading zero byte). """
+        return _exponent_to_bytes(self.secret_exponent())
+
+    @cachedproperty
+    def public_key(self):
+        """ Return the corresponding extended public key. """
+        verifying_key = self.signing_key.get_verifying_key()
+        parent_pubkey = self.parent.public_key if self.parent else None
+        return PubKey(self.coin, verifying_key, self.chain_code, self.n, self.depth,
+                      parent_pubkey)
+
+    def ec_point(self):
+        return self.public_key.ec_point()
+
+    def secret_exponent(self):
+        """ Return the private key as a secret exponent. """
+        return self.signing_key.privkey.secret_multiplier
+
+    def wif(self):
+        """ Return the private key encoded in Wallet Import Format. """
+        return self.coin.private_key_to_wif(self.private_key_bytes)
+
+    def address(self):
+        """ The public key as a P2PKH address. """
+        return self.public_key.address
+
+    def child(self, n):
+        """ Return the derived child extended private key at index N."""
+        if not 0 <= n < (1 << 32):
+            raise ValueError('invalid BIP32 private key child number')
+
+        if n >= self.HARDENED:
+            serkey = b'\0' + self.private_key_bytes
+        else:
+            serkey = self.public_key.pubkey_bytes
+
+        msg = serkey + struct.pack('>I', n)
+        L, R = self._hmac_sha512(msg)
+
+        curve = self.CURVE
+        L = bytes_to_int(L)
+        exponent = (L + bytes_to_int(self.private_key_bytes)) % curve.order
+        if exponent == 0 or L >= curve.order:
+            raise DerivationError
+
+        privkey = _exponent_to_bytes(exponent)
+
+        return PrivateKey(self.coin, privkey, R, n, self.depth + 1, self)
+
+    def sign(self, data):
+        """ Produce a signature for piece of data by double hashing it and signing the hash. """
+        key = self.signing_key
+        digest = double_sha256(data)
+        return key.sign_digest_deterministic(digest, hashlib.sha256, ecdsa.util.sigencode_der)
+
+    def identifier(self):
+        """Return the key's identifier as 20 bytes."""
+        return self.public_key.identifier()
+
+    def extended_key(self):
+        """Return a raw extended private key."""
+        return self._extended_key(
+            self.coin.extended_private_key_prefix,
+            b'\0' + self.private_key_bytes
+        )
+
+
+def _exponent_to_bytes(exponent):
+    """Convert an exponent to 32 big-endian bytes"""
+    return (int2byte(0)*32 + int_to_bytes(exponent))[-32:]
+
+
+def _from_extended_key(coin, ekey):
+    """Return a PubKey or PrivateKey from an extended key raw bytes."""
+    if not isinstance(ekey, (bytes, bytearray)):
+        raise TypeError('extended key must be raw bytes')
+    if len(ekey) != 78:
+        raise ValueError('extended key must have length 78')
+
+    depth = indexbytes(ekey, 4)
+    fingerprint = ekey[5:9]   # Not used
+    n, = struct.unpack('>I', ekey[9:13])
+    chain_code = ekey[13:45]
+
+    if ekey[:4] == coin.extended_public_key_prefix:
+        pubkey = ekey[45:]
+        key = PubKey(coin, pubkey, chain_code, n, depth)
+    elif ekey[:4] == coin.extended_private_key_prefix:
+        if indexbytes(ekey, 45) != 0:
+            raise ValueError('invalid extended private key prefix byte')
+        privkey = ekey[46:]
+        key = PrivateKey(coin, privkey, chain_code, n, depth)
+    else:
+        raise ValueError('version bytes unrecognised')
+
+    return key
+
+
+def from_extended_key_string(coin, ekey_str):
+    """Given an extended key string, such as
+
+    xpub6BsnM1W2Y7qLMiuhi7f7dbAwQZ5Cz5gYJCRzTNainXzQXYjFwtuQXHd
+    3qfi3t3KJtHxshXezfjft93w4UE7BGMtKwhqEHae3ZA7d823DVrL
+
+    return a PubKey or PrivateKey.
+    """
+    return _from_extended_key(coin, Base58.decode_check(ekey_str))

torba/coin/__init__.py

@@ -0,0 +1 @@
+__path__ = __import__('pkgutil').extend_path(__path__, __name__)

torba/coin/btc.py

@@ -0,0 +1,43 @@
+from six import int2byte
+from binascii import unhexlify
+from torba.baseledger import BaseLedger
+from torba.basenetwork import BaseNetwork
+from torba.basescript import BaseInputScript, BaseOutputScript
+from torba.basetransaction import BaseTransaction, BaseInput, BaseOutput
+from torba.basecoin import BaseCoin
+
+
+class Ledger(BaseLedger):
+    network_class = BaseNetwork
+
+
+class Input(BaseInput):
+    script_class = BaseInputScript
+
+
+class Output(BaseOutput):
+    script_class = BaseOutputScript
+
+
+class Transaction(BaseTransaction):
+    input_class = Input
+    output_class = Output
+
+
+class BTC(BaseCoin):
+    name = 'Bitcoin'
+    symbol = 'BTC'
+    network = 'mainnet'
+
+    ledger_class = Ledger
+    transaction_class = Transaction
+
+    pubkey_address_prefix = int2byte(0x00)
+    script_address_prefix = int2byte(0x05)
+    extended_public_key_prefix = unhexlify('0488b21e')
+    extended_private_key_prefix = unhexlify('0488ade4')
+
+    default_fee_per_byte = 50
+
+    def __init__(self, ledger, fee_per_byte=default_fee_per_byte):
+        super(BTC, self).__init__(ledger, fee_per_byte)

torba/coinselection.py

@@ -0,0 +1,95 @@
+import six
+from random import Random
+from typing import List
+
+from torba.basetransaction import BaseOutputAmountEstimator
+
+MAXIMUM_TRIES = 100000
+
+
+class CoinSelector:
+
+    def __init__(self, txos, target, cost_of_change, seed=None):
+        # type: (List[BaseOutputAmountEstimator], int, int, str) -> None
+        self.txos = txos
+        self.target = target
+        self.cost_of_change = cost_of_change
+        self.exact_match = False
+        self.tries = 0
+        self.available = sum(c.effective_amount for c in self.txos)
+        self.random = Random(seed)
+        if six.PY3 and seed is not None:
+            self.random.seed(seed, version=1)
+
+    def select(self):
+        if not self.txos:
+            return
+        if self.target > self.available:
+            return
+        return self.branch_and_bound() or self.single_random_draw()
+
+    def branch_and_bound(self):
+        # see bitcoin implementation for more info:
+        # https://github.com/bitcoin/bitcoin/blob/master/src/wallet/coinselection.cpp
+
+        self.txos.sort(reverse=True)
+
+        current_value = 0
+        current_available_value = self.available
+        current_selection = []
+        best_waste = self.cost_of_change
+        best_selection = []
+
+        while self.tries < MAXIMUM_TRIES:
+            self.tries += 1
+
+            backtrack = False
+            if current_value + current_available_value < self.target or \
+               current_value > self.target + self.cost_of_change:
+                backtrack = True
+            elif current_value >= self.target:
+                new_waste = current_value - self.target
+                if new_waste <= best_waste:
+                    best_waste = new_waste
+                    best_selection = current_selection[:]
+                backtrack = True
+
+            if backtrack:
+                while current_selection and not current_selection[-1]:
+                    current_selection.pop()
+                    current_available_value += self.txos[len(current_selection)].effective_amount
+
+                if not current_selection:
+                    break
+
+                current_selection[-1] = False
+                utxo = self.txos[len(current_selection) - 1]
+                current_value -= utxo.effective_amount
+
+            else:
+                utxo = self.txos[len(current_selection)]
+                current_available_value -= utxo.effective_amount
+                previous_utxo = self.txos[len(current_selection) - 1] if current_selection else None
+                if current_selection and not current_selection[-1] and \
+                   utxo.effective_amount == previous_utxo.effective_amount and \
+                   utxo.fee == previous_utxo.fee:
+                    current_selection.append(False)
+                else:
+                    current_selection.append(True)
+                    current_value += utxo.effective_amount
+
+        if best_selection:
+            self.exact_match = True
+            return [
+                self.txos[i] for i, include in enumerate(best_selection) if include
+            ]
+
+    def single_random_draw(self):
+        self.random.shuffle(self.txos, self.random.random)
+        selection = []
+        amount = 0
+        for coin in self.txos:
+            selection.append(coin)
+            amount += coin.effective_amount
+            if amount >= self.target+self.cost_of_change:
+                return selection

torba/constants.py

@@ -0,0 +1,3 @@
+
+CENT = 1000000
+COIN = 100*CENT

torba/hash.py

@@ -0,0 +1,180 @@
+# Copyright (c) 2016-2017, Neil Booth
+# Copyright (c) 2018, LBRY Inc.
+#
+# All rights reserved.
+#
+# See the file "LICENCE" for information about the copyright
+# and warranty status of this software.
+
+""" Cryptography hash functions and related classes. """
+
+import os
+import six
+import base64
+import hashlib
+import hmac
+from binascii import hexlify, unhexlify
+from cryptography.hazmat.primitives.ciphers import Cipher, modes
+from cryptography.hazmat.primitives.ciphers.algorithms import AES
+from cryptography.hazmat.primitives.padding import PKCS7
+from cryptography.hazmat.backends import default_backend
+
+from torba.util import bytes_to_int, int_to_bytes
+
+_sha256 = hashlib.sha256
+_sha512 = hashlib.sha512
+_new_hash = hashlib.new
+_new_hmac = hmac.new
+
+
+def sha256(x):
+    """ Simple wrapper of hashlib sha256. """
+    return _sha256(x).digest()
+
+
+def sha512(x):
+    """ Simple wrapper of hashlib sha512. """
+    return _sha512(x).digest()
+
+
+def ripemd160(x):
+    """ Simple wrapper of hashlib ripemd160. """
+    h = _new_hash('ripemd160')
+    h.update(x)
+    return h.digest()
+
+
+def pow_hash(x):
+    r = sha512(double_sha256(x))
+    r1 = ripemd160(r[:len(r) // 2])
+    r2 = ripemd160(r[len(r) // 2:])
+    r3 = double_sha256(r1 + r2)
+    return r3
+
+
+def double_sha256(x):
+    """ SHA-256 of SHA-256, as used extensively in bitcoin. """
+    return sha256(sha256(x))
+
+
+def hmac_sha512(key, msg):
+    """ Use SHA-512 to provide an HMAC. """
+    return _new_hmac(key, msg, _sha512).digest()
+
+
+def hash160(x):
+    """ RIPEMD-160 of SHA-256.
+        Used to make bitcoin addresses from pubkeys. """
+    return ripemd160(sha256(x))
+
+
+def hash_to_hex_str(x):
+    """ Convert a big-endian binary hash to displayed hex string.
+        Display form of a binary hash is reversed and converted to hex. """
+    return hexlify(reversed(x))
+
+
+def hex_str_to_hash(x):
+    """ Convert a displayed hex string to a binary hash. """
+    return reversed(unhexlify(x))
+
+
+def aes_encrypt(secret, value):
+    key = double_sha256(secret)
+    init_vector = os.urandom(16)
+    encryptor = Cipher(AES(key), modes.CBC(init_vector), default_backend()).encryptor()
+    padder = PKCS7(AES.block_size).padder()
+    padded_data = padder.update(value) + padder.finalize()
+    encrypted_data2 = encryptor.update(padded_data) + encryptor.finalize()
+    return base64.b64encode(encrypted_data2)
+
+
+def aes_decrypt(secret, value):
+    data = base64.b64decode(value)
+    key = double_sha256(secret)
+    init_vector, data = data[:16], data[16:]
+    decryptor = Cipher(AES(key), modes.CBC(init_vector), default_backend()).decryptor()
+    unpadder = PKCS7(AES.block_size).unpadder()
+    result = unpadder.update(decryptor.update(data)) + unpadder.finalize()
+    return result
+
+
+class Base58Error(Exception):
+    """ Exception used for Base58 errors. """
+
+
+class Base58(object):
+    """ Class providing base 58 functionality. """
+
+    chars = u'123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
+    assert len(chars) == 58
+    char_map = {c: n for n, c in enumerate(chars)}
+
+    @classmethod
+    def char_value(cls, c):
+        val = cls.char_map.get(c)
+        if val is None:
+            raise Base58Error('invalid base 58 character "{}"'.format(c))
+        return val
+
+    @classmethod
+    def decode(cls, txt):
+        """ Decodes txt into a big-endian bytearray. """
+        if isinstance(txt, six.binary_type):
+            txt = txt.decode()
+
+        if not isinstance(txt, six.text_type):
+            raise TypeError('a string is required')
+
+        if not txt:
+            raise Base58Error('string cannot be empty')
+
+        value = 0
+        for c in txt:
+            value = value * 58 + cls.char_value(c)
+
+        result = int_to_bytes(value)
+
+        # Prepend leading zero bytes if necessary
+        count = 0
+        for c in txt:
+            if c != u'1':
+                break
+            count += 1
+        if count:
+            result = six.int2byte(0) * count + result
+
+        return result
+
+    @classmethod
+    def encode(cls, be_bytes):
+        """Converts a big-endian bytearray into a base58 string."""
+        value = bytes_to_int(be_bytes)
+
+        txt = u''
+        while value:
+            value, mod = divmod(value, 58)
+            txt += cls.chars[mod]
+
+        for byte in be_bytes:
+            if byte != 0:
+                break
+            txt += u'1'
+
+        return txt[::-1].encode()
+
+    @classmethod
+    def decode_check(cls, txt, hash_fn=double_sha256):
+        """ Decodes a Base58Check-encoded string to a payload. The version prefixes it. """
+        be_bytes = cls.decode(txt)
+        result, check = be_bytes[:-4], be_bytes[-4:]
+        if check != hash_fn(result)[:4]:
+            raise Base58Error('invalid base 58 checksum for {}'.format(txt))
+        return result
+
+    @classmethod
+    def encode_check(cls, payload, hash_fn=double_sha256):
+        """ Encodes a payload bytearray (which includes the version byte(s))
+            into a Base58Check string."""
+        be_bytes = payload + hash_fn(payload)[:4]
+        return cls.encode(be_bytes)

torba/manager.py

@@ -0,0 +1,83 @@
+import functools
+from typing import List, Dict, Type
+from twisted.internet import defer
+
+from torba.account import AccountsView
+from torba.basecoin import CoinRegistry
+from torba.baseledger import BaseLedger
+from torba.wallet import Wallet, WalletStorage
+
+
+class WalletManager:
+
+    def __init__(self, wallets=None, ledgers=None):
+        self.wallets = wallets or []  # type: List[Wallet]
+        self.ledgers = ledgers or {}  # type: Dict[Type[BaseLedger],BaseLedger]
+        self.running = False
+
+    @classmethod
+    def from_config(cls, config):
+        wallets = []
+        manager = cls(wallets)
+        for coin_id, ledger_config in config.get('ledgers', {}).items():
+            manager.get_or_create_ledger(coin_id, ledger_config)
+        for wallet_path in config.get('wallets', []):
+            wallet_storage = WalletStorage(wallet_path)
+            wallet = Wallet.from_storage(wallet_storage, manager)
+            wallets.append(wallet)
+        return manager
+
+    def get_or_create_ledger(self, coin_id, ledger_config=None):
+        coin_class = CoinRegistry.get_coin_class(coin_id)
+        ledger_class = coin_class.ledger_class
+        ledger = self.ledgers.get(ledger_class)
+        if ledger is None:
+            ledger = ledger_class(self.get_accounts_view(coin_class), ledger_config or {})
+            self.ledgers[ledger_class] = ledger
+        return ledger
+
+    @property
+    def default_wallet(self):
+        for wallet in self.wallets:
+            return wallet
+
+    @property
+    def default_account(self):
+        for wallet in self.wallets:
+            return wallet.default_account
+
+    def get_accounts(self, coin_class):
+        for wallet in self.wallets:
+            for account in wallet.accounts:
+                if account.coin.__class__ is coin_class:
+                    yield account
+
+    def get_accounts_view(self, coin_class):
+        return AccountsView(
+            functools.partial(self.get_accounts, coin_class)
+        )
+
+    def create_wallet(self, path, coin_class):
+        storage = WalletStorage(path)
+        wallet = Wallet.from_storage(storage, self)
+        self.wallets.append(wallet)
+        self.create_account(wallet, coin_class)
+        return wallet
+
+    def create_account(self, wallet, coin_class):
+        ledger = self.get_or_create_ledger(coin_class.get_id())
+        return wallet.generate_account(ledger)
+
+    @defer.inlineCallbacks
+    def start_ledgers(self):
+        self.running = True
+        yield defer.DeferredList([
+            l.start() for l in self.ledgers.values()
+        ])
+
+    @defer.inlineCallbacks
+    def stop_ledgers(self):
+        yield defer.DeferredList([
+            l.stop() for l in self.ledgers.values()
+        ])
+        self.running = False

torba/mnemonic.py

@@ -0,0 +1,163 @@
+# Copyright (C) 2014 Thomas Voegtlin
+# Copyright (C) 2018 LBRY Inc.
+
+import os
+import io
+import hmac
+import math
+import hashlib
+import unicodedata
+import string
+from binascii import hexlify
+
+import ecdsa
+import pbkdf2
+
+from torba.hash import hmac_sha512
+
+# The hash of the mnemonic seed must begin with this
+SEED_PREFIX = b'01'       # Standard wallet
+SEED_PREFIX_2FA = b'101'  # Two-factor authentication
+SEED_PREFIX_SW = b'100'   # Segwit wallet
+
+# http://www.asahi-net.or.jp/~ax2s-kmtn/ref/unicode/e_asia.html
+CJK_INTERVALS = [
+    (0x4E00, 0x9FFF, 'CJK Unified Ideographs'),
+    (0x3400, 0x4DBF, 'CJK Unified Ideographs Extension A'),
+    (0x20000, 0x2A6DF, 'CJK Unified Ideographs Extension B'),
+    (0x2A700, 0x2B73F, 'CJK Unified Ideographs Extension C'),
+    (0x2B740, 0x2B81F, 'CJK Unified Ideographs Extension D'),
+    (0xF900, 0xFAFF, 'CJK Compatibility Ideographs'),
+    (0x2F800, 0x2FA1D, 'CJK Compatibility Ideographs Supplement'),
+    (0x3190, 0x319F, 'Kanbun'),
+    (0x2E80, 0x2EFF, 'CJK Radicals Supplement'),
+    (0x2F00, 0x2FDF, 'CJK Radicals'),
+    (0x31C0, 0x31EF, 'CJK Strokes'),
+    (0x2FF0, 0x2FFF, 'Ideographic Description Characters'),
+    (0xE0100, 0xE01EF, 'Variation Selectors Supplement'),
+    (0x3100, 0x312F, 'Bopomofo'),
+    (0x31A0, 0x31BF, 'Bopomofo Extended'),
+    (0xFF00, 0xFFEF, 'Halfwidth and Fullwidth Forms'),
+    (0x3040, 0x309F, 'Hiragana'),
+    (0x30A0, 0x30FF, 'Katakana'),
+    (0x31F0, 0x31FF, 'Katakana Phonetic Extensions'),
+    (0x1B000, 0x1B0FF, 'Kana Supplement'),
+    (0xAC00, 0xD7AF, 'Hangul Syllables'),
+    (0x1100, 0x11FF, 'Hangul Jamo'),
+    (0xA960, 0xA97F, 'Hangul Jamo Extended A'),
+    (0xD7B0, 0xD7FF, 'Hangul Jamo Extended B'),
+    (0x3130, 0x318F, 'Hangul Compatibility Jamo'),
+    (0xA4D0, 0xA4FF, 'Lisu'),
+    (0x16F00, 0x16F9F, 'Miao'),
+    (0xA000, 0xA48F, 'Yi Syllables'),
+    (0xA490, 0xA4CF, 'Yi Radicals'),
+]
+
+
+def is_cjk(c):
+    n = ord(c)
+    for start, end, name in CJK_INTERVALS:
+        if start <= n <= end:
+            return True
+    return False
+
+
+def normalize_text(seed):
+    seed = unicodedata.normalize('NFKD', seed)
+    seed = seed.lower()
+    # remove accents
+    seed = u''.join([c for c in seed if not unicodedata.combining(c)])
+    # normalize whitespaces
+    seed = u' '.join(seed.split())
+    # remove whitespaces between CJK
+    seed = u''.join([
+        seed[i] for i in range(len(seed))
+        if not (seed[i] in string.whitespace and is_cjk(seed[i-1]) and is_cjk(seed[i+1]))
+    ])
+    return seed
+
+
+def load_words(filename):
+    path = os.path.join(os.path.dirname(__file__), 'words', filename)
+    with io.open(path, 'r', encoding='utf-8') as f:
+        s = f.read().strip()
+    s = unicodedata.normalize('NFKD', s)
+    lines = s.split('\n')
+    words = []
+    for line in lines:
+        line = line.split('#')[0]
+        line = line.strip(' \r')
+        assert ' ' not in line
+        if line:
+            words.append(line)
+    return words
+
+
+file_names = {
+    'en': 'english.txt',
+    'es': 'spanish.txt',
+    'ja': 'japanese.txt',
+    'pt': 'portuguese.txt',
+    'zh': 'chinese_simplified.txt'
+}
+
+
+class Mnemonic(object):
+    # Seed derivation no longer follows BIP39
+    # Mnemonic phrase uses a hash based checksum, instead of a words-dependent checksum
+
+    def __init__(self, lang='en'):
+        filename = file_names.get(lang, 'english.txt')
+        self.words = load_words(filename)
+
+    @classmethod
+    def mnemonic_to_seed(self, mnemonic, passphrase=u''):
+        PBKDF2_ROUNDS = 2048
+        mnemonic = normalize_text(mnemonic)
+        passphrase = normalize_text(passphrase)
+        return pbkdf2.PBKDF2(mnemonic, passphrase, iterations=PBKDF2_ROUNDS, macmodule=hmac, digestmodule=hashlib.sha512).read(64)
+
+    def mnemonic_encode(self, i):
+        n = len(self.words)
+        words = []
+        while i:
+            x = i%n
+            i = i//n
+            words.append(self.words[x])
+        return ' '.join(words)
+
+    def mnemonic_decode(self, seed):
+        n = len(self.words)
+        words = seed.split()
+        i = 0
+        while words:
+            w = words.pop()
+            k = self.words.index(w)
+            i = i*n + k
+        return i
+
+    def make_seed(self, prefix=SEED_PREFIX, num_bits=132):
+        # increase num_bits in order to obtain a uniform distribution for the last word
+        bpw = math.log(len(self.words), 2)
+        # rounding
+        n = int(math.ceil(num_bits/bpw) * bpw)
+        entropy = 1
+        while entropy < pow(2, n - bpw):
+            # try again if seed would not contain enough words
+            entropy = ecdsa.util.randrange(pow(2, n))
+        nonce = 0
+        while True:
+            nonce += 1
+            i = entropy + nonce
+            seed = self.mnemonic_encode(i)
+            if i != self.mnemonic_decode(seed):
+                raise Exception('Cannot extract same entropy from mnemonic!')
+            if is_new_seed(seed, prefix):
+                break
+        return seed
+
+
+def is_new_seed(seed, prefix):
+    seed = normalize_text(seed)
+    seed_hash = hexlify(hmac_sha512(b"seed version", seed.encode('utf8')))
+    return seed_hash.startswith(prefix)

torba/msqr.py

@@ -0,0 +1,96 @@
+# from http://eli.thegreenplace.net/2009/03/07/computing-modular-square-roots-in-python/
+
+
+def modular_sqrt(a, p):
+    """ Find a quadratic residue (mod p) of 'a'. p
+    must be an odd prime.
+
+    Solve the congruence of the form:
+    x^2 = a (mod p)
+    And returns x. Note that p - x is also a root.
+
+    0 is returned is no square root exists for
+    these a and p.
+
+    The Tonelli-Shanks algorithm is used (except
+    for some simple cases in which the solution
+    is known from an identity). This algorithm
+    runs in polynomial time (unless the
+    generalized Riemann hypothesis is false).
+    """
+    # Simple cases
+    #
+    if legendre_symbol(a, p) != 1:
+        return 0
+    elif a == 0:
+        return 0
+    elif p == 2:
+        return p
+    elif p % 4 == 3:
+        return pow(a, (p + 1) / 4, p)
+
+    # Partition p-1 to s * 2^e for an odd s (i.e.
+    # reduce all the powers of 2 from p-1)
+    #
+    s = p - 1
+    e = 0
+    while s % 2 == 0:
+        s /= 2
+        e += 1
+
+    # Find some 'n' with a legendre symbol n|p = -1.
+    # Shouldn't take long.
+    #
+    n = 2
+    while legendre_symbol(n, p) != -1:
+        n += 1
+
+    # Here be dragons!
+    # Read the paper "Square roots from 1; 24, 51,
+    # 10 to Dan Shanks" by Ezra Brown for more
+    # information
+    #
+
+    # x is a guess of the square root that gets better
+    # with each iteration.
+    # b is the "fudge factor" - by how much we're off
+    # with the guess. The invariant x^2 = ab (mod p)
+    # is maintained throughout the loop.
+    # g is used for successive powers of n to update
+    # both a and b
+    # r is the exponent - decreases with each update
+    #
+    x = pow(a, (s + 1) / 2, p)
+    b = pow(a, s, p)
+    g = pow(n, s, p)
+    r = e
+
+    while True:
+        t = b
+        m = 0
+        for m in xrange(r):
+            if t == 1:
+                break
+            t = pow(t, 2, p)
+
+        if m == 0:
+            return x
+
+        gs = pow(g, 2 ** (r - m - 1), p)
+        g = (gs * gs) % p
+        x = (x * gs) % p
+        b = (b * g) % p
+        r = m
+
+
+def legendre_symbol(a, p):
+    """ Compute the Legendre symbol a|p using
+    Euler's criterion. p is a prime, a is
+    relatively prime to p (if p divides
+    a, then a|p = 0)
+
+    Returns 1 if a has a square root modulo
+    p, -1 otherwise.
+    """
+    ls = pow(a, (p - 1) / 2, p)
+    return -1 if ls == p - 1 else ls

torba/stream.py

@@ -0,0 +1,144 @@
+from twisted.internet.defer import Deferred, DeferredLock, maybeDeferred, inlineCallbacks
+from twisted.python.failure import Failure
+
+
+def execute_serially(f):
+    _lock = DeferredLock()
+
+    @inlineCallbacks
+    def allow_only_one_at_a_time(*args, **kwargs):
+        yield _lock.acquire()
+        allow_only_one_at_a_time.is_running = True
+        try:
+            yield maybeDeferred(f, *args, **kwargs)
+        finally:
+            allow_only_one_at_a_time.is_running = False
+            _lock.release()
+
+    allow_only_one_at_a_time.is_running = False
+    return allow_only_one_at_a_time
+
+
+class BroadcastSubscription:
+
+    def __init__(self, controller, on_data, on_error, on_done):
+        self._controller = controller
+        self._previous = self._next = None
+        self._on_data = on_data
+        self._on_error = on_error
+        self._on_done = on_done
+        self.is_paused = False
+        self.is_canceled = False
+        self.is_closed = False
+
+    def pause(self):
+        self.is_paused = True
+
+    def resume(self):
+        self.is_paused = False
+
+    def cancel(self):
+        self._controller._cancel(self)
+        self.is_canceled = True
+
+    @property
+    def can_fire(self):
+        return not any((self.is_paused, self.is_canceled, self.is_closed))
+
+    def _add(self, data):
+        if self.can_fire and self._on_data is not None:
+            self._on_data(data)
+
+    def _add_error(self, error, traceback):
+        if self.can_fire and self._on_error is not None:
+            self._on_error(error, traceback)
+
+    def _close(self):
+        if self.can_fire and self._on_done is not None:
+            self._on_done()
+        self.is_closed = True
+
+
+class StreamController:
+
+    def __init__(self):
+        self.stream = Stream(self)
+        self._first_subscription = None
+        self._last_subscription = None
+
+    @property
+    def has_listener(self):
+        return self._first_subscription is not None
+
+    @property
+    def _iterate_subscriptions(self):
+        next = self._first_subscription
+        while next is not None:
+            subscription = next
+            next = next._next
+            yield subscription
+
+    def add(self, event):
+        for subscription in self._iterate_subscriptions:
+            subscription._add(event)
+
+    def add_error(self, error, traceback):
+        for subscription in self._iterate_subscriptions:
+            subscription._add_error(error, traceback)
+
+    def close(self):
+        for subscription in self._iterate_subscriptions:
+            subscription._close()
+
+    def _cancel(self, subscription):
+        previous = subscription._previous
+        next = subscription._next
+        if previous is None:
+            self._first_subscription = next
+        else:
+            previous._next = next
+        if next is None:
+            self._last_subscription = previous
+        else:
+            next._previous = previous
+        subscription._next = subscription._previous = subscription
+
+    def _listen(self, on_data, on_error, on_done):
+        subscription = BroadcastSubscription(self, on_data, on_error, on_done)
+        old_last = self._last_subscription
+        self._last_subscription = subscription
+        subscription._previous = old_last
+        subscription._next = None
+        if old_last is None:
+            self._first_subscription = subscription
+        else:
+            old_last._next = subscription
+        return subscription
+
+
+class Stream:
+
+    def __init__(self, controller):
+        self._controller = controller
+
+    def listen(self, on_data, on_error=None, on_done=None):
+        return self._controller._listen(on_data, on_error, on_done)
+
+    @property
+    def first(self):
+        deferred = Deferred()
+        subscription = self.listen(
+            lambda value: self._cancel_and_callback(subscription, deferred, value),
+            lambda error, traceback: self._cancel_and_error(subscription, deferred, error, traceback)
+        )
+        return deferred
+
+    @staticmethod
+    def _cancel_and_callback(subscription, deferred, value):
+        subscription.cancel()
+        deferred.callback(value)
+
+    @staticmethod
+    def _cancel_and_error(subscription, deferred, error, traceback):
+        subscription.cancel()
+        deferred.errback(Failure(error, exc_tb=traceback))

torba/util.py

@@ -0,0 +1,60 @@
+from binascii import unhexlify, hexlify
+from collections import Sequence
+
+
+class ReadOnlyList(Sequence):
+
+    def __init__(self, lst):
+        self.lst = lst
+
+    def __getitem__(self, key):
+        return self.lst[key]
+
+    def __len__(self):
+        return len(self.lst)
+
+
+def subclass_tuple(name, base):
+    return type(name, (base,), {'__slots__': ()})
+
+
+class cachedproperty(object):
+
+    def __init__(self, f):
+        self.f = f
+
+    def __get__(self, obj, type):
+        obj = obj or type
+        value = self.f(obj)
+        setattr(obj, self.f.__name__, value)
+        return value
+
+
+def bytes_to_int(be_bytes):
+    """ Interprets a big-endian sequence of bytes as an integer. """
+    return int(hexlify(be_bytes), 16)
+
+
+def int_to_bytes(value):
+    """ Converts an integer to a big-endian sequence of bytes. """
+    length = (value.bit_length() + 7) // 8
+    h = '%x' % value
+    return unhexlify(('0' * (len(h) % 2) + h).zfill(length * 2))
+
+
+def rev_hex(s):
+    return hexlify(unhexlify(s)[::-1])
+
+
+def int_to_hex(i, length=1):
+    s = hex(i)[2:].rstrip('L')
+    s = "0" * (2 * length - len(s)) + s
+    return rev_hex(s)
+
+
+def hex_to_int(s):
+    return int(b'0x' + hexlify(s[::-1]), 16)
+
+
+def hash_encode(x):
+    return hexlify(x[::-1])

torba/wallet.py

@@ -0,0 +1,164 @@
+import stat
+import json
+import os
+from typing import List, Dict
+
+from torba.account import Account
+from torba.basecoin import CoinRegistry, BaseCoin
+from torba.baseledger import BaseLedger
+
+
+def inflate_coin(manager, coin_id, coin_dict):
+    # type: ('WalletManager', str, Dict) -> BaseCoin
+    coin_class = CoinRegistry.get_coin_class(coin_id)
+    ledger = manager.get_or_create_ledger(coin_id)
+    return coin_class(ledger, **coin_dict)
+
+
+class Wallet:
+    """ The primary role of Wallet is to encapsulate a collection
+        of accounts (seed/private keys) and the spending rules / settings
+        for the coins attached to those accounts. Wallets are represented
+        by physical files on the filesystem.
+    """
+
+    def __init__(self, name='Wallet', coins=None, accounts=None, storage=None):
+        self.name = name
+        self.coins = coins or []  # type: List[BaseCoin]
+        self.accounts = accounts or []  # type: List[Account]
+        self.storage = storage or WalletStorage()
+
+    def get_or_create_coin(self, ledger, coin_dict=None):  # type: (BaseLedger, Dict) -> BaseCoin
+        for coin in self.coins:
+            if coin.__class__ is ledger.coin_class:
+                return coin
+        coin = ledger.coin_class(ledger, **(coin_dict or {}))
+        self.coins.append(coin)
+        return coin
+
+    def generate_account(self, ledger):  # type: (BaseLedger) -> Account
+        coin = self.get_or_create_coin(ledger)
+        account = Account.generate(coin, u'torba')
+        self.accounts.append(account)
+        return account
+
+    @classmethod
+    def from_storage(cls, storage, manager):  # type: (WalletStorage, 'WalletManager') -> Wallet
+        json_dict = storage.read()
+
+        coins = {}
+        for coin_id, coin_dict in json_dict.get('coins', {}).items():
+            coins[coin_id] = inflate_coin(manager, coin_id, coin_dict)
+
+        accounts = []
+        for account_dict in json_dict.get('accounts', []):
+            coin_id = account_dict['coin']
+            coin = coins.get(coin_id)
+            if coin is None:
+                coin = coins[coin_id] = inflate_coin(manager, coin_id, {})
+            account = Account.from_dict(coin, account_dict)
+            accounts.append(account)
+
+        return cls(
+            name=json_dict.get('name', 'Wallet'),
+            coins=list(coins.values()),
+            accounts=accounts,
+            storage=storage
+        )
+
+    def to_dict(self):
+        return {
+            'name': self.name,
+            'coins': {c.get_id(): c.to_dict() for c in self.coins},
+            'accounts': [a.to_dict() for a in self.accounts]
+        }
+
+    def save(self):
+        self.storage.write(self.to_dict())
+
+    @property
+    def default_account(self):
+        for account in self.accounts:
+            return account
+
+    def get_account_private_key_for_address(self, address):
+        for account in self.accounts:
+            private_key = account.get_private_key_for_address(address)
+            if private_key is not None:
+                return account, private_key
+
+
+class WalletStorage:
+
+    LATEST_VERSION = 2
+
+    DEFAULT = {
+        'version': LATEST_VERSION,
+        'name': 'Wallet',
+        'coins': {},
+        'accounts': []
+    }
+
+    def __init__(self, path=None, default=None):
+        self.path = path
+        self._default = default or self.DEFAULT.copy()
+
+    @property
+    def default(self):
+        return self._default.copy()
+
+    def read(self):
+        if self.path and os.path.exists(self.path):
+            with open(self.path, "r") as f:
+                json_data = f.read()
+                json_dict = json.loads(json_data)
+                if json_dict.get('version') == self.LATEST_VERSION and \
+                        set(json_dict) == set(self._default):
+                    return json_dict
+                else:
+                    return self.upgrade(json_dict)
+        else:
+            return self.default
+
+    @classmethod
+    def upgrade(cls, json_dict):
+        json_dict = json_dict.copy()
+
+        def _rename_property(old, new):
+            if old in json_dict:
+                json_dict[new] = json_dict[old]
+                del json_dict[old]
+
+        version = json_dict.pop('version', -1)
+
+        if version == 1:  # upgrade from version 1 to version 2
+            _rename_property('addr_history', 'history')
+            _rename_property('use_encryption', 'encrypted')
+            _rename_property('gap_limit', 'gap_limit_for_receiving')
+
+        upgraded = cls.DEFAULT
+        upgraded.update(json_dict)
+        return json_dict
+
+    def write(self, json_dict):
+
+        json_data = json.dumps(json_dict, indent=4, sort_keys=True)
+        if self.path is None:
+            return json_data
+
+        temp_path = "%s.tmp.%s" % (self.path, os.getpid())
+        with open(temp_path, "w") as f:
+            f.write(json_data)
+            f.flush()
+            os.fsync(f.fileno())
+
+        if os.path.exists(self.path):
+            mode = os.stat(self.path).st_mode
+        else:
+            mode = stat.S_IREAD | stat.S_IWRITE
+        try:
+            os.rename(temp_path, self.path)
+        except:
+            os.remove(self.path)
+            os.rename(temp_path, self.path)
+        os.chmod(self.path, mode)

tox.ini

@@ -0,0 +1,12 @@
+[tox]
+envlist = py{27,36}
+
+[testenv]
+deps =
+  coverage
+  mock
+
+changedir = {toxinidir}/tests
+
+commands =
+  coverage run -p --source={envsitepackagesdir}/torba -m unittest discover -v