About this repo
---------------

Barebones Python 3.6+ implementation (no dependencies/standard lib only) of some common cryptographic functions for educational purposes.
Feel free to fork the repo and play around with it. Performance is ..abysmal but otherwise it works fine. Please do not
use this for anything serious because I am not a security expert.


Install
-------

.. code-block:: bash

    $ pip install git+https://github.com/mcdallas/cryptotools.git@master#egg=cryptotools


Examples
--------

HD Wallets

.. code-block:: Python

    from cryptotools.BTC import Xprv

    >>> m = Xprv.from_mnemonic('impulse prize erode winner pupil fun off addict ...')
    >>> m.encode()
    'xprv9s21ZrQH143K38bNJiHY54kkjio8o6aw3bRjCbzi8KgRxNy98avUribz1wk85ToSUV2VwVuc73NJWc2YGwpMtqz7bBFUh9Q77RtJeuh2zvy'

    >>> m/44/0/0/0
    Xprv(path=m/44/0/0/0, key=L1WKXyMwKnp8wPwAtjwiKWunACY5RSUXAzmS6jDRRHcHnDbeRiKu)

    >>> m/0./123/5.  # Use floats for hardened path, alternative is // e.g m//0/123//5
    Xprv(path=m/0h/123/5h, key=L3qskbdzgNu4kwjx2QU63q59khpEHVaSbqd2Pc268Jngiha6mbfQ)

    >>> M = m.to_xpub()

    >>> (m/123/456).to_xpub() == M/123/456
    True

    >>> (m/44./0./0./0/0).address('P2PKH')  # bip44
    '1BTYXdyrBh1yRCDpqyDhoQG896bnzqtaPz'

    >>> (m/84./0./0./0/0).address('P2WPKH')  # bip84
    'bc1qjnx8cq32z2t72tsmuwql3wz22lywlpcm3w52lk'


BIP39 checksum

Say you lost the first of your 12 mnemonic words and you want to filter out the possible mnemonics from 2048 to 128 by veryfing the checksum

.. code-block:: Python

    from cryptotools.BTC.HD import check, WORDS

    phrase = "{x} decrease enjoy credit fold prepare school midnight flower wrong false already"

    for word in WORDS:
        mnemonic = phrase.format(x=word)
        if check(mnemonic):
            print(mnemonic)


Sign/Verify message:

.. code-block:: Python

    import secrets
    from cryptotools.ECDSA.secp256k1 import generate_keypair, Message

    private, public = generate_keypair()

    >>> message = Message(secrets.token_bytes(32))
    >>> sig1 = message.sign(private)          # ECDSA
    >>> sig2 = message.sign_schnorr(private)  # Schnorr
    >>> message.verify(sig1, public)
    True
    >>> message.verify(sig2, public)
    True


Verify a transaction:

.. code-block:: Python

    from cryptotools.BTC import Transaction

    tx = Transaction.get('454e575aa1ed4427985a9732d753b37dc711675eb7c977637b1eea7f600ed214')

    >>> tx
    Transaction(inputs=1, outputs=2)

    >>> tx.outputs
    [Output(type=P2SH, value=0.0266 BTC),
     Output(type=P2WSH, value=0.00468 BTC)]

    >>> tx.verify()  # this runs the bitcoin script
    True


Create a transaction and submit it automatically

.. code-block:: Python

    import os
    os.environ['CRYPTOTOOLS_NETWORK'] = 'test'  # sets network to testnet (before library import)

    from cryptotools.BTC import PrivateKey, send

    key = PrivateKey.from_hex('mysupersecretkey')

    >>> send(source='n4SbPWR6EmQMsWaQVYYFXiJgjweGKE4XnQ', to={'n2NGrooSecJaiD6ssp4YqFoj9eZ7GrCJ66': 0.46}, fee=0.01, private=key)
    '907b92969cb3a16ddb45591bf2530f177b7f10cef4e62c331596a84f66c3b8c3'  # txid


Create and broadcast manually

.. code-block:: Python

    import os
    os.environ['CRYPTOTOOLS_NETWORK'] = 'test'

    from cryptotools.BTC import PrivateKey, Address

    private = PrivateKey.from_hex('mysupersecretkey')
    address = Address('n2NGrooSecJaiD6ssp4YqFoj9eZ7GrCJ66')

    >>> address.balance()
    0.55

    >>> send_to = {'n4SbPWR6EmQMsWaQVYYFXiJgjweGKE4XnQ': 0.1, 'n2NGrooSecJaiD6ssp4YqFoj9eZ7GrCJ66': 0.4}
    >>> tx = address.send(to=send_to, fee=0.05, private=private)

    >>> tx
    Transaction(inputs=1, outputs=2)

    >>> tx.inputs[0].is_signed()
    True

    >>> tx.verify()  # Make sure transaction is valid before broadcasting
    True

    >>> tx.broadcast()
    'Transaction Submitted'

Create keys/addresses (including segwit)

.. code-block:: Python

    from cryptotools.BTC import generate_keypair, push, script_to_address, OP
    private, public = generate_keypair()

    >>> private.hex()
    'de4f177274d29f88a5805333e10525f5dd41634455dfadc8849b977802481ccd'

    >>> private.wif(compressed=False)
    '5KWCAYLo35uZ9ibPTzTUDXESTE6ne8p1eXviYMHwaoS4tpvYCAp'

    >>> public.hex()
    '047e30fd478b44869850352daef8f5f7a7b5233044018d465431afdc0b436c973e8df1244189d25ae73d90c90cc0f998eb9784adecaecc46e8c536d7d6845fa26e'

    >>> public.to_address('P2PKH')
    '19dFXDxiD4KrUTNFfcgeekFpQmUC553GzW'

    # Simple <key> <OP_CHECKSIG> script
    >>> script = push(public.encode(compressed=True)) + OP.CHECKSIG.byte
    >>> script_to_address(script, 'P2WSH')
    'bc1q8yh8l8ft3220q328hlapqhflpzy6xvkq6u36mctk8gq5pyxm3rwqv5h5dg'

    # nested P2WSH into P2SH -- use with caution
    >>> script_to_address(script, 'P2WSH-P2SH')
    '34eBzenHJEdk5PK9ojuuBZvCRtNhvvysYZ'

.. code-block:: Python

    from cryptotools.ECDSA.secp256k1 import CURVE, PrivateKey
    private = PrivateKey.random()

    >>> private.int()
    8034465994996476238286561766373949549982328752707977290709076444881813294372

    >>> public = private.to_public()
    >>> public
    PublicKey(102868560361119050321154887315228169307787313299675114268359376451780341556078, 83001804479408277471207716276761041184203185393579361784723900699449806360826)

    >>> public.point in CURVE
    True

    >>> public.to_address('P2WPKH')
    'bc1qh2egksgfejqpktc3kkdtuqqrukrpzzp9lr0phn'


Configuration
--------

By default the library communicates with the bitcoin network (for fetching transactions) via a block 
explorer but as an alternative you can use a bitcoin node via it's RPC interface. Just set the following 
enviromental variables

.. code-block:: bash

    CRYPTOTOOLS_BACKEND=rpc
    CRYPTOTOOLS_RPC_HOST=localhost
    CRYPTOTOOLS_RPC_PORT=8332

and optionally

.. code-block:: bash

    CRYPTOTOOLS_RPC_USER=myuser
    CRYPTOTOOLS_RPC_PW=mypassword


to switch the network to Testnet set

.. code-block:: bash

    CRYPTOTOOLS_NETWORK=test


to run tests

.. code-block:: bash

   $ python -m unittest

from the project directory