Flask-bitjws 0.1.1.5
A Flask extension for bitjws authentication.
License: MIT

flask-bitjws |PyPi version| |Build Status| |Coverage| |Gitter|
==============================================================

Flask extension for `bitjws <https://github.com/g-p-g/bitjws>`__
authentication.

Install
-------

By default it's expected that
`secp256k1 <https://github.com/bitcoin/secp256k1>`__ is available, so
install it before proceeding; make sure to run
``./configure --enable-module-recovery``. If you're using some other
library that provides the functionality necessary for this, check the
**Using a custom library** section of the bitjws README.

Flask-bitjws can be installed by running:

``pip install flask-bitjws``

Building secp256k1
''''''''''''''''''

In case you need to install the ``secp256k1`` C library, the following
sequence of commands is recommended. If you already have ``secp256k1``,
make sure it was compiled from the expected git commit or it might fail
to work due to API incompatibilities.

::

    git clone git://github.com/bitcoin/secp256k1.git libsecp256k1
    cd libsecp256k1
    git checkout d7eb1ae96dfe9d497a26b3e7ff8b6f58e61e400a
    ./autogen.sh
    ./configure --enable-module-recovery
    make
    sudo make install

Initialization
--------------

Initialize a flask\_bitjws Application
''''''''''''''''''''''''''''''''''''''

The flask-bitjws package provides a Flask Application wrapper. To enable
bitjws authentication, initialize FlaskBitjws with your flask app as the
first argument.

.. code:: Python

    from flask import Flask
    from flask_bitjws import FlaskBitjws

    app = Flask(__name__)
    FlaskBitjws(app)

Customizing LoginManager
''''''''''''''''''''''''

| Flask-bitjws uses
`flask-login <https://github.com/maxcountryman/flask-login>`__ to manage
user login and authentication. By default,
| the FlaskBitjws initialization will create a new LoginManager for you.
If you need to customize, you can alternately provide your own. Just be
aware that it's request\_loader needs to be left as is.

.. code:: Python

    from flask import Flask
    from flask_bitjws import FlaskBitjws
    from flask.ext.login import LoginManager

    # Your LoginManager
    lm = LoginManager()

    app = Flask(__name__)
    FlaskBitjws(app, loginmanager=lm)

Initialize with private key
'''''''''''''''''''''''''''

To provide a private key for your server to use in signing, include a
privkey argument to Application.\ **init**\ ().

.. code:: Python

    from flask import Flask
    from flask_bitjws import FlaskBitjws

    # Your bitjws private key in WIF
    privkey = "KweY4PozGhtkGPMvvD7vk7nLiN6211XZ2QGxLBMginAQW7MBbgp8"

    app = Flask(__name__)
    FlaskBitjws(app, privkey=privkey)

Usage
-----

Requests
''''''''

For all routes that require login (i.e. wrapped in @login\_required),
the FlaskBitjws login manager will validate the bitjws headers and data,
and match it up to a user.

If authentication is successful, the request will have two new
attributes "jws\_payload", and "jws\_header".

If authentication fails, flask-login will return a 401 error.

::

    from flask import Flask
    from flask_bitjws import FlaskBitjws

    # Your bitjws private key in WIF
    privkey = "KweY4PozGhtkGPMvvD7vk7nLiN6211XZ2QGxLBMginAQW7MBbgp8"

    app = Flask(__name__)
    FlaskBitjws(app, privkey=privkey)

    @app.route('/user', methods=['POST'])
    @login_required
    def post_user():
        # request.jws_payload should exist and have the deserialized JWT claimset
        username = request.jws_payload.get('username')
        # request.jws_header should exist and have the sender's public key
        address = request.jws_header['kid']
        user = {'username': username, 'address': address}
        # return a bitjws signed and formatted response
        return current_app.create_bitjws_response(user)

Responses
'''''''''

When you're ready to respond, use the create\_bitjws\_response method to
construct your response in bitjws format.

::

    response_object = {'can be': 'a dict', 'or any': 'valid json'}
    return current_app.create_bitjws_response(response_object)

Your Database
-------------

Flask-bitjws comes with an example, in-memory data store for users and
nonces. Using this example "database" is extremely insecure and
unstable. It is recommended to provide bindings to your own persistent
database for production use. This can be done by passing
``FlaskBitjws.__init__`` two functions: get\_last\_nonce, and
get\_user\_by\_key. These should do pretty much what their names say.

SQLAlchemy Example
''''''''''''''''''

::

    def get_last_nonce(app, key, nonce):
        """
        This method is only an example! Replace it with a real nonce database.

        :param str key: the public key the nonce belongs to
        :param int nonce: the latest nonce
        """
        uk = ses.query(UserKey).filter(UserKey.key==key)\
                .filter(UserKey.last_nonce<nonce * 1000).first()
        if not uk:
            return None
        lastnonce = copy.copy(uk.last_nonce)
        # TODO Update DB record in same query as above, if possible
        uk.last_nonce = nonce * 1000
        try:
            ses.commit()
        except Exception as e:
            print e
            ses.rollback()
            ses.flush()
        return lastnonce


    def get_user_by_key(app, key):
        """
        This method is only an example! Replace it with a real user database.

        :param str key: the public key the user belongs to
        """
        user = ses.query(SLM_User).join(UserKey).filter(UserKey.key==key).first()
        return user

    FlaskBitjws(app, get_last_nonce=get_last_nonce,
                get_user_by_key=get_user_by_key)

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