Cryptography
============

.. image:: https://farm5.staticflickr.com/4220/33907152824_bf91078cc1_k_d.jpg

Cryptography
------------

`Cryptography <https://cryptography.io/en/latest/>`_ is an actively developed
library that provides cryptographic recipes and primitives. It supports 
Python 2.6-2.7, Python 3.3+ and PyPy.


Cryptography is divided into two layers of recipes and hazardous materials
(hazmat).  The recipes layer provides simple API for proper symmetric
encryption and the hazmat layer provides low-level cryptographic primitives.



Installation
~~~~~~~~~~~~

.. code-block:: console

    $ pip install cryptography

Example
~~~~~~~

Example code using high level symmetric encryption recipe:

.. code-block:: python

	from cryptography.fernet import Fernet
	key = Fernet.generate_key()
	cipher_suite = Fernet(key)
	cipher_text = cipher_suite.encrypt(b"A really secret message. Not for prying eyes.")
	plain_text = cipher_suite.decrypt(cipher_text)




GPGME bindings
--------------

The `GPGME Python bindings <https://dev.gnupg.org/source/gpgme/browse/master/lang/python/>`_ provide pythonic access to `GPG Made Easy <https://dev.gnupg.org/source/gpgme/browse/master/>`_, a C API for the entire GNU Privacy Guard suite of projects, including GPG, libgcrypt and gpgsm (the S/MIME engine). It supports Python 2.6, 2.7, 3.4 and above. Depends on the SWIG C interface for Python as well as the GnuPG software and libraries.

Available under the same terms as the rest of the GnuPG Project: GPLv2 and LGPLv2.1, both with the "or any later version" clause.

Installation
------------

Included by default when compiling GPGME if the configure script locates a supported python version (which it will if it's in $PATH during configuration).

Example
-------

.. code-block:: python3

	import gpg
	import os
	
	# Encryption to public key specified in rkey.
	rkey = "0xDEADBEEF"
	text = "Something to hide."
	plain = gpg.core.Data(text)
	cipher = gpg.core.Data()
	c = gpg.core.Context()
	c.set_armor(1)
	c.op_keylist_start(rkey, 0)
	r = c.op_keylist_next()
	c.op_encrypt([r], 1, plain, cipher)
	cipher.seek(0, os.SEEK_SET)
	ciphertext = cipher.read()

	# Decryption with corresponding secret key
	# invokes gpg-agent and pinentry.
	plaintext = gpg.Context().decrypt(ciphertext)

	# Matching the data.
	if text == plaintext[0].decode("utf-8"):
	    print("Hang on ... did you say *all* of GnuPG?  Yep.")
	else:
	    pass




PyCrypto
--------

`PyCrypto <https://www.dlitz.net/software/pycrypto/>`_ is another library,
which provides secure hash functions and various encryption algorithms. It
supports Python version 2.1 through 3.3.

Installation
~~~~~~~~~~~~

.. code-block:: console

    $ pip install pycrypto

Example
~~~~~~~

.. code-block:: python

	from Crypto.Cipher import AES
	# Encryption
	encryption_suite = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')
	cipher_text = encryption_suite.encrypt("A really secret message. Not for prying eyes.")

	# Decryption
	decryption_suite = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')
	plain_text = decryption_suite.decrypt(cipher_text)