Merge pull request realpython#465 from amiralis/master

add crypto

Author: kennethreitz

docs/contents.rst.inc

@@ -59,6 +59,7 @@ different scenarios.
    scenarios/scientific
    scenarios/imaging
    scenarios/xml
+   scenarios/crypto
 
 
 Shipping Great Code

docs/scenarios/crypto.rst

@@ -0,0 +1,67 @@
+Cryptography
+============
+
+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 3.2+ 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)
+
+
+
+
+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)