From c8b79bf686113c3418d8d65ff0a1920da2b409bc Mon Sep 17 00:00:00 2001
From: Micah Anderson <micah@riseup.net>
Date: Thu, 14 Nov 2013 16:35:32 -0500
Subject: initial commit

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+=========================
+ Python scrypt_ bindings
+=========================
+
+This is a set of Python_ bindings for the scrypt_ key derivation
+function.
+
+Scrypt is useful when encrypting password as it is possible to specify
+a *minimum* amount of time to use when encrypting and decrypting. If,
+for example, a password takes 0.05 seconds to verify, a user won't
+notice the slight delay when signing in, but doing a brute force
+search of several billion passwords will take a considerable amount of
+time. This is in contrast to more traditional hash functions such as
+MD5 or the SHA family which can be implemented extremely fast on cheap
+hardware.
+
+Installation
+============
+
+You can install py-scrypt from this repository if you want the latest
+but possibly non-compiling version::
+
+    $ hg clone http://bitbucket.org/mhallin/py-scrypt
+    $ cd py-scrypt
+    $ python setup.py build
+
+    Become superuser (or use virtualenv):
+    # python setup.py install
+
+    Run tests after install:
+    $ python setup.py test
+
+Or you can install the latest release from PyPi::
+
+    $ pip install scrypt
+
+If you want py-scrypt for your Python 3 environment, just run the
+above commands with your Python 3 interpreter. Py-scrypt supports both
+Python 2 and 3.
+
+From version 0.6.0 (not available on PyPi yet), py-scrypt supports
+PyPy as well.
+
+Usage
+=====
+
+Fore encryption/decryption, the library exports two functions
+``encrypt`` and ``decrypt``::
+
+    >>> import scrypt
+    >>> data = scrypt.encrypt('a secret message', 'password', maxtime=0.1) # This will take at least 0.1 seconds
+    >>> data[:20]
+    'scrypt\x00\r\x00\x00\x00\x08\x00\x00\x00\x01RX9H'
+    >>> scrypt.decrypt(data, 'password', maxtime=0.1) # This will also take at least 0.1 seconds
+    'a secret message'
+    >>> scrypt.decrypt(data, 'password', maxtime=0.05) # scrypt won't be able to decrypt this data fast enough
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+    scrypt.error: decrypting file would take too long
+    >>> scrypt.decrypt(data, 'wrong password', maxtime=0.1) # scrypt will throw an exception if the password is incorrect
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+    scrypt.error: password is incorrect
+
+From these, one can make a simple password verifier using the following
+functions::
+
+    def randstr(length):
+        return ''.join(chr(random.randint(0,255)) for i in range(length))
+
+    def hash_password(password, maxtime=0.5, datalength=64):
+        return scrypt.encrypt(randstr(datalength), password, maxtime=maxtime)
+
+    def verify_password(hashed_password, guessed_password, maxtime=0.5):
+        try:
+            scrypt.decrypt(hashed_password, guessed_password, maxtime)
+            return True
+        except scrypt.error:
+            return False
+
+
+But, if you want output that is deterministic and constant in size,
+you can use the ``hash`` function::
+
+    >>> import scrypt
+    >>> h1 = scrypt.hash('password', 'random salt')
+    >>> len(h1)  # The hash will be 64 bytes by default, but is overridable.
+    64
+    >>> h1[:10]
+    '\xfe\x87\xf3hS\tUo\xcd\xc8'
+    >>> h2 = scrypt.hash('password', 'random salt')
+    >>> h1 == h2 # The hash function is deterministic
+    True
+
+
+Acknowledgements
+================
+
+Scrypt_ was created by Colin Percival and is licensed as 2-clause BSD.
+Since scrypt does not normally build as a shared library, I have included
+the source for the currently latest version of the library in this
+repository. When a new version arrives, I will update these sources.
+
+`Kelvin Wong`_ on Bitbucket provided changes to make the library
+available on Mac OS X 10.6 and earlier, as well as changes to make the
+library work more like the command-line version of scrypt by
+default. Kelvin also contributed with the unit tests, lots of cross
+platform testing and work on the ``hash`` function.
+
+Burstaholic_ on Bitbucket provided the necessary changes to make
+the library build on Windows.
+
+License
+=======
+
+This library is licensed under the same license as scrypt; 2-clause BSD.
+
+.. _scrypt: http://www.tarsnap.com/scrypt.html
+.. _Python: http://python.org
+.. _Burstaholic: https://bitbucket.org/Burstaholic
+.. _Kelvin Wong: https://bitbucket.org/kelvinwong_ca
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