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Cryptographic modules for Python.

Project description

Python Cryptography Toolkit (pycrypto)

This is a collection of both secure hash functions (such as MD5 and SHA),
and various encryption algorithms (AES, DES, IDEA, RSA, ElGamal, etc.). The
package is structured to make adding new modules easy. I consider this
section to be essentially complete, and the software interface will almost
certainly not change in an incompatible way in the future; all that remains
to be done is to fix any bugs that show up. If you encounter a bug, please
report it in the SourceForge bug tracker at

An example usage of the MD5 module is:
>>> from Crypto.Hash import MD5
>>> hash.update('message')
>>> hash.digest()

An example usage of an encryption algorithm (AES, in this case) is:

>>> from Crypto.Cipher import AES
>>>'This is a key456', AES.MODE_ECB)
>>> message="The answer is no"
>>> ciphertext=obj.encrypt(message)
>>> ciphertext
>>> obj2 ='This is a key456', AES.MODE_ECB)
>>> obj2.decrypt(ciphertext)
'The answer is no'

One possible application of the modules is writing secure
administration tools. Another application is in writing daemons and
servers. Clients and servers can encrypt the data being exchanged and
mutually authenticate themselves; daemons can encrypt private data for
added security. Python also provides a pleasant framework for
prototyping and experimentation with cryptographic algorithms; thanks
to its arbitrary-length integers, public key algorithms are easily

Development of the toolkit can be discussed on the pct mailing list;
archives and instructions for subscribing at at


The toolkit is written and tested using Python 2.2, though it should
also work with Python 2.1. Python 1.5.2 is not supported, and the script will abort if you run it with 1.5.2.

The modules are packaged using the Distutils, so you can simply run
"python build" to build the package, and "python
install" to install it.

If the script crashes with a DistutilsPlatformError
complaining that the file /usr/lib/python2.2/config/Makefile doesn't
exist, this means that the files needed for compiling new Python
modules aren't installed on your system. Red Hat users often run into
this because they don't have the python2-devel RPM installed. The fix
is to simply install the requisite RPM.

To verify that everything is in order, run "python". It will test
all the cryptographic modules, skipping ones that aren't available. If the
test script reports an error on your machine, please report the bug using
the bug tracker (URL given above). If possible, track down the bug and
include a patch that fixes it.

To install the package under the site-packages directory of
your Python installation, run "python install".

If you have any comments, corrections, or improvements for this package,
please send it to the 'pct' mailing list. Good luck!

--amk (

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