symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/crypt.rst
author johnathan.white@2718R8BGH51.accenture.com
Mon, 08 Mar 2010 18:45:03 +0000
changeset 46 b6935a90ca64
parent 1 2fb8b9db1c86
permissions -rw-r--r--
Modify framebuffer and NGA framebuffer to read screen size from board model dtb file. Optimise memory usuage of frame buffer Add example minigui application with hooks to profiler (which writes results to S:\). Modified NGA framebuffer to run its own dfc queue at high priority


:mod:`crypt` --- Function to check Unix passwords
=================================================

.. module:: crypt
   :platform: Unix
   :synopsis: The crypt() function used to check Unix passwords.
.. moduleauthor:: Steven D. Majewski <sdm7g@virginia.edu>
.. sectionauthor:: Steven D. Majewski <sdm7g@virginia.edu>
.. sectionauthor:: Peter Funk <pf@artcom-gmbh.de>


.. index::
   single: crypt(3)
   pair: cipher; DES

This module implements an interface to the :manpage:`crypt(3)` routine, which is
a one-way hash function based upon a modified DES algorithm; see the Unix man
page for further details.  Possible uses include allowing Python scripts to
accept typed passwords from the user, or attempting to crack Unix passwords with
a dictionary.

.. index:: single: crypt(3)

Notice that the behavior of this module depends on the actual implementation  of
the :manpage:`crypt(3)` routine in the running system.  Therefore, any
extensions available on the current implementation will also  be available on
this module.


.. function:: crypt(word, salt)

   *word* will usually be a user's password as typed at a prompt or  in a graphical
   interface.  *salt* is usually a random two-character string which will be used
   to perturb the DES algorithm in one of 4096 ways.  The characters in *salt* must
   be in the set ``[./a-zA-Z0-9]``.  Returns the hashed password as a string, which
   will be composed of characters from the same alphabet as the salt (the first two
   characters represent the salt itself).

   .. index:: single: crypt(3)

   Since a few :manpage:`crypt(3)` extensions allow different values, with
   different sizes in the *salt*, it is recommended to use  the full crypted
   password as salt when checking for a password.

A simple example illustrating typical use::

   import crypt, getpass, pwd

   def login():
       username = raw_input('Python login:')
       cryptedpasswd = pwd.getpwnam(username)[1]
       if cryptedpasswd:
           if cryptedpasswd == 'x' or cryptedpasswd == '*': 
               raise "Sorry, currently no support for shadow passwords"
           cleartext = getpass.getpass()
           return crypt.crypt(cleartext, cryptedpasswd) == cryptedpasswd
       else:
           return 1