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62 lines
2.2 KiB
62 lines
2.2 KiB
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:mod:`crypt` --- Function to check Unix passwords
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=================================================
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.. module:: crypt
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:platform: Unix
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:synopsis: The crypt() function used to check Unix passwords.
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.. moduleauthor:: Steven D. Majewski <sdm7g@virginia.edu>
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.. sectionauthor:: Steven D. Majewski <sdm7g@virginia.edu>
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.. sectionauthor:: Peter Funk <pf@artcom-gmbh.de>
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.. index::
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single: crypt(3)
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pair: cipher; DES
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This module implements an interface to the :manpage:`crypt(3)` routine, which is
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a one-way hash function based upon a modified DES algorithm; see the Unix man
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page for further details. Possible uses include allowing Python scripts to
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accept typed passwords from the user, or attempting to crack Unix passwords with
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a dictionary.
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.. index:: single: crypt(3)
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Notice that the behavior of this module depends on the actual implementation of
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the :manpage:`crypt(3)` routine in the running system. Therefore, any
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extensions available on the current implementation will also be available on
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this module.
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.. function:: crypt(word, salt)
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*word* will usually be a user's password as typed at a prompt or in a graphical
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interface. *salt* is usually a random two-character string which will be used
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to perturb the DES algorithm in one of 4096 ways. The characters in *salt* must
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be in the set ``[./a-zA-Z0-9]``. Returns the hashed password as a string, which
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will be composed of characters from the same alphabet as the salt (the first two
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characters represent the salt itself).
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.. index:: single: crypt(3)
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Since a few :manpage:`crypt(3)` extensions allow different values, with
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different sizes in the *salt*, it is recommended to use the full crypted
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password as salt when checking for a password.
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A simple example illustrating typical use::
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import crypt, getpass, pwd
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def login():
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username = raw_input('Python login:')
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cryptedpasswd = pwd.getpwnam(username)[1]
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if cryptedpasswd:
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if cryptedpasswd == 'x' or cryptedpasswd == '*':
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raise NotImplementedError(
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"Sorry, currently no support for shadow passwords")
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cleartext = getpass.getpass()
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return crypt.crypt(cleartext, cryptedpasswd) == cryptedpasswd
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else:
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return 1
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