:mod:`crypt` --- Function to check Unix passwords ================================================= .. module:: crypt :platform: Unix :synopsis: The crypt() function used to check Unix passwords. .. moduleauthor:: Steven D. Majewski .. sectionauthor:: Steven D. Majewski .. sectionauthor:: Peter Funk .. 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 NotImplementedError( "Sorry, currently no support for shadow passwords") cleartext = getpass.getpass() return crypt.crypt(cleartext, cryptedpasswd) == cryptedpasswd else: return 1