8.4 crypt -- Function to check Unix passwords
Availability: Unix.
This module implements an interface to the 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.
Notice that the behavior of this module depends on the actual implementation of the crypt(3) routine in the running system. Therefore, any extensions available on the current implementation will also be available on this module.
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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).
Since a few 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
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Release 2.4.1, documentation updated on 30 March 2005.