sam-t2/devtools/v8plus/html/python/lib/module-crypt.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python Documentation Index' />
<link rel="first" href="lib.html" title='Python Library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="module-dl.html" />
<link rel="prev" href="module-grp.html" />
<link rel="parent" href="unix.html" />
<link rel="next" href="module-dl.html" />
<meta name='aesop' content='information' />
<title>8.4 crypt -- Function to check Unix passwords</title>
</head>
<body>
<DIV CLASS="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="8.3 grp  "
  href="module-grp.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="8. Unix Specific Services"
  href="unix.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="8.5 dl  "
  href="module-dl.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="module-grp.html">8.3 grp  </A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="unix.html">8. Unix Specific Services</A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="module-dl.html">8.5 dl  </A>
</div>
<hr /></div>
</DIV>
<!--End of Navigation Panel-->

<H1><A NAME="SECTION0010400000000000000000">
8.4 <tt class="module">crypt</tt> --
         Function to check <span class="Unix">Unix</span> passwords</A>
</H1>

<P>
<A NAME="module-crypt"></A>
<p class="availability">Availability: <span
 class="platform">Unix</span>.</p>

<P>
This module implements an interface to the
<span class="manpage"><i>crypt</i>(3)</span><a id='l2h-2984' xml:id='l2h-2984'></a> routine, which is a one-way hash
function based upon a modified DES<a id='l2h-2982' xml:id='l2h-2982'></a> algorithm; see
the <span class="Unix">Unix</span> man page for further details.  Possible uses include
allowing Python scripts to accept typed passwords from the user, or
attempting to crack <span class="Unix">Unix</span> passwords with a dictionary.

<P>
Notice that the behavior of this module depends on the actual implementation
of the <span class="manpage"><i>crypt</i>(3)</span><a id='l2h-2985' xml:id='l2h-2985'></a> routine in the running system.
Therefore, any extensions available on the current implementation will also
be available on this module.
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2983' xml:id='l2h-2983' class="function">crypt</tt></b>(</nobr></td>
  <td><var>word, salt</var>)</td></tr></table></dt>
<dd>
  <var>word</var> will usually be a user's password as typed at a prompt or
  in a graphical interface.  <var>salt</var> is usually a random
  two-character string which will be used to perturb the DES algorithm
  in one of 4096 ways.  The characters in <var>salt</var> must be in the
  set <tt class="regexp">[./a-zA-Z0-9]</tt>.  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).

<P>
Since a few <span class="manpage"><i>crypt</i>(3)</span><a id='l2h-2986' xml:id='l2h-2986'></a> extensions allow different
  values, with different sizes in the <var>salt</var>, it is recommended to use
  the full crypted password as salt when checking for a password.
</dl>

<P>
A simple example illustrating typical use:

<P>
<div class="verbatim"><pre>
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
</pre></div>

<DIV CLASS="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="8.3 grp  "
  href="module-grp.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="8. Unix Specific Services"
  href="unix.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="8.5 dl  "
  href="module-dl.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="module-grp.html">8.3 grp  </A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="unix.html">8. Unix Specific Services</A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="module-dl.html">8.5 dl  </A>
</div>
</div>
<hr />
<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
</DIV>
<!--End of Navigation Panel-->
<ADDRESS>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</ADDRESS>
</BODY>
</HTML>