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<!-- $PostgreSQL: pgsql/doc/src/sgml/chkpass.sgml,v 1.3 2010/08/17 04:37:20 petere Exp $ -->
<sect1 id="chkpass">
<title>chkpass</title>
<indexterm zone="chkpass">
<primary>chkpass</primary>
</indexterm>
<para>
This module implements a data type <type>chkpass</> that is
designed for storing encrypted passwords.
Each password is automatically converted to encrypted form upon entry,
and is always stored encrypted. To compare, simply compare against a clear
text password and the comparison function will encrypt it before comparing.
</para>
<para>
There are provisions in the code to report an error if the password is
determined to be easily crackable. However, this is currently just
a stub that does nothing.
</para>
<para>
If you precede an input string with a colon, it is assumed to be an
already-encrypted password, and is stored without further encryption.
This allows entry of previously-encrypted passwords.
</para>
<para>
On output, a colon is prepended. This makes it possible to dump and reload
passwords without re-encrypting them. If you want the encrypted password
without the colon then use the <function>raw()</> function.
This allows you to use the
type with things like Apache's <literal>Auth_PostgreSQL</> module.
</para>
<para>
The encryption uses the standard Unix function <function>crypt()</>,
and so it suffers
from all the usual limitations of that function; notably that only the
first eight characters of a password are considered.
</para>
<para>
Note that the <type>chkpass</type> data type is not indexable.
<!--
I haven't worried about making this type indexable. I doubt that anyone
would ever need to sort a file in order of encrypted password.
-->
</para>
<para>
Sample usage:
</para>
<programlisting>
test=# create table test (p chkpass);
CREATE TABLE
test=# insert into test values ('hello');
INSERT 0 1
test=# select * from test;
p
----------------
:dVGkpXdOrE3ko
(1 row)
test=# select raw(p) from test;
raw
---------------
dVGkpXdOrE3ko
(1 row)
test=# select p = 'hello' from test;
?column?
----------
t
(1 row)
test=# select p = 'goodbye' from test;
?column?
----------
f
(1 row)
</programlisting>
<sect2>
<title>Author</title>
<para>
D'Arcy J.M. Cain (<email>[email protected]</email>)
</para>
</sect2>
</sect1>
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