[Dovecot] Password authentication and character set

Fredrik Grönqvist fredrik.gronqvist at gmail.com
Wed Nov 19 13:54:48 EET 2008

19.11.2008 10:27, Geert Hendrickx wrote:
> On Wed, Nov 19, 2008 at 08:44:21AM +0200, Fredrik Grönqvist wrote:
>> Yes, I agree that it should be in UTF-8. My specific problem is that about
>> 80% (a rough estimate) of our users are on either Windows or webmail. Those
>> having passwords containing umlauts etc can log on, using their current
>> client, if the passwords are kept ISO-8859-1 encoded instead of UTF-8.
>> As Timo pointed out, the options to "fix" this on the server side are
>> currently quite limited, so it seems I have to stick to the lowest common
>> denominator in our password policy.
> If you only have to support two or three different charsets, I think you could
> use a clever MySQL passdb query to match either of them.
> Have a look at http://wiki.dovecot.org/AuthDatabase/SQL under "Password
> verification by SQL server", and expand the password match to something like
> (passwd = PASSWORD('%w') OR passwd = PASSWORD(CONVERT(_latin1'%w' USING utf8)))
> assuming you store the passwords as UTF-8 and assume the input is either UTF-8
> or ISO-8859-1.
> 	Geert
Thanks for the info, a setup like this is what I opted for eventually. I 
added a note to that wiki page that the query also needs to return the 
"nopassword" -field for Dovecot 1.1+ to accept the NULL password:

> # NOTE: '\' line splitting is used only for readability, currently 
> Dovecot doesn't support it
> password_query = SELECT NULL AS password, 'nopassword', userid AS user \
>   FROM users WHERE userid = '%u' AND mysql_pass = password('%w')

In case someone else is looking for info about this, this workaround 
works for DB backed accounts, as you mention, but will probably not work 
with an LDAP (or other) backend.

Chears, Fredrik

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