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Posts Tagged ‘KMail’

Integrating keychain with KDE

November 29, 2010 2 comments

In the last post I introduced keychain and compare it with pam_ssh. I described some nice features of keychain, in particular how it can use long term running SSH/GPG agents. However the explained setup is not well integrated with KDE because of the environment problem described in that post. Although KMail can be configurated to sign sent messages with GPG keys, this feature doesn’t work with keychain out of the box. Let’s suppose that we want to sign our messages with the key 5E653DA8 -without entering the passphrase- and we want to use keychain for managing our GPG keys. In order to get our goal we configure properly the gpg.conf (ensuring that GPG will use the gpg-agent) file and add to our .bashrc file a block like

eval `keychain --nogui --noinherit --stop others id 5E653DA8`
if [ -f "${HOME}/.keychain/${HOSTNAME}-sh-gpg" ]; then
. "${HOME}/.keychain/${HOSTNAME}-sh-gpg"
fi

We restart the X session just to be sure that keychain will add the key to the gpg-agent. Now we start KMail from the KMenu and try to send a signed message using the GPG support. The result is a dialog displaying the message “Signing failed: Bad passphrase”. The reason, as you can guess, is that the environment variables that keychain uses to expose the GPG agent are not known by KMail (in fact they are not available to KDE). This can be fixed in several ways. We can launch KMail via command line from a shell running keychain. But we prefer to launch it from the KMenu so we discard this workaround. Other possibility is to use the KmenuEdit tool and change the launch command from KMail to something like:

GPG_AGENT_INFO=/tmp/gpg-xJRtSl/S.gpg-agent:2249:1; kmail

(of course we get the GPG_AGENT_INFO value from ~./keychain/${HOSTNAME}-sh-gpg). But this doesn’t work if we use KMail as a component of Kontact. We can try to do the KMenuEdit trick with Kontact but then KMail will show us again the error message if we try to sign a message (it seems that Kontact doesn’t pass the environment to the KMail plugin).

The proper way to deal with this problem is to use the ~/.kde/env folder, of course. After all is a environment problem. So we put the following script in this folder:

#!/bin/sh
eval `keychain --nogui --noinherit --stop others`
if [ -f "${HOME}/.keychain/${HOSTNAME}-sh-gpg" ]; then
. "${HOME}/.keychain/${HOSTNAME}-sh-gpg"
fi

This way the environment variables setup by keychain will be available to the KDE. Now we can start KMail in every possible way and we will be able to send signed messages without entering the passphrase (we may need to adjust the ttl of the passphrase to a value suitable for our needs. This change can be done in the gpg-agent.conf file).

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Categories: GNU/Linux, Security Tags: , ,