KMail Trunk: Signing

If, like me, you run KMail trunk (what will be 4.2), sign your emails and don’t use gpg-agent, you may have found that signing emails suddenly stopped working a while back.  I finally traced the problem: a change in the way signing is done with the gpgme backend means that kleo, the magic behind all things cryptographic in kdepim, no longer provides a password entry dialog.  The reason is that the signing is done in a side thread, and GUI stuff can only be done in the main thread.

The solution?  Use gpg-agent, of course.  You need to install gpg-agent and the pinentry package, and then put a script (call it gpg-agent.sh – the .sh is important) in $KDEHOME/env that starts gpg-agent.  The contents of my ~/.kde/env/gpg-agent.sh file are simply:

eval $(gpg-agent --daemon --pinentry-program /usr/bin/pinentry-qt)

You should also stop it again at logout.  To do this put the following script in the $KDEHOME/shutdown folder and make it executable:

!/bin/sh
# the second field of the GPG_AGENT_INFO variable is the
# process ID of the gpg-agent active in the current session
# so we'll just kill that, rather than all of them
[ -n "${GPG_AGENT_INFO}" ] &&
    kill $(echo "${GPG_AGENT_INFO}" | cut -d ':' -f 2)

All this stolen from a Gentoo HOWTO.