Konqueror is a good browser, but sometimes you need to use Firefox (called Iceweasel on Debian). I discovered a plugin to let FF store its passwords in kwallet, but after installation of the plugin all passwords were gone.

Fortunately you can disable the plugin and the old passwords are still there. So if you want to switch to this plugin you should use the following procedure:

1. install the Password Exporter plugin
2. export your passwords to a text file using the plugin
3. install the kwallet plugin
4. import your password file using the Password Exporter plugin
5. check the entries in the section Firefox of your kwallet using the kwalletmanager
6. don’t forget to delete the exported file

This worked for me.