You can use kmail and gpg to send encrypted or digitally signed mail. To do this, there are the buttons "sign" and "encrypt" in the kmail compose window. It appears if you click on "File|New|New message".
A web of trust are a lot of persons who trust each other. To show their trust, they have signed each other's keys. gpg allows you to do this.
The web of trust is extended in key signing parties that go like this:
Your private key is stored in secring.gpg, your public one is stored in pubring.gpg. You keep your private key and are free to distribute your public key.
gpg --list-keys /home/me/.gnupg/pubring.gpg ---------------------------------- pub 1024D/45E377BB 2008-02-03 [...]
gpg --search-key me@home
gpg --sign-key 45E377BB
gpg --send-key 45E377BB
If you have a keyring saved to your disk, reload ("import") it like this:
cat secring.skr | gpg --import #yours may be called 'secring.pub'
Then call kgpg and set your trust on your private key to ultimate.
Whatever problems arise, first make sure your gpg is properly set up:
gpg: no ultimately trusted keys found
Call kgpg and set the trust of your private key to ultimate.
You get an error message like this whenever you start up? You need scripts to make it start and stop cleanly. You can get scripts here:
Copy them into your ~/.kde/env and ~/.kde/shutdown folders, check permissions, and make sure they are executable.