This week i have studied the gmime and intoduced this lib into my projects at last, which is used to parse the MimeMultipartSigned message and get the PGP/GPG Key. And then import the keys into the local chain, i used the Seahorse DisplayNotification() DBus API at org.gnome.seahorse.KeyService to notify the key imported. there is a snapshot in my blog:)
The next week i will try to introduce the gnome-kering into my project(maybe far away from my original application's goal ? -- integration of the Seahorse), and use it to manage the certificates, mainly about the UI design.