Now that you’ve set up APG and K9 to allow you to send and receive encrypted and signed emails from your Android phone, you’ve probably found that you need to import OpenPGP keys. Fortunately, if the keys you need can be found on keyservers, APG can download and import them for you.
Start by launching APG.
Hit the menu button (the physical button). You will see several options. Hit the Key Server option.
You should now see a screen that has the address of a key server in a drop down menu, and a search box.
You can select a specific key server if you know where the key is hosted, or you can try several until you find it.
Enter the name or email address of the person whose public key you are trying to find, then hit the search button.
If their key is on the server, you should get a result quickly. You may have to look through a list of keys to find the correct key.
Once you find the correct key, tap it. It will add itself, and a message will display that says “Successfully added 1 key(s).” Once that is done, the email will been verified using the new public key.
Using the same method as described you can also update public keys, a process you need to go through whenever a change is made to the other person’s public key (just as you must re-upload your public key whenever you change it).