Antes de importar sua chave para o Launchpad, ela deve estar disponível no servidor de chaves Ubuntu.
Publishing your key
Your key is useful only if other people can verify items that you sign. By publishing your key to a keyserver, which acts as a directory of people's public keys, you can make your public key available to anyone else.
Before you add your key to Launchpad, you need to push it to the Ubuntu keyserver.
Using Passwords and Encryption Keys
Step 1 Open Passwords and Encryption Keys.
Step 2 Select the My Personal Keys tab, select your key.
Step 3 Select Remote > Sync and Publish Keys from the menu. Choose the Sync button. (You may need to add hkp://keyserver.ubuntu.com to your key servers if you are not using Ubuntu.)
It can take up to thirty minutes before your key is available to Launchpad. After that time, you're ready to import your new key into Launchpad!
De: link