Cara Mudah Menambahkan Public Key

Langsung saja menuju URL:http://keyserver.ubuntu.com:11371/pks/lookup?op=get&search=0x5A5366B134BA7AE9
Ganti angka 5A5366B134BA7AE9 dengan angka yang diminta.

Copy paste hasilnya di gedit.

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: SKS 1.0.10

mI0ES+NYnAEEAMrPp0DyZ4hXqvkt+zlRdLYUELvmm4qREsxahHJgi/v/V26p860wdMZ6Oalm
+PJhzIYLX1pb85QfT5AgAgUEnEsOiMmWHZwMiRHqwdj8eo0vayA4l5c9cVtOWWJcTkQg1Sp8
VT+A1w6Hyizdocnmfbderg6XtSjJLDKmk/stk56TABEBAAG0FExhdW5jaHBhZCBHTUE1MDAg
UFBBiLYEEwECACAFAkvjWJwCGwMGCwkIBwMCBBUCCAMEFgIDAQIeAQIXgAAKCRBaU2axNLp6
6bKcBADCPykCQkq/jPVSFLhkncMBhnF/qLUjwhEZ9q4jUa8rShkmujsywmcYUasgo8ke6gqt
b0lwcfh1v5JvX6AekBsLj4/ncMpOAYA/mj0dY/YOZXrxOpiseGq8JLG2736RfIQ2DF/uY0wT
bsANCH0zIsS7MrNokMNoCOmGDe4LkOKZFA==
=DT4Y
-----END PGP PUBLIC KEY BLOCK-----

Simpan hasilnya dengan nama ppa.key
Buka System = > Administration => Software Source
Klik tab Authentification
Add file ppa.key tadi
Tutup Software Source (klik Close)
Buka System => Administration => Synaptic Package Manager
Klik Reload
Klik Origin button
Pilih repositories yang baru saja Anda install.

Sumber: http://ubuntuforums.org/showpost.php?p=7589740&postcount=727