We normally get these gpg errors while running apt-get update or aptitude update.

Error:

W: GPG error: http://ppa.launchpad.net jaunty Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 7FB8BEE0A1F196A8
W: You may want to run apt-get update to correct these problems

You can fix this by importing the GPG keys from Ubuntu key server as follows:

Fix:

# sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 7FB8BEE0A1F196A8
Executing: gpg –ignore-time-conflict –no-options –no-default-keyring –secret-keyring /etc/apt/secring.gpg –trustdb-name /etc/apt/trustdb.gpg –keyring /etc/apt/trusted.gpg –recv-keys –keyserver keyserver.ubuntu.com 7FB8BEE0A1F196A8
gpg: requesting key A1F196A8 from hkp server keyserver.ubuntu.com
gpg: key A1F196A8: public key “Launchpad PPA for Pidgin Developers” imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)