try sudo apt-key adv --recv-keys --keyserver pgp.mit.edu 8D09D5BE298D57CC
and check to make sure you have the file /etc/apt/trusted.gpg and trusddb.gpg in that same location :S
try sudo apt-key adv --recv-keys --keyserver pgp.mit.edu 8D09D5BE298D57CC
and check to make sure you have the file /etc/apt/ trusted. gpg and trusddb.gpg in that same location :S