instalar las llaves multimedia

el error

Fetched 198 B in 5s (34 B/s)
Reading package lists... Done
W: GPG error: http://www.deb-multimedia.org testing Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 07DC563D1F41B907



la solucion

paso 1

# apt-get install debian-keyring

paso 2

# gpg --keyring /usr/share/keyrings/debian-keyring.gpg -a --export 07DC563D1F41B907 |apt-key add -


NOTA:
los numeros  raros  07DC563D1F41B907, los tome de el error que me salio  arriba



si tu problema no se  resuelve,
intenta :

1) apt-get install debian-archive-keyring

2) apt-get install deb-multimedia-keyring