signatures couldn't be verified #1
Description
W: GPG error: http://security.debian.org jessie/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY AA8E81B4331F7F50
W: GPG error: http://http.debian.net jessie-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7638D0442B90D010
W: GPG error: http://http.debian.net jessie Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7638D0442B90D010