gpg --keyserver hkp://keys.gnupg.net --recv-keys 1C4CBDCDCD2EFD2A: requesting key CD2EFD2A from hkp server keys.gnupg.net
gpgkeys: key 1C4CBDCDCD2EFD2A not found on keyserver
verified because the public key is not available: NO_PUBKEY 535C743689107B44gpg --keyserverhkp://keyserver.ubuntu.com:80 --recV 535C743689107B44sudo apt-key adv --keyserver.ubuntu.com --recv-keys535C743689107B44gpgkeys: key 53