I have 17.04 and today I installed Skype for Linux, but when I execute
sudo apt update I get the following:
W: Errore GPG: https://repo.skype.com/deb stable InRelease: Le seguenti firme non sono state verificate perché la chiave pubblica non è disponibile: NO_PUBKEY 1F3045A5DF7587C3 E: The repository 'https://repo.skype.com/deb stable InRelease' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.
(Translation of the first line: GPG error The following signatures were not verified since public key is not available)
How can I solve?