After many requests from several users and after many months of promise, the Dotdeb repositories are GPG-signed. Yes, you can now get rid of the annoying " WARNING: The following packages cannot be authenticated!" message!

Waiting for a dotdeb-keyring package, you just have to get the key and add it to your trusted keys’ keyring :

gpg --keyserver keys.gnupg.net --recv-key 89DF5277
gpg -a --export 89DF5277 | sudo apt-key add -

I hope you’ll enjoy it.