That's a valid question. Google Drive does not currently encrypt files on the server. Our team and our company take the security and privacy of our users very seriously. For example, we support 2-factor authentication, and as Julio mentioned, all transmissions to and from your device using HTTPS and TLS. However, you can encrypt a file (or all your files) before you add it to Google Drive, and Drive will sync any file (whether it's encrypted or not) to all your devices.