Google Drive is a good option for storing the files and saving your precious space on your computer but it has never been the most secure option since the Drive does not support encrypting individual files. It is now going to change in the future.
Based on the string that are found in the version 2.20.441.06.40 of the Google Drive, Google has been poised to introduce a feature that will allow the users to encrypt the Drive files which are saved on device. The files can be downloaded and open the encrypted files in the Drive.
Once it is enabled, the encrypted files that are downloaded to the device will appear with the small lock icon which is next to the icon that indicates its availability offline. Toggling of the encryption will delete all documents currently downloaded through the Drive though it is a bit inconvenient but that is what you pay for improved security.