Type the password into the "Password to unprotect sheet" field and click "OK." Re-enter the password when prompted and click "OK" to protect the spreadsheet. Press "Ctrl-S" to save the changes.

This simple script from tech blog Skipser will allow you to encrypt all your data in a document and put it behind a password. Initial setup is fairly straightforward.

Unrelated: Here’s how to create your own anonymous collaborative Google Sheet, for whatever reason, who knows! Make a New Google Account ...