OneNote in Google Drive or Dropbox? What? Why?
If you are really paranoid about the security and you desperately want two-step authentication, then Hotmail/Outlook.com/Skydrive is not something you would use. However, you might be a big fan of Microsoft OneNote that increases your productivity.
So what do you do in this case? Simple answer is run OneNote and save your notebooks in Google-Drive or Dropbox.
1. Install Google Drive or Dropbox client on your computer.
2. When creating your notebooks in OneNote, save them into GoogleDrive or Dropbox folder.
3. This automatically syncs it into the cloud.
4. Then you do the same setup on your other computers where you use OneNote.
5. When you go to your other computer, your OneNote notebooks will be automatically there.
Note: To keep the sync process very stable, make sure you close OneNote on one computer before you use it on the other computer.
Adding more security typically means the impact on usability and that is the case in this situation as well. If this is too complicated for you, then I suggest just using OneNote with SkyDrive and make your SkyDrive passwords very strong.