We introduced the two-factor authentication, or two-step authentication how Dropbox calls it, and why it is necessary.
Here is how you do this for Dropbox:
1. Go to Settings -> Security
2. Click on “(change)” on the “Two-Step verification”
IMPORTANT: There seems to be a bug in the web application of Dropbox because as soon as you click somewhere in the browser’s window outside of the front window (where the configuration of the Two-Step authentication takes place) you will have to start the entire process from the beginning.
3. Click on Get Started
4. Enter your password again
5. Select “Use text messages”
5. Write your mobile phone number
6. Write the code you received via SMS
7. Save this code on somewhere outside Dropbox on your hard drive and on a paper. Don’t use Post-It.
8. You’re done! Click on Done. If you don’t click, you have to start from the beginning.
Make sure you read the text in the window. Take this serious! Next you when you want to access your account from another device you have to receive an SMS on your mobile phone in order to authenticate yourself. If you don’t have your phone with you or you don’t have network coverage your only choice is the code you wrote down on step 7.
9. Check in the Settings->Security window that the “Two-step verification” is set to Enabled
Make sure that the Notifications are both checked (they are by default). This ensures that you receive an email as soon as somebody accesses your Dropbox account.
Authorize your devices from which you want to access your folders.
Next time when you login (you can try this with another browser) you see an authentication window similar to the one at step 6:
That’s all… you will have to do this step every time you authorize a new device.
The biggest advantage of this two-step authorization is that you will approve what device or application is allowed to access your files.