Duo Mobile is an "authenticator app" that supports any number of accounts. For instance, you can use it with your personal gmail or facebook account, or for your bank account web access, as long as the website has two-step login enabled.
- Search the support pages on the web service you wish to enable two-step login for. It may be called "two-factor authentication" or "two-step verification."
- Follow the instructions to turn on two-step login for your account. Ignore any mentions of Google Authenticator or other mobile authenticator applications — you'll be using Duo Mobile instead.
- At some point you'll be shown a barcode to scan. Open Duo Mobile and tap the "+" icon or the "Add Account" button to add a new account.
- Use Duo Mobile to scan the application's barcode.
- Most services also offer a secret key that you can enter if you can't scan the barcode. Tap the "No Barcode?" button and select an account type from the list. Use the "Account" field to name the account (e.g. "Dropbox", "firstname.lastname@example.org", etc.). Type the application's secret key into the "Key" field on your phone.
- Finally, tap the key next to the account name to generate a passcode. Type the passcode into the box on your computer to verify that the passcode generator is working properly. Then click "Next".
- You're done! Now you'll use the Duo Mobile app to generate a new passcode if you're asked for one when you log into your account.
IMPORTANT NOTE: if you wipe data from your device, or upgrade your device, you will need to re-provision all of your accounts. It is not possible to export third-party accounts from Duo Mobile. Please be sure to follow the recommended backup directions for your third-party accounts, e.g., a phone number or backup code.