Setting up Google Authenticator on Multiple Devices
Having a secondary device with your 2FA is a great way to have a backup in case of an emergency and for the added peace of mind.
After seeing a Twitter Thread about this very topic I decided it would be a good idea to walk through the steps on how to set up Authenticator on 2 devices.
SMS 2 Factor Authentication is incredibly insecure, leading to the loss of millions of dollars of cryptocurrencies over the years. Having worked for a large telecommunications company myself, it’s unbelievable how easy it is to port a number from one carrier to the other. Using an app based 2FA should always be used over SMS based 2FA. Google Authenticator is not without its inconveniences though.
When I initially set up my Google 2FA for cryptocurrency exchanges, email accounts, and apps it was nice to know that I wasn’t susceptible to SMS based attacks but what if my phone was lost or stolen? Going through the process of contacting exchanges and companies to get a 2FA reset is a laborious process and can take 1–2 weeks to complete. I wanted a better solution than relying on one device. That’s when I found out you can have Google Authenticator on multiple devices so long as you scan the same code with each device!
For this walkthrough, I went through the process on Binance but it is similar for most exchanges and other accounts such as your Google account.
Disabling 2FA and re-enabling with 2 Devices
Get a secondary device that you do not regularly use. It could be an old cell phone or iPad. I wanted a fresh start with a device that had no history and hadn’t ever been used. I purchased a cheap prepaid cell phone. I went to my local Walmart and purchased a prepaid Verizon Moto e4 for $39.99. Verizon prepaid phones will remain locked until you take the SIM card out but then you are free to use on WiFi.
Download the Authenticator App! As mentioned in @BitcoinBirch’s thread, the Authenticator App does not need to be online to use. After you have completed your download you can turn the Wifi off. Keep this device offline for maximum security.
Now it’s time to reset your 2FA on any site that you have set up. Click the disable button. Keep in mind that most exchanges will disable withdrawals or other functionality for a period of time. In Binance’s case it is 24 hours until you can withdraw again, please plan accordingly.
Do not delete your current 2FA codes! Binance will automatically replace/update the code on your app after you have successfully disabled and re-enabled with the new code.
Binance will ask for your login password and your current authenticator code.
Once you have successfully entered the required information Binance will disable your 2FA and prompt you to re-enable it. Click on Google Authentication.
You will then be brought to this setup page. Click “Next Step”
Open the Authenticator App on both phones and scan the same QR code presented with both phones.
You should compare the codes on both phones and make sure they match. If they do move on to the next step “Backup Key.” It is recommended to write down your backup key. Since I have the secondary device I usually don’t.
On the final step “Enable Google Authentication” You will be asked to provide the 6 digit code from your app to enable. Once you enter the code you are done!
Having a second device with my 2FA has saved me from some major headache. Recently with the release on Andriod Pie, my Galaxy s9+ took the update but required a factory reset because it would not boot properly. If I didn’t have my backup phone it would have made the already tedious process of recovering my data even worse. Things happen and it’s best to ready for worst.
While it’s not the best way to spend an hour, having a secondary device with your 2FA is worth the peace of mind knowing you have a way to get into your accounts if anything were to happen to your main device.
Let me know if you have any questions!