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I recently got a new phone that has various hardware issues with it. As such, before the warranty expires, I need to send it back for repairs. Unfortunately, I already have Google Authenticator authenticating many accounts that I do not want to lose access to while my phone is being repaired.

I have securely stored backup codes for all of these accounts, but those are to be used only if I permanently lose access to my primary authentication device. Using them while my phone is being repaired risks running out of codes, which will result in me permanently having no way to login after that because I intend to fully wipe my phone before giving it up (especially since the repair people are most likely to simply replace it). Stopping myself before I fully run out of codes will result in temporary depletion, which is also a problem.

I have no other mobile device to use in its place (mobile device meaning a device running Andrid or IOS), however I have several computers (both multiple laptops and multiple desktops). As such, I am thinking the least-bad solution would be to run Google Authenticator on my Linux Laptop that I carry with me most often, but this is not an ideal solution to me because that laptop is my primary computer, and one of the advantages of 2FA is that it can defend against certain attacks that compromise one's main computer, such as a keylogger. With that said, however, a valid answer provides a specific way to run Google Authenticator on a (Arch) Linux laptop.

How can I fully maintain my security while my phone is being repaired?

  • Not that it answers your question - you state that you have no other mobile device - but I do know some people that own two devices specifically to separate their 2FA from their daily use. – gowenfawr Oct 19 '18 at 4:36
  • Another option is using a 2FA Hardware device, .e.g. Titan Security Key, Yubico. – mootmoot Oct 19 '18 at 15:20
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Consider using an emulator such as BlueStacks and move your 2FA to the emulator. You don't need another device for this since BlueStacks is free.

There's also a chrome extension called Authy as stated by user in the comments to this answer.

  • Using the authy extension in Chrome might be easier than starting up an emulator for this. oathtool can also generate a totp on the command line. It might however require a slightly more sophisticated tool to extract the secret from BlueStacks than from Chrome or bash_history... – user2313067 Oct 19 '18 at 14:53
  • True, that was an option that I didn't consider. Added to my answer. – Andrew Greer Oct 19 '18 at 15:00
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If you didn't also let in your SIM card for repair along with your phone you can simply put it inside any phone (even a 2G one) and use that as most 2FA involve sending numerical digits in SMS and typing that back.

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Google Authenticator with TOTP enrolled has a major problem, which you can use as solution in this case. The downside is, that you would need to reenroll the 2nd factor of your accounts. You see, the Key URI that is contained in the QR Code that gets scanned by your Google Authenticator app contains the secret key in clear text. I.e. you can simply print out and copy this code or scan this code with thousands of smartphones or - as you only have one smartphone - use it with any TOTP application on a laptop. On Linux you can use the oathtool. (From a security standpoint, that sucks - I wrote a blog post about it earlier.)

But also: If you would reenroll your 2nd factors, print out the QR Code, wipe your phone, bring it to repair... ...you can easily rescan the QR Codes when the phone returns. Given that you securely stored the print outs ;-)

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Just to add to the suggestions listed above, you can also "clone" your Google Authenticator to a programmable hardware token

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