Re:Passwordless: a different kind of hell?
by hot_gril on Tuesday January 16, 2024 @05:39PM
(#39020142)
Why use a QR code reader app instead of the built in camera app?
Personally, I email the backup codes to myself. Yes it's less secure in theory, but the only time I'm using totp is against my will.
> Why use a QR code reader app instead of the built in camera app?
The QR code is on the screen of my desktop Mac. The camera is right above the screen facing me and can't see what is on the screen.
I could read it with the built in camera app on my iPhone or iPad, but that just tells me it is a QR code for the TOTP authenticator app I use and opens that if I tap. I don't see a way to get it to tell me the content of the QR code in text form. Even if it had a way that would be on the phone and I want the text to save it on the Mac.
If I ever want to set up a TOTP app on a new device it is not hard to decrypt all my saved QR codes, open them all at the same time in Preview on my Mac, select the option to show one page at a time, and then get into a nice rhythm using one hand to scan on the new device and the other to hit "page down" on the Mac keyboard.
If the site also gives a text form of the shared secret from the QR code I save that too. Having the text form around is handy in case I need to login but for some reason don't have the devices where I have the TOTP apps. Given the text form of the code, this command, from the oathtool package, will give the current login code:
That's if the secret is encoded in base32, which they commonly are. If it is in hex leave off the -b.If the site doesn't give a text form of the shared secret I read the QR code to get it. If you do that be careful. Some QR code reader apps do the processing server side which you probably don't want...and they don't necessarily make that clear in the description. I had to try a couple of apps from the Mac app store before finding one that did it client side. (Then I found out that Mathematica's BarcodeRecognize function can do it, and deleted the QR code reader app. Now I just open Mathematica, type BarcodeRecognize[], drag and drop an image file that has the QR code between the brackets, and hit shift-return).