Technically should work with any other MFA application like Microsoft Authenticator, I would expect, as I’m pretty sure they all use the same URI formatting for TOTP/HOTP syntax.
Preliminary - I have a user that just does not want to cooperate with installing the Duo app, and the Yubikey has lead to the discovery of an issue with a system maxing out at 64 character passwords, which led to the rabbit hole of Google authenticator and Duo.
Step 1: using the rootprojects site below, or by hand, create a secret key and build your OTP URL. Secrets should be 32 characters, all upper case and numbers for consistency. As an example URL using TOTP:
otpauth://totp/Duo:user@example.com?secret=ZW6SONMEFKMGFKKXPJE2SGZKMXWISO5Q&issuer=Duo&algorithm=SHA1&digits=6&period=30
Step 2: Using the google chart URL below, or another QR application, create a QR code, or if using the rootprojects page use the QR code that was generated on the page. An example google charts URL for the URI in step 1:
https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/Duo:user@example.com?secret=ZW6SONMEFKMGFKKXPJE2SGZKMXWISO5Q&issuer=Duo&algorithm=SHA1&digits=6&period=30
Step 3: Translate the secret from base32 to hexadecimal using something like the cryptii site above (encoded on left, set to decode, Base32 (RFC 3548, 4648), Bytes, Hexadecimal, group by – none):
ZW6SONMEFKMGFKKXPJE2SGZKMXWISO5Q → cdbd2735842a9862a9577a49a91b2a65ec893bb0
Step 4: Go to Duo admin panel, click on Import Hardware Token. For the serial number put in the [user@example.com] portion, then a comma followed by the hexadecimal secret from step 3.
Step 5: Assign the hardware token to the user.
Links/Helpful details:
https://rootprojects.org/authenticator/
Syntax for Google auth token:
Otpauth://[totp or hotp]/[issuer]:[Account detail, such as user@example.com]?secret=[secret key]&issuer=[issuer]
https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=[above OTP Path]
This has been tested using Duo proxy auth with comma delimited code and seems to work so far.
