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July 2022

A html/javascript based TOTP token generator

One Time Passwords are increasingly common and many companies prefer that you use their apps. This results in quite a number of apps that you have to have on you phone. Here is a javascript based solution that works on many platforms, browsers or phones. It works even on old phone where new apps will no longer install. The html/javascript based OTP generator can work with multiple systems. You just select the one you want from the drop-down list.

Here is the TOTP token generator. Save the html page of the token generator on your computer, edit the code (open it with a text editor) and safe it on your phone:

The code supports a drop-down list for multiple TOTP tokens.

Note the code in this html/javascript page executes locally only and does not send any data anywhere.

Here is how to use it e.g with Microsoft's MFA (Multi Factor Authentication).

Go to "security info" and click "Add sign-in method". This brings up a pop-up and click on "I want to use a different authenticator app".

click on "I want to use a different authenticator app"

This brings up a new page with a QR-code to scan. You can decode this code with the linux program zbarimg. Take a screenshot cut-out the QR-code and save it as file.png. Run "zbarimg file.png" and you get a sting that looks like
"otpauth://.... secret=....&issuer=Microsoft"

You want the code after the "secret=". This is the code you insert into the html code.

The algorithm of this html/javascript based OTP generator is a time based one time password known as google authenticator, OATH-TOTP or TOTP.

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