QR Code Generator for One-Time Passwords with Google Authenticator and mod_authn

QR Code Generator for One-Time Passwords

Add to the mod_authn_opt users file on your server:	HOTP/T30 zzz - 581d60c9cdfb4361fece
Write down your site label for the token:	AVH:zzz@av-huette.de
Write down your secret diceware password:	feed-green-wand-petal-rug-polo-puma-tarot-gulf-crank
or write down your secret token: Entropy > 100 bit. Base32( substr( sha256( diceware-password-without-dashes ), 0, 20 ) )	LAOWBSON7NBWD7WO

Scan the QR Code

Client-side (Javascript) generated:

otpauth://totp/AVH%3Azzz%40av-huette.de?secret=LAOWBSON7NBWD7WO&issuer=AVH

andOTP OTP Authenticator (source)
Google Authenticator
~~One-Time Password generator (This service is nice for understanding how it works, but unsafe, because the QR code is generated at Google)~~
otpauth-key-uri-format
How it works

updated 20210531