====== Google's authenticator ======

Google Authenticator is based on and implements the Time-based One-Time Password (TOTP) algorithm specified in RFC 6238.
6-digit code.

===== read image from file  =====

<code bash>
zbarimg -q Screenshot.png 
QR-Code:otpauth://totp/Google%3Auser%40example.com?secret=base32secret&issuer=Google
</code>

===== generate QR from command line  =====

<code bash>
qrencode -t ANSI256UTF8 'otpauth://totp/Google%3Auser%40example.com?secret=base32secret&issuer=Google'
</code>