Fun with a very basic implementation of TOTP

totp-fun.sh

#!/bin/sh

# generate shared secret for TOTP
secret='never gonna give you up'
# take only the last 16 characters less padding
# apply standard formatting (see https://github.com/google/google-authenticator/wiki/Key-Uri-Format )
# generate the QR code (remember to apply percent encoding for the url)
echo -n $secret | base32 | sed 's/=//g' | tail -c 16 | xargs -I $ echo 'otpauth://totp/savaged%20info:alice@test.com?secret=$&issuer=Savaged' | xargs qrencode -o ~/Downloads/savaged-qr-code.png

#finally, generate TOTP
#`echo -n $secret | base32 | sed 's/=//g' | tail -c 16 | xargs oathtool -b --totp`
zbarimg -q savaged-qr-code.png | sed -n -e 's/^.*secret=//p' | sed -E 's/^(.*)\&issuer\=\w+/\1/g' | xargs oathtool -b --totp