Simple Shell script for generating 2FA OATH Codes

#!/bin/bash
secret="${1}"
secret="${secret^^}$(printf "%$(( (8-${#secret}) % 8 ))s" | tr " " "=")"
key="$(base32 -d <<< "$secret" \
    | xxd -p \
    | tr -cd 0-9A-Fa-f)"
mac=$(printf "%016X" "$(( ($(date +%s)) / 30))" \
    | xxd -r -p \
    | openssl sha1 -binary -mac hmac -macopt "hexkey:$key" \
    | xxd -p)
offset="$(( 16#"${mac:39:1}" * 2))"
printf "%06d\n" "$(( (0x${mac:offset:8} & 0x7FFFFFFF) % 1000000 ))"

Usage

DOWNLOAD

[яøøt@waxxx.org ~]$ chmod +x 2fa.sh
[яøøt@waxxx.org ~]$ ./2fa.sh 'EQ2LQZE7YMVHHSL7DCZLPYG4WC2DV7BL'
594594