#!/bin/bash

trap '' 1 2 3 18
stty -echo
echo -n "Key: "
read key_1
echo
echo -n "Again: "
read key_2
echo
key_3=
if [ "$key_1" = "$key_2" ]
    then
        tput clear
        until [ "$key_3" = "$key_2" ]
        do
            read key_3
        done
    else
        echo "locktty: keys do not match" 1>&2
fi
stty echo