An added level of security is added to charge card transactions. Therefore, the insulating material can be plugged smoothly without a void, the processing is simplified by plugging the insulating material just to the height of the circuit pattern in a space between the circuit patterns and accordingly, damage to the circuit pattern can be prevented. new states are determined based on kn previous states and a most recently received sample, using J transitions, J being a less than L, where L is a size of a symbol alphabet.