A card with a magnetic stripe when fed into a card reader can be illegally
read by a read head unobtrusively attached to the outside of the card
reader adjacent to the slot into which the card is fed. To defeat this
illegal reading, movement of a card through the read head is interrupted
thereby making it difficult for the illegal read head to read the stripe.
This interruption occurs at the point where the proper read head inside
the card reader is not reading the magnetic stripe. The interruption can
be a brief stop or a brief reversal in direction. The interruption occurs
once while the card is being fed into the card reader and once when the
card is being fed out of the card reader.