Apparatus forming a portable charge, debit or similar identification card which can be read using a magnetic card reader and methods for securing information are described. The preferred apparatus includes a magnetic stripe for storing information, a jamming assembly configured to emit a jamming signal which temporarily renders at least a portion of the magnetic stripe unreadable when the card is swiped through the card reader without first entering correct authentication data, and a power source adapted to supply power to the jamming assembly. Other features are also disclosed.