A transaction card with improved security features, comprising: an authentication unit and a magnetic stripe wherein parts of the magnetic field pattern of said magnetic stripe are generated by currents running through coils only after the authentication unit authenticates the transaction card holder. One or more sensors detect attempts to read the card by two magnetic heads, and block the card if a cloning attempt is suspected. The transaction card is thus closed for transactions in a normal state, and the magnetic information is not readable. Only after the card holder authentication, then currents are run through the coils to generate the magnetic information and make the magnetic stripe readable by commercial devices. Authentication means may include entering a PIN via a keyboard, entering a PIN via a keypad, voice recognition identification of one or more voices, biometric identification, or identification via a connection to a remote device.