You can use a smart card and your device password to unlock your BlackBerry device. You can also use smart card certificates to send S/MIME-protected messages.
Smart cards store certificates and private keys. You can import certificates from a smart card to your device by using the BlackBerry Smart Card Reader or a microSD smart card. Private key operations such as signing and decryption use the smart card. Public key operations such as verification and encryption use the public certificates on your device.