Java Card
Java Card is a variant of the Java programming language , which allows Java Card applets, following a reduced Java standard, to run Java applets on chip cards .
Java Card applets are only executed if a chip card is connected to an external power supply and the Java VM of the card has received the instruction to select a specific applet. The security mechanisms of Java allow a Java chip card to contain several applets which do not influence each other as long as the memory capacity of the card is not exceeded. Java Card Applets can be installed subsequently on a Java chip card and, like Java programs, are independent of the hardware of the chip card. Java Card Applets only communicate with a connected card reader via APDUs ( Application Protocol Data Units ) ; A possible protocol for this data channel is Java Card Remote Method Invocation, a protocol for calling object methods between Java VMs.
Java Card Applets are primarily used for the secure storage and use of cryptographic keys. For this purpose, the keys can be generated on the chip card and the reading of the private key from the card is prevented if possible.