15-10-2009, 01:23 PM
Java Card refers to a technology that allows small Java-based applications (applets) to be run securely on smart cards and similar small memory footprint devices. Java Card is the tiniest of Java targeted for embedded devices. Java Card gives the user ability to program the device and make them application specific. It is widely used in SIM cards (used in GSM mobile phones) and ATM cards. The first Java Card was introduced in 1996 by Schlumberger's card division which later merged with Gemplus to form Gemalto. Java Card products are based on the Java Card Platform specifications developed by Sun Microsystems.
Security
Java Card technology was originally developed for the purpose of securing sensitive information stored on smart cards. Security is determined by various aspects of this technology:
* Data encapsulation. Data is stored within the application, and Java Card applications are executed in an isolated environment (the Java Card VM), separate from the underlying operating system and hardware.
* Applet Firewall. Unlike other Java VMs, a Java Card VM usually manages several applications, each one controlling sensitive data. Different applications are therefore separated from each other by an applet firewall which restricts and checks access of data elements of one applet to another.
* Cryptography. Commonly used encryption algorithms like DES, Triple DES, AES, RSA (including elliptic curve cryptography) are supported. Other cryptographic services like signing, key generation and key exchange are also supported.
* Applet.The applet is a state machine which processes only incoming command requests and responds by sending data or response status words back to the interface device.
Specific features
The Java Card runtime and virtual machine also support features that are specific to the Java Card platform:
* Persistence. With Java Card, objects are by default stored in persistent memory (RAM is very scarce on smart cards, and it is only used for temporary or security-sensitive objects). The runtime environment as well as the bytecode have therefore been adapted to manage persistent objects.
* Atomicity. As smart cards are externally powered and rely on persistent memory, persistent updates must be atomic. The individual write operations performed by individual bytecode instructions and API methods are therefore guaranteed atomic, and the Java Card Runtime includes a limited transaction mechanism.
* Applet isolation. The Java Card firewall is a mechanism that isolates the different applets present on a card from each other. It also includes a sharing mechanism that allows an applet to explicitly make an object available to other applets.
