Storing Large Amounts of Data

The most efficient way to take advantage of the large memory space is to use it to store data. Today's applications are required to securely store ever-growing amounts of information about the cardholder or network identity. This information includes certificates, images, security keys, and biometric and biographical information.

This information sometimes requires large amounts of storage. Before version 2.2.2, versions of the Java Card platform reference implementation had to save downloaded applications or user data in valuable persistent memory space. Sometimes, the amount of memory space required was insufficient for some applications. However, the memory access schemes introduced with version 2.2.2 allow applications to store large amounts of information, while still conforming to the Java Card specification.

The Java Card specification does not impose any requirements on object location or total object heap space used on the card. It specifies only that each object must be accessible by using a 16-bit reference. It also imposes some limitations on the amount of information an individual object is capable of storing, by using the number of fields or the count of array elements. Because of this loose association, it is possible for any given implementation to control how an object's information is stored, and how much data these objects can collectively hold.

The Java Card 3 Platform, Classic Edition reference implementation, enables you to use all of the available persistent memory space to store object information. By allowing you to separate data storage into distinct array and object types, this reference implementation enables you to store the large amounts of data demanded by today's applications.