A Type System for Checking Applet Isolation in Java Card

Abstract

Abstract. A Java Card applet is, in general, not allowed to access fields and methods of other applets on the same smart card. This applet isolation property is enforced by dynamic checks in the Java Card Virtual Machine. This paper describes a refined type system for Java Card that enables static checking of applet isolation. With this type system, firewall violations are detected at compile time. Only a special kind of downcast requires dynamic checks.

Formal Methods for Smartcard Security

“…D. Caromel, L. Henrio and B. Serpette [22] have proposed a static analysis that detects statically whether an application may raise a security exception, whereas M. Eluard and T. Jensen [40] have proposed a similar but finer analysis that covers more precise sharing policies. W. Dietl, P. Müller and A. PoetzschHeffter [36] manage a similar effect using a type system adapted from ownership type systems. In order for their approach to be practical, downcasts allow to add information to references that can belong to any context into more specific references, e.g.…”