USENIX Technical Program - Abstract - Smartcard 99
Secure Object Sharing in Java Card
Michael Montgomery and Ksheerabdhi Krishna, Austin Product Center, Schlumberger
Since the invention of the Java Card, the issue of code and data
sharing has been a topic of great interest. Early Java Cards shared
data via files secured with access control lists. Java Card 2.1
specification introduced a method of object sharing, allowing access
to methods of server applets using Shareable Interface Objects (SIO).
However, this SIO approach can be improved. It permits access to
all interfaces of the SIO, whereas some interfaces may be intended
only for particular clients. AID impersonation could be used to gain
access to services unless the card authenticates all applets. Access
to a SIO by future applets may be impossible. Passing object data
between applets is quite cumbersome.
An approach to object sharing
based on delegates is described, which provides needed improvements
with minimal modifications to Java Card 2.1. Using the delegate
approach, only the desired methods of an applet are exposed, and each
method can be protected by any security policy the applet wishes to
implement. A shared secret security policy is described, using
challenge/response phrases to avoid revealing the shared secret. Such
a security policy does not require applet authentication to avoid AID
impersonation, and lends itself readily to access by any future
applets that may be written.
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