Java Card 2.2 Off-Card Verifier

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Java Card 2.2 Off-Card Verifier
White Paper
June, 2002

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Contents iii
Contents
1. Introducing the Off-Card Verifier 1
Purpose of Off-Card Verification 1
Runtime Verification 2
Remote Verification 3
Limitations of Non-Incremental Remote Verification 4
Incremental Remote Verification 5
CAP File Verification 7
Verifying for Internal Consistency 8
Export File Verification 9
Compatibility Verification 10
Security Considerations 11
2. Byte Code Verification Algorithm 13
Introduction 13
CAP File Format 13
Context of the Algorithm 14
Entry Point 14
Definitions of States 15
Java Virtual Machine State 15
Abstract Interpreter State 15

iv Java CardTM 2.2 Off-Card Verifier • June, 2002
The Algorithm 16
simulate() 17
transition() 17
enterState() 18
Suggestions for Further Reading 19

1
1
Introducing the Off-Card Verifier
This paper describes Sun’s Java Card 2.2 Off-Card Verifier. The Off-Card
Verifier provides functionality for verifying CAP files and export files. When
applied to the set of CAP files that will reside on a Java Card-compliant smart
card and the set of export files used to construct those CAP files, the Off-Card
Verifier provides the means to assert that the content of the smart card has
been verified.
Verification determines whether CAP and export files conform to the Java
Card 2.2 specifications. As such, it is an enforcer of the Java Card
interoperability standards. The set of conformance checks provides that such
files do not attempt to compromise the integrity of a Java Card virtual machine
implementation, and hence other applets.
The Java Card 2.2 Off-Card Verifier is designed to be fully backward
compatible with the 2.1 product.
Purpose of Off-Card Verification
As is well known, many of today’s smart cards have extreme size limitations,
often making it infeasible to place verifiers onto Java Card-compliant smart
cards. As larger smart cards continue to become cost-effective, the move to on-
card verification will almost certainly occur. Both under today’s circumstances
and as on-card verification becomes available, Off-Card verification can play
an integral role in the construction of secure Java Card-compliant smart cards.
Off-Card verification provides a means for evaluating CAP and export files in
a desktop environment. Since debugging in a desktop environment is far easier