A User Centric Security Model for Tamper-Resistant Devices

8.2 Smart Card Runtime Environment
compared to the Multos AAM. The rationale is that the JCRE has an open specication,
and new attacks mostly target Java Cards. Furthermore, we consider that Java Card is
more closely related to the UCTD proposal.
Structure of the Chapter: We begin the discussion with a brief introduction of the
SCRT and the combined attacks (i.e. software and fault attacks). In section 8.3, we provide
the motivation behind the runtime protection mechanism, which is a collective term used
to refer to the proposed counter-measures. Subsequently, we discuss attacker's capability,
and detail the runtime protection mechanism. In section 8.4, we analyse the proposed
counter-measures for their security, and performance.
8.2 Smart Card Runtime Environment
In this section, we open the discussion with a brief description of the Java Card Virtual
Machine (JCVM) with emphasis on those components that we will refer to in the rest of the
chapter. Subsequently, we discuss the threat landscape that targets the SCRTs followed
by a brief discussion on related work, and nally, we nish the section with the description
of fault attacks.
8.2.1 Java Card Virtual Machine
The concepts regarding the Java Card application development and runtime environment
are not exhaustively covered in this section. Nevertheless, the rationale for a brief introduction
is to make it easy to follow the subsequent discussion regarding the SCRTs.
The JCRE illustrated in gure 3.3 consists of APIs, system classes, Java Card Virtual
Machine (JCVM), and native methods. The architecture of the JCVM is more or less similar
between various version of Java Cards including the latest Java Card 3.0.1 Connected
Edition [16]. The main dierence is the support for various system classes and APIs. As
far as the core processes are concerned, JCVM for both Java Card 2.X or 3.0.1 Classic
Edition and Java Card 3.0.1 Connected Edition are similar, which is in adherence to the
Java virtual machine specication [200] (i.e. JCVM is a subset of the Java virtual machine
specication [16, 28]).
Before we delve into the details of the JCVM, we rst look at the development process of
a Java Card application, as illustrated in gure 8.1. An application is coded in a subset
of Java language that is supported by the JCVM, which is represented as a Java le in
gure 8.1. The application is then compiled into a class le, and it is packaged along with
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