Untitled

The application of RFID as anti-counterfeiting technique 159
In the following section, we introduce a non-formal attack model that helps to
structure the requirement specification and the design phase. Thereafter, we
outline and critically assess four principal solution concepts and show a possible
migration path.
12.2 The use of RFID to avert counterfeit trade
The specification of auto-ID-based anti-counterfeiting technologies is strongly
influenced by security-related requirements as well as by the design parameters
which stem from an integration in the desired production and inspection settings;
both aspects are discussed below.
The attack model
A critical design parameter of anti-counterfeiting technologies is the desired level
of security. Attack models allow structuring of the requirement analysis. In
cryptography, such models usually take the form of an ‘‘experiment,’’ a program
that intermediates communications with a fictional adversary, and a runtime
environment containing the system components (often referred to as oracles) [3].
Security models have to accurately reflect real-world threats (i.e. the capabilities of
illicit actors) as well as the actual system characteristics. With respect to RFID,
appropriate models should address not only the top-layer protocols, but also the
basic characteristics of RFID transponders down to the bit level. The latter may
lead to less formal descriptions but is necessary in order to capture relevant threat
scenarios like power analyses (and other side-channel attacks) and destructive
reengineering tests. Therefore, the attack model outlined below consists of a nonformal
description of the system characteristics and the capabilities of the illicit
actors as well as the identification and evaluation of the – partly novel – attack
scenarios.
System capabilities
Low-cost RFID transponders are limited with respect to their maximum gate
count (as the chip size influences transponder cost), the available energy (due to
the restrictions on transmitting power of readers, the size of the antenna, and the
considerable distance between tag and reader devices which is often required), and
the frequency spectrum. This ultimately results in limited computational power,
confines the memory size and communication bandwidth, and hampers the integration
of sophisticated pseudo-random-number generators or sensors against
hardware attacks. Strong public key cryptography systems, for example, are still
out of scope for low-cost RFID transponders.
Another important characteristic of RFID results from the radio connection
between tag and reader. Connectivity is connectionless and communication is