5.1 Brief Review of Basic Techniques for Detection …
461
5.1.11 Improved Side-Channel Analysis Methods
Du et al. [20] suggested using a modernized method based on side-channel analysis
for detection of hardware Trojans. The power consumption of a specific fragment
of one information system is compared with the power consumption of the same
fragment of another similar information system. The cause of the detected difference
in the levels of power consumption values may be a Trojan. This technology is called
“self-reference” (a separate paragraph will be devoted to its consideration in Chap. 6).
Narasimhan et al. [35] applied the method in which various blocks are locally
stimulated by corresponding effects. Transient current (/) and maximum frequency
are determined by a side-channel analysis. Since I DDT and / ax are linearly interdependent, and f max is not subject to change, a Trojan can be detected if the fact of
increasing the / value is fixed.
To identify the most minimal theoretically detectable Trojan, Rad et al. [39] used
a transient signal spectrum sensitivity analysis along the supply circuit. The minimal
detectable Trojan can basically consist of a single logical element, but this Trojan
in any case responds to the test sequence. It is shown that if the measurement corresponds to a signal-to-noise ratio of 10 dB, the size of the minimum detectable Trojan
increases to seven logical elements.
5.1.12 Thermal Conditioning Methods
The method for detecting Trojans by combining the procedure characterization of
logical elements with so-called thermal conditioning is presented in work [43].
Thermal conditioning means that the examined microcircuit is heated unevenly. This
method is based on the universally known physical effect that the leakage current
value increases exponentially with increasing temperature.
The objective of this method is to exclude other possible correlations that arise
in the process of measuring the numeric value of extremely low leakage current
and are caused by the interdependence of characteristics of logical elements. Due to
the uneven heating of interconnected microcircuit elements, the calculation results
become more adequate. The results of such simulation can be used to calibrate the
measurement procedure itself and to minimize the differences in measurement results
caused by manufacturing tolerances in the process of making an IC. The advantage
of using this method is a complete characterization of all the logical elements of a
microcircuit.
The method for detecting Trojans by combining characterization of logical
elements with thermal conditioning is not suitable for microcircuits with a large
area, since their properties in this case are determined for the entire circuit. Highly
professional attackers can take advantage of this fact and install extremely small-sized
Trojans, the effect of which will be unnoticeable against process and measurement
interferences [48]. In order to make this process manageable and, therefore, suitable
461
5.1.11 Improved Side-Channel Analysis Methods
Du et al. [20] suggested using a modernized method based on side-channel analysis
for detection of hardware Trojans. The power consumption of a specific fragment
of one information system is compared with the power consumption of the same
fragment of another similar information system. The cause of the detected difference
in the levels of power consumption values may be a Trojan. This technology is called
“self-reference” (a separate paragraph will be devoted to its consideration in Chap. 6).
Narasimhan et al. [35] applied the method in which various blocks are locally
stimulated by corresponding effects. Transient current (/) and maximum frequency
are determined by a side-channel analysis. Since I DDT and / ax are linearly interdependent, and f max is not subject to change, a Trojan can be detected if the fact of
increasing the / value is fixed.
To identify the most minimal theoretically detectable Trojan, Rad et al. [39] used
a transient signal spectrum sensitivity analysis along the supply circuit. The minimal
detectable Trojan can basically consist of a single logical element, but this Trojan
in any case responds to the test sequence. It is shown that if the measurement corresponds to a signal-to-noise ratio of 10 dB, the size of the minimum detectable Trojan
increases to seven logical elements.
5.1.12 Thermal Conditioning Methods
The method for detecting Trojans by combining the procedure characterization of
logical elements with so-called thermal conditioning is presented in work [43].
Thermal conditioning means that the examined microcircuit is heated unevenly. This
method is based on the universally known physical effect that the leakage current
value increases exponentially with increasing temperature.
The objective of this method is to exclude other possible correlations that arise
in the process of measuring the numeric value of extremely low leakage current
and are caused by the interdependence of characteristics of logical elements. Due to
the uneven heating of interconnected microcircuit elements, the calculation results
become more adequate. The results of such simulation can be used to calibrate the
measurement procedure itself and to minimize the differences in measurement results
caused by manufacturing tolerances in the process of making an IC. The advantage
of using this method is a complete characterization of all the logical elements of a
microcircuit.
The method for detecting Trojans by combining characterization of logical
elements with thermal conditioning is not suitable for microcircuits with a large
area, since their properties in this case are determined for the entire circuit. Highly
professional attackers can take advantage of this fact and install extremely small-sized
Trojans, the effect of which will be unnoticeable against process and measurement
interferences [48]. In order to make this process manageable and, therefore, suitable