702
7 Countermeasures Against Hardware Trojans
In addition to improved detection methods developed within the framework of
traditional information forensic, the authors used a new theoretical concept of information forensic known as adverse dynamics [111] to develop previously unexamined
methods of Trojan identification in the cited work. Adverse dynamics uses mathematical instruments of games theory to determine optimal actions of the intruder
attempting to hide an electrical circuit with embedded hardware Trojan in the IC
design, as well as optimal countermeasures used in IC design process. Here, the
relations between a policeman and an intruder taken from the games theory are used,
and various possible actions of the intruder (hiding) and the policeman (finding and
arresting/liquidating the intruder) are analyzed from the mathematical point of view.
7.6.2 Technical Solutions to the Program
This method is based on using the side-channel method mentioned above, which
helps to measure insignificant changes in supply voltages and currents inside the
chip directly associated with the elements of the introduced hardware Trojan.
Using a special mathematical apparatus, as shown in [110–113], experts can identify footprints of such Trojans on images. For this purpose, complex statistical models
and signal processing algorithms, elements of graph theory, etc. are used.
The assessment of fluctuations (variations) the voltage levels in the circuits of IC
internal power sources, including noise levels in the power circuit and the common
bus, is specifically used here.
An important point here is that every IC topology is characterized by its own
individual profile of power circuit noise. Figuratively speaking, similarly to unique
fingerprints of each person, each microcircuit has its own unique noise fingerprint that
is individual to a specific topology. These profiles taken for the original microcircuit
will differ from the profile of the same microcircuit with emdedded hardware Trojan,
since the introduced integrated elements of the hardware Trojan will change the
structure of the circuit and increase the load on the internal power supply network
of the IC. This will accordingly cause changes in the interference profile, which
will indicate traces of an embedded Trojans. Since the number of elements of the
introduced Trojan is usually extremely small compared to the number of IC elements,
such task is extremely difficult. Thus, the authors of this method suggest a nontraditional solution for developers of ICs with high levels of protection from Trojans,
namely—to integrate embedded voltage sensors directly into ICs. It is suggested to
place them in critical IC locations, where the masking of a Trojan is most possible.
Moreover, in order to make traces of operation of a Trojan more noticeable, it is
suggested to deliberately increase interference levels in the supply circuits to a certain
acceptable level. Of course, this is not in line with standards and design rules applied
by microcircuit developers, which determine priority of interference reduction in IC
power supply circuits.
7 Countermeasures Against Hardware Trojans
In addition to improved detection methods developed within the framework of
traditional information forensic, the authors used a new theoretical concept of information forensic known as adverse dynamics [111] to develop previously unexamined
methods of Trojan identification in the cited work. Adverse dynamics uses mathematical instruments of games theory to determine optimal actions of the intruder
attempting to hide an electrical circuit with embedded hardware Trojan in the IC
design, as well as optimal countermeasures used in IC design process. Here, the
relations between a policeman and an intruder taken from the games theory are used,
and various possible actions of the intruder (hiding) and the policeman (finding and
arresting/liquidating the intruder) are analyzed from the mathematical point of view.
7.6.2 Technical Solutions to the Program
This method is based on using the side-channel method mentioned above, which
helps to measure insignificant changes in supply voltages and currents inside the
chip directly associated with the elements of the introduced hardware Trojan.
Using a special mathematical apparatus, as shown in [110–113], experts can identify footprints of such Trojans on images. For this purpose, complex statistical models
and signal processing algorithms, elements of graph theory, etc. are used.
The assessment of fluctuations (variations) the voltage levels in the circuits of IC
internal power sources, including noise levels in the power circuit and the common
bus, is specifically used here.
An important point here is that every IC topology is characterized by its own
individual profile of power circuit noise. Figuratively speaking, similarly to unique
fingerprints of each person, each microcircuit has its own unique noise fingerprint that
is individual to a specific topology. These profiles taken for the original microcircuit
will differ from the profile of the same microcircuit with emdedded hardware Trojan,
since the introduced integrated elements of the hardware Trojan will change the
structure of the circuit and increase the load on the internal power supply network
of the IC. This will accordingly cause changes in the interference profile, which
will indicate traces of an embedded Trojans. Since the number of elements of the
introduced Trojan is usually extremely small compared to the number of IC elements,
such task is extremely difficult. Thus, the authors of this method suggest a nontraditional solution for developers of ICs with high levels of protection from Trojans,
namely—to integrate embedded voltage sensors directly into ICs. It is suggested to
place them in critical IC locations, where the masking of a Trojan is most possible.
Moreover, in order to make traces of operation of a Trojan more noticeable, it is
suggested to deliberately increase interference levels in the supply circuits to a certain
acceptable level. Of course, this is not in line with standards and design rules applied
by microcircuit developers, which determine priority of interference reduction in IC
power supply circuits.