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4 Hardware Trojans in Microcircuits
the Trojan at the pre-programmed time. Such Trojans are also known as time
bombs. Trigger mechanisms of the Trojan can monitor physical parameters of
the target device, such as temperature and energy consumption.
(2) For external activation of a Trojan, an external effect on the target functional unit
is necessary. Such effect can be a user input or a component output. User input
triggers can be command keys, switches, keyboards, or even key words/phrases
in the input data stream. This mechanism can be activated from the outside by
any components interacting with the target device.
The next question: what are the consequences of activation of a hardware
Trojan? Hardware Trojans can be also classified based on their unwanted actions.
The degree of severity of their effect on the target hardware and/or system may vary
from insignificant violations to catastrophic failures of the microcircuit or the system
in general. For example:
(1) Hardware implant can alter function of the target device and cause minor
discrepancies (errors, failures) that can be hard to detect;
(2) A hardware Trojan can change specifications by deliberately altering device
parameters. It can alter functional specifications, interface, or technical parameter protocols (specifications), such as power and delay values;
(3) A hardware Trojan can cause leakage of confidential information. This can
happen via open and hidden channels. Data leakage can be organized via radio
channels, as well as optical, thermal, power, and temporary channels, as well as
through standard interfaces, such as RS 232 and JTAG;
(4) Denial of service (DoS). Hardware Trojans can prevent implementation of the
target function or resource. A hardware Trojan can cause a specific module
to exhaust limited resources, such as bandwidth, computing power, or battery
power. Some hardware Trojans can cause physical destruction, shutdown, or
changes in the device configuration. In the above example, the hardware Trojan
prohibits the system to carry out encryption functions. DoS can be either
temporary or permanent.
And, finally, last but not least: where are hardware Trojans located?
A hardware Trojan can be installed in a single component or distributed across a
number of components. Hardware Trojans can be located in processor units, memory
modules, inputs/outputs, electrical circuits, or tree-like synchronization structures.
Hardware Trojans composed of several components (installed in several components)
can operate independently from each other, like an IC-based criminal gang.
4 Hardware Trojans in Microcircuits
the Trojan at the pre-programmed time. Such Trojans are also known as time
bombs. Trigger mechanisms of the Trojan can monitor physical parameters of
the target device, such as temperature and energy consumption.
(2) For external activation of a Trojan, an external effect on the target functional unit
is necessary. Such effect can be a user input or a component output. User input
triggers can be command keys, switches, keyboards, or even key words/phrases
in the input data stream. This mechanism can be activated from the outside by
any components interacting with the target device.
The next question: what are the consequences of activation of a hardware
Trojan? Hardware Trojans can be also classified based on their unwanted actions.
The degree of severity of their effect on the target hardware and/or system may vary
from insignificant violations to catastrophic failures of the microcircuit or the system
in general. For example:
(1) Hardware implant can alter function of the target device and cause minor
discrepancies (errors, failures) that can be hard to detect;
(2) A hardware Trojan can change specifications by deliberately altering device
parameters. It can alter functional specifications, interface, or technical parameter protocols (specifications), such as power and delay values;
(3) A hardware Trojan can cause leakage of confidential information. This can
happen via open and hidden channels. Data leakage can be organized via radio
channels, as well as optical, thermal, power, and temporary channels, as well as
through standard interfaces, such as RS 232 and JTAG;
(4) Denial of service (DoS). Hardware Trojans can prevent implementation of the
target function or resource. A hardware Trojan can cause a specific module
to exhaust limited resources, such as bandwidth, computing power, or battery
power. Some hardware Trojans can cause physical destruction, shutdown, or
changes in the device configuration. In the above example, the hardware Trojan
prohibits the system to carry out encryption functions. DoS can be either
temporary or permanent.
And, finally, last but not least: where are hardware Trojans located?
A hardware Trojan can be installed in a single component or distributed across a
number of components. Hardware Trojans can be located in processor units, memory
modules, inputs/outputs, electrical circuits, or tree-like synchronization structures.
Hardware Trojans composed of several components (installed in several components)
can operate independently from each other, like an IC-based criminal gang.