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7 Countermeasures Against Hardware Trojans
contracted production (also known as horizontal business model). The contract
production model provides a significant economic advantage for large production
volumes, since the same production units serve several design companies at the
same time. Therefore, industrial production of ICs developed by large design centers
is taken to developing offshore states with lower labor and operating costs.
In this new model of semiconductor business, the ratio between the developer and
the production is asymmetric: developed IP blocks today are fully transparent for
manufacturers, who are theoretically able to reproduce (or even remake) ICs with
low costs, since original sets of masks are easily accessible to the manufacturers.
However, main technical details of the manufacturing process, technical parameters,
and possible modifications of documentation packages from the original developer
(in the form of topology files, such as the OASIS format) are hidden in the design
center. Complexity of modern VLSIs with multiple internal layers causes problems
with testability and traceability of products, which in turn complicate acquisition of
confirmation of authorship of packaged ICs. As demonstrated by multiple studies of
counterfeit production, many of falsified products didn’t undergo complete testing or
were differently (incorrectly) assembled in package, which affected both the developer’s trademark and requirements of the end user in terms of reliability and security.
This complicates the problem as well as the wide use of ICs in various critical applications with the need to ensure protection from copying, with high protection levels and
requirements for security, such as banking cards, devices with built-in access control
and weapon systems. Prevention of theft of intellectual property (IP), piracy, and
unauthorized alterations becomes more and more important for the tasks of defense,
business, and customers due to critical nature of requirements of these applications
as well as moral and material damages caused by IC falsification, theft, and piracy.
This section contains a brief overview of the main methods to protect microcircuits
from such threats [94, 97, 116–137]. Even though the original primary task of these
methods is the protection from unauthorized copying, both of them can be used as
measures to counter hardware Trojans in microcircuits.
Hardware metering belongs to the category of security methods and protocols that
allow developers (owners of IP rights) to have real control over developed microcircuits after their manufacture in silicon. The term “hardware metering” was first
coined in 2001 in [128, 129], where the first passive methods of unique identification
of functionality of each IC during implementation of the standard production process
using the same set of masks for producing all chips were presented.
These metering methods are preceded by methods of identifying microcircuits
after their manufacturing in silicon and application of special marks to separate microcircuits manufactured with a single set of masks. In case with passive metering, ICs
are specially identified based on their functionality or by means of using other forms
of unique identification. It is subsequently possible to determine correspondence (or
non-correspondence) of such identified ICs to the original with the help of recording
them in the previously created database, which can help identify gray (unregistered)
ICs or metered ICs (in case of conflict situations). Active metering helps not only to
uniquely identify microcircuits, but also organize the situation where access to all
chip functions or a part of them can be locked or unlocked only by the developer
7 Countermeasures Against Hardware Trojans
contracted production (also known as horizontal business model). The contract
production model provides a significant economic advantage for large production
volumes, since the same production units serve several design companies at the
same time. Therefore, industrial production of ICs developed by large design centers
is taken to developing offshore states with lower labor and operating costs.
In this new model of semiconductor business, the ratio between the developer and
the production is asymmetric: developed IP blocks today are fully transparent for
manufacturers, who are theoretically able to reproduce (or even remake) ICs with
low costs, since original sets of masks are easily accessible to the manufacturers.
However, main technical details of the manufacturing process, technical parameters,
and possible modifications of documentation packages from the original developer
(in the form of topology files, such as the OASIS format) are hidden in the design
center. Complexity of modern VLSIs with multiple internal layers causes problems
with testability and traceability of products, which in turn complicate acquisition of
confirmation of authorship of packaged ICs. As demonstrated by multiple studies of
counterfeit production, many of falsified products didn’t undergo complete testing or
were differently (incorrectly) assembled in package, which affected both the developer’s trademark and requirements of the end user in terms of reliability and security.
This complicates the problem as well as the wide use of ICs in various critical applications with the need to ensure protection from copying, with high protection levels and
requirements for security, such as banking cards, devices with built-in access control
and weapon systems. Prevention of theft of intellectual property (IP), piracy, and
unauthorized alterations becomes more and more important for the tasks of defense,
business, and customers due to critical nature of requirements of these applications
as well as moral and material damages caused by IC falsification, theft, and piracy.
This section contains a brief overview of the main methods to protect microcircuits
from such threats [94, 97, 116–137]. Even though the original primary task of these
methods is the protection from unauthorized copying, both of them can be used as
measures to counter hardware Trojans in microcircuits.
Hardware metering belongs to the category of security methods and protocols that
allow developers (owners of IP rights) to have real control over developed microcircuits after their manufacture in silicon. The term “hardware metering” was first
coined in 2001 in [128, 129], where the first passive methods of unique identification
of functionality of each IC during implementation of the standard production process
using the same set of masks for producing all chips were presented.
These metering methods are preceded by methods of identifying microcircuits
after their manufacturing in silicon and application of special marks to separate microcircuits manufactured with a single set of masks. In case with passive metering, ICs
are specially identified based on their functionality or by means of using other forms
of unique identification. It is subsequently possible to determine correspondence (or
non-correspondence) of such identified ICs to the original with the help of recording
them in the previously created database, which can help identify gray (unregistered)
ICs or metered ICs (in case of conflict situations). Active metering helps not only to
uniquely identify microcircuits, but also organize the situation where access to all
chip functions or a part of them can be locked or unlocked only by the developer