When are "tamper-proof" components useful?

"Tamper-proof" components are nothing new. Back in the 90s, many owners of inkjet printers felt offended when manufacturers began equipping cartridges with chips that prevented refilling. Today, iPhone owners are annoyed by corresponding warning messages about a potentially faulty battery.

At the same time, however, we now carry out our banking transactions on our smartphones without a care in the world. We can only do this because digitally signed software components guarantee the integrity of the device (hopefully!).

These are just two examples from the consumer sector. The topic is at least as important (and controversial) in commercial applications, such as spare parts. This is an important interface topic that we as systems engineers should definitely address.

Why tamper-proof components?

Security is one of the main drivers of tamper-proof components. This applies to both functional safety and Attack security.

An inferior copy of an airbag affects the functional safety of a vehicle.

The topic Attack security so present that we hardly need to go into it any further.

But there are also other reasons for tamper-proof components. First and foremost, we like to accuse manufacturers of greed: they just want to sell their expensive ink cartridges or original replacement batteries. There is certainly some truth in this. But I don't want to condemn this behavior here; after all, every product needs a functioning business model.

I find the issue more problematic when functioning products are rendered unusable by such measures, such as the Zune MP3 player from Microsoft.

Realize counterfeit protection

The issue of counterfeit protection is thousands of years old. Seals, stamps, embossing, printing and the like are the means of choice and are still relevant today. But such approaches are rarely controversial. After all, these techniques do not restrict the consumer.

However, tamper-proof components that prevent the use of a non-original replacement component are controversial. Users generally find this bad (see above), especially if they feel they are being cheated. Manufacturers, on the other hand, often argue that the user should be protected.

Counterfeit protection can be realized physically, for example through the use of special screws or threads. However, such measures can be overcome comparatively easily. Electronic measures, such as the aforementioned chips in printer cartridges, are much more complex.

For pure software components, developers generally rely on Public key encryption method (There is also a good explanatory video at Privacy Tutor). The author of a component creates a hash of the software and signs it with the public key of the infrastructure operator. The operator can then use his private key to check whether the software component has been manipulated or replaced.

Counterfeit protection in systems engineering

We need to take a systematic approach to attack security in particular. Security must be considered from the outset. The architect must take security requirements into account right from the start. Furthermore, measures to protect against counterfeiting are just one of many.

In systems engineering in particular, it is not enough for a single component to be forgery-proof. A chain is only as strong as its weakest link. This chain often consists of hardware and software. We therefore need to secure all relevant components to the same degree.

In principle, we do not need to secure all components. After all, counterfeit protection increases costs and increases the risk of configuration problems. With this in mind, we should classify components accordingly. However, caution is also required here. After all, attackers often gain access to systems via less critical components. For example hackers broke into a Jeep via the infotainment system back in 2015. in.

Conclusion

The drivers for tamper-proof components today are primarily functional security and attack protection. The protection of business models plays a secondary role. For us as systems engineers, attack security is by far the most important challenge. We can only guarantee attack security if we incorporate it into the architecture of the system from the outset. But even then, forgery protection is only one of many tools we have at our disposal for this task. And often it is not even the best tool.

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