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Designing a secure PCB

Hackers are a risk to the security of any device but while they can hack machines and steal essential details and data, it is possible to prevent hackers accessing your printed circuit board (PCB) design and it’s not as difficult as it seems if you implement security using a series of steps.

A useful means to avoid hackers is to design your PCB with full security. If assembly takes place after adding dedicated researched designs for protection, there really is no need to be afraid of hackers and if you add a number of techniques and components that can stop data loss, then that too will help.

However, one single step cannot by itself prevent a determined hacker from hacking a PCB design.

Most hackers are computer experts or engineers (in the case of PCB hackings) who have the technical knowledge to exploit any weaknesses within a system or device.

According to one ethical hacker, Joe Grand, there are several ways hackers like him can target PCBs. The first is surprisingly simple they gather information that’s publicly available and start digging into, for example, data buses and programming points.

After that more advanced forms of hacking tend to be employed. Grand has exposed some of the advanced processes which can include chip decapping, simple and differential power analysis, among many other techniques. Through these techniques they are able to find entry points to the PCB and then access information and data.

There are a number of techniques designers can bring to the development of PCBs that are able to counter these attacks, whether that’s in terms of the PCB design or assembly process.

Unnecessary information

The most helpful thing for hackers that they can use against your PCB is information. Without adequate information, hacking isn’t going to be possible.

Anyone related to the PCB assembly – the marketing and sales team, designers, engineers, etc. – that doesn't require extensive details or information regarding the PCB should have limited or no access to

technical data. Engineers are there to design your PCB so refrain from giving out additional information that is unnecessary to them. Chances are, the information may get leaked, and will find its way into the hands of the hacker.

Removing extraneous information from the PCB assembly and designing process will prevents hackers from getting the information they need.

Embedded and planar capacitors

Another factor that can help to prevent hackers is the addition of embedded and planar capacitors to a PCB design. If you are using a multilayer PCB, it will be easier to embed integrated circuits inside the PCBs and will add another level of difficulty in terms of the hacking process.

Hackers can also use differential power analysis to get details from inside a chip (in a PCB) to read memories, determine information, and so forth.

One key countermeasure is adding embedded and planar capacitors. They contribute a crucial part in saving PCB space and help to reduce the ground bounce effect where the voltage level of a ground reference changes value – ‘bounces’ – to a different value which can cause circuit operation to perform erroneously.

By making all the state-dependent power signatures look the same – it can also help to confuse the hackers.

Use parts without leads

If your PCB has probe points, then it could be prone to hackings. So to safeguard your PCB from hackers you will need to clear the probe points.

One approach is to use a BGA (Ball-grid Array) to your PCB. They don't leave probe points or leads while getting connected to your PCB. Also, use footprints for your integrated circuits that have no leads.

In a multilayer PCB, you will notice that from the BGA parts, the electric connections get taken down to a PCB's intermediate layers. The electric connections will stay in the intermediate layers until they get to re-emerge (under a sensor).

Nothing is possible without leads or probe points, debugging/ reprogramming, or inter-chips' interception so this approach helps block another route for the determined hacker.

Encrypt data

In a PCB design, an unsecured UART port helps engineers to encrypt the debug port. Storing such a process is challenging since encryption of the debug port is crucial so you can add an asymmetric key to stop an adversary due to an unsecured UART.

Engineers will be able to use the key to encrypt a chip's serial communication and this can be carried out during the programming process.

All such activists using the key will remain unknown to the hackers and without a key, all the data will seem random to an intruder. Thus, during the PCB assembly, adding an asymmetric key to your PCB design can prevent hackers.

Use a MCU with low electromagnetic emissions

Security in a microcontroller used in a PCB is essential however in some circumstances, it may arise that the microcontroller doesn't have integrated security units. In that case you can easily add security modules to your PCB.

In a PCB, there exist electromagnetic disturbances. Now, to prevent hacking of a PCB, there need to be fewer electromagnetic disturbances. It will ensure that the hackers won't be able to get much information.

To safeguard your PCB, you need to install in it a microcontroller that emits fewer electromagnetic disturbances. The low electromagnetic emissions can prevent different adversaries by a hacker, thus preventing hacking.

Hide your traces or unintended emissions

Another great idea to design your PCB that can prevent hackers is hiding traces. With the help of through-hole PCB Assembly, you can ensure to place different components in the outer layer of the PCB, and it should be ground-placed.

To prevent or hide any traces (it can be unintended emissions as well), you need to oversee if the ground-planes are going through the process of through-hole PCB assembly or not. All it takes place through the stitching to the ground layers.

Thus, you can effectively prevent hackers if you hide any of your tracks through different PCB assembly processes.

Conclusion

In the end, we can say that hackers can be quite harmful to PCB; and extremely harmful if the PCB asset is highly valuable. You cannot let them hack it and exploit all the data and information. Thus, you have to take countermeasures.

Countermeasures in the sense that can help prevent hackings from getting their hands on your PCB or a device. As we have already discussed above, you can see six different ideas for designing a PCB to prevent potential hackers.

You can remove any unnecessary information regarding the PCB design so that no one can get hands-on with it. It won't be a problem since an engineer won't require much information to design a PCB or even assemble it. They probably won't even notice.

Also, components and parts that don't leave any traces or leads can help prevent hackers since they wouldn't get information. Even hiding the unintended emissions from a PCB can stop hackers from using your PCB's confidential information.

What's more, you can use embedded and planar capacitors and asymmetric keys to protect your PCB from hackers. Along with it, it will be highly beneficial if you add microcontrollers to your PCB design that has considerably less electromagnetic emissions.

Author details: Ken Ghadia works as a Sales Engineer at Technotronix

Author
Ken Ghadia

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