How to secure hardware against side-channel attacks

For companies that produce IoT devices, embedded systems and chipsets, side-channel attacks are a serious and growing risk. Therefore, engineers and designers must understand how they work to secure electronics.

Zac Amos, Contributing Writer further explores.

What are side-channel attacks?

A side-channel attack is a method of extracting sensitive informationby analysing indirect data that leaks from a hardware device during operation. Rather than breaking encryption, attackers monitor these devices to uncover secrets, including cryptographic keys and authentication codes.

These leaks are known as side channels because they are not the system's intended output. Even when the device is running secure software, the physical characteristics of how that software executes can expose critical data.

Side-channel attacks can be especially concerning because hackers can deploy them with low-cost tools. Sometimes, even passive monitoring can yield enough data to reconstruct sensitive information. That makes them a potent threat for everything from smart cards and mobile devices to industry hardware systems.

How side-channel attacks work

Side-channel attacks exploit data leakage from a system’s physical operations. Attackers monitor characteristics – such as power consumption, electromagnetic emissions or execution timing – to infer confidential information. Common techniques include:

• Timing attacks: analysing the time taken to execute cryptographic algorithms to deduce secret keys
• Power analysis: measuring consumption during operations to reveal data-dependent patterns
• Electromagnetic analysis: capturing electromagnetic emissions to reconstruct processed information

One recent side-channel vulnerability occurred in Apple processors. Researchers identified flawsin Apple’s speculative execution implementation involving techniques to enhance processing speed by predicting future instructions. Mispredictions in these mechanisms can lead to unauthorised computations on out-of-bounds data values, potentially allowing attackers to escape web browser sandboxes and access sensitive information from Safari or Chrome.

Instances like these establish a critical need for better security and hardware design. While it is difficult to defend against side-channel attacks, there are various practices to mitigate vulnerabilities.

Strategies to secure hardware against side-channel attacks

Protecting hardware involves addressing design-time and runtime risks. The following strategies offer a starting point for minimising vulnerabilities and hardening systems against information leakage.

Assess the attack surface

The attack surface refers to all the points in a hardware system where an attacker could extract data. In side-channel attacks, this includes observable system characteristics that correlate with sensitive operations.

Assessing the attack surface means identifying where and how a system could leak information and then taking steps to reduce or eliminate those leaks. This could involve examining where cryptographic processes occur, how data moves through memory or how often a component performs high-risk operations.

The goal is to shrink the number of observable variables, making the system less predictable and harder to analyse. A smaller attack surface gives attackers fewer opportunities to gather usable data.

Employ design-level protections

Integrating security measures at the design phase is crucial for mitigating side-channel attacks. One approach is incorporating hardware-generated random numbers. This method introduces unpredictability into cryptographic operations, masking power and timing signatures from attackers.

Another common tactic is constant-time algorithms, which ensure operations take the same amount of time regardless of the input values. This reduces the risk of timing attacks that exploit variations in execution time. Designers may even implement techniques where sensitive data splits into multiple random shares during processing, ensuring that power analysis reveals no useful patterns.

Strengthen physical protections

While design-level defences obscure data patterns, physical protections add even more protection by keeping attackers from observing or interacting with hardware. One key method is electromagnetic shielding, which reduces the radiated signals from the device. Enclosing sensitive components in protective casings can make electromagnetic analysis much harder.

Another approach is using active tamper-detection mechanisms. They can detect probing attempts, voltage or temperature shifts, and physical intrusion. In response, they erase cryptographic keys or halt operations.

Simple steps like decoy circuits or multi-layered PCBs can protect against direct physical access. These measures raise the barrier for attackers, especially when devices may be exposed to hostile environments.

Building better hardware from the ground up

Side-channel attacks are growing and evolving, which makes it all the more important to crack down on security. Through a layered approach, engineers can reduce leakage significantly. However, regular testing is required to ensure security is strong from the start.