Electromagnetic Side-Channel Analysis of Cryptographically Secured Devices

Electromagnetic (EM) side-channel analysis has emerged as a significant threat to cryptographically secured devices, particularly in the era of the Internet of Things (IoT).

These attacks exploit information leakages through physical parameters such as EM radiation, which is emitted by all powered electronic devices due to internal current flows.

Unlike traditional power analysis attacks, EM side-channel attacks can be performed non-invasively using low-cost EM probes, making them more accessible and affordable for potential attackers.

Methodology

The methodology behind EM side-channel attacks typically involves two phases: data collection and analysis.

In the first phase, EM emanations from a device are captured using EM probes, often connected to a low-noise amplifier for better signal quality.

The collected traces are then analyzed using various models, including Simple Electromagnetic Analysis (SEMA), Differential Electromagnetic Analysis (DEMA), and Correlation Electromagnetic Analysis (CEMA).

CEMA is particularly effective as it can retrieve secret keys without requiring detailed knowledge of the device’s operations.

For instance, a CEMA attack on the PRESENT lightweight cipher can recover up to 8 bytes of a 10-byte encryption key using just 256 EM waveforms.

Impact

Recent studies have highlighted the importance of preprocessing techniques in enhancing the efficiency of EM side-channel attacks.

By applying optimal preprocessing methods, the number of traces required for key recovery can be significantly reduced, improving the success rate of attacks.

Additionally, profiling attacks, such as template and machine learning-based methods, have shown promising results in extracting sensitive information from complex devices like System-on-Chips (SoCs).

To mitigate EM side-channel vulnerabilities, researchers have proposed various countermeasures.

One approach involves routing cryptographic signals through lower metal layers to reduce EM leakage, as demonstrated by the STELLAR solution.

This method aims to eliminate critical signal radiation from higher metal layers, thus enhancing the security of cryptographic ICs.

Furthermore, ongoing research focuses on developing low-overhead solutions that can protect against both power and EM side-channel attacks, emphasizing the need for a comprehensive security strategy in the design of future cryptographic devices.

As EM side-channel analysis continues to evolve, it is crucial for device manufacturers to integrate robust countermeasures to safeguard against these increasingly sophisticated threats.

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