The growing complexity and frequency of security threats facing organisations across the globe is leading to an even greater focus on what is needed to keep devices secure. Antitamper IP such as clock attack monitors, voltage glitch detectors, temperature sensors, and electromagnetic sensors can play a vital role in detecting and repelling security attacks in electronic systems.
Clock attack monitors
Clock attacks involve manipulating the clock signal that controls the timing of operations in a microprocessor. A hacker can force a device into a vulnerable state by physically tweaking the incoming clock’s frequency or timing to cause setup and hold violations, glitches, or to single-step the clock. Clock attack monitors closely follow the frequency and timing of the clock signal. Sudden changes in frequency or unexpected delays, indeed any irregularity in the clock signals, could be a warning of a potential attack. A clock attack monitor reacts quickly to potential threats allowing the secure system to implement counter-measures, including going into safe mode, starting a reset, or sending alerts, if variations in the clock signal are identified.
The secure area within a microprocessor and a SoC involves sensitive computations, such as key generation or encryption, which require precise timing. This makes them vulnerable to clock attacks. These attacks are also a concern for embedded systems and IoT devices. However, if a device’s clock is being manipulated it can be detected if a clock attack monitor is used.
Voltage glitch detectors
Voltage glitching attacks involve an attacker tampering with the incoming power supply of a device to bypass security features or impact on the system’s operations. A precisely timed voltage glitch can leave a device open to side-channel attacks and bypass even extensive security measures. A voltage glitch detector continuously monitors the power supply. This will trigger an alert and the system may be shut down to prevent damage or data leaks if an unexpected difference in voltage is identified. Attackers may try to create voltage drops or spikes to cause errors that allow them to break encryption algorithms.
Voltage glitch detectors help by constantly monitoring the power supply, minimising the chances of a successful attack.
There have been several recently reported SoC security breaches where a precisely timed voltage glitch has been exploited to breach the security of high profile devices, such as Raspberry Pi and Xbox. Voltage glitch detectors have a vital role in tamper detection. They are especially important in organisations with financial systems, defence equipment, and cryptographic devices. In smartcards, secure microcontrollers or cryptographic hardware, voltage glitch detectors are commonly used.
Temperature monitors
Whilst voltage and clock glitches can easily be applied to clocks and supplies with external pins, it is also possible to cause supply and timing faults without having physical access to the critical clock and supply lines. Thermal attacks, where the device is rapidly heated, cooled, or taken out of its designed operating specification, can generate timing errors, including set-up and hold violations to modify device behaviour. Temperature monitors can detect unforeseen thermal variations. High temperatures or temperature changes, either cooling or heating, could indicate tampering activity. Fast detection means a prompt response to prevent potential tampering, by triggering an alarm or initiating safe mode.
Electromagnetic sensors
Another increasingly common attack route which does not require physical access to individual signals is electro-magnetic fault injection (EMFI). The researcher Thomas Roth published a security attack of Apple’s ACE3 custom USB-C controller at the 38C3 conference in 2024, demonstrating the dangers of electromagnetic attacks. Electromagnetic sensors identify very small changes in external magnetic fields, making them ideal for these types of attacks. If an attacker tries to tamper with a device using an electromagnetic pulse the sensor detects this and triggers an alert. They offer real-time detection and a fast response, crucial to responding quickly to these attacks.
Combining anti-tamper tools
The EU’s Common Criteria defines several levels of vulnerability assurance as part of its EAL (evaluation assurance level) called AVA_VAN. The higher the AVA_VAN level the more secure a device or system is against security threats. Combining multiple monitors and sensors can offer a comprehensive anti-tamper solution which, when implemented correctly, supports an improved AVA_VAN score. Delivering devices and systems with higher EAL levels opens additional market opportunities and gives assurance that the device is secure against a range of attack routes.
Product advances
Recently, there have been new product advances in the anti-tamper security space. Agile Analog has introduced the agileSecure portfolio of anti-tamper IP that is designed to protect SoCs and addresses a critical industry need for robust hardware-level security, particularly for devices operating in sensitive applications on advanced process nodes. The tamper detection IP includes a clock attack monitor, voltage glitch detector, temperature sensor, and electromagnetic sensor, and provides enhanced protection over existing digital solutions for secure enclaves and Root of Trust (RoT) systems. The tamper prevention IP includes an internally biased LDO, bandgap reference and oscillator, as well as Power-on-reset and Power-ok circuits to further secure critical circuitry from external attack.
As the risk of security attacks accelerates, tamper detection and tamper prevention IP are becoming crucial tools to help organisations maintain the security of critical infrastructure, confidentiality of data, and reliability of electronic systems.
This article originally appeared in the October’25 magazine issue of Electronic Specifier Design – see ES’s Magazine Archives for more featured publications.
