Fault injection

As explained in Hacking Cryptography

An attack that deliberately perturbs a system's physical or electrical conditions to induce faults or influence its output.

Fault injection deliberately perturbs a system’s physical or electrical conditions to influence its output. In a ring-oscillator TRNG, an attacker can inject power-supply noise near the oscillator’s frequency, causing it to lock onto that frequency and produce predictable bits. section 2.2.1

Reduce the impact of noise-injection attacks by:

• Adding a binary transition counter and exposing raw counter bits to detect abnormal output bias. section 2.2.1
• Adding physical barriers, such as potting, to increase the attacker’s distance from the chip. section 2.2.1
• Combining TRNG output with a protected flash seed and refreshing that seed through a CSPRNG. section 2.2.1

Power-supply frequency injection

A sine-wave generator applies noise close to a ring oscillator’s frequency. The oscillator follows the injected signal, making the TRNG’s output trivial to guess. section 2.2.1

Figure 2.6 A ring oscillator

Use the ring-oscillator figure to connect the vulnerable physical oscillator to the fault-injection mechanism. section 2.2.1

How Hacking Cryptography covers it

How deep it goes

Explains frequency lock-on and gives monitoring, shielding, and reseeding countermeasures.

Examples

Uses a sine-wave generator targeting a ring oscillator through the chip’s power source.

What it assumes

Assumes a ring-oscillator TRNG and its physical noise source rather than developing either concept from zero.

What you can do after

Operate and harden a ring-oscillator TRNG using health counters, physical barriers, and protected reseeding.

How it connects

Connects fault injection with TRNGs, ring oscillators, noise injection, CSPRNGs, and secure flash.

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Related concepts

• fault toleranceused by · Fault tolerance is the ability of a system to continue providing correct or acceptable service despite failures in its components or operating environment.
• traffic managementpart of · Traffic management is the coordinated control, routing, distribution, or shaping of moving flows through a system.
• verificationpart of · Verification is the process of checking a system, result, or claim against specified requirements, criteria, or evidence to determine whether it conforms or is correct.

This explainer was generated by Manning's knowledge graph from the text of Hacking Cryptography. The section links point to the parts of the book it draws on.