Dual TRNG Circuits for IC Tamper Detection

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Solution Overview

Problem

Integrated circuits face challenges in generating true random numbers internally, as they are susceptible to tampering and environmental factors, and external generation is vulnerable to interface monitoring attacks.

Innovation Solution

Implementing two identical True Random Number Generator (TRNG) circuits in close proximity within an Integrated Circuit (IC) to detect correlation between their outputs, using logic circuitry to combine and analyze outputs for tamper detection, ensuring non-correlated outputs produce true random numbers while correlated outputs indicate potential tampering or environmental issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If random numbers are generated outside the integrated circuit, then the cryptographic application can obtain random numbers, but the system becomes susceptible to attack by monitoring the integrated circuit interface

Engineering Contradiction:

Improverandom number generation capabilityVSAvoidsecurity against interface monitoring attacks

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent divides the random number generation function into two identical TRNG circuits operating in parallel within the IC. Each circuit generates random numbers independently, and their outputs are correlated to detect tampering. This segmentation provides both functionality and security without requiring external generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces correlation checking as an intermediary mechanism between the two TRNG circuits. By monitoring whether the outputs of both circuits correlate (should be different for true random numbers), the system detects tampering attempts without exposing the random number generation process to external monitoring attacks.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If an integrated circuit uses internal methods for generating random numbers, then the system avoids interface monitoring attacks, but the circuit becomes susceptible to tampering if the method is susceptible to changes in temperature, voltage supplies, or other environmental factors

Engineering Contradiction:

Improveprotection against interface monitoring attacksVSAvoidsusceptibility to environmental factors and tampering

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent combines two identical TRNG circuits in close proximity within the same IC, sharing the same environmental conditions. By merging their outputs through correlation checking, the system maintains immunity to interface monitoring attacks while using the combined output to detect environmental tampering - if both circuits are affected equally by environmental factors, their outputs will correlate, signaling potential tampering.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements feedback through correlation checking of the two TRNG outputs. The system continuously monitors whether the outputs correlate (when they should be different), and uses this feedback to detect tampering or environmental changes. This feedback mechanism enables real-time detection of harmful factors affecting the random number generation.

Inventive Principle:

Principle #23Feedback

3Reliability

If two identical TRNG circuits are implemented in close proximity to detect correlation, then tampering and environmental changes can be detected, but the device complexity increases

Engineering Contradiction:

Improvetamper detection capabilityVSAvoidnumber of TRNG circuits and logic circuitry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent places the two TRNG circuits in close proximity to each other within the IC, giving them identical local environmental conditions. This local quality ensures that both circuits experience the same temperature, voltage, and physical conditions, making correlation checking effective for detecting tampering while minimizing the area overhead of having duplicate circuits.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8321773B1Hardware true random number generator in integrated circuit with tamper detection

Publication Date: 2012.11.27 ALTERA CORP

AI summary

Circuits and methods to generate a True Random Number Generator (TRNG) with tamper-detection are presented. In one embodiment, the circuit includes two identical TRNG circuits and logic circuitry that combines and correlates the outputs of the two TRNG circuits. The two identical TRNG circuits are located in close proximity to each other inside an Integrated Circuit (IC). The logic circuitry analyzes the outputs of the two TRNG circuits and the historical values of the relation between the outputs of the two TRNG circuits to determine if the outputs are correlated. If the outputs are not correlated, the logic circuitry outputs a true random number sequence based on the combination of the two TRNG circuits. As a result, circuit tampering, such as changes in temperature or voltage supplies, is detected in the IC.