Mixed-Signal IC Authentication via Process-Specific Functions
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Solution Overview
Problem
Existing methods for authenticating and identifying integrated circuits are cumbersome, costly, and lack sensitivity to process variability, making them ineffective against counterfeit and malicious ICs, especially in analog mixed-signal circuits where digital designs cancel out variability, requiring extensive resources and external monitoring circuits.
Innovation Solution
The method involves using process-specific functions (PSF) that exploit inherent physical differences in integrated circuits by applying inputs to generate predictable analog responses, allowing for quick, non-destructive authentication and identification within the circuit itself, eliminating the need for external security features and providing a deterministic statistical representation of circuit behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory-based PUFs or auxiliary PUF circuits are used for authentication, then security and identification capability are improved, but device area increases and measurement overhead increases
Solution Approach 1:
The patent merges the authentication function with the main circuit functionality by using process variations inherent in the main circuit transistors themselves, rather than adding separate PUF circuits. The main circuit serves dual purposes: its primary function and authentication, eliminating the need for dedicated security circuit area.
Solution Approach 2:
The main circuit is designed to perform both its primary computational function and authentication function simultaneously. The same transistors and interconnects used for logic operations are also used to generate authentication responses, making the circuit universal and eliminating redundant components.
2Reliability
If digital PUF designs are used, then cryptographic authentication is improved, but the system becomes vulnerable to machine learning attacks and requires error correction overhead
Solution Approach 1:
The patent replaces digital challenge-response PUF mechanisms with an analog measurement approach. Instead of digital bit sequences vulnerable to ML attacks, the system uses continuous analog measurements of circuit behavior under process variation, which are inherently more resistant to discrete pattern recognition attacks.
Solution Approach 2:
The system changes from digital parameter space (discrete bits) to analog parameter space (continuous measurements). By measuring analog characteristics like delay, current, or frequency that naturally vary with process conditions, the system achieves both stability and attack resistance without requiring error correction codes.
3Measurement precision
If RF-DNA fingerprinting is used for device identification, then device recognition capability is improved, but deterministic signature generation is lost and library training is required
Solution Approach 1:
The patent performs preliminary characterization during manufacturing to establish expected ranges for circuit parameters under normal process variation. This pre-established baseline allows for deterministic authentication without requiring runtime library training or comparison against stored reference profiles.
Solution Approach 2:
The circuit inherently provides its own authentication signature through its natural response to input signals. The process variations in the circuit itself generate the unique fingerprint, eliminating the need for external RF emissions measurement or comparison against a library of known devices.
4Measurement precision
If extensive testing and external monitoring circuits are used for authentication, then detection capability is improved, but productivity decreases and cost increases
Solution Approach 1:
The main circuit performs self-authentication by using its own operational characteristics as the authentication mechanism. No external monitoring circuits are needed because the circuit's natural behavior under process variation serves as its own fingerprint, enabling quick authentication without separate testing infrastructure.
Solution Approach 2:
The same circuit operations used for normal functionality are also used for authentication purposes. The circuit doesn't require separate testing modes or external monitoring equipment, as its regular operational measurements provide sufficient authentication data, improving productivity.
Data Source
AI summary
Method and apparatus for authenticating analog mixed-signal integrated circuits using process-specific functions (PSF) comprising: presenting wafer having plurality of dies, each die having circuit with identical design but having inherent physical differences due to process variation in their manufacture, each circuit designed to enhance the effects of the inherent differences; defining selected number of inputs/stimuli for authenticating and identifying each integrated circuit; defining expected response for each circuit, wherein the expected response for each circuit is the same due to the identical design; defining statistical window for analog response by the circuit to the inputs/stimuli; applying the inputs/stimuli to each circuit; receiving analog response corresponding to the applied inputs/stimuli, wherein the analog response falls outside statistical window when there are functional or physical changes to the circuit; separating from plurality of dies each die providing a response outside the statistical window, wherein only identified/authenticated dies remain.