Security Circuit Flip-Flop Test Chain Authentication
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Solution Overview
Problem
Existing security systems fail to accurately verify whether a security product is genuine, especially when the security circuit is modified or copied, as they cannot correctly authenticate such changes.
Innovation Solution
Incorporating a test chain that connects multiple flip-flops within a security circuit to verify its executing functions, with a hardware test controller generating test signals and comparing them to expected outputs to determine authenticity, and enabling a protection mode or disabling the circuit if authentication fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If authentication is performed using a common processor structure, then the authentication procedure can be implemented, but the system cannot correctly verify modified or copied security circuits
Solution Approach 1:
The security circuit is divided into functional blocks connected by test chains, where each block's output is verified against expected values. This segmentation allows verification of individual circuit components to detect modifications or copies while maintaining overall authentication functionality.
Solution Approach 2:
Test patterns and expected output values are pre-calculated and stored in the authentication system. During authentication, these predetermined values are used to verify the security circuit's responses, enabling detection of modifications before final authentication decisions are made.
2Measurement precision
If a test chain connecting flip-flops is added to verify hardware executing functions, then authentication accuracy improves, but device complexity increases
Solution Approach 1:
The test chain infrastructure serves multiple purposes: it verifies flip-flop functionality, validates combinational logic operations, and detects circuit modifications. By making the verification mechanism multi-functional, the patent reduces the need for separate testing components, thereby limiting the increase in device complexity.
Solution Approach 2:
The security circuit authenticates itself by processing test patterns and generating outputs that are verified against expected values. This self-verification approach eliminates the need for external testing equipment during authentication, reducing overall system complexity while maintaining high measurement precision.
Data Source
AI summary
A security circuit may include a functional circuit including a test chain that connects flip-flops to verify hardware of the functional circuit, the functional circuit configured to generate an output signal by encrypting an input signal based on a control signal, a mode signal, and the chain; and/or a test controller configured to generate the input, control, and mode signals, and configured to generate an authentication result based on the output signal. A security circuit may include a first device including a plurality of flip-flops in a test chain, the first device configured to receive first, second, and third signals, and configured to generate a fourth signal by encrypting the first signal based on the second and third signals and the chain; and/or a second device configured to generate the first, second, and third signals, and configured to generate an authentication result based on the fourth signal.