Secure Circuit Assembly with Tamper-Sensing Sensor Film
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Solution Overview
Problem
Electronic circuits that process sensitive information, such as cryptographic modules, face challenges in meeting security standards like FIPS 140-2 level 4, which require protection against unauthorized physical access while maintaining the ability to be repairable.
Innovation Solution
A secure circuit assembly design featuring a tamper-resistant sensor film and electrical loops that detect unauthorized access, allowing for the cryptographic module to be protected by erasing sensitive information upon breach, while allowing for repair and troubleshooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryptographic module is encapsulated using potting material to meet FIPS 140-2 level 4 security standards, then security protection against unauthorized physical access is improved, but the secure circuit assembly becomes unrepairable
Solution Approach 1:
The patent divides the secure circuit assembly into distinct segments: a secure area containing the cryptographic module with tamper-resistant encapsulation, and a non-secure area with accessible circuitry. This segmentation allows the secure portion to meet FIPS 140-2 level 4 requirements while the non-secure portion remains accessible for repair and troubleshooting, resolving the contradiction between security protection and repairability.
2Reliability
If complete encapsulation is applied to protect cryptographic module, then detection of unauthorized physical access is improved, but maintenance capability is lost
Solution Approach 1:
The assembly is segmented into secure and non-secure areas, allowing tamper detection mechanisms to be applied only where needed for security, while maintaining open access to non-secure areas for maintenance operations.
Solution Approach 2:
The patent introduces a secure area as an intermediary zone that houses the cryptographic module with full tamper protection, while allowing external interaction through controlled interfaces. This intermediary structure enables both detection of unauthorized access and legitimate maintenance activities.
Data Source
AI summary
A secure circuit assembly includes a printed circuit board including first and second surfaces and a secure boundary area in the first surface. A circuit to be protected is located in the secure boundary area. A first inner enclosure is attached to the first surface of the printed circuit board and covers the secure boundary area in the first surface. A first sensor film is attached to the first inner enclosure and is electrically coupled to the printed circuit board. The secure circuit assembly also includes first and second outer enclosures, the first outer enclosure covering the first inner enclosure and the second outer enclosure covering the second inner enclosure. A method for providing security to a circuit assembly is also disclosed.