Tamper-Resistant Memory Device Using Charge-Accumulating Storage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing game cartridges are vulnerable to illegal copying due to the ability to analyze input and output signals, and storing encryption keys in mask ROMs poses risks of key information exposure.
Innovation Solution
A memory device with a first storage section for key information and a second storage section for data, utilizing a decryption control unit to process encrypted read instructions and addresses, with a circuit structure incorporating both low and high tamper-resistant areas to prevent data analysis and key extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If key information is stored in mask ROM with wired logic, then the memory device can perform decryption function, but the key information becomes vulnerable to circuit structure analysis
Solution Approach 1:
The patent replaces the wired logic circuit structure with a charge-accumulating storage section that uses charge storage mechanisms instead of logical circuit interconnections. This substitution makes the key information storage resistant to circuit structure analysis while maintaining the decryption function.
Solution Approach 2:
The patent changes the storage mechanism parameter from wired logic to charge accumulation. By storing key information in a charge-accumulating storage section rather than in circuit connections, the system maintains functionality while changing the physical parameter that makes the data vulnerable to analysis.
2Object-affected harmful factors
If the entire memory device uses high tamper-resistant circuit area, then key information is protected from reverse-engineering, but the device complexity increases
Solution Approach 1:
The patent divides the memory device into different storage sections: a charge-accumulating storage section for key information (high tamper resistance) and a separate storage section for data (lower tamper resistance). This segmentation allows selective application of security measures only where needed, reducing overall device complexity.
Solution Approach 2:
The patent applies high tamper-resistant characteristics locally only to the charge-accumulating storage section that stores key information, while other parts of the device can use simpler circuit structures. This local application of security features optimizes the balance between protection and complexity.
3Object-affected harmful factors
If encrypted read instructions and addresses are used, then data analysis through signal analysis becomes difficult, but the device requires additional decryption processing
Solution Approach 1:
The patent performs encryption of read instructions and addresses before they are stored or transmitted. By encrypting the data in advance and using a charge-accumulating storage section for key protection, the system prevents signal analysis attacks without requiring complex real-time decryption processing during data access.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution makes it difficult to illegally copy data by encrypting read instructions and addresses, and using high tamper-resistant storage for key information, thereby protecting the data from reverse-engineering and unauthorized access.
Implementation Method 1
The first storage section is a charge-accumulating storage section
Data Source
AI summary
A memory device includes a storage unit having a decryption key storage section that stores key information for decryption and a data storage section that stores to-be-read data requested from the exterior, and a decryption control unit capable of decrypting an externally input encrypted read instruction and address based on the key information stored in the decryption key storage section, and causing data corresponding to the decrypted read instruction and address to be output from the data storage section. The decryption key storage section is composed of arrays of a flash memory.