Memory Authentication via Asymmetric Key Segmentation
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Solution Overview
Problem
Current authentication methods in information security, such as CPRM and AACS, face challenges in preventing unlawful extraction and use of secret information, especially in software-based systems where tamper-resistance is lower, and there is a need for efficient countermeasures against card-falsifying software and false SD cards, while also considering circuit scale restrictions.
Innovation Solution
A memory system architecture that includes a NAND flash memory as an authenticatee and a host device as an authenticator, using a configuration with asymmetric secret information levels, where the NAND flash memory hides first key information and the host device hides second key information, generating a shared session key using a constant and a random number, ensuring high tamper-resistance and preventing unlawful use even if host device information leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If software-based authentication systems are used, then ease of operation is improved, but tamper-resistance deteriorates
Solution Approach 1:
The authentication system is segmented into two distinct parts: a software-based authentication protocol that provides ease of operation and a hardware-based secure element (NAND flash memory with protected memory areas) that provides tamper-resistance. The host device stores encrypted secret identification information in a first memory area that is prohibited from being read and written from outside, while the NAND flash memory stores encrypted data in a second memory area that is required to be read-only from outside. This segmentation allows each component to optimize for its specific function.
Solution Approach 2:
An intermediary authentication mechanism is introduced between the host device and the NAND flash memory. The host device generates a random number, encrypts it with the first key to create a session key, and uses this session key to generate authentication information. The NAND flash memory performs the same operations with its own keys and compares the authentication information. This intermediary protocol ensures that even if software is compromised, the hardware-based secret information remains protected.
2Reliability
If asymmetric secret information levels are implemented, then security against card-falsifying software is improved, but device complexity increases
Solution Approach 1:
Different memory areas are assigned different access qualities and security levels. The first memory area in the host device stores the first key and secret identification information with restricted access (prohibited from being read and written from outside). The second memory area in the NAND flash memory stores encrypted secret identification information with read-only access from outside. This local differentiation of access rights creates asymmetric security levels that prevent card-falsifying software from accessing critical secrets while maintaining manageable complexity through clear access control rules.
3Ease of manufacture
If shared secret information is used for authentication, then ease of manufacture is improved, but vulnerability to unlawful extraction increases
Solution Approach 1:
The system performs preliminary actions to protect shared secret information before any authentication occurs. During manufacturing, the host device and NAND flash memory are pre-configured with different key pairs (first key/first secret identification information in the host device, second key/second secret identification information in the NAND flash memory). The encrypted secret identification information is pre-stored in protected memory areas. This preliminary setup ensures that even if the shared authentication protocol is known, the actual secret information cannot be unlawfully extracted because it is protected by the asymmetric access controls and hardware security features.
Data Source
AI summary
According to one embodiment, a memory includes a first storage region capable of storing first key (NKey) information, and secret identification information (SecretID) unique to the authenticate, reading and writing data from and to the first storage region from an outside of the authenticatee being inhibited at least after the authenticatee is shipped.