Non-volatile Memory Secure Data Deletion via Mapping Erasure
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Solution Overview
Problem
Current methods for deleting data in non-volatile memory devices do not securely erase data, allowing it to be potentially recovered, compromising user data security.
Innovation Solution
A non-volatile memory device and control method that securely deletes data by determining current and prior mappings of logical addresses to physical addresses and either erasing or overwriting the data stored at those addresses, using a deletion process that can be selected based on security and performance requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is deleted by updating only metadata in the OS file system without actually erasing data in the non-volatile memory device, then device performance is improved, but data security is compromised as deleted data can be recovered
Solution Approach 1:
The patent applies preliminary action by erasing or overwriting data in advance at the non-volatile memory device level before the data becomes vulnerable to recovery. When deletion notification is received, the system proactively erases the actual data contents and updates metadata, ensuring data cannot be recovered even if the device is compromised later. This preliminary data destruction prevents future security breaches while maintaining performance through efficient notification-based deletion.
2Reliability
If data is erased by processing deletion notification in the non-volatile memory device, then data security is improved, but device performance deteriorates due to additional processing overhead
Solution Approach 1:
The patent applies local quality by making the deletion process adaptive and selective. The system determines whether to perform full data erasure or simpler deletion based on local conditions such as security requirements, data sensitivity, and device state. This allows security-critical data to be fully erased while less sensitive data can use faster deletion methods, optimizing the balance between security and performance on a per-data basis.
Solution Approach 2:
The patent applies partial action by implementing a tiered deletion approach. Instead of always performing complete data erasure, the system can apply partial erasure or metadata-only deletion when security requirements allow. This partial action reduces processing overhead and maintains device performance while providing adequate security for non-critical data, reserving full erasure for high-security scenarios.
3Reliability
If encryption is applied to protect user data, then data security is improved, but device complexity increases
Solution Approach 1:
The patent applies the extraction principle by separating the security function from the storage function. Instead of implementing complex encryption within the non-volatile memory device, the system extracts the security mechanism to the host system level where encryption/decryption is handled. The memory device simply stores encrypted data and receives deletion notifications, significantly reducing device complexity while maintaining strong security through host-side cryptographic protection.
Data Source
AI summary
A storage device for a host device includes a non-volatile semiconductor memory and a control section configured to execute a delete process in response to a command from the host device to delete data stored at locations in the non-volatile semiconductor memory corresponding to a selected logical address included in the command. The delete process includes determining a selected mapping and at least one prior mapping of the selected logical address to physical addresses of the non-volatile semiconductor memory, and erasing or overwriting the data stored at the physical addresses.