Verifiable Persistent Data Structures for Selective Data Removal
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Solution Overview
Problem
Conventional distributed ledger technology (DLT) systems do not support controlled forms of data modification, such as data removal, which is necessary for compliance with regulations like GDPR, as they ensure data immutability and cryptographic integrity.
Innovation Solution
A method is proposed where removable data portions are stored in a non-persistent data structure, and non-removable data portions, including digests of the removable data, are appended to a persistent data structure, allowing updates and removals while maintaining cryptographic verifiability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored in a conventional distributed ledger with cryptographic hashes to ensure immutability and integrity, then data integrity and security are improved, but data removal and modification capabilities are lost
Solution Approach 1:
The data structure is segmented into two distinct parts: a persistent data structure (blockchain) that stores only cryptographic hashes of data portions, and a removable data structure (off-chain storage) that stores the actual data portions. This segmentation allows the persistent structure to maintain immutability while the removable structure enables data deletion and modification capabilities.
Solution Approach 2:
The data portions are extracted from the persistent distributed ledger and stored in a separate removable data structure. Only the cryptographic hashes (digests) remain in the persistent structure, while the actual data can be removed from the removable structure without affecting the integrity of the persistent ledger.
2Measurement precision
If cryptographic hashes are used to verify data integrity in a distributed ledger, then data tamper verification is improved, but controlled data modification and removal are not supported
Solution Approach 1:
Cryptographic hashes act as an intermediary between the persistent data structure and the removable data structure. The hashes verify the integrity of data portions stored off-chain while enabling controlled modification and removal operations. The hash serves as a reference that maintains verification capability without constraining data management operations.
3Duration of action of stationary object
If a persistent data structure is used to ensure data cannot be removed, then data preservation and integrity are improved, but compliance with privacy regulations like GDPR is worsened
Solution Approach 1:
The system transitions from a static persistent structure to a dynamic dual-structure system where data portions can be selectively removed from the removable data structure while maintaining their cryptographic references in the persistent structure. This dynamic capability enables compliance with GDPR right-to-be-forgotten requirements while preserving historical audit trails through the immutable hash records.
Data Source
AI summary
A solution is proposed for storing data in the form of one or more fields each one comprising a respective field identifier and a respective field value. The solution comprises, for each one of said one or more fields, storing the field identifier and a first value of the field value by storing (410) an indication of the first value in a non-persistent data structure (110), and appending (420) a first data block to a persistent data structure (115). The first data block comprises the field identifier and a digest of the indication of the first value. The solution comprises, for each one of said one or more fields, updating the field value from the first value to a second value by storing (430) an indication of the second value in the non-persistent data structure, and appending (445; 470) a second data block to the persistent data structure. The second data block comprises the field identifier and a digest of the indication of the second value.