Blockchain Data Access Revocation With Obsolescence Locks
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Solution Overview
Problem
Existing blockchain systems lack a secure method to revoke access to data at any time, as modifying blocks disrupts the immutability of the data, and revoking certificates affects all associated blocks.
Innovation Solution
Implement an obsolescence lock mechanism that allows authorized parties to delete access keys by adding new blocks with cryptographic proof, using an obsolescence lock public and private key system, split into secret shares, and reconstructing the private key for key deletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blockchain data is made immutable to ensure trust between untrusting parties, then data integrity and security are improved, but the ability to revoke access to data at any time deteriorates
Solution Approach 1:
The patent segments the access control mechanism by separating the data storage (immutable blockchain blocks) from the access key management (metadata with obsolescence locks). This allows the data to remain immutable while the access keys can be selectively revoked through metadata updates, resolving the contradiction between immutability and access revocation capability
Solution Approach 2:
The patent introduces metadata as an intermediary layer between the immutable blockchain data and the access control mechanism. The metadata contains obsolescence locks that can be updated to revoke access keys without modifying the underlying blockchain blocks, enabling access revocation while preserving data immutability
2Ease of operation
If certificates are revoked to disable access to blockchain data, then access control is improved, but the validity of all blocks signed by that party deteriorates
Solution Approach 1:
The patent applies local quality by making the obsolescence lock specific to individual blocks or data items rather than affecting the entire blockchain or all blocks signed by a party. This allows selective access revocation for specific data while preserving the validity and accessibility of other blocks, resolving the contradiction between access control and block validity
3Adaptability or versatility
If encryption keys are deleted to rescind access to blockchain data, then access revocation is improved, but the ability to prove authorized key deletion deteriorates
Solution Approach 1:
The patent applies preliminary action by creating the obsolescence lock and distributing secret shares before any key deletion occurs. When access revocation is needed, the reconstructed private key provides cryptographic proof that the deletion was authorized, resolving the contradiction between access revocation and proof of authorized deletion
Solution Approach 2:
The patent implements feedback through the confirmation instruction block that is signed with the reconstructed obsolescence lock private key. This signature provides verifiable proof that the key deletion was authorized, creating a feedback mechanism that confirms the legitimacy of the access revocation while maintaining the ability to prove authorized deletion
Data Source
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AI summary
A method of rescinding access to a designated block within a blockchain, wherein the blockchain comprises a plurality of blocks, wherein the designated block contains data encrypted with a content encryption key and is associated with metadata, wherein the metadata for the designated block include an obsolescence lock public key. The method comprises creating, at the time the designated block is created, an obsolescence lock for supporting a rescission request if the rescission request is agreed upon by a required number of authorized parties for the designated block; splitting the obsolescence lock private key into a number of secret shares; and upon receiving particular rescission instruction block, an agreement instruction block and a confirmation instruction block, removing all encrypted content encryption keys from the metadata of the designated block, thereby rescinding access to the original data within the designated block. An equivalent method is presented to rescind access to a blockchain.