Stable Pseudonymous Identifier Generation via Key Rotation Mapping
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Solution Overview
Problem
Existing pseudonymization methods using one-way hash functions become unstable when cryptographic keys are rotated, leading to inconsistent pseudonymous identifiers and reduced effectiveness in linking data before and after key rotations.
Innovation Solution
The system generates stable pseudonymous identifiers by using a keyed-hash message authentication code (HMAC) and an identity mapping function, which ensures that the same identifier remains constant even after key rotations by updating the mapping table to associate the new key with the same random value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryptographic keys are rotated regularly to maintain security, then security is improved, but pseudonymous identifier stability deteriorates
Solution Approach 1:
The system segments the pseudonymization process into two independent components: (1) a stable random value that remains constant across key rotations, and (2) a mapping table that associates different cryptographic keys with the same random value. This segmentation allows the system to rotate keys for security while maintaining identifier stability through the persistent random value.
Solution Approach 2:
A mapping table acts as an intermediary between cryptographic keys and pseudonymous identifiers. When a key is rotated, the mapping table is updated to associate the new key with the same random value that was previously associated with the old key. This intermediary mechanism ensures that pseudonymous identifiers remain stable even as cryptographic keys change.
2Loss of information
If a one-way hash function with a secret is used for pseudonymization, then data privacy is improved, but identifier consistency deteriorates after key rotation
Solution Approach 1:
The system performs preliminary action by pre-generating a stable random value and storing it in the mapping table associated with the initial cryptographic key. This preliminary setup ensures that when key rotation occurs, the system can immediately retrieve the pre-stored random value and assign it to the new key, maintaining identifier consistency without requiring complex real-time computations.
Solution Approach 2:
The system changes the parameter being hashed from the combination of sensitive data and rotating cryptographic key to instead use a stable random value that is selected independently of the cryptographic key. This parameter change ensures that the pseudonymous identifier remains consistent even as cryptographic keys rotate, while data privacy is maintained through the one-way nature of the hash function applied to the random value.
Data Source
AI summary
Systems, devices, and methods are provided for stable pseudonymous identifiers. A system may obtain first data, and obtain a first cryptographic key from a cryptography service. The system may determine, based at least in part on the first data and the first cryptographic key, a first hash output of a hash function. The system may determine that a mapping table does not include a first record associated with the first hash output. The system may create, in the mapping table, a first record comprising the first hash output and a random value. The system may provide the random value as a stable pseudonymous identifier of the first data. If the first cryptographic key is subject to a key rotation, the pseudonymous identifier of the first data may remain constant even though the value of the key changes as a result of the key rotation.