Secure Hash Collation Using Dummy Vectors to Hide Match Counts
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Solution Overview
Problem
Existing secure join methods reveal the number of common keys when collating hash value lists, compromising data privacy.
Innovation Solution
A secure collation system that adds dummy hash values and random permutations to hash value vectors, allowing only one party to ascertain the number of matched IDs while hiding the common ID count from the other party.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hash value lists are collated to join data between two parties, then data joining function is achieved, but the number of common keys is revealed compromising data privacy
Solution Approach 1:
The patent introduces a third party (trusted third party or blockchain) as an intermediary to perform the collation operation. This mediator processes the hash value lists and returns only the count of common keys without revealing which specific keys match, thus achieving data joining while preserving privacy. The intermediary's computed result is used by both parties without exposing their individual data sets.
Solution Approach 2:
The patent creates copies of hash value lists with modified structures (adding dummy values, shuffling) before collation. These copied versions are used for the privacy-preserving collation operation, while the original hash value lists remain private to each party. The copies allow the collation process to proceed without exposing the actual data contents.
2Loss of information
If dummy values are added to hash value vectors, then the number of common IDs is hidden from the other party, but the system complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-generating dummy hash values and pre-computing their hashes before the actual collation operation. These pre-prepared dummy values are then inserted into the hash value vectors at predetermined positions. This preliminary preparation simplifies the main collation process while achieving the privacy protection effect.
Solution Approach 2:
The patent changes parameters of the hash value vectors by adding dummy values and modifying vector lengths. The first vector has dummy values added at specific positions, while the second vector has different dummy values added at different positions. These parameter changes create asymmetric vectors that prevent the other party from determining the actual number of common keys through collation.
Data Source
AI summary
A secure collation system performs secure-data-collation between first and second information processing apparatuses and includes the first and second information processing apparatuses. The second information-processing-apparatus creates, when receiving a first vector having a hash value of a key value of the first information-processing-apparatus as an element, a second vector by adding a dummy hash value to the first vector and rearranging the first vector by random permutation; creates a third vector having, as elements, a hash value of a key value of the second information-processing-apparatus and a hash value of a dummy key value; and transmits the second and third vectors to the first information-processing-apparatus. The first information-processing-apparatus calculates a hash value of an element of the third vector and creates a fourth vector having the hash value as an element; and collates matched values between each element of the third vector and each element of the fourth vector.