Private Set Intersection via Homomorphic Encryption
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Solution Overview
Problem
Existing technologies fail to enable private computation of the intersection between two sets held on different devices without revealing the values in either set, which is essential for scenarios like instant messaging applications where user privacy and legal compliance are concerns.
Innovation Solution
Implementing a system where a sender device stores a set of values and a receiver device performs homomorphic encryption of its value, allowing computation on encrypted data to determine if the encrypted value is in the sender's set without exposing the actual values, using techniques like homomorphic encryption and oblivious pseudorandom functions to maintain privacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional set intersection computation is used, then the intersection can be determined efficiently, but the values in both sets are revealed to the other party
Solution Approach 1:
The patent introduces homomorphic encryption as an intermediary mechanism that allows computation on encrypted data. The receiver device encrypts its set values using the sender device's public key, enabling the sender to perform intersection computation on ciphertexts without decrypting them, thus preserving privacy while maintaining computational functionality
Solution Approach 2:
The patent transforms the computation from operating on plaintext values to operating on ciphertexts with specific mathematical properties. By changing the parameter space from plain values to homomorphically encrypted values, the system enables privacy-preserving computation where the sender can evaluate polynomial functions over encrypted data to determine set intersection without learning the actual values
2Measurement precision
If set values are transmitted for intersection computation, then the intersection can be computed accurately, but sensitive information is exposed
Solution Approach 1:
Homomorphic encryption serves as an intermediary that preserves the mathematical structure needed for accurate intersection determination while preventing information leakage. The encryption scheme allows the sender to compute whether encrypted receiver values match sender values without decrypting or learning the actual receiver values
Solution Approach 2:
The patent replaces the mechanical process of transmitting and comparing plaintext values with a cryptographic substitution system. Instead of directly comparing values, the system uses homomorphic encryption to transform the comparison into an operation on ciphertexts, where the result can be determined without exposing the underlying information
3Reliability
If homomorphic encryption is used for private computation, then privacy is preserved, but computational overhead increases
Solution Approach 1:
The patent performs preliminary actions by pre-computing polynomial representations of the sender's set and pre-establishing homomorphic encryption keys. This allows the actual intersection computation to be performed more efficiently during the interaction phase, reducing the real-time computational energy consumption while maintaining strong privacy guarantees
Data Source
AI summary
Systems and methods for computing a private set intersection are disclosed. A method includes storing, at a sender device, a first set of values. The method includes receiving, from a receiver device, a homomorphic encryption of a receiver device value. The method includes computing a homomorphically encrypted number based on a difference between the homomorphic encryption of the receiver device value and each value in the first set of values, and based on a hash function of the encryption of the receiver device value. The method includes transmitting the homomorphically encrypted number to the receiver device for determination, at the receiver device, whether the receiver device value is in the first set of values.