Multi-Key Homomorphic Encryption with Reused Multiplication-Key Error
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Solution Overview
Problem
In multi-key homomorphic encryption systems, the increasing number of users leads to a linear increase in the number of public and multiplication keys required by the server, causing significant memory usage and prolonged operation times, especially when inter-client communication is impossible.
Innovation Solution
A method is introduced to generate a multiplication key by reusing the public key protection error in a modified RLWE environment, reducing the size of the multiplication key and optimizing memory usage and operation time by using a Re-RLWE sample format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of users increases in multi-key homomorphic encryption, then the system supports more clients, but the number of public keys and multiplication keys that the server must possess increases linearly, requiring more memory and longer operation times
Solution Approach 1:
The patent merges the public key protection error and multiplication key protection error into a single shared error term. By combining these two previously separate error components into one common error, the system reduces the total number of error terms that need to be managed and stored, thereby reducing memory requirements while supporting multiple users
Solution Approach 2:
The shared error term serves multiple functions simultaneously: it acts as both the public key protection error and the multiplication key protection error. This multi-functional error term is reused across different key generation processes, eliminating the need for separate error terms for each function and reducing overall key material
2Adaptability or versatility
If the number of users increases, then more clients can be served, but the operation time for ciphertext operation increases due to having more public keys and multiplication keys
Solution Approach 1:
The patent merges the public key protection error and multiplication key protection error into a single shared error term. By combining these two previously separate error components into one common error, the system reduces the total number of error terms that need to be managed and stored, thereby reducing memory requirements while supporting multiple users
Solution Approach 2:
The shared error term serves multiple functions simultaneously: it acts as both the public key protection error and the multiplication key protection error. This multi-functional error term is reused across different key generation processes, eliminating the need for separate error terms for each function and reducing overall key material
3Adaptability or versatility
If the number of users increases, then more clients can be served, but the arithmetic resources such as memory are consumed in large amounts due to storing multiple public keys and multiplication keys
Solution Approach 1:
The patent merges the public key protection error and multiplication key protection error into a single shared error term. By combining these two previously separate error components into one common error, the system reduces the total number of error terms that need to be managed and stored, thereby reducing memory requirements while supporting multiple users
Solution Approach 2:
The shared error term serves multiple functions simultaneously: it acts as both the public key protection error and the multiplication key protection error. This multi-functional error term is reused across different key generation processes, eliminating the need for separate error terms for each function and reducing overall key material
Data Source
AI summary
A device for performing multi-key homomorphic encryption includes a public key generator configured to generate a public key by using a secret key for each client, and a multiplication key generator configured to generate a multiplication key by reusing a public key protection error used in the generating of the public key. By reducing the size of the multiplication key by reusing the public key protection error, the operation time and memory may be reduced.