Enhancing the Multikey GSW Scheme with CRT Decomposition and Ciphertext Compression for Efficient Distributed Decryption

This paper enhances the multikey scenario in the Gentry–Sahai–Waters (GSW) fully homomorphic encryption scheme to increase its real-world applicability. We integrate the advantages of two existing GSW multikey approaches: one enabling distributed decryption and the other reducing memory requirements. We also apply the CRT decomposition and ciphertext compression techniques to the multikey settings. While leveraging the effectiveness of decomposition, we adapt the compression technique for practical cryptographic applications, as demonstrated through simulations in federated learning and multiparty communication scenarios. Our work’s potential impact on the cryptography field is significant, as it offers a more efficient and secure solution for distributed data processing in real-world scenarios, thereby advancing the state of the art in secure communication systems.