Another Compression Method for Homomorphic Ciphertexts

Abstract

In this work we describe a message packing and unpacking method for homomorphic ciphertexts. Messages are packed into the coefficients of plaintext polynomials. We propose an unpacking procedure which allows to obtain a ciphertext for each packed message. The packing and unpacking of ciphertexts represents a solution for reducing the transmission bottleneck in cloud based applications, in particular when sending homomorphic calculations results. The results we obtain (packing ratio, unpacking time) are compared to existing packing methods based on trans-ciphering.