Privacy Preserving Data Processing with Collaboration of Homomorphic Cryptosystems

摘要

We propose a privacy-preserving data processing system using homomorphic cryptosystem. Proposed system consists of several functionalities corresponding to addition and multiplication of plaintexts encrypted in ciphertexts. Using these functionalities repeatedly, any multivariate polynomial evaluation of secret inputs can be achieved. We clarify the role and the function of each organization participating in the process - custodians of personal data, processing center of cryptographic function, and computing center. The cooperation of several entities makes arbitrary times of the calculations, which is a requirement of fully homomorphic encryption, more efficient. We give security proofs of the scheme and show the result of implementation of the scheme.