Further Methods for Encrypted Linear Dynamic Controllers Utilizing Re-Encryption

Homomorphic encryption applied to a networked controller enables secure operation, but in most cases it allows for addition and multiplication over integers only, because of computation efficiency. Several related results deal with such constraints by means of re-encrypted controller output, based on which the controller can be reconstructed and operate over integers. This article presents two modified methods based on the output re-encryption, which will further reduce the required communication effort and computational burden, respectively.