A Lossless Data Hiding Scheme in Public Key Encrypted Domain Based on Homomorphic Key-Switching

This paper proposes a lossless data hiding in encrypted domain (RDH-ED) scheme. To realize the data extraction directly from the encrypted domain without the private key, a key-switching based least-significant-bit (KS-LSB) data hiding method has been designed. In application, the user first encrypts the plaintext and uploads ciphertext to the server. Then the server performs KS-LSB to obtain the marked ciphertext. Additional data can be extracted directly from the marked ciphertext by the server without the private key, which enables the (trusted or untrusted) third party to manage ciphertext flexibly under the premise of keeping the plaintext secret. The Experimental results demonstrate that the embedding capacity is 1bit per bit of plaintext. Data hiding would not affect the accuracy and the security of encryption.