Reversible data-hiding in an encrypted image (RDHEI) embeds additional data into the encrypted image content, in a manner such that the data-hidingoperation does not affect the lossless recovery of the encrypted image content. In previous RDHEI methods, the encrypted images contain little redundantspace; thus, these approaches may feature a low embedding rate and burden content owners with too many tasks. In contrast, in this paper, we propose a novel RDHEI by redundant space transfer (RST) scheme, which involves transferring redundant space from the original image to the encrypted image. Then, the encrypted image will necessarily contain redundant space. Thus, reversibly embedding data into this encrypted image becomes easy and efficient, and general reversible data hiding (RDH) algorithms can be used. The proposed scheme has the advantages of a high embedding rate and requires few tasks of the content owner. The experimental results show that the performance of the proposed scheme outperforms other RDHEI algorithms. (C) 2017 Elsevier Inc. All rights reserved.