Medical imaging security using partial encryption and histogram shifting watermarking

Rapid advancements in information and communication technologies facilitated sharing of digital medical images in telemedicine applications. However, due to the sensitivity of medical images, their security has become a challenging requirement that must be addressed. In this paper, a simple and efficient joint reversible data hiding and encryption algorithm is proposed for watermarking medical images while providing high embedding capacity. The proposed algorithm combines reversible data hiding techniques with standard encryption techniques in order to provide the needed security of transmitted and stored medical images. The algorithm utilizes substitution-based encryption and transposition-based encryption to achieve high degree of entropy in the encrypted watermarked images. The operation of the algorithm is based on dividing the original medical image randomly into two halves, each of which is assigned a different watermark. One of the watermarks is embedded before encryption and the other watermark is embedded after encryption. Aside from providing high entropy, the proposed algorithm provides relatively high embedding capacity because of the existence of two watermarks, while keeping low computational complexity.