A secure data hiding technique with heterogeneous data-combining capability for electronic patient records

It is an enabling technology to transmit electronic patient records (EPR) across distances to hospitals and countries through the Internet. However, since EPR is a highly personal medical documentation, transmission of secure EPR is required to reduce the risk of security breach on the network and prevent accessing of data by unauthorized end-users. Here, the authors propose a bi-polar multiple-base data hiding technique, where a pixel value difference between an original image and its default JPEG (Joint Photographic Experts Group) lossy decompressed image is taken to be a number conversion base. The authors hide doctors' digital seals and the EPR data within a still image by using this approach. The still image could be the mark of a hospital to identify where the EPR comes from. The doctors' digital seals are essential to the authentication of EPR. A diagnostic report and a biomedical signal such as an electrocardiogram (ECG) can also be hidden in the image. The proposed approach allows multiple data types to be hidden in the same image. All the data can be separated and restored perfectly by the intended users. In addition, the proposed data hiding technique has higher peak signal to noise ratio than that of using default JPEG alone. Thus, the transparency of the hidden image and the invisibility of the EPR data are guaranteed.