Digitalizing medical images, such as images in ultrasonography or mammography, or magnetic resonance imaging, can be applied for telemedicine applications in telediagnosis and telesurgery, and can be stored in a cloud database via computer networking transmission or wireless communications. Besides, these images contain the patient privacy information. Thus, their reliability and availability should be protected to ensure medical image infosecurity in public channels or open spaces. Medical images can also be hacked by unauthorized people. Therefore, in the picture archiving and communication system (PACS), this study proposes against-hacker attacks with two-round symmetric cryptography models for medical image infosecurity. Hash transformation with multi secret keys is performed to change the pixel values and produce dynamic errors for the two-round encryption processes. In image decryption, two-round decryption processes are employed to estimate the possible hacker attacks at the routing path and to determine the decryption key parameter by using an optimization-based controller. For a case study of mammographic images consisting of 50 benign tumors and 50 malignant tumors, the peak signal-to-noise ratio (PSNR) is employed to evaluate the decryption quality between the plain and decrypted images.
