An Encryption Algorithm For Medical Image Based On Multiple Chaos Systems

Abstract:With the development of computer technology and the popularity of medical informalization, digital image has been used by more and more hospitals as the main way of medical image storage and transmission. Patient’s personal information is contained in these medical images, once these information is leaked and exploited by malicious people, serious social problems will occur, especially the information of some important leaders. Thus medical image encryption begins to receive the attention and concern of the industry.Unlike the ordinary file encryption, image encryption needs to eliminate the correlation between pixels in the encryption process. The medical image usually has a large amount of data and a large continuous region of the same color, the algorithm will inevitably have safety defects if it doesn’t take the factors above into account. Most existing encryption algorithms for medical image are simply applying ordinary digital image encryption, or designed based on DICOM format, without taking the characteristics of medical image into account.The main work and contributions of this paper are as follows:1. Considering medical images always have a large amount of data, this paper proposed a chaotic sequence generating algorithm based on multiple chaos systems. The algorithm uses multiple one-dimensional chaos systems to generate chaotic sequence, by which improve the security while keeping a high efficiency to generate chaotic sequence. The chaotic sequence generated by the system has a long period, this property solves the weak key problem caused by the restriction of the computer’s limited calculation accuracy which makes the sequence gets a short period. The sequence having long period makes the algorithm can be well perform on medical images having a large amount of data.2. The medical image usually has a large continuous region of the same color, the attacker can analyze and crack the encryption algorithm according to this feature. Combine with the sequence generating algorithm based on multiple chaos systems, this paper proposed a medical image encryption can be applied to the scene with high security requirements. A feedback mechanism is added into this algorithm, and a duplex feedback is applied to improve the sensitivity of the algorithm.3. This paper analyzes the traditional image scrambling algorithm and a fast image scrambling algorithm is proposed. The robustness brought by image scrambling improves the possibility to keep the diagnosis go on while the medical image is damaged.