Medical image encryption algorithm based on a new five-dimensional three-leaf chaotic system and genetic operation

Abstract

Current image encryption methods have many shortcomings for the medical image encryption with high resolution, strong correlation and large storage space, and it is difficult to obtain reliable clinically applicable medical images. Therefore, this paper proposes a medical image encryption algorithm based on a new five-dimensional three-leaf chaotic system and genetic operation. And the dynamic analysis of the phase diagram and bifurcation diagram of the five-dimensional three-leaf chaotic system selected in this paper is carried out, and NIST is used to test the randomness of its chaotic sequence. This algorithm follows the diffusion-scrambling framework, especially using the principle of DNA recombination combined with the five-dimensional three-leaf chaotic system to generate a chaotic matrix that participates in the operation. The bit-level DNA mutation operation is introduced in the diffusion, and the scrambling and diffusion effects have been further improved. Algorithm security and randomness have been enhanced. This paper evaluates the efficiency of this algorithm for medical image encryption in terms of security analysis and time performance. Security analysis is carried out from key space, information entropy, histogram, similarity between decrypted image and original image, PSNR, correlation, sensitivity, noise attack, cropping attack and so on. Perform time efficiency analysis from the perspective of time performance. The comparison between this algorithm and the experimental results obtained by some of the latest medical image encryption algorithms shows that this algorithm is superior to the existing medical image encryption algorithms to a certain extent in terms of security and time efficiency.

Fig 1. Logistic chaotic bifurcation diagram.

Fig 2. Phase diagram of the new five-dimensional three-leaf chaotic system.

(a) x-y-z, (b) z-w-v.

Fig 3. Schematic diagram of DNA recombination.

Fig 4. Encryption flowchart.

Fig 5. Bit-level dynamic DNA coding process diagram.

Fig 6. Simulation results of MRI images.

(a) Axillaty encrypted image, (b) Axillaty encrypted image, (c) Axillaty decrypted image, (d) Brain original image, (e) Brain encrypted image, (f) Brain decrypted image, (g) Lumbar original image, (h) Lumbar encrypted image, (i) Lumbar decrypted image, (j) Patient brain original image, (k) Patient brain encrypted image, (l) Patient brain decrypted image.

Fig 7. Simulation results of X-ray images.

(a) Ankle original image, (b) Ankle encrypted image, (c) Ankle decrypted image, (d) Cervical original image, (e) Cervical encrypted image, (f) Cervical decrypted image, (g) Chest original image, (h) Chest encrypted image, (i) Chest decrypted image, (j) Feet original image, (k) Feet encrypted image, (l) Feet decrypted image.

Fig 8. Simulation results of CT images.

(a) Brain original image, (b) Brain encrypted image, (c) Brain decrypted image, (d) Old man testicular original image, (e) Old man testicular encrypted image, (f) Old man testicular decrypted image, (g) Testicular original image, (h) Testicular encrypted image, (i) Testicular decrypted image, (j) Tibial original image, (k) Tibial encrypted image, (l) Tibial decrypted image.

Fig 9. Histogram of the original image.

Fig 10. Histogram of the encrypted image.

Fig 11. Horizontal, vertical, diagonal correlation point diagrams of original image and encrypted image.

(a) original image horizontal, (b) original image vertical, (c) original image diagonal, (d) encrypted image horizontal, (e) encrypted image vertical, (f) encrypted image diagonal.

Fig 12. Encrypted and decrypted image after changing the key.

(a) encrypted image, (b) decrypted image.

Fig 13. Decrypted images of different levels of salt and pepper noise attacks.

(a) 0.005 salt and pepper noise, (b) 0.05 salt and pepper noise, (c) 0.1 salt and pepper noise.

Fig 14. Encrypted image after cropping.

(a) 1/16 cropped image, (b) 1/4 cropped image, (c) 1/2 cropped image.

Fig 15. Decrypted image after cropping attack.

(a) 1/16 decrypted image, (b) 1/4 decrypted image, (c) 1/2 decrypted image.

Fig 16. Simulation experiment results of ordinary image.

(a) original image, (b) encrypted image, (c) decrypted image, (d) histogram of original image, (e) histogram of encrypted image, (f) histogram of decrypted image.