Medical Image Protection Algorithm Based on Deoxyribonucleic Acid Chain of Dynamic Length

Abstract

Current image encryption algorithms have various deficiencies in effectively protecting medical images with large storage capacity and high pixel correlation. This article proposed a new image protection algorithm based on the deoxyribonucleic acid chain of dynamic length, which achieved image encryption by DNA dynamic coding, generation of DNA dynamic chain, and dynamic operation of row chain and column chain. First, the original image is encoded dynamically according to the binary bit from a pixel, and the DNA sequence matrix is scrambled. Second, DNA sequence matrices are dynamically segmented into DNA chains of different lengths. After that, row and column deletion operation and transposition operation of DNA dynamic chain are carried out, respectively, which made DNA chain matrix double shuffle. Finally, the encrypted image is got after recombining DNA chains of different lengths. The proposed algorithm was tested on a list of medical images. Results showed that the proposed algorithm showed excellent security performance, and it is immune to noise attack, occlusion attack, and all common cryptographic attacks.

Keywords: DNA dynamic chain; DNA dynamic encoding; FOCHC system; deletion and transposition operation; medical image encryption.

FIGURE 1

The process diagram of DNA dynamic encoding and decoding by binary bit.

FIGURE 2

Attractors of the fractional-order Chen hyper chaotic system: (A) x-y plane; (B) x-z plane; (C) y-w plane; and (D) z-w plane.

FIGURE 3

The operating principle of DNA chains.

FIGURE 4

The flowchart of the proposed algorithm: yellow blocks are the input, green block is the output, and blue blocks from the DNA coding algorithm.

FIGURE 5

Flowchart of the DNA dynamic chain operations.

FIGURE 6

Test of key sensitivity. (A) The original image of “MRI-knee joint.” (B) The encrypted image with the initial key set. (C) The encrypted image with x0+t. (D) The differential image between (B,C). (E) The decrypted image with x0+t. (F) The decrypted image with ${\text{R}}_{\text{h}}^{\prime }+1$. (G) The decrypted image with the hash value + “1.” (H) The decrypted image with the correct key.

FIGURE 7

The histogram of the original image and the encrypted image. (A) The histogram of the original image for “MRI-brain.” (B) The histogram of the encrypted image for the “MRI-brain.” (C) The histogram of the original image for the “CT-chest.” (D) The histogram of the encrypted image for the “CT-chest.” (E) The histogram of the original image for the “X-ray-chest.” (F) The histogram of the encrypted image for the “X-ray-chest.”

FIGURE 8

Correlation of adjacent pixels of the original image and the encrypted image for “CT-chest.” (A) Horizontal direction. (B) Vertical direction. (C) Diagonal direction.

FIGURE 9

Salt-and-pepper noise attack of encrypted CT-chest, decrypted image with density value (A) 0.002, (B) 0.005, (C) 0.05, (D) 0.1, (E) 0.25, and (F) 0.5.

FIGURE 10

Occlusion attack: the data loss of encrypted “CT-chest” with (A) 1/16, (B) 1/8, (C) 1/4, and (D) 1/2; corresponding decrypted image (E–H) in accordance with (A–D).

FIGURE 11

The part of DNA encoding matrix of “pure white” image: (A) DNA fixed encoding (B) DNA dynamic encoding of the proposed algorithm.

FIGURE 12

The encrypted image and histogram of “pure white” image and “pure black” image: (A) The encrypted image of “pure white.” (B) The histogram of (A). (C) The encrypted image of “pure black.” (D) The histogram of (C).