A new dynamic DNA-coding model for gray-scale image encryption

Abstract

To protect the images and provide a more secure cipher image, DNA encoding is crucial in image encryption. Applying a single, easily detectable coding rule to the image during DNA encoding has no impact on the encryption model's security level. Therefore, using various coding rules while applying encryption to the image, dynamic DNA-coding techniques have emerged to strengthen and improve the encryption of the image and its security. This study integrates a dynamic DNA-coding method with an encryption model. The model is applied to gray-scale images, where using a predetermined coding rule, every two bits are DNA-encoded in the image. The proposed model generates the key by sending the image and its metadata to hash functions. Following that, the hyperchaotic system constructs three chaotic sequences using the key, and the Lorenz–Liu chaotic system generates a sequence of coding rules. Then, the image is passed to Arnold Transform, where the resulted image is diffused by applying five chaotic maps. Last, using the coding rules, it is DNA-encoded, provided with the chaotic sequences to DNA, and DNA-decoded. Twelve metrics were used to assess the proposed model on ten widely used images. Results show a promising improvement in performance, since it enhanced the security of the model.

Silent Mutation for Gray-Scale Image Encryption

“…The proposed model, its elements, and the encryption and decryption techniques are all thoroughly explained in this section. Modifications to the model from [5] are described in the following subsections. Step 1: Creation of 256-bit Hash Value.…”

“…The Arnold Transform parameters a, b, and c, the Hyper-Chaos system initial values w0, x0, y0, and z0, the Liu chaotic system parameters r2, s2, t2, u, and v, and the Lorenz-Liu chaotic system parameters r1, s1, t1, and λ are obtained by applying the average of each part and H to the equations in model [10]. The starting values of LCS and LLCS are then determined together using the original model [5] equations.…”

“…Using the parameters and initial values, LLCS is iterated, resulting in the three sequences L1, L2, and L3. Equations from the model [5] are utilized in L1 to create coding rules for a chaotic sequence CR.…”

“…It represents the computational complexity of the steps applied in the encryption model [13]. The computational complexity of the main model is O(M * N) [5]. The computational complexity of data embedding is O(M * N).…”

“…In this study, we overcome this issue by incorporating the model from [5] with data embedding into DNA. The suggested methodology involves DNA encoding the image using a variety of coding rules, followed by silent mutation to embed the image into a real DNA sequence.…”