2 Laboratory of Network Computer and Security Technology in Shaanxi Province, Xi’an University of Technology, Xi’an, China,
Because a DNA nucleotide sequence has the characteristics of large storage capacity, high parallelism, and low energy consumption, DNA cryptography is favored by information security researchers. Image encryption algorithms based on DNA coding have become a research hotspot in the field of image encryption and security. In this study, based on a comprehensive review of the existing studies and their results, we present new insights into the existing image encryption algorithms based on DNA coding. First, the existing algorithms were summarized and classified into five types, depending on the type of DNA coding: DNA fixed coding, DNA dynamic coding, different types of base complement operation, different DNA sequence algebraic operations, and combinations of multiple DNA operations. Second, we analyzed and studied each classification algorithm using simulation and obtained their advantages and disadvantages. Third, the DNA coding mechanisms, DNA algebraic operations, and DNA algebraic combination operations were compared and discussed. Then, a new scheme was proposed by combining the optimal coding mechanism with the optimal DNA coding operation. Finally, we revealed the shortcomings of the existing studies and the future direction for improving image encryption methods based on DNA coding.
Since Dr. Adleman of the United States used DNA molecular biological computing to solve the directed path problem of seven nodes  in 1994, DNA computing has attracted the attention of researchers across the world [2–5]. In DNA computing, DNA nucleotide bases A, C, G, and T coding sequences are used as carriers of information; it has great advantages in dealing with large storage capacity, parallelism, and energy consumption of information [6–9]. DNA computing essentially uses biochemical experiments to address practical problems. However, because of the limitations of biochemical reaction conditions, such as expensive experimental equipment, environmental requirements, difficulty in extracting DNA sequence, and difficulties in controlling the concentration, temperature, and PH of the reactant, studying DNA computing is difficult. Regarding image encryption in DNA computing, researchers ignore the complex experimental links of DNA, only use DNA coding to carry image information, and design a reasonable and effective encryption algorithm by combining chaotic mapping with different DNA coding algorithms. This idea gives rise to new perspectives in the research on image encryption.