# DNA-PRESENT: An Improved Security and Low-Latency, Lightweight Cryptographic Solution for IoT
###### Abstract
[38; 39; 40; 31] PRESENT has a weak key schedule with evident dependency between round keys, resulting in a slow and predictable bits transition. This issue has been addressed using an improved KSA, using linear and non-linear functions, ensuring improved confusion [41]. Secondly, the produced ciphertext also has low diffusion properties due to the simple design of the permutation box (pLayer) and the presence of non-permuted static bits at multiple locations [42; 43; 44]. The design of PRESENT's pLayer is kept simple to limit hardware cost, but the leftmost bit (bit 0), central bits 21 and 42, and the rightmost bit (bit 63) are never permuted--these bits are static. This permutation box design is an hourglass design, as explained in [44] and presented in Figure 2, keeping the leftmost, central, and rightmost bits unaltered. This is one of the leading causes of slow diffusion in ciphertext, endorsing that the permutation layer alone cannot introduce enough diffusion [45; 46; 44] and requires the identification of other methods to enhance the diffusion property of the algorithm. Figure 1: Cost, security, and performance trade-off triangle [10]. Several efforts have been made to address the slow diffusion and the corresponding improvements in the PRESENT block cipher. The most relevant and impactful of these are discussed here. In the year 2016, an improved PRESENT using a dynamic s-box was presented [45]. The improved design was compared against PRESENT for the avalanche effect, where significant security improvements regarding the diffusion property were observed in the improved design. In the year 2020 [46], a new variant, D-PRESENT, was introduced, which used dynamic key-dependent s-boxes to improve the randomness in the ciphertext. D-PRESENT successfully increased the avalanche effect and reduced the number of rounds to half, which resulted in execution time reduction. However, calculating the active s-box before each iteration can significantly increase the algorithm's complexity. In the year 2021 [44], the authors improved the SPN structure using the keyed permutation of PRESENT to ensure resistance against side-channel attacks that resulted in different bit permutations for each round. However, a thorough analysis showed that this technique also increased system-level overhead and power consumption. Recent research by [PERSON] et al. [46] improved the security of the PRESENT block cipher using chaotic systems to achieve robustness and better randomness for resource-constrained devices. All these approaches mentioned above improved the PRESENT block cipher using recent cryptographic advancements. However, there has been no evidence where the cumulative impact of the improvements on security, cost, and performance has been studied collectively. Moreover, this suggests that the algorithm's weakness should be mitigated through an alternative low-cost diffusion technique. With the recent advances in cryptography, many researchers have used DNA cryptography as a means to enhance the security of encryption algorithms [47; 48; 49] because the effectiveness of any DNA-based genetic scheme is directly associated with the level of randomness it offers [50; 51]. In addition to providing randomness, DNA cryptography ensures  
Figure 2: Hourglass design of the _pLayer()_[44]. robust confusion and diffusion, and fast and low-cost implementation functions [52; 53; 54; 55]. Building on the research mentioned earlier, the diffusion property of the algorithms can be enhanced using operations derived from Deoxyribonucleic Acid (DNA) cryptography. Another research [14] used a DNA-based transposition layer and randomly chosen DNA sequences for the generation of secret keys, resulting in additional image security. Recent research used DNA-sequencing and permutation-based functions to ensure image security with improved entropy, reduced time, and complexity [55].