The purpose is to maintain the confidentiality of UAV-captured images by encrypting them using two novel chaotic map-based dynamic substitution methods.
We have proposed two chaotic maps, Coupled-Cosine-Sine (CCS) map and the Amplified-Cosine-Sine (ACS) map. When examined for bifurcation diagrams and Lyapunov exponents, the suggested chaotic maps show a broader continuous chaotic range, complicated behaviour and random distribution. The work also presents an image encryption scheme using the CCS and ACS chaotic maps. The scheme uses permutation and dynamic substitution operations to encrypt the image. The permutation process reorders the pixel positions, while the substitution changes the pixel values. The method employs a two-level permutation approach, operating at both the row and column levels. The dynamic substitution process uses pseudorandom keys and an initial seed, both updated dynamically, CCS, ACS chaotic maps and mathematical operators (XOR and Modulus) to change pixel values. In our scheme, the chaotic map used is not fixed. One of the proposed CCS or ACS maps is used based on the least significant bit of the initial seed; this selection induces the dynamic nature in the scheme.
The various result such as UACI, NPCR, BCR etc. are close to their ideal values.
1. Proposed the novel CCS map and the ACS chaotic map. 2. Developed a new medical image encryption scheme utilizing these chaotic maps. 3. Introduced a two-level permutation process at the pixel level, comprising row-wise and column-wise transformations. 4. Designed a dynamic substitution mechanism that modifies pixel values based on dynamically updated pseudorandom keys and initial seed, and mathematical operations (XOR and Modulus). 5. Enabled adaptive selection of chaotic maps (CCS or ACS) based on the least significant bit of the initial seed, enhancing the dynamic behaviour of the encryption scheme. 6. A comprehensive security analysis of the proposed system using multiple evaluation metrics is performed to validate its cryptographic strength.
