  Given the security concerns of Internet of Things (IoT) networks and limited
computational resources of IoT devices, this paper presents RNA-TransCrypt, a
novel image encryption scheme that is not only highly secure but also efficient
and lightweight. RNA-TransCrypt integrates the biocryptographic properties of
RNA encoding with the non-linearity and unpredictability of chaos theory. This
scheme introduces three novel contributions: 1) the two-base RNA encoding
method, which transforms the image into RNA strands-like sequence, ensuring
efficient scrambling; 2) the transformative substitution technique, which
transforms the s-box values before replacing the pixel values, and is
responsible for making the scheme lightweight; and 3) three mathematical
cryptographic operations designed especially for image encryption that ensure
the effective transformation of the s-box values, resulting in a new outcome
even for the same input values. These modules are key-dependent, utilizing
chaotic keys generated by the De Jong Fractal Map and the Van der Pol
Oscillator. Extensive security analysis, including histogram analysis,
correlation analysis, and the results of the statistical security parameters
obtained from the Gray-Level Co-occurrence Matrix (GLCM) validate the efficacy
of the proposed scheme in encrypting input images with close-to-ideal results
of 7.997 entropy and 0.0006 correlation.
