A lightweight symmetric image encryption cryptosystem in wavelet domain based on an improved sine map

In the era of big data, the number of images transmitted over the public channel increases exponentially. As a result, it is crucial to devise the efficient and highly secure encryption method to safeguard the sensitive image. In this paper, an improved sine map (ISM) possessing a larger chaotic region, more complex chaotic behavior and greater unpredictability is proposed and extensively tested. Drawing upon the strengths of ISM, we introduce a lightweight symmetric image encryption cryptosystem in wavelet domain (WDLIC). The WDLIC employs selective encryption to strike a satisfactory balance between security and speed. Initially, only the low-frequency-low-frequency component is chosen to encrypt utilizing classic permutation and diffusion. Then leveraging the statistical properties in wavelet domain, Gaussianization operation which opens the minds of encrypting image information in wavelet domain is first proposed and employed to all sub-bands. Simulations and theoretical analysis demonstrate the high speed and the remarkable effectiveness of WDLIC.