###### Abstract  
Reversible data hiding (RDH), a promising data-hiding technique, is widely examined in domains such as medical image transmission, satellite image transmission, crime investigation, cloud computing, etc. None of the existing RDH schemes addresses a solution from a real-time aspect. A good compromise between the information embedding rate and computational time makes the scheme suitable for real-time applications. As a solution, we propose a novel RDH scheme that recovers the original image by retaining its quality and extracting the hidden data. Here, the cover image gets encrypted using a stream cipher and is partitioned into non-overlapping blocks. Secret information is inserted into the encrypted blocks of the cover image via a controlled local pixel-swapping approach to achieve a comparatively good payload. The new scheme \(\mathit{MPSA}\) allows the data hider to hide two bits in every encrypted block. The existing reversible data-hiding schemes modify the encrypted image pixels leading to a compromise in image security. However, the proposed work complements the support of encrypted image security by maintaining the same entropy of the encrypted image in spite of hiding the data. Experimental results illustrate the competency of the proposed work accounting for various parameters, including embedding rate and computational time. reversible data hiding; entropy; secure data transmission; block partition; pixel swapping 20232556330  
forms a watermark. The embedded watermark gets extracted for data authentication or copyright protection. For this purpose, the original watermark gets compared with the extracted watermark. Robust watermarking schemes or fragile watermarking schemes are employed depending on the application. For copyright protection, the preferred scheme is a robust watermarking scheme since the embedded watermark will not be destroyed by common image processing operations such as compression, scaling, rotation, etc. [4]. Fragile watermarking schemes are useful for data authentication in which the embedded watermark cannot survive any kind of operation on the watermarked image [5]. So any unauthorized operations in the watermarked image can be claimed by extracting the hidden watermark. Reversible watermarking is different from irreversible watermarking. In reversible watermarking, apart from extracting the embedded watermark, the cover medium should also be recovered. 2. Steganography: Steganography is similar to the watermarking approach that varies in its purpose. In steganography, the information hidden is much larger in capacity, and the receiver does not care about the cover image used for concealing purposes. Here, the cover medium at the receiver end is not so significant after the extraction of hidden information [6]. As noted in the reversible watermarking, the cover medium is significant in reversible steganography. Reversible data-hiding (RDH) schemes are derived from steganography, which aims at lossless recovery of the actual cover medium, along with the extraction of the hidden secret information [7; 8]. In this technique, the data are embedded in mediums such as an image, videos, or audio. Apart from this, a hologram is another example of the cover medium used in RDH [9; 10]. The crust of RDH is in extracting the embedded data and recovering the actual cover medium, both in a lossless manner [11; 12; 13]. Hence, both the medium and the data are significant. A few applicable areas of RDH are medical image transmission, satellite image transmission, defense intelligence operations, and criminal investigations. The basic working of RDH is given in Figure 2.  
Two main approaches in RDH are histogram shifting and difference expansion. In the case of difference expansion-based RDH, the adjacent pairs of pixels are selected, and their difference is expanded to hide the message bits [14; 15]. Overflow and underflow are the two major concerns with difference expansion-based RDH schemes.