A new four-tier technique for efficient multiple images encryption

People transmit millions of digital images daily over various networks, where securing these images is a big challenge. Image encryption is a successful approach widely used in securing digital images while transmitting. Researchers developed different encryption techniques that focus on securing individual images. Recently, encryption of multiple images has gained more interest as an emerging encryption approach. In this paper, we proposed a four-tier technique for multiple image encryption (MIE) to increase the transmission speed and improve digital image security. First, we attached the plain images to create an augmented image. Second, the randomized augmented image is obtained by randomly changing the position of each plain image. Third, we scrambled the randomized augmented image using the zigzag pattern, rotation, and random permutation between blocks. Finally, we diffuse the scrambled augmented image using an Altered Sine-logistic-based Tent map (ASLT). We draw a flowchart, write a pseudo-code, and present an illustrative example to simplify the proposed method and make it easy to understand. Many experiments were performed to evaluate this Four-Tier technique, and the results show that this technique is extremely effective and secure to withstand various attacks.