In the recent decade, chaos‐based image encryption algorithms gained attention due to their pros and cons. The authors suggest one such algorithm of image encryption for different colour space using feed forward initial condition to pursue random permutation by combining 1D logistic map with a series of tent maps. The algorithm adds one more novel step to protect and encrypt binary image by concealing it within a cover grey image using bit‐plane decomposition methods. Sensitivity towards initial condition is shown using block division of image by applying a stream of random initial conditions to each block for encryption along with XOR operation which leads the key space high . For better performance analysis, the proposed scheme has been tested with many colour space images including a binary image. The proposed technique is more efficient with respect to time complexity and resistance to vulnerability aspects.

Steganography is a technique of hiding information imperceptibly inside other medium so that the very fact of communication taking place remains hidden. Recently, the reach of internet has extensively widened through social networking and blogging websites and a high amount of digital media interchange, especially in the form of digital images is being witnessed. This poses a huge threat to security from hackers and terrorists, as this medium can be used for covert communication, thus justifying the need for good steganalysis techniques to detect the existence of hidden messages in digital images. This paper analyses some steganalysis techniques which attack various kinds of spatial domain steganography techniques. Some of them are chi-square attack, triples analysis, sample pair analysis, TPVD steganalysis and analysis of adjacent pixel pair steganalysis. This paper also identifies the current research challenges and discusses possible directions for future research in this field.

Most of the digital image watermarking techniques are susceptible to geometric attacks such as cropping, rotation and scaling. These attacks are the easiest yet most successful in rendering the survival of watermark difficult. Such geometric operations alter the pixel orientation in the cover thereby rendering the watermark difficult to locate and extract. However, if the alterations produced by the geometric attacks such as scaling, cropping and rotation can be modeled in terms of the change in the image geometry, it is possible to relocate the watermark even after the original cover has suffered an attack. This paper contributes to the state of the art by proposing an image watermarking technique that attempts to model the attacks like cropping, scaling and rotation in terms of the image geometry. The proposed scheme is acceptably resistant to common geometric attacks and common image processing attacks. The watermark embedding is also done efficiently to offer resistance to image processing attacks. The watermark detection procedure is blind and key based, also not requiring the original cover work for watermark extraction. Efforts have been given to ensure that the proposed scheme conforms to robustness against attacks and exhibits high visual fidelity of the watermarked cover.

Majority of research in steganography focuses on hiding the secret information into the cover directly. The payload can be more secured by not embedding the secret in the cover at all. Instead, a partial information about the secret may be embedded which can be used for later payload realisation. This typically appears analogous to random noise and cannot regenerate the payload without a key. Common approaches to achieve such information include pre-embedding payload encryption. However, simpler cover-secret map-based techniques can also be thought of where such information is generated with optimal resource utilisation. This paper proposes a map-based data hiding scheme in images through image realisation steganography. The proposed technique works for colour and grey images. It also incorporates a multi-stage decoding key and there have been efforts to ensure that the technique conforms to high fidelity of the stego image and performs decently against steganalysis attacks.