International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 08, Special Issue | Oct 2021 www.irjet.net p-ISSN: 2395-0072 International Conference on Recent Trends in Science & Technology-2021 (ICRTST - 2021) Organised by: ATME College of Engineering, Mysuru, INDIA © 2021, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 36 Mosaic Covert Communication for Data Security Nagendra M S 1 PG Student, Department of Electronics & Communication Engineering, Sri Siddhartha Institute of Technology, Tumakuru, Karnataka, India Manjula Y 2 Assistant Professor, Department of Electronics & Communication Engineering, Sri Siddhartha Institute of Technology, Tumakuru, Karnataka, India Dr. M Z Kurian 3 Professor & Head, Department of Electronics & Communication Engineering, Sri Siddhartha Institute of Technology, Tumakuru, Karnataka, India -----------------------------------------------------------------------------***---------------------------------------------------------------------------- Abstract— The security of the image needs to be warranted when it is directed over Internet. The menace can be deliberate or accidental. Guaranteeing security comes with cost. In many of the cases, only a tiny portion of the whole image contains the sensitive information and only that portion need to be safeguarded. Securing only a small portion of the image is cost-effective, efficient, achievable and easier to implement. To do this, various encryption algorithms put together with Steganography methods are in use. In this work, securing the face in the photo of an individual using two level of encryption is discussed. The face is sliced from the main image and Fractal encryption is applied to get cipher image. Additionally, this cipher image is cosine transformed and the recovery information is lodged using LSB algorithm. Inspired by this, a little modification is proposed to the existing work in which, encryption phase is replaced by Mosaic phase. Mosaic technology is a powerful tool using which real sized images can be completely secured using covert communication. Here, mosaic technique is utilized to hide only a part of the image. Using this method, faces are swapped by Mosaics so that, it is less inclined to Hackers attack. The implementation details and experimental results for Mosaic image creation are briefly discussed. The results were pleasing with high PSNR, less RMSE and high correlation. Keywords- Image Mosaic; Fractal Images; Cosine transform; LSB hiding I. INTRODUCTION This is a digital world. Exchange of information over internet had become integral part of life. When data is sent over internet, it is really not safe for lot of obvious reasons. The channel is unsafe for transmission of any type of unprotected data. Hacking, Steganolysis, malwares, cyber criminals contribute in their own way to make the channel an unsafe. Therefore, there is a strong need for ensuring the security and integrity of data. In some cases, unauthorized access to the data needs to be stopped. Variety of solutions is being practiced since a long time. Encryption and password security are the most common methods. In the recent approaches, as a measure of additional security, the encrypted and password protected data is sent covertly. Cryptography takes care of encryption aspect and Steganography take care of covert communication aspect. Both have their own advantages and disadvantages A. Securing Image There are various types of data are transmitted over internet such as textual messages, voice messages (audio), various types of photos (image data) and video. They are together called as multimedia content. Various types of data encounter various types of attacks. The data in the form of an “image” occupies majority of portion of the data being circulated in internet. An image can hold huge amount of data in the pictorial form or, it can be used as a container to hold other form of data. (Example: An image containing hidden text information). In any case, the image needs to be safeguarded from various types of possible attacks. The definition of “securing an image” varies depending upon the context. In some cases, the whole image need to be safeguarded and in some other case, only a small portion of image need to be safeguarded.