Review of Spatial and Frequency Domain Steganographic Approaches Jasvir Singh Department of Electronics and Communication Engineering Gaganjot Kaur (A.P) Department of Electronics and Communication Engineering BFCET, Deon, Bathinda, Punjab Manveer Kaur Garcha Department of Information Technology Chandigarh Engineering College Landran, Chandigarh, Punjab Abstract— Now days, by the fast evolution of internet it is very important to protect secret information from cyberpunks while communication. Steganography is the technique that exerts for invisible broadcasting, in which unfrequented data or information is transmitted and collected. In digital image steganography, conveyance is achieved by embedding the data into cover-image for producing the steganographic-image. Till date number of techniques has been proposed for embedding the secret message in multimedia object like images. This paper is aimed at reviewing couple of techniques in the spatial as well as frequency domain. These techniques are comparing in terms of robustness and imperceptibility using peak signal to noise ratio. Keywords — Steganography; entropy; robustness; imperceptibility. I. INTRODUCTION In this age of digitization communication is very essential in every progressive field. All sectors that are influenced by communication aspire to preserve confidential concerns. Steganography occupies a crucial role in exchanging the sensitive information across the network. It can be defined as data hiding technique in which confidential textual detail are concealed by displaying the irrelevant multimedia object. In this era of technology, it is really very difficult to protect the confidential information across the internet from illegitimate recipients. So in order to protect the sensitive information, number of techniques has been proposed till date. Steganography is one of them. The word steganography comes from Greek wordbook which is a synthesis of two words, namely, “Stegano” signifying “covered” and “Graphie” signifying “writing”. Thus the term can be defined as the method of concealed writing. In the field of information hiding, steganography is the extensively used secret communication technique in which confidential data is concealed from the viewer by hiding it in some multimedia object like image, audio or video. The significance of the topic lies in the fact that steganography outmatches its sister data hiding disciplines because it hides the existence of message from unintended recipients rather than making the contents of message meaningless like cryptography. Steganography is not newfangled idea; its background is dates back to ages. This technique was initiated by ancient Greeks. They were accustomized to shave the head of their slaves and tattoo the messages on their heads. After the hair had grown back, the slaves were sent to their allies without the enemy’s knowledge. This method had obvious disadvantage of delayed transmission and limited size. Later people used to hide message written on wood underneath wax known as wax tablets. Wax tablets were then sent to intended receiver and wax was peeled off extract the hidden message. During World War I and II, Germans used null ciphers for sharing the hidden text. Invisible inks were used to write text on paper during American Revolution. These messages were retrieved by exposing that paper to rays or fires. The general process of steganography is shown in Fig.1 Cover file is any multimedia object and secret message is the confidential information to be transmitted. Embedding process is an operation of inserting the secret message inside cover file to generate stego-file. Stego-file is the cover file with secret message present in it, but the two are indistinguishable to human eye. This stego-file is then transferred over the network. At the receiver end, stego-file is input to extraction operation for plucking out the secret message from it. Secret key used can by a simple password or asymmetric key depending on the use case in which it is used. Secret key is used in extraction only in case if it is used while embedding. In digital image steganography, the cover file to be used can be any random image. II. REQUIRED PROPERTIES OF STEGANOGRAPHIC TECHNIQUES Though Steganography is not a new technique it is still under research and development because of its quality and quantity trade off. Quality is related to the cover image and quantity is related to the maximum length of message that can be embedded in the cover image. when a lengthy message is embedded in the image it degrades the quality more as compare to shorter messages so it can be said quality is inversely to quantity. Quantity is measured in bits per pixel (bpp) and quality can be measured using any performance metric like peak signal to noise ratio (PSNR) or structural similarity index measure (SSIM). Robustness is another factor that may significantly affect the steganographic algorithm. This term is related to the survival of message when the steganographic image is prone to various intentional or unintentional attacks like cropping, noising, compression etc. if the message survive under attacks, the technique is referred to as robust else it is called fragile technique. International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 www.ijert.org IJERTV4IS061082 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Vol. 4 Issue 06, June-2015 1122