INTRODUCTION In Greek terminology, STEGANOS – “Covered” GRAPHIE – “Writing” Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message. This can be achieved by concealing the existence of information within seemingly harmless carriers or cover. Carrier: text, image, video, audio, etc
History of Steganography 440 B.C. Histiaeus shaved the head of his most trusted slave and tattooed it with a message which disappeared after the hair had regrown. To instigate a revolt against Persians. 1st and 2nd World Wars German spies used invisible ink to print very small dots on letters. A message sent by a German spy during World War II read: “Apparently neutral’s protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects for pretext embargo on by- products, ejecting suets and vegetable oils.” By taking the second letter of every word the hidden message “Pershing sails for NY June 1” can be retrieved
Evolution Cryptography Steganography Watermarkin g
Steganography Terms Carrier or Cover File - A Original message or a file in which hidden information will be stored inside of it . Stego-Medium - The medium in which the information is hidden. Embedded or Payload - The information which is to be hidden or concealed. Steganalysis - The process of detecting hidden information inside a file.
Types of SteganographySteganography in Texts/DocumentsSteganography in ImagesSteganography in AudioSteganography in Video
Steganography in text Line Shift Coding: Lines are vertically shifted. In line shift coding, shift various lines inside the document up or down by a small fraction (such as 1/300th of an inch). Word Shift Coding: Code words are horizontally shifted. The decoding technique is measuring the spaces between each word and a left shift could represent a 0 bit and a right shift representing a 1 bit. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. White Space Manipulation: It is done by adding a certain amount of white space to the end of lines. The amount of white space corresponds to a certain bit value.
Steganography in imagesThe simplest and most common type of steganography is LSB (least significant bit). The one’s bit of a byte is used to encode the hidden information.Suppose we want to encode the letter A (ASCII 65 or binary 01000001) in the following 8 bytes of a carrier file. 01011101 11010000 00011100 10101100 11100111 10000111 01101011 11100011 becomes 01011100 11010001 00011100 10101100 11100110 10000110 01101010 11100011
Variations of LSBUse password as a seed for pseudo random number generator.Use only those bytes separated by the value of the next random number to hide data.Advantages - More difficult to detect and decode.Disadvantage – Limits the number of bytes that are available for holding the payload.
Least significant bit insertion technique 4 bits to hide the secret image Host Pixel: 10110001 Secret Pixel: 00111111 New Image Pixel: 10110011
Steganography in audioPHASE CODINGSPREAD SPECTRUM Makes use of the fact that small changes are more difficult for the human eye or ear to detect at high energy levels (loud audio or bright video).The message is hidden in those areas of the carrier file with the greatest energy.
Steganography in video For video, a combination of sound and image techniques can be used. This is due to the fact that video generally has separate inner files for the video (consisting of many images) and the sound. So techniques can be applied in both areas to hide data. Due to the size of video files, the scope for adding lots of data is much greater and therefore the chances of hidden data being detected is quite low.
Generic Process of encoding & decoding
APPLICATIONS OF STEGANOGRAPHYSecure Communication • It is a state-of-the-art digital steganography software package developed for confidential multimedia communication. •The software allows the user to select a multimedia data file or "container" for embedding hidden text, audio sequence, video clip, or any form of data file. •The contents of the text message are hashed with those of the container file to produce a key file. The key file is also known as a “Stegfile”.
DIGITAL WATERMARKINGDigital watermarking software for copyright protection of digital images, music CDs,DVDs, and other forms of multimedia data.How robust a watermark is depends on whether it can survive various "attacks" that include contrast changes, cropping, scratches, and filtering.The digital image watermark is able to survive most of these attacks..
DIGITAL SIGNATURE AUTHENTICATION•It is a software product specifically developed to prevent malicious tampering ofprivate and confidential documents.•This will detect any unwarranted tampering and alert the receiver sideimmediately. A digital signature and a multimedia container password areembedded into the confidential document.
DIGITAL LINKAGE AND STORAGE It provides a secure data linkage between a digital image and attribute text information. The attribute information can be any personal records The main function is to securely link the personal record and digital photograph together and then create a hash file that can be safely stored in a database. This hash file is unique and can only be decoded with the original photograph and associated personal record. An optional password is also available to protect the hash file prior to data storage.
Illustrates the operations of StegSafe™ through a data flow diagram
CONCLUSIONSteganography can protect data by hiding it but using it alone may not guarantee total protection. In case of encryption, by seeing the meaningless appearing sequence of bits enemy can detect that some illegal message is being sent. However, if one uses both methods, this will lead to ‘security in depth’. The message should first be encoded using a strong encryption algorithm and then embedded into a carrier.
REFERENCES Steganography And Digital Watermarking Jonathan Cummins, Patrick Diskin, Samuel Lau and Robert Parlett, School of Computer Science, The University of Birmingham.www.scribd.com/doc/27459895www.authorstream.com/Presentation/pavankumar 4b7-473085-steganography/