Published on February 18, 2014
Prepared By- Saurabh Walia Submitted to- Ms. Neha Kapur Senior Lecturer (C.S.)
Steganography, Cryptography, and Watermarking There are two major branches of information hiding, Steganography and Watermarking Watermarking: ℗ – Communication in watermarking is the host signal, with the embedded data providing copyright protection. – The existence of a watermark is often declared openly. – Any attempt to remove or invalidate the embedded content renders the host useless. Cryptography: – – – – Doesn’t conceal the communication. Scrambles the data to prevent eavesdroppers understanding the content. Cryptography involves various methods and implementations. May be considered complementary and orthogonal (unrelated). Once the presence of hidden information is revealed or even suspected, the purpose of steganography is defeated.
EVOLUTION-: steganography cryptography watermarking
History of Steganography 440 B.C. (physical and wax based) 1st and 2nd world wars.(letters) Modern Times(microdot)
Examples-: Ancient times• Demeratus sent a warning about a forthcoming attack to Greece by writing it on a wooden panel and covering it in wax. • Histiaeus, who shaved the head of his most trusted slave and tattooed a message on it. After his hair had grown the message was hidden. The purpose was to instigate a revolt against the Persians. World War II Invincible inks Null ciphers (unencrypted messages): Apparently neutral's protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects pretext for embargo on by products, ejecting suets and vegetable oils. Sent by a German Spy in WWII, by taking the second letter in each word the following message emerges: Pershing sails from NY June 1. Microdot Technology Shrinking messages down to the size of a dot became a popular method. Since the microdot could be placed at the end of a sentence or above a j or an i .
Introduction- Art and science of writing hidden messages A form of security through obscurity No one apart from the sender and intended recipients suspects the existence of messages.
Terminology-: Steganalysis StegoMedium Carrier/ Cover File Embedded/ payload
Basics of Modern Steganography fE: fE-1: cover: emb: key: stego: steganographic function "embedding" steganographic function "extracting" cover data in which emb will be hidden message to be hidden parameter of fE cover data with the hidden message
Text/ document Video Types of Steganography Audio Images
Steps In SteganographySteganography Encoding a message Decoding a message
Encoding -: Prepare a VESSEL FILE Stego Data Embed the payload in cover file.
Decoding-: Payload Plain Document StegoData
SteganographyTools-: Programs Images files Audio files Video files Document files DarkCryptTC BMP, JPG, TIFF, PNG, PSD, TGA, MNG WAV - TXT, HTML, XML, ODT OpenPuff S-Tools MP3, WAV BMP, GIF Steg ImageSpyer G2 3gp, MP4, MPEG1, MPEG-2, VOB, SWF, FLV Pdf Wav BMP, JPEG, PNG, TGA - - BMP, PNG, JPEG, GIF - - - BMP, TIFF - - -
Steganalysis-: Art and science of detecting hidden messages. Just discovers steganography Not related with decryption of data.
Least significant bit method-
LBS Example- The message"Boss said that we should blow up the bridge at midnight." encrypted with mozaiq using "växjö" as password.
Audio Steganography-: • • • • • • Watermarking of audio signals is more challenging compared to the watermarking of images or video sequences, due to wider dynamic range of the HAS in comparison with human visual system (HVS). The sensitivity of the HAS to the additive white Gaussian noise (AWGN) is high as well; this noise in a sound file can be detected as low as 70 dB. Some commonly used methods of audio steganography are discussed below-. Least Significant Bit (LSB) Coding : One of the earliest techniques studied in the information hiding of digital audio (as well as other media types) is LSB coding. In this technique LSB of binary sequence of each sample of digitized audio file is replaced with binary equivalent of secret message. Parity Coding : Instead of breaking a signal down into individual samples, the parity coding method breaks a signal down into separate regions of samples and encodes each bit from the secret message in a sample region's parity bit. If the parity bit of a selected region does not match the secret bit to be encoded, the process flips the LSB of one of the samples in the region. Advantage: The sender has more of a choice in encoding the secret bit, and the signal can be changed in a more unobtrusive manner. Disadvantage: This method like LSB coding is not robust in nature.
Video steganography-: • Algorithm of hiding messages in video files:
Users and Applications-: Cyber Forensics Modern Printers (HP) Terrorists Intelligence agencies Hackers
Future Scope-: Finding Needle in a haystack is a very cumbersome task. •So we hope in future techniques would be developed that gonna detect the presence of smallest and tiniest of sentences in the Huge text, audio and video files effeciently.
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As opposed to digital watermarking, the main property of steganography is statistica ... Digital Watermarking and Steganography (Second Edition)
Digital Watermarking and Steganography, 2nd Edition. Chapter One: Introduction Chapter Two: Applications and Properties Chapter Three: Models of Watermarking