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I would like to express my deep gratitude towards my project guide Dr. Ashish
Khare for his able guidance and supervision which helped me for starting this
project. I am extremely grateful and remain indebted to him for being a source of
inspiration and for his constant support in the idea and starting of the project.
I am thankful to him for his constant constructive criticism and invaluable
suggestions, which benefited me a lot while starting the project on “Image
I would also like to thank to Prof R.R.Tewari and Dr. T.J. Siddhiquie who were
directly and indirectly instrument in enabling me to stay committed for the
I am also very much thankful to my parents and other family members for being
such a great source of inspiration of mine.
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Subject of steganography, mainly focused on embedding text data in digital images. The goal of steganography is covert communication. So, a fundamental requirement of this steganography system is that the hider message carried by stego-media should not be sensible to human beings. The other goal of steganography is to avoid drawing suspicion to the existence of a hidden message. This approach of information hiding technique has recently become important in a number of application areas. This project has following objectives:
To product security tool based on steganography techniques.
To explore techniques of hiding data using encryption module of this
To extract techniques of getting secret data using decryption module.
Steganography sometimes is used when encryption is not permitted. Or, more
commonly, steganography is used to supplement encryption. An encrypted file
may still hide information using steganography, so even if the encrypted file is
deciphered, the hidden message is not seen.
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The word steganography is derived from the Greek words “stegos” meaning “cover” and “grafia” meaning “writing” defining it as “covered writing”. Steganography refers to the science of invisible" communication. Steganographic techniques strive to hide the very presence of the message itself from an observer. The general idea of hiding some information in digital content has a wider class of applications that go beyond steganography. Steganography is the process of hiding a secret message within a larger one in such a way that someone cannot know the presence or contents of the hidden message. Although related, Steganography is not to be confused with Encryption, which is the process of making a message unintelligible—Steganography attempts to hide the existence of communication. Steganography is the practice of hiding private or sensitive information within something that appears to be nothing out to the usual.
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History of Steganography
440 B.C. Herodotus recounts the story of Histaiaeus, who wanted to encourage Aristagoras of Miletus to revolt against the Persian king. In order to securely convey his plan. 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. The messenger, apparently carrying nothing contentious, could travel freely. Arriving at his destination, he shaved his head and pointed it at the recipient.
1st and 2nd World Wars German spies used invisible ink to print very small dots on letters. Microdots – Blocks of text or images scaled down to the size of a regular
Early Sreganography Pictographs: e.g., Sherlock Holmes’s Dancing Men.
“Come Here At Once”
Although steganography is an ancient subject, the modern formulation of it is often given in terms of the prisoner’s problem proposed by Simmons, where two inmates wish to communicate in secret to hatch an escape plan. All of their communication passes through a warden who will throw them in solitary confinement should she suspect any covert communication. The warden, who is free to examine all communication exchanged between the inmates, can either be passive or active. A passive warden simply examines the communication to try and determine if it potentially contains secret information.
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If she suspects a communication to contain hidden information, a passive warden takes note of the detected covert communication, reports this to some outside party and lets the message through without blocking it. An active warden, on the other hand, will try to alter the communication with the suspected hidden information deliberately, in order to remove the information.
Image Steganography has many applications, especially in today’s modern, high-tech world. Privacy and anonymity is a concern for most people on the internet. Image Steganography allows for two parties to communicate secretly and
It allows for some morally-conscious people to safely whistle blow on internal actions.
It allows for copyright protection on digital files using the message as a
One of the other main uses for Image Steganography is for the transportation of high-level or top-secret documents between international governments.
Image Steganography has many legitimate uses; it can also be quite nefarious. It can be used by hackers to send viruses and Trojans to compromise machines, and also by terrorists and other organizations that rely on covert operations to communicate secretly and safely.
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Basic Structure of Steganography
Steganography is the practice of hiding private or sensitive information within something that appears to be nothing out to the usual.
The basic structure of Steganography is made up of three components:
Carrier - The carrier can be a painting, a digital image, an mp3, even a
TCP/IP packet among other things. It is the object that will ‘carry’ the
Message - The message (hidden) is being carried by the object (carrier).
Key - A key is used to decode/decipher/discover the hidden message. This
can be anything from a password, a pattern, a black-light, or even lemon
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Steganography versus Cryptography
Steganography is often confused with cryptology because the two are similar in the way that they both are used to protect important information. The difference between two is that steganography involves hiding information so it appears that no information is hidden at all. If a person or persons views the object that the information is hidden inside of he or she will have no idea that there is any hidden information, therefore the person will not attempt to decrypt the information. Steganography differs from cryptography in the sense that where cryptography focuses on keeping the contents of a message secret, steganography focuses on keeping the existence of a message secret . Steganography and cryptography are both ways to protect information from unwanted parties but neither technology alone is perfect and can be compromised. Once the presence of hidden information is revealed or even suspected, the purpose of steganography is partly defeated. The strength of steganography can thus be amplified by combining it with cryptography.
Hide, Without altering Obfuscates the fact of
communication, not the data Preventative – deter attacks
Alter, without hiding Obfuscates the data, not fact of
the communication Curative - defends attacks
Two other technologies that are closely related to steganography are watermarking and fingerprinting. These technologies are mainly concerned with the protection of intellectual property, thus the algorithms have different requirements than steganography.
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Different kinds of steganography
Almost all digital file formats can be used for steganography, but the formats that are more suitable are those with a high degree of redundancy. Redundancy can be defined as the bits of an object that provide accuracy far greater than necessary for the object’s use and display. The redundant bits of an object are those bits that can be altered without the alteration being detected easily . Image and audio files especially comply with this requirement, while research has also uncovered other file formats that can be used for information hiding.
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To a computer, an image is a collection of numbers that constitute different light intensities in different areas of the image. This numeric representation forms a grid and the individual points are referred to as pixels. Most images on the Internet consists of a rectangular map of the image’s pixels (represented as bits) where each pixel is located and its colour. These pixels are displayed horizontally row by row. An image is a rectangular grid of pixels. It has a definite height and a
definite width counted in pixels.
Each pixel has a color. The color is a 32-bit integer. The first eight bits determine the redness of the pixel, the next eight bits the greenness, the next eight bits the blueness, and the remaining eight bits the transparency of the pixel.
• We can think of an image as a function f.
• f: R2 R – f (x, y) gives the intensity at position (x, y) – Realistically, we expect the image only to be defined over a
rectangle, with a finite range: • f: [a,b]x[c,d] [0,1]
• A color image is just three functions pasted together. We can write this as
a “vector-valued” function:
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Images are the most popular cover objects used for steganography. In the domain of digital images many different image file formats exist, most of them for specific applications. For these different image file formats, different steganographic algorithms exist.
Image Steganography techniques
There have been many techniques for hiding information or messages in
images in such a manner that the alterations made to the imag.
Image steganography techniques can be divided into two groups:
1) Image Domain
2) Transform Domain
The Common approaches are:
1) Least significant bit insertion (LSB)
2) Masking and filtering
3) Transform techniques
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Least significant bit insertion (LSB)
Least significant bits (LSB) insertion is a simple approach to embedding
information in image file.
The simplest steganographic techniques embed the bits of the message
directly into least significant bit plane of the cover-image in a deterministic
Used in BMP and GIF images.
Masking and filtering
Masking and filtering techniques, usually restricted to 24 bits and gray scale
images, hide information by marking an image, in a manner similar to paper
The techniques performs analysis of the image, thus embed the
information in significant areas so that the hidden message is more integral
to the cover image than just hiding it in the noise level.
Transform techniques embed the message by modulating coefficients in a
transform domain, such as the Discrete Cosine Transform (DCT) used in
JPEG compression, Discrete Fourier Transform, or Wavelet Transform.
These methods hide messages in significant areas of the cover-image, which
make them more robust to attack.
Transformations can be applied over the entire image, to block through out
the image, or other variants
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In images there are two types of compression: lossy and lossless. Both methods save storage space, but the procedures that they implement differ. Lossy compression creates smaller files by discarding excess image data from the original image. It removes details that are too small for the human eye to differentiate, resulting in close approximations of the original image, although not an exact duplicate. An example of an image format that uses this compression technique is JPEG (Joint Photographic Experts Group). Lossless compression, on the other hand, never removes any information from the original image, but instead represents data in mathematical formulas. The original image’s integrity is maintained and the decompressed image output is bit-by-bit identical to the original image input. The most popular image formats that use lossless compression is GIF (Graphical Interchange Format) and 8-bit BMP (a Microsoft Windows bitmap file).
Compression plays a very important role in choosing which steganographic algorithm to use. Lossy compression techniques result in smaller image file sizes, but it increases the possibility that the embedded message may be partly lost due to the fact that excess image data will be removed. Lossless compression though, keeps the original digital image intact without the chance of lost, although it does not compress the image to such a small file size. Different steganographic algorithms have been developed for both of these compression types and will be explained in the following sections.
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As this project is get done only on introductory level, so lots of further work
required to complete this project titled as “Image Steganography (A
technique to hide information within image file) ”
I decided to follow particularly Least significant bit insertion (LSB)
approach in order