Project Steganography

1.INTRODUCTION

Steganography is the art and science of communicating in a way which hides the

existence of the communication , which is the art of hiding information in ways that

prevent the detection of hidden messages . Steganography, derived from Greek, literally

means “covered writing “. It includes a vast array of secret communications methods that

conceal the message's very existence . These methods include invisible inks , microdots ,

character arrangement, digital signatures, covert channels , and spread spectrum

communications.

Steganography and Cryptography are cousins in the spy craft family. A message in

cipher text , for instance , might arouse suspicion on the part of the recipient while an

" invisible " message created with Steganography methods will not. In contrast to

Cryptography ,where the " enemy " is allowed to detect, intercept and modify messages

without being able to violate certain security premises guaranteed by a Cryptosystem ,the

goal of Steganography is to hide messages inside other " harmless " messages in a way

that does not allow any " enemy " to even detect that there is a second secret

message present.

Now Steganography is gaining new popularity with the current industry demands

for digital watermarking and fingerprinting of audio and video. Steganography in images has

truly come of age with the invention of fast ,powerful computers. The most popular

technique in image Steganography is Least Significant Bit Insertion . More precisely, as Kuhn

puts it :

The goal of Steganography is to hide messages inside other harmless messages in a way that does not allow any enemy to detect that there is a second secret message present.

Steganography become more important as more people join the cyberspace

revolution. Steganography is the art of concealing information in ways that

prevents the detection of hidden messages. Stegranography include an array

of secret communication methods that hide the message from being seen or

discovered.

Due to advances in ICT, most of information is kept electronically.

Consequently, the security of information has become a fundamental issue.

Besides cryptography, streganography can be employed to secure

information. In cryptography, the message or encrypted message is

embedded in a digital host before passing it through the network, thus the

existence of the message is unknown. Besides hiding data for confidentiality,

this approach of information hiding can be extended to copyright protection

for digital media: audio, video and images.

The growing possibilities of modern communications need the special means

of security especially on computer network. The network security is

becoming more important as the number of data being exchanged on the

internet increases. Therefore, the confidentiality and data integrity are

requires to protect against unauthorized access and use. This has resulted in

an explosive growth of the field of information hiding.

The advantage of Steganography is that it can be used to secretly transmit messages

without the fact of the transmission being discovered .Often, using encryption might

identify the sender or receiver as somebody with some-thing to hide . For example ,that

picture of your cat could conceal the plans for your company's latest technical innovation.

However ,Steganography has a number of disadvantages as well .Unlike encryption ,it generally

requires a lot of overhead to hide a relatively few bits of information . However, there are

ways around this . Also, once a Steganographic system is discovered , it is rendered useless.

This problem, too , can be overcome if the hidden data depends on some sort of key for

its insertion and extraction.

2. History of Steganography

During World War 2 invisible ink was used to write information on pieces of paper.

In Ancient Greece they used to select messengers and shave their head, they would then write a message on their head.

Another method used in Greece was where someone would peel wax off a tablet that was covered in wax, write a message underneath the wax then re-apply the wax.

Pirate legends tell of the practice of tattooing secret information, such as a map, on the head of someone, so that the hair would conceal it.

There are rumors that during the 1980's Margareth Thatcher, then Prime Minister in UK, became so irritated about press leaks of cabinet documents, that she had the word processors programmed to encode the identity of the writer in the word spacing, thus being able to trace the disloyal ministers.

During the "Cold War" period, US and USSR wanted to hide their sensors in the enemy's facilities. These devices had to send data to their nations, without being spotted.

Today, steganography is researched both for legal and illegal reasons. Among the first ones there is war telecommunications, which use spread

spectrum or meteor scatter radio in order to conceal both the message and its source.

In the industry market, with the advent of digital communications and storage, one of the most important issues is copyright enforcement, so digital watermarking techniques are being developed to restrict the use of copyrighted data.

3. Types of Steganography:

Text Steganography : Since everyone can read, encoding text in neutral sentences is doubtfully effective. But taking the first letter of each word of the previous sentence, you will see that it is possible and not very difficult. Encoding secret messages in text can be a very challenging task. This is becausetext files have a very small amount of redundant data to replace with a secret message.

Image Steganography : Coding secret messages in digital images is by far the most widely used of all methods in the digital world of today. This is because it can take advantage of the limited power of the human visual system (HVS)

Audio Steganography : Because of the range of the human auditory system (HAS), data hiding in audio signals is especially challenging. The HAS perceives over a range of power greater than one billion to one and range of frequencies greater than one thousand to one. Also, the auditory system is very sensitive to additive random noise. Any disturbances in a sound file can be detected as low as one part in ten million (80dB below ambient level).

Printed steganography : Digital steganography output may be in the

form of rinted documents. A message, the plaintext, may be first

encrypted by traditional means, producing a ciphertext. Then, an

innocuous covertext is modified in some way so as to contain the

ciphertext, resulting in thestegotext. For example, the letter size,

spacing, typeface, or other characteristics of a covertext can be

manipulated to carry the hidden message. Only a recipient who knows

the technique used can recover the message and then decrypt

it. Francis Bacon developed Bacon's cipher as such a technique.

4. Project Scope:

This project is developed for hiding information in any image file. The scope

of the project is implementation of steganography tools for hiding

information includes any type of information file and image files and the path

where the user wants to save Image and extruded file.

5. The main aim:

The user should be able to conceal a text message in an image file without any visible

alterations to the image as such. I.e. there should not be any noticeable changes to the coloring or

the position of the various objects in the image.

5.1 Sub: aims:

It is preferred that we use a windows based front end.

The user should be able to pick out the image file he wants to use in the hiding

process.

The format of the image files which can be used for the hiding process should be 24-bit

bitmap.

User should be able to enter the text message he wants to hide.

User should be able to view the image before and after the hiding process is complete. It

is preferable that a new image be created and displayed with the old image which will allow

the user to compare the original image with the new one which will help him to decide

whether his choice of image file was appropriate or whether he needs a new one.

User should be able to transfer the image freely without any problems. I.e. he should be

able to copy the new image file. Send or trade it with others without any special hardware

requirements other than the normal communication systems available with a computer.

There should be a encryption process to encrypt the text for better security.

The user must be able to save the image in which the message is hidden in any desired

folder.

The user should be able to select and view the picture from which to decode.

When the decode is demanded the encryption key should be demanded and when entered

the decrypted text displayed.

He should be able to save the decrypted text message in a file.

The picture inside picture option should have all the above qualities like view both,

compare and decide whether to proceed, and also have an option to save the new image

where the user chooses.

To retrieve the picture the user must be able to view it, and then retrieve and save the

picture

6. Methodology:

User needs to run the application. The user has two tab options – encrypt

and decrypt. If user select encrypt, application give the screen to select

image file, information file and option to save the image file. If user select

decrypt, application gives the screen to select only image file and ask path

where user want to save the secrete file.

This project has two methods – Encrypt and Decrypt.

In encryption the secrete information is hiding in with any type of

image file.

Decryption is getting the secrete information from image file.

7. Object Oriented Analysis (OOA) approach consists of the following steps :

Understanding the problem:

This is the first step in the analysis process. The problem statement should be refined and

redefined in terms of computer system engineering that could suggest a computer based

solution . The problem statement should be stated, as far as possible , in a single , grammatically

correct sentence . The problem statement provides the basis for drawing the requirements

specification of both the user and the software .

Therefore the problem statement is

“ This project attempts to make use of the standard steganographic tool and

some modified version of standard encryption algorithm to perform the task of data hiding for

the purpose of observing privacy “.

7.1 Requirements Specifications:

Once the problem is clearly defined, the next step is to understand what the proposed to do.

Based on the user requirements, the specification for the software should be drawn. The

developer should state clearly,

What outputs are required?

A set of screens displaying the output of data hiding and retrieval of hidden data .

What inputs are necessary?

Various interactive inputs that take the user through the different stages encountered during

the execution of the application .

What processes are involved to produce these outputs?

8. HARDWARE SPECIFICATION

Processor : Pentium.

RAM : 64 MB.

Hard Disk : 2 GB.

Cache : 512 KB.

Monitor : SVGA Color Monitor.

Keyboard : 101 keys.

Mouse : 2 buttons.

9. Image Encoding Techniques:

Information can be hidden many different ways in images. Straight message insertion can be done, which

will simply encode every bit of information in the image. More complex encoding can be done to embed

the message only in "noisy" areas of the image that will attract less attention. The message may also be

scattered randomly throughout the cover image.

The most common approaches to information hiding in images are:

Least significant bit (LSB) insertion

Masking and filtering techniques

Algorithms and transformations

Each of these can be applied to various images, with varying degrees of success. Each of them suffers to

varying degrees from operations performed on images, such as cropping, or resolution decrementing, or

decreases in the colour depth.

LEAST SIGNIFICANT BIT INSERTION:

One of the most common techniques used in steganography today is called least significant bit (LSB)

insertion. This method is exactly what it sounds like; the least significant bits of the cover-image are

altered so that they form the embedded information. The following example shows how the letter A can

be hidden in the first eight bytes of three pixels in a 24-bit image.

Pixels:

(00100111 11101001 11001000) (00100111 11001000 11101001) (11001000 00100111 11101001)

A: 10000001

Result: (00100111 11101000 11001000) (00100110

11001000 11101000)

(11001000 00100111 11101001)

The three underlined bits are the only three bits that were actually altered. LSB insertion requires

on average that only half the bits in an image be changed. Since the 8-bit letter A only requires eight bytes

to hide it in, the ninth byte of the three pixels can be used to hide the next character of the hidden

message.

A slight variation of this technique allows for embedding the message in two or more of the least

significant bits per byte. This increases the hidden information capacity of the cover-object, but the cover-

object degrades more statistically, and it is more detectable. Other variations on this technique include

ensuring that statistical changes in the image do not occur. Some intelligent software also checks for areas

that are made up of one solid color. Changes in these pixels are then avoided because slight changes

would cause noticeable variations in the area.

Advantages of LSB Insertion:

Major advantage of the LSB algorithm is it is quick and easy.

There has also been steganography software developed which work around LSB color alterations

via palette manipulation.

LSB insertion also works well with gray-scale images.

> A slight variation of this technique allows for embedding the message in two or more of the least

significant bits per byte. This increases the hidden information capacity.

Masking and filtering :

Masking and filtering techniques hide information by marking an image in a manner similar to paper

watermarks. Because watermarking techniques are more integrated into the image, they may be applied

without fear of image destruction from lossy compression. By covering, or masking a faint but perceptible

signal with another to make the first non-perceptible, we exploit the fact that the human visual system

cannot detect slight changes in certain temporal domains of the image.

Technically, watermarking is not a steganographic form. Strictly, steganography conceals data in the

image; watermarking extends the image information and becomes an attribute of the cover image,

providing license, ownership or copyright details.

Masking techniques are more suitable for use in lossy JPEG images than LSB insertion because of their

relative immunity to image operations such as compression and cropping.

Algorithms and transformations:

Because they are high quality color images with good compression, it is desirable to use JPEG images

across networks such as the Internet. Indeed, JPEG images are becoming abundant on the Internet.

JPEG images use the discrete cosine transform (DCT) to achieve compression. DCT is a lossy

compression transform, because the cosine values cannot be calculated precisely, and rounding errors

may be introduced. Variance between the original data and the recovered data depends on the values and

methods used to calculate the DCT.

Images can also be processed using fast Fourier transformation and wavelet transformation. Other

properties such as luminance can also be utilised. The HVS has a very low sensitivity to small changes in

luminance, being able to discern changes of no less than one part in thirty for random patterns. This figure

goes up to one part in 240 for uniform regions of an image.

Modern steganographic systems use spread-spectrum communications to transmit a narrowband signal

over a much larger bandwidth so that the spectral density of the signal in the channel looks like noise.

The two different spread-spectrum techniques these tools employ are called direct-sequence and

frequency hopping. The former hides information by phase-modulating the data signal (carrier) with a

pseudorandom number sequence that both the sender and the receiver know. The latter divides the

available bandwidth into multiple channels and hops between these channels (also triggered by a

pseudorandom number sequence).

The Patchwork method is based on a pseudorandom, statistical process that takes advantage of the human

weaknesses to luminance variation. Using redundant pattern encoding to repeatedly scatter hidden

information throughout the cover image, like a patchwork, Patchwork can hide a reasonably small

message many times in a image. In the Patchwork method, n pairs of image points (a,b) are randomly

chosen. The brightness of a is decreased by one and the brightness of b is increased by one. For a labeled

image, the expected value of the sum of the differences of the n pairs of points is then 2n. Bender shows

that after JPEG compression, with the quality factor set to 75, the message can still be decoded with an 85

This algorithm is more robust to image processing such as cropping and rotating, but at the cost of

message size. Techniques such as Patchwork are ideal for watermarking of images. Even if the image is

cropped, there is a good probability that the watermark will still be readable.

Other techniques encrypt and scatter the hidden throughout the image in some predetermined manner. It

is assumed that even if the message bits are extracted, they will be useless without the algorithm and

stego-key to decode them. Although such techniques do help protect against hidden message extraction,

they are not immune to destruction of the hidden message through image manipulation.

10. Encryption Process

IMAGE FILE INFORMATION FILE

BMP FILE

Encryption - Encryption is the process of passing data or plaintext through a series of mathematical operations that generate an alternate form of the original data known as ciphertext. The encrypted data can only be read by parties who have been given the necessary key to decrypt the cipher text back into its original plaintext form. Encryption doesn't hide data, but it does make it hard to read!

In encryption the secret information is hiding in with any type of image file.

11. Decryption Process

BMP FILE

INFORMATION FILE IMAGE FILE

Decryption - The process of decoding data that has been encrypted into a

secret format. Decryption requires a secret key or password.

Decryption is getting the secrete information from image file.

12. DATA FLOW DIAGRAMS

LEVEL 0 DFD DIAGRAM

Level 1 DFD DIAGRAM

Embedding information in a file Retrieving original information

13. USE CASE DIAGRAM

Flow Diagram