DATA HIDING BASED ON TRANSFORM DOMAIN TECHNIQUE

DATA HIDING BASED ON TRANSFORM DOMAIN TECHNIQUE

Aditi Kumari

Masters in Technology, School of Future Studies and Planning, DAVV, Indore, (India)

ABSTRACT

Steganography is an art of secret data communications. Its main purpose is to hide the occurrence of communication over a public channel. Steganography tends to hide the existence of the message or communication in any form. Hiding the occurrence of communication can be done by embedding a secret message into an innocent cover medium, such as an image, which no one else other than the sender and the recipient can suspect. There could be some important data that need to be protected during transmission.

Therefore, how to protect the secret messages during transmission becomes an important research issue. In this paper we will discuss about Transform domain technique(DWT) base algorithm and check quality of image. In this paper we focus on skin tone based of transform domain technique.

Keywords: Steganography, Data hiding, Transform domain technique (DWT).

I. INTRODUCTION

“Steganography is defined as the hiding of a message within another so that the presence of the hidden message is not detectable to the casual eye.”

Steganography comes from the Greek word “stegano” meaning covered (or secret) and “graphy” meaning writing. In steganography, where possible to send a secret message from one person to other in such a way that no-one will recognize that the secret message was exists. In steganography, where message is being hidden in another object which is called by cover object. Steganography is more secure as compare to cryptography, because existence of secret message is not visible.

1.1 Streaming Media

“Streaming media means continuous transaction of information, i.e., where not compulsory all data is needed before the receive can take part of the information [1]. The part of stream is independent to each other.”

There were many information hiding techniques which is classified by the media where the information is hidden. First, Hiding in Text, methods such as line-shift coding, word shift coding, and feature coding are the commonly used methods to hide data in text. When using a text data as a host media, the embedded data are usually secret word that is hidden within the text by changing their various textual characteristics [2].

II. STEGANOGRAPHY

Steganography comes from the greek word stegano meaning protected and graphy meaning writing. It is a combination of other language (Stego-Graphy) which means covered writing[3]. Data should be hidden in cover object in such a manner that just by viewing (image or video) or listening (audio), you cannot even judge that there is any data or not. It is used for security communication. Once it is detected that there is any data hidden, complete file can be destroyed so that the data cannot be delivered to the receiver. So the purpose does not accomplish. We can say that, no one know about existence of secret message.

2.1 Steganographic System

Main structure of a steganography system consists of following part [4]:

1. Cover image: The information or image where inside the secret message.

2. Secret message: Which we want to embed in cover image.

3. Stego image: The resultant information after embedding is known as Stego information.

4. Key: Additional secret data that is needed for the embedding and extracting processes and must be known to both, the sender and the recipient.

Fig: Block diagram of steganographic system [5]

2.2 Type of Steganography

Steganography Techniques are broadly classified into two categories such as spatial domain techniques and transform domain techniques. Spatial domain methods take advantage of the human visual system and directly embed data by manipulating the pixel intensities. In transform domain procedures, the image is first transformed into frequency domain and then the message is embedded.

According to the embedding and extraction procedures used Steganographic systems can again be classified into the following three different categories [6]:

A. Pure Steganography (or No Key Steganography - NKS): Pure steganography is the simplest and weakest form of Steganography in which the secret message is directly embedded into the cover image without any

COVER IMAGE

SECRET DATA

STEGO

IMAGE

B. Secret Key Steganography (SKS): In this form of Steganography, both the receiver and transmitter have common agreed upon secret keys. The secret message is embedded into and extracted out of the stego image using these keys.

C. Public Key Steganography (PKS): This methods use a pair of public and private keys to hide the secret information. The key benefits of this system are its robustness as well as easy key managemet.

III.LITERATURE REVIEW 3.1 Past

Steganography technically means covered or hidden writing. In ancient time, message were hidden on the back of wax writing tables, written on the stomachs of rabbits, or tattooed on the scalp of slaves. At that time invisible ink used for hide the message.

3.2 Present

Today steganographic system use multimedia like image, text, audio, video etc as a cover media because people often transmit digital picture via email. Modern steganography use the opportunity to hide the information into digital multimedia files or network packet level.

3.3 Techniques of Image Steganography

There are sereval Steganographic techniques for image which are as follows [7]:

1. Spatial Domain Technique 2. Transform Domain Technique 3. Masking And Filtering 4. Distortion Technique

In this paper where we use Transform Domain Techniques. Which is divided into followings part , such as:

1. DFT (Discrete Fourier transformation technique) 2. DCT (Discrete Cosine transformation technique) 3. DWT (Discrete Wavelet transformation technique)

3.4 Discrete Wavelet Transformation

In our thesis we use the Discrete Wavelet transform technique. Wavelet analysis can be used separated the information of an image into approximation and detailed sub signal. The approximation sub signal demonstrate the general trend of pixel value, and three detailed sub signal demonstrate vertical, horizontal and diagonaldetails or alterations in image. There is two variety of wavelet is used [8].

1. Continues wavelet transfom 2. Discrete wavelet transfom

In our steganography method we use Haar-DWT, the simplest DWT. A 2-dimensionalHaar-DWT consists of two operation: One is the horizontal operation and other is vertical. There are two type of filter which is as follows:

1. High pass filter: High frequency information is kept, low frequency information is lost.

2. Low pass filter: Low frequency information is kept, high is lost.

3.

IV. PROPOSED WORK 4.1 Algorithm

4.1.1 Algorithm to skin Detection

Step 2: Detect the skin portion.

Step 3: Applying cropping task.

Step 4: Perform histogram modification.

4.1.2 Algorithm to Embedding

Step 1: Read secret key & convert into binary form.

Step 2: Transform the secret text message into binary. 2D- Haar transform perform on cover image.

Step 3: Embed the secret key.

Step 4: Perform OPA.

Step 5: Perform inverse DWT.

Step 6: Generate the stego image.

4.1.3 Algorithm to Extraction

Step 2: Perform cropping.

Step 2: calculate the DWT.

Step 3: retrieve the message.

LL HL

LH HH

V. RESULT

The algorithm is code in Matlab and run on a windows 7 platform and version is R2012b. This paper discusses the performance of the DWT technique using Skin Tone based (STB). BY applying STB algorithm it is possible to improve the PSNR and decrease the mean square error. This paper compared the results with previous work.

The DWT technique using STB algorithm gave highest PSNR compared to the DCT and LSB techniques. LSB also gives highest PSNR and has less computation time compared to DWT but since DWT hiding is done in the approximate coefficient it is less prone to attacks. We calculate performance parameter MSE, PSNR, wgich are discussed below:

 MSE: MSE denote the Mean Square Error, which is given as:

MSE= 1/MN( (S-C)²) Cmax=255

Where M and N are the dimensions of the image. S is the resultant stego-image and C is the cover image.

 PSNR: PSNR well-known peak-signal-to noise ratio.

PSNR= 10log(Cmax)2=MSE

VI. CONCLUSION

In this paper, we explored varieties of approaches for Steganography. Steganography is effective way to hide the information. In this paper where we use the Transform domain technique. In this technique, where types are like DFT, DCT and DWT. Where we use DWT (Discrete Wavelet Transform) technique. In this paper the basic steganography techniques are compared. The DWT technique gives better performance compared to DCT and less attack to compared to LSB. Where we calculate PSNR value and MSE value. It gives better PSNR compared to other. So STB algorithm improve the performance with highest PSNR. The LSB technique also gives better PSNR but is prone to attack.

The STB using DWT gives highest PSNR but DWT technique takes higher computation time as compared to LSB technique. So the future work would be decrease the computation time with better PSNR.

REFRENCES

[1] https;//en.m.wikipedia.org/wiki/steaming media.

[2] Jawad M. J., ”Hiding Audio Using Wavelet Transform”, M.Sc. thesis, college of science, Al-Nahrain University, Iraq, 2005.

[3] https;//en.m.wikipedia.org/wiki/steganography.

[4] Minati Mishra, Priyadarsini Mishra and Flt. Lt. Dr. M.C. Adhikary. “ DIGITAL IMAGE DATA HIDING TECHNIQUES: A COMPARATIVE STUDY”. ANSVESA, 7(2), p.p.- 105-115, 2012.

[5] E Divya, P. Rajkumar, “Steganographic Data Hiding using DWT and Particle Swarm Optimization”, IJCA May 2015.

[6] Neil F. Johnson: “Exploring Steganography: Seeing the Unseen”, George Mason University, IEEE Computer, pp. 26-34, Feb 1998.

[7] N.F. Johnson and S. Jajodia, “Exploring Steganography: Seeing the Unseen”, IEEE, pp. 26-34, 1998.

[8] Po-Yueh Chen and Hung-Ju Lin, “A DWT Based Approach for Image Steganography” International Journal of Applied Science and Engineering, 2006.