, Prof. Arjun R. Nichal, Mr. Abhinav C. Gorle, Mr. Nitin S. Chavan, Ms. Rohini R. Kondhalkar

English

International Journal on Recent and Innovation Trends in Computing and Communication

International Journal on Recent and Innovation Trends in Computing and Communication                                       ISSN: 2321-8169 Volume: 2 Issue: 4                                                                                                                                                                            885 – 889 _______________________________________________________________________________________________ 885 IJRITCC | April 2014, Available @ http://www.ijritcc.org                                                                 _______________________________________________________________________________________  Implementation and Performance Analysis of LSB Based Steganography  Prof. Arjun R. Nichal Departement of ETC AITRC Vita Vita, India arjunnichal@gmail.com Mr. Abhinav C. Gorle Departement of ETC AITRC Vita Vita, India gorleabhinav@gmail.com Mr. Nitin S. Chavan Departement of ETC AITRC Vita Vita, India chavan_nitin90@yahoo.in Ms. Rohini R. Kondhalkar Departement of ETC AITRC Vita Vita, India rohinikondalkar27@gmail.com  Abstract—Protecting privacy for exchanging information through the media has been a topic researched by many people. Up to now, cryptography has always had its ultimate role in protecting the secrecy between the sender and the intended receiver. How-ever, nowadays steganography techniques are used increasingly besides cryptography to add more protective layer to the hidden data. Keywords- Steganography, Data Hiding, LSB Substitution, ) __________________________________________________*****_________________________________________________  I.  INTRODUCTION  Information hiding in digital images has drawn much attention in recent years. Secret message encrypted and em-bedded in digital cover media. The redundancy of digital me-dia as well as characteristics of human visual system makes it possible to hide secret messages. Two competing aspects are considered while designing information hiding scheme 1) Hid-ing capacity and 2) Imperceptibility. Hiding capacity means maximum payload. Imperceptibility means keeping undetecta-ble. A least significant bits (LSB) substitution method is wide-ly used for hiding data in digital images. This method widely used because of large capacity and easy implementation.  Cryptography was created as a technique for securing the secrecy of communication and many different methods have been developed to encrypt and decrypt data in order to keep the message secret. Unfortunately it is sometimes not enough to keep the contents of a message secret, it may also be necessary to keep the existence of the message secret. The technique used to implement is called steganography. It is the art and science of invisible communication.  The advantage of steganography over cryptography alone is that messages do not attract attention to themselves, to messengers, or to recipients. Steganographic messages are often first encrypted by some traditional means, and then a cover text is modified in some way to contain the encrypted message, resulting in stego text. This is a technique to embed additional message into some distortion-unacceptable cover media, such as military or medical images, with a reversible manner so that the original cover content can be perfectly res-tored after extraction of the hidden message.  II. IMPLEMENTATION OF STEGANOGRAPHY METHOD 1) Image Method  In Image method we hide an image in another image. In this method we hide the data inside another image. This Purpose we use the Grayscale images as an Input and the Bi-nary Secret image data. In this we can transmit the hidden data that is encrypted secret data inside the cover image and the receiver using the decryption method we decrypt the data and recover the secret image/data as well as the cover/input image.  1.1 Image Transmitter:                                       Fig1.1: Block diagram of image transmitter  Cover image: Cover image is simply a grayscale image used for hiding our secret image/message. This images have in various formats like BMP, GIF and PNG etc. Cover image is pre-process, and the secret message/text is hide by using LSB (Least significant bit) substitution.   Pre-processing:  Before an embedding of secret message into cover image, the cover image is pre-processed for denoising an im-age. Image denoising is an important step in pre-processing of  Images. Thresholding is applied to remove the noise without blurring edges. Gaussian filter, anisotropic PDE, wavelets are some important denoising techniques. These denoising tech-niques can reduce noise without destroying edges in an image. So edge information is preserved and noise is well attenuated. Secret image Encrypted secret im-age Message embedding block Stego image Pre-processing Cover image Secret key Embedding bit International Journal on Recent and Innovation Trends in Computing and Communication                                       ISSN: 2321-8169 Volume: 2 Issue: 4                                                                                                                                                                            885 – 889 _______________________________________________________________________________________________ 886 IJRITCC | April 2014, Available @ http://www.ijritcc.org                                                                 _______________________________________________________________________________________  Encryption method:  Image encryption is an important and effective tech-nique to protect image security. In our project the size of se-cret image (binary image) is checked. After that generating key stream of same size of secret image. XORing of secret message and generated key stream will complete the encryption process. Encrypted Image=Binary Image       Keystream Message embedding: For embedding we used LSB (Least significant bit) substitution.       LSB (Least significant bit) substitution:  Least significant bit (LSB) insertion is a common, simple approach to embedding information in a cover image. The least significant bit (in other words, the 8th bit) of some or all of the bytes inside an image is changed to a bit of the secret message. When using a 24-bit image, a bit of each of the red, green and blue color components can be used, since they are each represented by a byte. In other words, one can store 3 bits in each pixel. An 800 × 600 pixel image, can thus store a total amount of 1,440,000 bits or 180,000 bytes of embedded data.     Principle:  This Principle involved in this method is to replace all LSB bits of pixels of the cover image with secret bits. This method embeds the fixed length secret bits in the same fixed length LSBs of pixels. Although this technique is simple, it generally causes noticeable distortion when the number of embedded bits for each pixels exceeds three.  Advantages:  1. This method having high embedding capacity and easily implementable. 2. This method is directly replace LSBs.  1.2 Image receiver:           Fig1.2: Block diagram of image receiver  Stego image:                   Encrypted secret image is embedded in cover im-age at given embedding bit position, after embedding process an image is form called stego image. Stego image contains our encrypted secret message, that message is hidden inside cover image will secure our secret message. Extraction method:                   Extraction process is opposite to embedding process. In extraction an encrypted secret message is extract from stego image from given embedding bit position. Ex-tracted bits are in encrypted form so we can’t get any secret message from this bits.     Decryption process:                  From extraction we will get only encrypted message but to identify secret message decryption process is used, for decryption of secret message we require same keystream that we have used at transmitter for encryption of message. After decryption process user will get information from secret mes-sage. 2) Text Method  In Text method we Encrypt the text data in the image. In this method we hide the data inside the image. This Purpose we use the Grayscale images as an Input and the secret data is the Text file. In this we can transmit the hidden data that is encrypted secret data inside the cover image and the receiver using the decryption method we decrypt the data and recover the secret image/data as well as the cover/input image. 2.1Text Transmitter:                                                                                                             Fig1.3: Block diagram of text transmitter  The same logic is used for transmission of secret im-age /text.in text transmitter secret text is converted into binary then used for further processing like encryption of secret mes-sage, embedding encrypted message into cover image (grays-cale image).  2.2 Text Receiver: Message extraction block:  In message extraction process an encrypted secret message is extract from stego image, but user can’t get any information from extracted message because the message is in encrypted form.  Decryption of secret message: An encrypted secret message is decrypted using se-cret keystream which is used at transmitter for encryption.  Binary to text conversion: Message extraction block Encrypted image Recovered secret image Secret key Embedded bit Stego image Stego image Secret text Text to binary conversion Encrypted secret text Message embedding block Cover image Pre-processing  Secret key Embedding bit International Journal on Recent and Innovation Trends in Computing and Communication                                       ISSN: 2321-8169 Volume: 2 Issue: 4                                                                                                                                                                            885 – 889 _______________________________________________________________________________________________ 887 IJRITCC | April 2014, Available @ http://www.ijritcc.org                                                                 _______________________________________________________________________________________ Binary-to-text encoding is encoding of data in text. This decrypted message in binary form so user will get secret text after binary to text conversion                                Fig1.4: Block diagram of text receiver III. RESULTS ANALYSIS AND DISCUSSION   1) Quality Parameters  For comparing Image with Image, Image with Text, Method we have considered various quality parameters such as Compression Ratio (CR), Peak Signal to Noise Ratio (PSNR) and Embedding Capacity (EC).   1.1 Peak-Signal to Noise Ratio (PSNR)  The PSNR is most commonly used as a measure of quality of reconstruction of lossy compression codec’s (e.g., for image compression). The signal in this case is the original data, and the noise is the error introduced by compression. When comparing compression codec’s it is used as an approx-imation to human perception of reconstruction quality, there-fore in some cases one reconstruction may appear to be closer to the original than another, even though it has a lower PSNR (a higher PSNR would normally indicate that the reconstruc-tion is of higher quality).  The PSNR is calculated by using following formula.                                              Where MAXI is maximum possible pixel value of image I(i,j) MSE is a mean square error. I(i,j )is an original cover image. K(i,j )is a reconstructed cover image. m is number of rows and n is number of columns.  1.2 Embedding Capacity (EC):   Embedding capacity is one of the most important quality parameter of the steganography. Embedding capacity is calculated by using following formula.                EC=m*n                                  m is number of rows and n is number of columns of cover im-age.   1.3 Number of bits Embedded (NBE): Total pixels in Image, Total bits in Text, Total length of single stream for secret image.  For image = row*col  For Text = length of signal stream which is converted into binary from Text   2) Results: Here same grayscale cover images are used for hiding the Images, Text inside this images. First technique consists of image method where hiding the images inside that. Second method consist of text method where hiding the text message inside the cover image. Various secret images are used for embedding.  This experiment is carried out on different class of cover images. The performance of these three techniques is compared on the basis of various quality measures such as Peak-Signal to Noise Ratio (PSNR) and Embedding Capacity (EC), Number of bits embedded (NBE).  Following results are obtained for some class of cover images. Lena image is used for hiding the data.  2.1 Image Method  A) Following results are obtained for Lena Image with the devi image. The terms in table are EC = Embed-ding capacity, NBE = Number of bits embedded,  PSNR = Peak signal to noise ratio.                Lena input image (512*512)                Secret image (510*510)  TABLE I. Results for Lena image with Devi Image Embedding Bits EC NBE PSNR 1 262144 260130 50.6635 2 262144 260130 44.637 3 262144 260130 38.612 4 262144 260130 32.592 5 262144 260130 26.5666 6 262144 260130 20.5496 7 262144 260130 14.5152 8 262144 260130 8.5079  Message extraction block Encrypted secret message Binary to text conver-sion Recovered secret text Embedded bit Secret key Stego image International Journal on Recent and Innovation Trends in Computing and Communication                                       ISSN: 2321-8169 Volume: 2 Issue: 4                                                                                                                                                                            885 – 889 _______________________________________________________________________________________________ 888 IJRITCC | April 2014, Available @ http://www.ijritcc.org                                                                 _______________________________________________________________________________________                           (a)                                                   (b)                             (c)                                                (d)                                (e)                    (f)                            (g)                  (h)      Fig1.5: Stego Images after embedding secrete image into cover image bit by bit. (1-8)         Fig1.6: Graph of Embedding bit versus PSNR for Devi image (secret image) 2.2 Text Method  The same logic is used for transmission of secret im-age /text.in text transmitter secret text is converted into binary then used for further processing like encryption of secret mes-sage, embedding encrypted message into cover image (grays-cale image).Stego image is then transfer.     Recovered secret image at receiver:                                                                               recovered Secret image (510*510)      Graphical User Interface (GUI): For user friendly operation graphical user interface (GUI) plays very important role. International Journal on Recent and Innovation Trends in Computing and Communication                                       ISSN: 2321-8169 Volume: 2 Issue: 4                                                                                                                                                                            885 – 889 _______________________________________________________________________________________________ 889 IJRITCC | April 2014, Available @ http://www.ijritcc.org                                                                 _______________________________________________________________________________________                        Fig1.7: Image steganography transmitter                                          Fig1.8: Text steganography transmitter  CONCLUSION As user increases embedding bit position in cover image for hiding encrypted secret message, the Peak signal to noise ratio (PSNR) decreases linearly as well as quality of stego image decreases. References [1] Xinpeng Zhang ―Reversible Data Hiding in En-crypted Image‖, IEEE SIGNAL PROCESSING LETTERS, VOL. 18, NO. 4, APRIL 2011  [2]  J. Tian, ―Reversible data embedding using a differ-ence expansion,‖ IEEE Trans. Circuits Syst. Video Technol., vol. 13, no. 8, pp. 890–896, Aug. 2003.  [3] Z.Ni,Y.-Q.Shi,N.Ansari, andW.Su, ―Reversibledata-hiding,‖IEEE Trans. Circuits Syst. Video Technol., vol. 16, no. 3, pp. 354–362, 2006.  [4] M.U.Celik, G.Sharma, A.M.Tekalp and E.Saber, ―Losslessgen-eralized-LSB data embedding,‖IEEE Trans. Image Process.,vol.14, no. 2, pp. 253–266, Feb. 2005. [5] Websites  [1] http://www.IEEE.org.in  [2]http://www.strangehorizons.com/2001/20011008/steganography  BIOGRAPHY   Prof.A.R.Nichal received his B.E. degree in Electronics and tele-communication from Shivaji University at Ashta in 2010 and received M.Tech in Electronics from Walchand College of engineering, Sangli in 2012. His area of interest is Digital Image Processing and embedded system. He published 8 Inter-national journal papers, 1 Conference paper, 1 Ebook and He has one blog on Fundamentals of Image Processing, lab Basics and Embedded System.  URL: www.imagelpcmatlab.blogspot.com    Mr. Abhinav Gorle pursuing his BE in Electronics and Telecommunication from Shivaji University at AITRC vita. His area of Interest is Image Processing and Embedded System      Mr. Nitin Chavan pursuing his BE in Electronics and Telecommunication from Shivaji University at AITRC vita. His area of Interest is Image Processing and VLSI.      Ms. Rohini kondhalkar pursuing her BE in Electronics and Telecommuni-cation from Shivaji University at AITRC vita. Her area of Interest is Image Processing and Embedded System      

Implementation and Performance Analysis of LSB Based Steganography

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Implementation and Performance Analysis of LSB Based Steganography

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International Journal on Recent and Innovation Trends in Computing and Communication