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A NOVEL METHOD FOR HIDING INFORMATION

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In this paper, we introduce a new method to hide information in an image, the sequence of hiding message bits in the cover pixels and the number of bits used for hiding information are differ from one block to another and depend on the gray scale values of the pixels in the center of cover image blocks. The proposed system like all steganography system consists of two stages. The first stage used for hiding message by using two keys , the first one used for determining the sequence that will be used in hiding message pixels, while the second key used to select the number of least significant bits in the cover image that will be used in hiding information. The second stage used for extracting and retrieving message information and reconstruct the message image precisely. http://www.ijccse.com
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  ISSN: 2312-7694 Samer et al. / International Journal of Computer and Communication System Engineering (IJCCSE) 107 | Page   © 2014, IJCCSE All Rights Reserved Vol. 1 No.03 October 2014 www.ijccse.com A NOVEL METHOD FOR HIDING INFORMATION Samer Thaaban Abaas Al-Shibley Education College, Kufa University  samir-alshebly@uokufa.edu.iq Abstract  —   In this paper, we introduce a new method to hide information in an image, the sequence of hiding message bits in the cover pixels and the number of bits used for hiding information are differ from one block to another and depend on the gray scale values of the pixels in the center of cover image blocks. The proposed system like all steganography system consists of two stages. The first stage used for hiding message by using two keys , the first one used for determining the sequence that will be used in hiding message pixels, while the second key used to select the number of least significant bits in the cover image that will be used in hiding information. The second stage used for extracting and retrieving message information and reconstruct the message image precisely. Keywords: Steganography, hiding information, stego image, cover. I.   I  NTRODUCTION  Steganography is the art and science of hiding information in a deterministic sequence to prevent any person from detecting the hiding Information without authentication, the secret Information is embedded in a digital file by using a suitable algorithm, there are two types of materials existing in steganography system which are the message and the carrier (cover), Message is the secret Information that should be hidden and carrier is the material that takes the message in it according to steganography algorithm and keys. The file  produced after hiding the message in the cover is called stego object that translated from the source of the message to its destination. There are many applications for steganography which are military, diplomatic, and personal applications. There are three related principles that determining the effectiveness of steganography algorithm which are 1-   The size of the message file. 2-   The difficulty of detecting the message. 3-   The difficulty of altering the message by simple changing in the cover file Steganography can be classified into three types as illustrated in figure (1) II.   A CCORDING TO COVER FILE TYPE    Text steganography.    Image steganography.    Audio steganography.    Video steganography. Image Steganography can be classified into three types a)   Least Significant Bits (LSBs):    Blind hide algorithm.    Hide seek algorithm.    Filter first algorithm.    Battle steg algorithm.  b)   Masking and filtering techniques, take a different approach to hiding a message. These methods are effectively similar to  paper watermarks, creating markings in an image. This can be achieved for example  by modifying the luminance of parts of the image. While masking does change the visible properties of an image, it can be done in such a way that the human eye will not notice the anomalies. c)   Transform Domain techniques utilize an algorithm such as the Discrete Cosine Transformation (DCT) or wavelet transformation to hide information in significant areas of the image. III.   According to the type of the steganography key:    Pure steganography.    Secret key steganography. IV.   PROPOSED SYSTEM  In generl,the proposed system as illustrated in figure (2) consist of two steges, the first one is Message hiding stage and the second stage is message extracting from the stego object  ISSN: 2312-7694 Samer et al. / International Journal of Computer and Communication System Engineering (IJCCSE) 108 | Page   © 2014, IJCCSE All Rights Reserved Vol. 1 No.03 October 2014 www.ijccse.com Steganography Classification according to cover file type Classification according to how the information has been hidden    Classification according to the type of the key Line shift Word shift Feature Pure Secret Key Public Key Insertion Substitution    Generation Text Image Audio Video Transformation Masking and filtering LSBs SS Phase Parity LSBs Echo Blind hide    Hide seek    Filter first    Battle   s  teg     ISSN: 2312-7694 Samer et al. / International Journal of Computer and Communication System Engineering (IJCCSE) 109 | Page   © 2014, IJCCSE All Rights Reserved Vol. 1 No.03 October 2014 www.ijccse.com Figure (1) classification of steganography systems Message hiding stage Figure (2) block diagram of the proposed system a.   message hiding stage this stage is divided into the following steps:- 1-   Divided cover image into non overlap blocks with size (3×3) pixels. 2-   Check the three LSBs of the pixel in the center of each block (TLSBS) . 3-   Hiding the message in each pixel in the blocks except the centers as illustrated in figure (3) to produce stego object . figure (3) 1 2 3 1 2 3 4 5 6 4 5 6 7 8 9 7 8 9 Case (1) TLSB = 0 NBITS = 2 Case (2) TLSB = 1 NBITS = 1 9 8 7 9 8 7 6 5 4 6 5 4 3 2 1 3 2 1 Case (3) TLSB = 2 NBITS = 2 Case (4) TLSB = 3 NBITS = 1 7 8 9 7 8 9 4 5 6 4 5 6 1 2 3 1 2 3 Case (5) TLSB = 4 NBITS = 2 Case (6) TLSB = 5 NBITS = 1 3 2 1 3 2 1 6 5 4 6 5 4 9 8 7 9 8 7 Case (7) TLSB = 6 NBITS = 2 Case (8) TLSB = 7 NBITS = 1 Message extracting stage    Image Messag e Divided into non overlap blocks with size (3×3) Apply inverse proposed hiding algorithm to extract message from stego image Stego image (= 0) Hiding in two bits by starting from top left corner Cover (Image)    Message (Image) Divided into non overlap blocks with size (3×3) Check the value of three LSBs of    each pixel in the center    of the block    (= 1) Hiding in one bit by starting from top left corner (= 2) Hiding in two bits by starting from down right (= 3) Hiding in one bit by starting from down right (= 4) Hiding in two bits by starting from down left (= 5) Hiding in one bit by starting from down left corner (= 6) Hiding in two bits by starting from top right corner (= 7) Hiding in one bit by starting from top right corner  ISSN: 2312-7694 Samer et al. / International Journal of Computer and Communication System Engineering (IJCCSE) 110 | Page   © 2014, IJCCSE All Rights Reserved Vol. 1 No.03 October 2014 www.ijccse.com Figure (3) the direction of hiding information and number of  bits for eight cases of variable (TLSBS) Where  NBITS is the number of bits used in hiding information. TLSB is the value of three least significant bits. In addition to above operations in hiding stage, hiding information starting by substituting message bits in cover  blocks with (TLSBS = 0) then in blocks with (TLSBS = 1) and so on. This make hiding operation progress in random fashion. If the message pixels are (104, 128…), this mean (01101000, 10000000, …….), and the cover block is   190 200 210 185 202 207 180 190 200 TLSBS = 2, so case (3) will be applied, Then the numbers are represented in binary as 202 1 1 0 0 1 0 1 0 Values Before hiding 2 LSBs Before 2 LSBs After Values After hiding 200 1 1 0 0 1 0 0 0 0 1 201 190 1 0 1 1 1 1 1 0 1 0 190 180 1 0 1 1 0 1 0 0 1 0 182 207 1 1 0 0 1 1 1 1 0 0 204 185 1 0 1 1 1 0 0 1 1 0 186 210 1 1 0 1 0 0 1 0 0 0 208 200 1 1 0 0 1 0 0 0 0 0 200 190 1 0 1 1 1 1 1 0 0 0 188 At the end this block becomes 188 200 208 186 202 204 182 190 201  b.   Message extracting stage This stage consist of the following steps 1-   Divided stego object image into non overlap blocks with size (3×3) pixels. 2-   Check the three LSBs of the pixel in the center of each block (TLSBS). 3-   Extracting the message in each pixel in the blocks except the centers as illustrated in figure (3). For the same block resulted in hiding stage the center of block (202) represented in binary as 1 1 0 0 1 0 1 0 The variable (TLSBTS= 2), so case 3 will be applied to extract message bits as follow 201 1 1 0 0 1 0 0 1 190 1 0 1 1 1 1 1 0 182 1 0 1 1 0 1 1 0 204 1 1 0 0 1 1 0 0 186 1 0 1 1 1 0 1 0 208 1 1 0 1 0 0 0 0 200 1 1 0 0 1 0 0 0 188 1 0 1 1 1 1 0 0 Te message bits are ( 01 10 10 00 10 00 00 00 ) that mean (104, 128) V.   R  ESULTS 1-   The   cover image is gray scale image of size (552×340) pixels, while message is gray scale image of size (144×144) pixels, the peak signal to noise ratio is (47) which calculated by applying the following equation )1(110 10102210 )],(),([ )1(log     nr mc peak  cr  I cr  g  l SNR mn  Where, l is the number of gray levels in cover image. I(r,c) are the pixels before embedding process in cover image. g(r,c) are the pixels after embedding process in stego image. n,m are the width and height of cover image respectively. Figure (4) result (1) of the proposed system
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