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Stegnography

Aug 07, 2015

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Engineering

  1. 1. STEGNOGRAPHYSTEGNOGRAPHY
  2. 2. What is StegnographyWhat is Stegnography The word stegnography is of Greek origin andThe word stegnography is of Greek origin and meansmeans concealed writingconcealed writing from the greek wordfrom the greek word stegnosstegnos meansmeans coveredcovered or protected andor protected and grapheingraphein meansmeans writingwriting.. It is a art of hiding the fact that communicationIt is a art of hiding the fact that communication is taking place by hiding info. in other info.is taking place by hiding info. in other info. Mostly digital images are used because of theirMostly digital images are used because of their frequency on the internet.frequency on the internet.
  3. 3. Some KeywordsSome Keywords Cover imageCover image:: An image containing in embeddedAn image containing in embedded imageimage Cipher text:Cipher text: refers to encrypted datarefers to encrypted data Cryptography:Cryptography: the art of protecting informationthe art of protecting information by encrypting it into an unreadable format,by encrypting it into an unreadable format, called cipher text. A secret key is used to decryptcalled cipher text. A secret key is used to decrypt the message plain text.the message plain text. Plain text:Plain text: refers to any message that is notrefers to any message that is not encrypted.encrypted. Stego image:Stego image: It is result of applying someIt is result of applying some stegnograpic processes to a plain text.stegnograpic processes to a plain text.
  4. 4. Lossless compression:Lossless compression: for most types offor most types of data,lossless compression technique candata,lossless compression technique can reduce the space needed by about only 50%.reduce the space needed by about only 50%. No data lost in this process.No data lost in this process. Lossy compression:Lossy compression: It attempt to eliminateIt attempt to eliminate unnecessary information.unnecessary information. Least Significant Bit (LSB):Least Significant Bit (LSB): The bitThe bit contributing the least value in a string of bits.contributing the least value in a string of bits. Steganalysis:Steganalysis: The art of discovering andThe art of discovering and rendering useless convert messages.rendering useless convert messages. Stego image:Stego image: The result of combining theThe result of combining the cover image and embedded image.cover image and embedded image.
  5. 5. HistoryHistory During World War 2 invisible ink was used to writeDuring World War 2 invisible ink was used to write informationinformation on pieces of paper so that the paper appeared to the average person as just being blank pieces of paper. Liquids such as milk, vinegar and fruit juices were used, because when each one of these substances are heated they darken and become visible to the human eye. In Ancient Greece they used to select messengers and shave their head, they would then write a message on their head. Once the message had been written the hair was allowed to grow back. After the hair grew back the messenger was sent to deliver the message, the recipient would shave off the messengers hair to see the secrete message.
  6. 6. Evolution Of StegnographyEvolution Of Stegnography
  7. 7. TechniquesTechniques Stegnography in TextStegnography in Text Stegnography in AudioStegnography in Audio Stegnography in VideoStegnography in Video Stegnography in ImagesStegnography in Images
  8. 8. Image SteganographyImage Steganography :: Images are used as the popular cover mediumImages are used as the popular cover medium for steganography. A message is embedded in afor steganography. A message is embedded in a digital image using an embedding algorithm,digital image using an embedding algorithm, using the secret key. The resulting stego-imageusing the secret key. The resulting stego-image is send to the receiver. On the other side, it isis send to the receiver. On the other side, it is processed by the extraction algorithm using theprocessed by the extraction algorithm using the same key. During the transmission of stego-same key. During the transmission of stego- image unauthenticated persons can only noticeimage unauthenticated persons can only notice the transmission of an image but cant see thethe transmission of an image but cant see the existence of the hidden message.existence of the hidden message.
  9. 9. Stegnography modelStegnography model Cover image (C)Cover image (C) Stego-key (K)Stego-key (K) Message(M)Message(M) F(C,M,K) Stego-object(Z)
  10. 10. Bitmap Pictures and StegnographyBitmap Pictures and Stegnography Bitmap Pictures(bmp) are the most popularBitmap Pictures(bmp) are the most popular choices for stegnography.choices for stegnography. JPEG,GIF formats are rarely used.JPEG,GIF formats are rarely used. Software automatically converts other fileSoftware automatically converts other file formats toformats to bmpbmp file formats.file formats. BMP file formats is the simplest type of picturesBMP file formats is the simplest type of pictures because it doesnt have any technology forbecause it doesnt have any technology for decreasing file size.decreasing file size.
  11. 11. Bitmap image created from pixels that any pixelBitmap image created from pixels that any pixel created from three colors (RGB) each color ofcreated from three colors (RGB) each color of pixel has one byte info that show density ofpixel has one byte info that show density of color.color.
  12. 12. Least Significant Bit inLeast Significant Bit in StegnographyStegnography Every byte is created from 8-bit that first is MostEvery byte is created from 8-bit that first is Most Significant Bit(MSB) and last bit is LeastSignificant Bit(MSB) and last bit is Least Significant Bit(LSB).Significant Bit(LSB). We use LSB for writing our security informationWe use LSB for writing our security information inside BMP pictures.inside BMP pictures. We use 8We use 8thth layer of information , we shouldlayer of information , we should change last bit of pixel,on other hand we have 3change last bit of pixel,on other hand we have 3 bits in each pixel so we havebits in each pixel so we have 3*height*width3*height*width to write our information.to write our information.
  13. 13. Before writing our data must write name of dataBefore writing our data must write name of data (file), size.(file), size. Using 3 pixel of picture to save a byte of data.Using 3 pixel of picture to save a byte of data.
  14. 14. EncryptionEncryption Image fileImage file Information fileInformation file BMP fileBMP file
  15. 15. DecryptionDecryption Image fileImage fileInformation fileInformation file BMP fileBMP file
  16. 16. Stegnography vs. CryptographyStegnography vs. Cryptography Same purpose:Same purpose: To hide/protect important informationTo hide/protect important information Different approach:Different approach: Stegnography:Stegnography: conceal information, making itconceal information, making it unseenunseen Cryptography:Cryptography: encrypts information, making itencrypts information, making it unreadableunreadable Crypto + Stegno =Crypto + Stegno = Added layer of Security (oneAdded layer of Security (one complements the other).complements the other).
  17. 17. AdvantagesAdvantages It provide better security in LAN.It provide better security in LAN. Important files carrying confidential informationImportant files carrying confidential information can be stored in server in encrypted form.can be stored in server in encrypted form. Public key and private key can encrypt file.Public key and private key can encrypt file. No intruder can get any useful information fromNo intruder can get any useful information from the original file during transmission.the original file during transmission. It provide a better secured data storage andIt provide a better secured data storage and transmission both at the system level andtransmission both at the system level and network level.network level.
  18. 18. DisadvantagesDisadvantages It provide the storing of data inIt provide the storing of data in unprotected mode.unprotected mode. Password leakage may occur and leads toPassword leakage may occur and leads to unauthorised access of data.unauthorised access of data. The intruder will affect stegos.The intruder will affect stegos.
  19. 19. Data Flow DiagramData Flow Diagram DFD Level 0 SOURCE 0.0 DESTINATION PERSONAL DATA
  20. 20. DFD Level 1 Encryption phase Transmission Phase Decryption Phase Secret Data 0.0 1.0 2.0 3.0
  21. 21. DFD Level 2 INFORMATION FILE IMAGE FILE ENCRYPTION TRANSMISSION DECRYPTION ENCRYPTION ALGORITHM INFORMATION FILE IMAGE FILE DECRYPTION ALGORITHM 1.0 2.0 3.0
  22. 22. Waterfall modelWaterfall model
  23. 23. UML DiagramsUML Diagrams Use Case Diagram
  24. 24. Sequence Diagram
  25. 25. FutureFuture The development of a system that will utilize theThe development of a system that will utilize the Stegnographic Obliterator on incoming andStegnographic Obliterator on incoming and email messages and attachments.email messages and attachments. Investigate the feasibility of embedding theInvestigate the feasibility of embedding the program in firewalls to act as a first line ofprogram in firewalls to act as a first line of defense against stegnographic datadefense against stegnographic data transmission.transmission. Expand the stegnographic algorithm attackExpand the stegnographic algorithm attack method beyond LSB using some othermethod beyond LSB using some other techniques.techniques.