Steganography

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Steganography

  1. 1. SteganographyImplementation SM 1
  2. 2. Contents• Introduction• History• Steganography v/s Cryptograpy• Types of Steganography• Steps Involved in Steganography• Steganography Techniques• Digital Images• Lossy and Lossless Compression• Advantages• Negative Aspects• Applications• Conclusions 2
  3. 3. Introduction• Greek Words: STEGANOS – “Covered” GRAPHIE – “Writing”• Advance security is not maintained by the password protection but it is gained by hiding the existence of the data, which can only be done by Steganography.• Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message.• This can be achieve by concealing the existence of information within seemingly harmless carriers or cover• Carrier: text, image, video, audio, etc. 3
  4. 4. History• Greeks used it writing message on some material and later covering it with wax, tattooing messages on bald head, later growing hair to cover it up.• In World War II invisible inks were used to write messages in between the lines of normal text message .• Currently, cryptography and steganography are used to hide and send the secret data. 4
  5. 5. Steganography v/s Cryptography• Cryptography hides the contents of a secret message from a malicious people, whereas Steganography even conceals the existence of the message• In cryptography, the structure of a message is scrambled to make it meaningless and unintelligible unless the decryption key is available• Steganography does not alter the structure of the secret message, but hides it inside a cover-image so it cannot be seen. 5
  6. 6. • Cryptography :-• Steganography :- 6
  7. 7. Types of Steganography• Steganography In Text/Documents• Steganography In Images• Steganography In Audio• Steganography In Video 7
  8. 8. Steps involved in Steganography 8
  9. 9. Steganography Techniques• Injection: Injection is quite a simple method which simply involves directly injecting the secret information into the carrier file.• Substitution: Replacement of the least significant bits of information that determine the meaningful content of the original file with new data in a way that causes the least amount of distortion.• Generation: The generation technique, unlike injection and substitution, requires only a covert file, as it is used to create the overt file. 9
  10. 10. Digital Images• By digital Images we presume to deal with bits that is 0’s and 1’s.• Digital Images having 24-bit depth color images are selected using RGB color model.• The idea is to hide text in image with the conditions that the image quality is retained along with the size of the image.• 24-bit BMP is preferred over 24-bit JPEG because it is lossless compression. 10
  11. 11. Lossy and Lossless Compression• File compression software looks for redundancies, and eliminates those redundancies in order to reduce the size of the file.• Lossy compression reduces a file by permanently eliminating certain information. When the file is uncompressed, only a part of the original information is still there.• With lossless compression, every single bit of data that was originally in the file remains after the file is uncompressed. All of the information is completely restored. 11
  12. 12. Least Significant Bit Insertion:• The most common and popular method of modern day steganography.• Overall image distortion is kept to a minimum while the message is spaced out over the pixels in the images.• This technique works best when the image file is larger then the message file and if the image is grayscale.• Messages are encoded in LSB of every byte in a image.• Value of each pixel change slightly.• Grey scale palettes due to least pronounced shades are recommended. 12
  13. 13. LSB Implementation• Take T of binary value 11100110. To store these 8 bits of character T, we will require 8 pixels.• Each bit is then replaced by LSB of each Image byte 13
  14. 14. • Example : Insert a word TEXT - T = 01100010 - E = 01101111 - X = 01101101 - T = 01100010• Image Bits before• Image Bits after 14
  15. 15. 15
  16. 16. Why LSB?
  17. 17. Detecting Steganography :• The art of detecting Steganography is referred to as Steganalysis.• Using different tools like sendsecret, Steganography 8.1 , Stegdetect, Hiderman etc.• Steganalysis does not deal with trying to decrypt the hidden information inside of a file, just discovering it.• It is mainly done with comparing the encrypted file with the original copy. 17
  18. 18. Detecting Steganography 18
  19. 19. Detecting By histogram technique : 19
  20. 20. Advantages• It is used in the way of hiding not the Information but the password to reach that Information.• Messages do not attract attention to themselves i.e difficult to detect. Only receiver can detect.• The proposed technique uses LSB to hide data from a pre defined position agreed between two parties. Same position is only used once to enhance security.• Can be applied differently in digital image, audio & video file. 20
  21. 21. Negative Aspects• Huge number of data results in huge file size, so some one can suspect about it.• In sending and receiving information can be leaked.• It is Vulnerable to almost all media transformations.• If this technique is used in a wrong way then this can be very much dangerous. 21
  22. 22. Applications• Confidential communication and secret data storing• Protection of data alteration• Used in modern printers• Protect copyrights, to maintain confidentiality. 22
  23. 23. Conclusion• Steganography is in the nascent stage of development.• The importance of Steganography has not been realized to that stage where it is preferred over its close rival “Encryption”.• New techniques are being discovered and implemented. It is analyzed that time is not far away when its importance would be realized by organizations in general and the arm forces in particular. 23
  24. 24. References :- http://en.wikipedia.org/wiki/Steganography8 http://computer.howstuffworks.com/file-compression3.htm http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4547669 http://www.math.ucsd.edu/~crypto/Projects/MaxWeiss/steganography.pdf http://www.sans.org/reading_room/whitepapers/covert/steganography-matters- post-911-world_676 http://www.scribd.com/doc/49683406/1/Steganography-vs-Cryptography 24
  25. 25. Thank You! 25

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