Steganography in images


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This presentation is based on the steganography techniques used with images.

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Steganography in images

  2. 2. OVERVIEW oSteganography Defined oExamples in History oDigital Approaches oReasons For Using Digital Images oImage Attributes oPopular Techniques That Use Images oSteganalysis oAdvancements in image steganography oTechnical limitations
  3. 3. STEGANOGRAPHY DEFINED oGreek for “covered writing”. o“The art and science of writing hidden messages in such a way that no one apart from the intended recipient even knows that a message has been sent.”
  4. 4. EXAMPLES IN HISTORY oTattoos on shaved heads oWax-covered tablets oInvisible Inks - milk, fruit juice
  5. 5. STEGANOGRAPHY V/S CRYPTOGRAPHY oSteganography involves the hiding of the data while Cryptography involves the encryption and decryption of data. oSteganalysis involves finding out whether there is really a hidden message or not while Cryptanalysis involves breaking of the encrypted into decrypted message.
  6. 6. STEGANOGRAPHY with CRYPTOGRAPHY oVery very strong when combined. oA message sent in secret (steganography) in an encrypted form (cryptography) is much more secure than a "plain text" message sent by secret means or a clearly sent encrypted message.
  7. 7. DIGITAL APPROACHES oToday, it often exists within digital formats. oIt makes use of seemingly innocent cover files such as text, audio, and image files. oThe embedded message may be anything that can be encoded in binary.
  8. 8. REASONS FOR USING DIGITAL IMAGES oIt is the most widely used medium being used today. oTakes advantage of our limited visual perception of colors. oThis field is expected to continually grow as computer graphics power also grows. oMany programs are available to apply steganography.
  9. 9. IMAGE ATTRIBUTES oDigital images are made up of pixels. o8-bit and 24-bit images are common. oThe larger the image size, the more information you can hide. However, larger images may require compression to avoid detection.
  10. 10. IMAGE-BASED TECHNIQUES oLeast Significant Bit Insertion oMasking and Filtering
  11. 11. LSB INSERTION oReplaces least significant bits with the message to be encoded. oMost popular technique when dealing with images. oSimple, but susceptible to lossy compression and image manipulation.
  12. 12. LSB - Example A sample raster data for 3 pixels (9 bytes) may be: 00100111 11101001 11001000 00100111 11001000 11101001 11001000 00100111 11101011 Inserting the binary value for A (10000001) changes 4 bits 00100111 11101000 11001000 00100110 11001000 11101000 11001000 00100110 11101011
  13. 13. LSB Continued… oBest to use a grayscale palette or one with gradual changes in shades. oOtherwise, it is best to use images with “noisy areas” – areas with ample color variation.
  14. 14. LSB - Uses oStoring passwords and/or other confidential information. oCovert communication of sensitive data. oSpeculated uses in terrorist activities. oBeing widely used to hide and/or transfer illegal content.
  15. 15. MASKING & FILTERING oMasks secret data over the original data by changing the luminance of particular areas. oDuring masking, it embed the message within significant bits of the cover image. oNot susceptible to lossy techniques because image manipulation does not affect the secret message.
  16. 16. MASKING & FILTERING - Uses oDigital Watermarking – provides identification pertaining to the owner; i.e. license or copyright information. o Fingerprinting – provides identification of the user; used to identify and track illegal use of content.
  17. 17. Visible Watermark - Example
  18. 18. STEGANALYSIS Five classes of steganalysis: o Stego-only o Known-cover o Known-message o Chosen-stego and o Chosen-message
  19. 19. ADVANCEMENTS oUse of steganography for malwares to embed it in crafted HTML and JPEG files. e.g. Duqu worm (2011) oAccording to recent report(30th Jan, 2012), it will be used in android applications to send premium rates messages. oSelecting multiplayers’ games to use as a covert channel. oUse of private chat rooms as a carrier. oResearch are being done to practice steganography using a key not by using a method.
  20. 20. TECHNICAL CHALLENGES Limitations due to these three properties which work in opposition to each other:- oCAPACITY of the cover object. oUNDETECTABILITY of the stego-object. oROBUSTNESS of the stego-object. oStrength often depends on attackers not knowing how data could be hidden.
  21. 21. SUMMARY oSteganography as a whole has existed in many forms throughout much of history. oLossless compression of images with a great deal of color variation work best as a cover image to embed a message. oSteganography can be used as beneficial tool for privacy. oSteganography will work best if combined with cryptography.
  22. 22. REFERENCES  lbDEmNM for techniques of steganography CERIAS Steganography by John Oritz youtube videos.  tml   for watermarking techniques. 
  23. 23. QUERIES ?
  24. 24. <THANK YOU>