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Steganography and Digital Watermarking

Steganography and Digital Watermarking. Prisoners Problem Michael Scofield and Lincoln Burrows are in jail They want to develop an escape plan The only way to communicate is through Captain Bellick They must communicate in a manner that does not raise suspicion. THE LEADER.

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Steganography and Digital Watermarking

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  1. Steganography and Digital Watermarking

  2. Prisoners Problem • Michael Scofield and Lincoln Burrows are in jail • They want to develop an escape plan • The only way to communicate is through Captain Bellick • They must communicate in a manner that does not raise suspicion

  3. THE LEADER • Patient and steady with all he must bear, • Ready to meet every challenge with care, • Easy in manner, yet solid as steel, • Strong in his faith, refreshingly real. • Isn't afraid to propose what is bold, • Doesn't conform to the usual mould, • Eyes that have foresight, for hindsight won't do, • Never backs down when he sees what is true, • Tells it all straight, and means it all too. • Going forward and knowing he's right, • Even when doubted for why he would fight, • Over and over he makes his case clear, • Reaching to touch the ones who won't hear. • Growing in strength he won't be unnerved, • Ever assuring he'll stand by his word. • Wanting the world to join his firm stand, • Bracing for war, but praying for peace, • Using his power so evil will cease, • So much a leader and worthy of trust, • Here stands a man who will do what he must.

  4. Cover Generation www.spammimic.com Dear Friend , This letter was specially selected to be sent to you . This is a one time mailing there is no need to request removal if you won't want any more ! This mail is being sent in compliance with Senate bill 1622 ; Title 1 ; Section 307 ! This is not a get rich scheme . Why work for somebody else when you can become rich inside 94 MONTHS . Have you ever noticed how many people you know are on the Internet plus society seems to be moving faster and faster ! Well, now is your chance to capitalize on this . WE will help YOU SELL MORE plus sell more . You can begin at absolutely no cost to you ! But don't believe us ! Ms Anderson of Wisconsin tried us and says "I was skeptical but it worked for me" . We are a BBB member in good standing ! We BESEECH you - act now . Sign up a friend and you'll get a discount of 60% . Best regards . Dear Professional ; Thank-you for your interest in our briefing ! If you are not interested in our publications and wish to be removed from our lists, simply do NOT respond and ignore this mail . This mail is being sent in compliance with Senate bill 2216 ; Title 6 , Section 301 ! Do NOT confuse us with Internet scam artists ! Why work for somebody else when you can become rich as few as 11 months ! Have you ever noticed people will do almost anything to avoid mailing their bills & people love convenience . Well, now is your chance to capitalize on this . We will help you turn your business into an E-BUSINESS & deliver goods right to the customer's doorstep ! You are guaranteed to succeed because we take all the risk . But don't believe us ! Prof Ames who resides in North Dakota tried us and says "Now I'm rich many more things are possible" . We assure you that we operate within all applicable laws ! We beseech you - act now ! Sign up a friend and you'll get a discount of 20% ! Cheers .

  5. PatchworkBender, Gruhl, Morimoto and Lu • Choose any 2 random points A and B • ai ,bi be the luminance of A and B • S = ai - bi • Summing S for large n • Sn = ∑i=1n (ai - bi ) • Sn is approx 0 because for large n • The pixels are independent and identically distributed • The no of times ai > bi and bi > ai should be roughly same for large n

  6. Patchwork –continuedBender, Gruhl, Morimoto and Lu • communicating parties share a key k • Choose A, B pseudo randomly based on k • Raise the brightness in ai by 1 • Lower the brightness in bi by 1 • ai’= ai + 1 • bi’ = bi - 1 • Sn’ = ∑i=1n (ai + 1– (bi – 1) ) • Sn’ = ∑i=1n (ai - bi ) + ∑i=1n 2 • Sn’ is approximately2n • because ∑i=1n (ai - bi ) approx 0 for large n

  7. Conditions for watermarking Keep in mind the following considerations before embedding a digital watermark in your image. Color variation The image must contain some degree of variation or randomness in color to embed the watermark effectively and imperceptibly. The image cannot consist mostly or entirely of a single flat color. Pixel dimensions The Digimarc technology requires a minimum number of pixels to work. Digimarc recommends the following minimum pixel dimensions for the image to be watermarked: • 100 pixels by 100 pixels if you don't expect the image to be modified or compressed prior to its actual use. • 256 pixels by 256 pixels if you expect the image to be cropped, rotated, compressed, or otherwise modified after watermarking. • 750 pixels by 750 pixels if you expect the image to appear ultimately in printed form at 300 dpi or greater. There is no upper limit on pixel dimensions for watermarking.

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