VISUAL CRYPTOGRAPHY USING TAGGED AND COVER IMAGESClick to edit Master subtitle stylePresenting by, Ambika Anitha L Khadija Kaousar M.A Mahadevi Amaravati

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Contents Introduction Problem statement Modules Module 1 Module 2 Module 3 Module 4

Requirements Conclusion3/20/12

IntroductionVISUAL Cryptography is a technique which

was proposed by Naor and Shamir.A secret image can be encrypted as

different share images printed on transparencies, which are then distributed to n- participants.By stacking transparencies directly, the

secret images can be revealed.

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Problem StatementWe propose a scheme in whichPixel reduction which is a problem in conventional VC. Additional information in the form of tag . Cover images for distinguishing the shares from noise

images.

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Module 11.1 Basic Vcs proposed by Naor and Shamir.

Secret image

Share 1

Share 2

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Share1+share2

Continue... 1.2 Basic Vcs with 2 out of 2Encoding: Image is split into 2 shares with an increase of 2 times Decoding stacking of tranparenices

Secret image

Share 1

Share 2

Overlapping share 1 and share 23/20/12

Recovered secret image

1.3 Basic Vcs with 2 out of 3Encoding: Image is split into 3 shares with an increase of 2 times Decoding stacking of any 2 tranparenices out of 3

Secret Image

Share 1

Share 2

Share 3 Overlapping of any 2 shares

Recovered secret images

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Method Basic vcs technique

Advantage

User can encrypt the image without any computational device Pixel increases four times the original image.

Disadvantage

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Module 22.1 Using tag image

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MethodSubliminal channel

By using this method we can add tag to original image this reveals extra information regarding original image

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Module 33.1 Using Cover image Encoding : secret image is recorded in the shares and the cover is stamped on each share Decoding: overlapping of shares

Secret 3/20/12 image

Cover image1

Cover image 2

Cover image 3

Share 1

Shar e2

Share 3

Share 1+2

Share 1+33/20/12

Share 2+3

Share 1+2+3

MethodModule 4 Tagged cover images Encoding : 1.secret is recorded into non pixel expanded shares 2: shares are tagged 3:tagged are stamped with cover images Decoding : overlapping of shares to obtain the secret image3/20/12

floding of shares for tag images

Module 44.1 Using Tag image and Cover image reveal secret image

Secret image Cover image2

Cover image1

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Tag

Tag

Continue...

Share 1

Share 2

Tag 1 from share1

Tag 2 from share 2

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Share 1+share

MethodHilbert curve and zigzag scan for pixel reduction Subliminal channel for tag image Meaningful share and halftoning technique for cover

image

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RequirementsHardware Requirements

Intel Processor with minimum 20GB hard disk capacity.

Operating System Windows XP Operating System

Software Requirements

Matlab3/20/12

ConclusionModule 1 is about basic vc schemes,this has pixel

expansion high.Module 2 is using tag images it reveals the secret

image.

Module 3 is using cover image to reveal the secret

image with non-pixel expansion.Module 4 is using tag image and cover image to reveal

the secret image with non-pixel expansion and high contrast.3/20/12

THANK YOU

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