Visual Cryptography for biometric privacy

Visual Cryptography
For Biometric Privacy
Waseem Ahmad
M.Tech

 Preserving the privacy of digital biometric data (e.g., face images)
stored in a central database has become of paramount importance.
This work explores the possibility of using visual cryptography for
imparting privacy to biometric data.
 In the case of faces, private face image is dithered into two host face
images (known as sheets) that are stored in separate database servers
such that the private image can be revealed only when both sheets
are simultaneously available; at the same time.

 Cryptography is one of the most important technique for
protecting the data such as biometric templates. It is the concept of
sending and receiving encrypted messages that is the
communication of the messages that can be decrypted only by the
authorized sender or the receiver.
 The original image is divided into the two cover images and, then
each cover image is stored in two different databases
geographically apart. When both the cover images are
simultaneously available then only we can access that original
image.

 "Biometrics" means "life measurement" but the term is usually
associated with the use of unique physiological characteristics to
identify an individual. The application which most people
associate with biometrics is security.
 A biometric system can be either an 'identification' system or a
'verification' (authentication) system, which are defined below.

Biometrics can be used to determine a person's identity even
without his knowledge or consent. For example, scanning a crowd
with a camera and using face recognition technology, one can
determine matches against a known database
• Fingerprint identification
• Hand geometry
• Palm Vein Authentication
• Face recognition

 Biometrics can also be used to verify a person's identity. For
example, one can grant physical access to a secure area in a
building by using finger scans or can grant access to a bank
account at an ATM by using retinal scan.

Visual Cryptography is a special encryption technique to hide information in
images in such a way that it can be decrypted by the human vision if the
correct key image is used.
1. Visual cryptography Scheme
a. Secret Image
b. Host Image
c. Sheet
d. Pixel

The Original image that has to be hidden In Our Application
This is private biometric image.

These are face image used to encrypt the secret image using the
EVCS In our application these correspond to the face image in a
public data sheet.

The secret image is encrypted into n sheet image which appear as
random noise image

Pixel is the smallest element of an image. Each pixel correspond to
any one value. In an 8-bit gray scale image, the value of the pixel
between 0 and 255. The value of a pixel at any point correspond to
the intensity of the light photons striking at that point.

Gray scaling is a process that uses gray shades to capture tone
variations. This is usually applied to monochrome graphics and
photos.
Gray-scaling is the process of converting a continuous-tone image
to an image that a computer can manipulate.

A pixel is made up 4 component
Alpha
Red
Green
Blue

Front –end
In this paper use c# technology as a frond end
Back-end
Sql server 2008 is a back-end

 Input: Secret Gray scale image (SI)
 Output: Valid Shares Share1, Share2
 Metod:
 Step1h:- Pixel Sij with position i and j is the input called original
 pixel.
 Step2:- Apply pixel reversal i.e Sij´ = 255 – Sij .
 Step3:- Use pseudo - random number generator (0.1 to 0.9) to
 reduce Si j´ randomly.
 Step4:- Take the difference of Sij´ with original pixel Sij.
 Step5:- Use pseudo-random number generator to reduce reversed
 value of Sij´ randomly.
 Step6:- Apply pixel reversal i.e Sij´´ = 255 – Sij´
 Step7:- Store in matrix as image called share 1.
 Step8:- Take the difference of two random number generators
 with original pixel S ij .
 Step9:- Apply pixel reversal i.e Sij´´´ = 255 - Sij´.
 Step10:- Store Sij´´´ in matrix as image called share 2.
 Step 11:- Stack both the share 1 and share 2
 Step 12:- Apply the sigmoid mask to each pixel
 Step 13:- Display the final encrypted image.

HARDWARE REQUIREMENTS
Processor : core i3 & above
CPU clock : 850 MHZ
RAM : 1GB Min
Hard Disk : 80GB
Display : Intel Graphic Adapter.

 Core Technology : Microsoft .Net 2010
 Framework : .Net Framework 2.0
 Front End : C#.Net
 Back End : SQL 2008

 Enrollment
 Authentication

 User Interface
In this user image , primary key ,username and password have
got from the user and it is stored successfully in database.
 Business layer
In this the user image is splited as 2 images. This 2 images are
hided randomly chose 2 host images. The 2host images are
encrypted with username and password. This images is saved in
the database.

 User Interface
In authentication form the enrolled user give their new image
,username, password and primary key.
 Business Layer:
By using the primary key the encrypted host image is retrieved
from the database. And that 2 host image is decrypted as username
with host image1 and password with host image2. Then the hided
images are retrieved from the host images(split1 and split2).
Concept is privet face image is can revealed
only both host image are simultaneously available.

1. This project at start should aim at the security of private face
image .
2. Only qualified subset of shares can recover the secret image
3. Any forbidden subset of share can not obtain any information
of the secret image other than the size of the secret image
4. It can be used at all security related institution like military
,office ,confidential lab or laboratories

 The contribution of this paper includes a methodology to protect
the privacy of a face data-base by decomposing an input private
face image into two independent sheet images such that the
private face image can be reconstructed only when both sheets are
simultaneously available.

Visual Cryptography for biometric privacy

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