Hand Biometric Steganography

Steganography:

It is the technique of concealing the secret data in to the one of the cover files, so that no one can suspect the data apart from the sender and receiver.

Image Steganography:

Taking the cover object as image in steganography is known as image steganography. Generally, in this technique pixel intensities are used to hide the information.

Biometric Steganography:

This project is divided into 8 phases:

• Feature Extraction
• Key generation
• Message Encryption
• Data Embedding
• Stego-Image Encryption
• Stego-Image Decryption
• Data Extraction
• Message Decryption

Step 1: Feature Extraction

Here hand geometric features are extracted by following 3 steps.

• Image Acquisition
• Image preprocessing
• Feature Extraction

Image preprocessing

• convert the colour image into the black and white image
• unnecessary part of the captured hand image has cropped
• Gaussian filter had used to remove the background noise of the image
• Binary Image by Otsu Thresholding

Feature Extraction

• Trace contours of image used to plot all the contours point and find convex hull
• Find tip points
• Find centre point of the hand
• Euclidean distance is calculated between tip points & center point of hand image.

Step 2: Key Generation

Key has generated in four ways -

• From extracted features, tip points are located
• Pairwise distance has calculated using Euclidean distance.
• Variance has calculated for pairwise distance
• And lastly unique key has generated using variance result

Unique key generation :

Key= (Most Significant 2 Digits of p1) * 10 + (Least Significant 1 Digits p2) Where, P1 = variance of Hand points pairwise distance P2 = standard deviation of Hand points pairwise distance

● From this unique key we will get unique pixel position to embed the secret data instead of embedding the data in sequential pixels of cover image.

Step 3: Message Encryption

• Applied “Caesar Cipher” cryptography technique to encrypt the message user wants to hide.
• Encryption phase with shift n ( E(x) = (x + n) mod26 )
• Here, n = sum of digit of key obtained

Step 4: Data Embedding

Steps for LSB data insertion-

• First carrier image or cover image has been read and converted in to array of bits.
• Then the secret message which is in the form of bytes/characters are converted into the “ASCII” values and then ASCII values are converted into an array of bits.
• A unique key which has generated from hand geometric features, based on this we start embedding the secret data
• Here key will gives unique pixel position of cover image to embed the data least significant bit of particular image pixel of cover object. Here 1 pixel = 1 byte.
• Stego-image has been generated which contains secret message embedded within cover image.

Cover image:

Step 5: Stego-image Encryption

Encrypted stego-image using AES Cryptography technique.

Step 6: Stego-image Decryption

• Decrypted the encrypted stego-image using AES using 128 bits key.
• Key used is same as previous generated key but this key is transformed to 128 bits.

Step 7: Data Extraction

Steps for LSB data extraction-

• The extracting of the embedded data is done in opposite direction of hiding process.
• Here embedded secret data has extracted from stego-image
• While extracting secret data the hand key is used. while embedding the data we have used key to select the embedding position in cover image so while extracting also we need that key to extract secret data
• This gives complete security to the embedded data in the cover image.

Step 8: Message Decryption

• We have the encrypted msg.
• Caesar Cipher Decryption technique is performed to get the original msg.
• Decryption phase with shift n
• D(x) = (x-n) mod 26
• Here, n = sum of digits of key