05-04-2011, 12:48 PM
Presented by:
AJAYA SIMHA K.J.
[attachment=11742]
VISUAL CRYPTOGRAPHIC STEGANOGRAPHY IN IMAGES
BASIC OVERVIEW ON CRYPTOGRAPHY
Cryptography- meaning “secret writing”
Definition-practice and study of hiding information
Encryption- To obtain a cipher
Use- To secure information
The most commonly used techniques are:
Joint key cryptography-Symmetric key cryptography
Public key cryptography-Asymmetric key cryptography
HYBRID CRYPTOSYSTEM-Combines both the features
Joint Key Cryptography (Symmetric Key)
This technique uses a common key.
This key is shared privately.
Process
But the key should also be shared securely.
Public Key Cryptography (Asymmetric Key)
Uses two different keys
Process
There is no need to privately share a key
More secure
STEGANOGRAPHY
Steganography- meaning “concealed writing”
Definition- security through obscurity
Advantage of steganography
Visual steganography- Secure, implemented in image files
THE RGB COLOR MODEL
Image-pixel-pixel depth
RGB COLOR MODEL- additive colour model
Purpose- sensing, representation, and display of images in electronic systems
Device dependent
Digital representation- For 24 bit per pixel image, each colour is represented by 8 bits.
Primary colours- R-red, G-green, B-blue
Secondary colours- R+G=yellow, G+B=cyan,
B+R=magenta
Zero intensity- Black and Full intensity- White
LSB insertion technique
LSB insertion technique- A common technique in image steganography
Grid of 3 pixels of a 24-bit image
(00101101 00011100 11011100)
(10100110 11000100 00001100)
(11010010 10101101 01100011)
LSB is changed
A number 200-binary equivalent 11001000
needs to be embedded
(00101101 00011101 11011100)
(10100110 11000101 00001100)
(11010010 10101100 01100011)
Cryptography and steganography combined systems can be created
THE VISUAL CRYPTOGRAPHIC STEGANOGRAPHY SYSTEM
Advanced system of encrypting data
Visual steganography- Secure, implemented in image files
Concept of multiple cryptography
Only jpeg image will be used
SYSTEM FLOW CHART
THE REFERENCE DATABASE
In order to provide higher security levels the algorithm is designed to use a reference database as shown in the figure.
Encryption Algorithm
The message will first be encrypted
The pixel values of the image are truncated
Then a specific number which corresponds to the 3-D representation of the character in the cipher code sequence can be added to this number
Only the edited message will be transmitted to the receiver
In the first few lines of image properties, the attributes of the image will be encrypted and saved
The edited image will be transmitted to the receiver
Decryption Algorithm
The message can be decoded using the receiver’s private key.
The receiver’s private key is used to identify the reference grid from the reference database.
The x and y components can define the block that has been used to encrypt the message.
RGB value-point to the data in the block
The cipher is retrieved by obtaining the difference in the pixel value
This cipher can now be decrypted using an inverse function of the DEA algorithm to get the message text
Applications of steganography
Confidential communication and secret data storing
Protection of data alteration
Access control system for digital content distribution
Media Database systems
Applications of cryptography
Confidentiality
Authentication
Integrity
Non-repudiation
Advantages of the technique
It provides higher levels of security to the information being transmitted
More secure than other systems
The image bits are not used to store the message
Applications and future scope
To increase security on web based applications
A part of message can be sent in each image
AJAYA SIMHA K.J.
[attachment=11742]
VISUAL CRYPTOGRAPHIC STEGANOGRAPHY IN IMAGES
BASIC OVERVIEW ON CRYPTOGRAPHY
Cryptography- meaning “secret writing”
Definition-practice and study of hiding information
Encryption- To obtain a cipher
Use- To secure information
The most commonly used techniques are:
Joint key cryptography-Symmetric key cryptography
Public key cryptography-Asymmetric key cryptography
HYBRID CRYPTOSYSTEM-Combines both the features
Joint Key Cryptography (Symmetric Key)
This technique uses a common key.
This key is shared privately.
Process
But the key should also be shared securely.
Public Key Cryptography (Asymmetric Key)
Uses two different keys
Process
There is no need to privately share a key
More secure
STEGANOGRAPHY
Steganography- meaning “concealed writing”
Definition- security through obscurity
Advantage of steganography
Visual steganography- Secure, implemented in image files
THE RGB COLOR MODEL
Image-pixel-pixel depth
RGB COLOR MODEL- additive colour model
Purpose- sensing, representation, and display of images in electronic systems
Device dependent
Digital representation- For 24 bit per pixel image, each colour is represented by 8 bits.
Primary colours- R-red, G-green, B-blue
Secondary colours- R+G=yellow, G+B=cyan,
B+R=magenta
Zero intensity- Black and Full intensity- White
LSB insertion technique
LSB insertion technique- A common technique in image steganography
Grid of 3 pixels of a 24-bit image
(00101101 00011100 11011100)
(10100110 11000100 00001100)
(11010010 10101101 01100011)
LSB is changed
A number 200-binary equivalent 11001000
needs to be embedded
(00101101 00011101 11011100)
(10100110 11000101 00001100)
(11010010 10101100 01100011)
Cryptography and steganography combined systems can be created
THE VISUAL CRYPTOGRAPHIC STEGANOGRAPHY SYSTEM
Advanced system of encrypting data
Visual steganography- Secure, implemented in image files
Concept of multiple cryptography
Only jpeg image will be used
SYSTEM FLOW CHART
THE REFERENCE DATABASE
In order to provide higher security levels the algorithm is designed to use a reference database as shown in the figure.
Encryption Algorithm
The message will first be encrypted
The pixel values of the image are truncated
Then a specific number which corresponds to the 3-D representation of the character in the cipher code sequence can be added to this number
Only the edited message will be transmitted to the receiver
In the first few lines of image properties, the attributes of the image will be encrypted and saved
The edited image will be transmitted to the receiver
Decryption Algorithm
The message can be decoded using the receiver’s private key.
The receiver’s private key is used to identify the reference grid from the reference database.
The x and y components can define the block that has been used to encrypt the message.
RGB value-point to the data in the block
The cipher is retrieved by obtaining the difference in the pixel value
This cipher can now be decrypted using an inverse function of the DEA algorithm to get the message text
Applications of steganography
Confidential communication and secret data storing
Protection of data alteration
Access control system for digital content distribution
Media Database systems
Applications of cryptography
Confidentiality
Authentication
Integrity
Non-repudiation
Advantages of the technique
It provides higher levels of security to the information being transmitted
More secure than other systems
The image bits are not used to store the message
Applications and future scope
To increase security on web based applications
A part of message can be sent in each image