12-04-2011, 10:54 AM
PRESENTED BY:
MUKESH KUMAR THAKUR
[attachment=12071]
IMAGE AUTHENTICATION TECHNIQUES Based on Automatic video surveillance (AVS) systems
AUTOMATIC VISUAL SURVEILLANCE SYSTEM
• Automatic Visual Surveillance system is a self monitoring system which consists of a video camera unit, central unit and transmission networks.
AUTHENTICATION TECHNIQUES
• Authentication: It ensures that whoever supplies or accesses sensitive data is an authorized party.
CRYPTOGRAPHY
• In Cryptography, the meaning of the message is hidden, not its existence.
– Kryptos = “hidden” in Greek
• Cryptography is the science of transforming documents.
• It has mainly two functions:
• Encryption
• Decryption
Basic Terms
• Encryption: scrambling a message or data using a specialized cryptographic algorithm.
• Plaintext: the message or data before it gets encrypted.
• Ciphertext: the encrypted (scrambled) version of the message.
• Cipher: the algorithm that does the encryption.
• Decryption: the process of converting ciphertext back to the original plaintext.
CRYPTOGRAPHY
• The key is a randomly selected string of numbers.
• Encryption schemes are classified as:
1. Symmetric encryption :
In which the same key is used to both encode and decode the document.
2. Public key or asymmetric encryption:
It requires a pair of keys: one for encrypting the plain text and the other for decrypting the cipher text. A file encrypted with one key of a pair can be decrypted with other key of the same pair.
CRYPTOGRAPHIC DATA AUTHENTICATION
• Data Integrity
• This involves ensuring that when a message (or any kind of data, including documents and programs) is sent over a network, the data that arrives is the same as the data that was originally sent. It is important that the data has not been tampered with.
• Technical solutions include:
– Encryption
– Hashing algorithms
DRAWBACKS OF CRYPTOGRAPHIC AUTHENTICATION:
• Knowledge of private key :
If the manipulator knows the private key of the camera, he can change the digest to involve the modifications he had made on the actual sequence.
High requirements of video camera:
To avoid the above discussed problem, the video camera should perform the compression of the video sequences prior to digest calculation. This requires the video camera to have high computation as storage requirements.
Delay in transmission:
Digest calculations and encryption introduces a delay in transmission of video documents. This is harmful in system where the timely generation of alarm is critical
• Protecting privacy is difficult :
A part of the program cannot be removed for privacy reasons since it will alter the calculated digest.
WATERMARKING
Watermark = Water (Invisible) + Mark
Digital watermarking is the art and science of embedding copyright information in the original files. The information embedded is called ‘watermarks ‘. Digital watermarks are difficult to remove without noticeably degrading the content .
Watermark task consists of two main steps:
1. Watermark casting:-in which the signal represented by the watermark is transmitted over the channel, that is in watermark casting an encoder function Є takes a host image ‘f’ and a watermark ‘w’ and generate a new image
Fw= Є (f, w)
2. Watermark detection:-in which the signal is received and extracted from possibly corrupted image.
• Watermark Image
CLASSIFICATION OF WATERMARKING AUTHENTICATION SCHEMS
Fragile watermarking
• Fragile watermarking refers to the case where watermark inserted within the data is lost or altered as soon as host data undergoes any modification. Watermark loss or alternation is taken as evidence that data has been tampered with, whereas the information contained within data used to demonstrate data origin.
Robust watermarking
• Robust watermarking a summary of the candidate frame or video sequence is computed and is inserted within the video sequence. Information about the data origin is also with the summary. To prove data integrity the information conveyed by the watermark is recovered and compared with the actual content of the sequence. Their mismatch is taken as an evidence of data tampering. The capability to localize the manipulation will depend on the summary of which is embedded in to the image.
MUKESH KUMAR THAKUR
[attachment=12071]
IMAGE AUTHENTICATION TECHNIQUES Based on Automatic video surveillance (AVS) systems
AUTOMATIC VISUAL SURVEILLANCE SYSTEM
• Automatic Visual Surveillance system is a self monitoring system which consists of a video camera unit, central unit and transmission networks.
AUTHENTICATION TECHNIQUES
• Authentication: It ensures that whoever supplies or accesses sensitive data is an authorized party.
CRYPTOGRAPHY
• In Cryptography, the meaning of the message is hidden, not its existence.
– Kryptos = “hidden” in Greek
• Cryptography is the science of transforming documents.
• It has mainly two functions:
• Encryption
• Decryption
Basic Terms
• Encryption: scrambling a message or data using a specialized cryptographic algorithm.
• Plaintext: the message or data before it gets encrypted.
• Ciphertext: the encrypted (scrambled) version of the message.
• Cipher: the algorithm that does the encryption.
• Decryption: the process of converting ciphertext back to the original plaintext.
CRYPTOGRAPHY
• The key is a randomly selected string of numbers.
• Encryption schemes are classified as:
1. Symmetric encryption :
In which the same key is used to both encode and decode the document.
2. Public key or asymmetric encryption:
It requires a pair of keys: one for encrypting the plain text and the other for decrypting the cipher text. A file encrypted with one key of a pair can be decrypted with other key of the same pair.
CRYPTOGRAPHIC DATA AUTHENTICATION
• Data Integrity
• This involves ensuring that when a message (or any kind of data, including documents and programs) is sent over a network, the data that arrives is the same as the data that was originally sent. It is important that the data has not been tampered with.
• Technical solutions include:
– Encryption
– Hashing algorithms
DRAWBACKS OF CRYPTOGRAPHIC AUTHENTICATION:
• Knowledge of private key :
If the manipulator knows the private key of the camera, he can change the digest to involve the modifications he had made on the actual sequence.
High requirements of video camera:
To avoid the above discussed problem, the video camera should perform the compression of the video sequences prior to digest calculation. This requires the video camera to have high computation as storage requirements.
Delay in transmission:
Digest calculations and encryption introduces a delay in transmission of video documents. This is harmful in system where the timely generation of alarm is critical
• Protecting privacy is difficult :
A part of the program cannot be removed for privacy reasons since it will alter the calculated digest.
WATERMARKING
Watermark = Water (Invisible) + Mark
Digital watermarking is the art and science of embedding copyright information in the original files. The information embedded is called ‘watermarks ‘. Digital watermarks are difficult to remove without noticeably degrading the content .
Watermark task consists of two main steps:
1. Watermark casting:-in which the signal represented by the watermark is transmitted over the channel, that is in watermark casting an encoder function Є takes a host image ‘f’ and a watermark ‘w’ and generate a new image
Fw= Є (f, w)
2. Watermark detection:-in which the signal is received and extracted from possibly corrupted image.
• Watermark Image
CLASSIFICATION OF WATERMARKING AUTHENTICATION SCHEMS
Fragile watermarking
• Fragile watermarking refers to the case where watermark inserted within the data is lost or altered as soon as host data undergoes any modification. Watermark loss or alternation is taken as evidence that data has been tampered with, whereas the information contained within data used to demonstrate data origin.
Robust watermarking
• Robust watermarking a summary of the candidate frame or video sequence is computed and is inserted within the video sequence. Information about the data origin is also with the summary. To prove data integrity the information conveyed by the watermark is recovered and compared with the actual content of the sequence. Their mismatch is taken as an evidence of data tampering. The capability to localize the manipulation will depend on the summary of which is embedded in to the image.
