1. IMAGE AUTHENTICATION TECHNIQUES Based on Automatic video surveillance (AVS) systems Guided by: K ASTURI MISHRA PRESENTED BY: MUKESH KUMAR THAKUR REG NO:0801800032 BRANCH:INFORMATION TECHNOLOGY

2. 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. The central unit is in charge of analyzing the sequence and generating an alarm whenever a suspicious situation is detected. Central unit also transmits the video sequences to an intervention centre such as security service provider, the police department or a security guard unit. Somewhere in the system the video sequence or some part of it may be stored and when needed the stored sequence can be used as a proof in front of court of law. If the stored digital video sequences have to be legally credible, some means must be envisaged to detect content tampering and reliably trace back to the data origin

3. DIGITAL CAMERAS AT DIFFERENT POSITION

4.  Authentication  Authentication : It ensures that whoever supplies or accesses sensitive data is an authorized party. Major techniques for authenticating video data are as follows: 1.Cryptographic Data Authentication 2. Watermarking- based authentication

5. 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

6.  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.

7. CRYPTOGRAPHY The key is a randomly selected string of numbers. ENCRYPTION ALGORITHM DECRYPTION ALGORITHM PLAIN TEXT CIPHER TEXT DECRYPTION KEY PLAIN TEXT CIPHER TEXT ENCRYPTION KEY

8. 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.

9. . CRYPTOGRAPHIC DATA AUTHENTICATION Cameras calculate a digital summary or digest of the video by means of a proper hash function. The digest is then encrypted with their private key. Encryption is done by considering the digitized value of the brightness of each pixel. Digital signal is a sequence of zeros and ones and it is encrypted with the private key using a proper algorithm. The signed digest thus obtained is then transmitted to the central unit together with the acquired visual sequence. Later the signal digest is used to prove data integrity or to trace back to their origin. The signed digest is read using the public key of the camera which produce the video and check if it corresponds to the digest derived from the decrypted video content using the same hash function.

10. Data Integrity 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

11.  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.

12. 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.

13. Watermark Image

14. Watermark images

15. CLASSIFICATION OF WATERMARKING AUTHENTICATION SCHEMS WATERMARKING FRAGILE WATERMARKING ROBUST WATERMARKING INVISIBLE WATERMARKING DUAL WATERMARKING

16. 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. Watermark image Under goes any modification Watermark loss Evidence:data has been tampered ?

17. 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. ROBUST WATERMARKING SUMMARY OF FRAME AND DATA ORIGIN INSERTED WITHIN DATA TAMPERING WITH VIDEO MISMATCH DATA HAS BEEN TAMPERED

18. FRAME

19. THANK YOU