PRESENTED BY:
Deepak Sharma

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MPEG Video Watermarking Technologies: Techniques and Issues
Abstract
With the current growth rate of broadband networks, distribution of multimedia content over the Internet will become the norm. With such a growth the major concern for the content providers will be security. A lot of research is currently going on that combines public key cryptography, watermarking and other techniques. This report presents a brief overview of several watermarking techniques that may be used for protecting MPEG video files. It starts by presenting why watermarking is needed and then goes on to present some watermarking schemes.
1. Introduction
Current research will lead to computers with 2GHz microprocessors, 1 GB memory and over 80 GB of hard disk space available for only a few hundred dollars. Such computers will be able to connect to the Internet via a 1 GB connection. With the amazing configuration of these machines and networks, many things that are barely imaginable today will become feasible. Online movies (VoD – Video on Demand), audio streaming, games, ebooks, etc will be more efficient than what we know them today. With such technology available and multimedia content flowing across networks, a major issue will be developing secure technologies to protect the multimedia content. With the expanse of the Internet, online multimedia distribution is the fastest and cheapest way for the content providers to distribute their content. However, with the benefits of the Internet comes its lack of security. Research is now being focused on public key cryptography/watermarking schemes to protect multimedia content.
2. Watermarking
Digital watermarking is the enabling technology to prove ownership of copyrighted material, detect the originator of illegally made copies (also called fingerprinting), monitor the usage of copyrighted multimedia data and analyze the spread spectrum of the data over networks and servers [2]. In the two types of watermarking the first one is for ownership where an identical watermark is embedded into every copy of the digital content. Hence, it cannot be used to distinguish who is the user that distributed the illegal copy. In the other type of watermarking, called fingerprinting, different watermarks are embedded into different copies of the digital content. Hence it can be used to trace the illegal users. The disadvantage of this scheme is that it is quite expensive to resist colluding attacks. In order to prevent any copyright forgery, misuse or violation, the key to the copyright labeling technique (watermarking) is to provide security and robustness of the embedded label against a variety of threats that include
• Detecting embedding locations by comparing differently labeled versions of the same original material.
• Finding or altering the embedded label through visual or statistical analysis.
• “The IBM-attack”: Instead of introducing a new watermark with an own algorithm and claiming the authorship, a counterfeit original of the watermarked picture is produced by removing a watermark, thus claiming that the original of the real owner contains the watermark which we removed.
• Damaging or removing the embedded label using common multimedia processing.
MPEG compression itself performs multimedia processing like lossy compression and scaling, hence all necessary transformations on the frames may lead to a distortion of the embedded information and the owner cannot retrieve the label anymore.
3. Requirements for MPEG Video Watermarking
MPEG compression algorithms employ Discrete Cosine Transform (DCT) coding techniques on image blocks of 8x8, prediction and motion compensation. The resulting output stream contains a sequence of I-, P- and B- frames [2]. The following requirements are considered important for MPEG video watermarking:
• Robustness against high compression rates of the DCT compression, motion compensation and prediction.
• Robustness against scaling.
• Labeling of every single video frame (I-, P- and B- frames) to provide continuous watermarking and avoid attacks of cutting single frames.
• Ensuring correct decoding of the frame sequences without visual artifacts.
• Runtime performance for streaming video or stored video.
4. Watermarking Algorithms
4.1 Tamper Resistant Hardware
This scheme uses both public key encryption and symmetric key encryption. A tamper resistant hardware includes:
Sn  A unique serial number
SK_sn  Private key
PK_sn  Public key
WE_sn  Watermark embedding process
M  Multimedia file
K  Symmetric key