Chapter 1 Introduction
1.1 Development Status of Digital Cinema
The digitalization of the information medium provides great convenience, and also significantly increases the efficiency and accuracy of information expression. Especially with the development of computer network communication technology, data exchange and transmission becomes a relatively simple process. People can be easily and quickly transmitted digital information to all parts of the world with a means of electronic devices such as computer, digital scanners, printers. The side effects of the following are to transfer data files or works through the network, so that malicious individuals or groups may be copied and disseminated with copyright content without obtaining the work owner. Therefore, how to implement valid copyright protection and information security (Information security) means in a network environment has become an imminent real issue. In recent years, digital watermarking technology has provided a potential solution for copyright protection and information security, which has attracted extensive attention from international academic circles, corporate communities, and government departments.
Similarly, in the movie industry, people have widely recognized that the digital process is an inevitable trend. Digital Theater will greatly reduce the materials, human costs of the entire movie industry, and bring more digital unique effects. However, security issues have always been a big problem that plagues the digital theater, and has become the current international industry, the focus of the academic circles. For example, the American Film Student Association has set up a special working group Digital Cinema DC28 [1].
1.2 digital copyright issues of digital theater
There are several challenge issues in the construction of digital cinema: (1), establish a reliable, fast content distribution network system from the data center to each cinema; (2) the development of high quality audio and video projectors; Third) Safe and effective digital copyright management system. This article will mainly examine the security issues of digital cinema, and propose a digital copyright management system combined with digital watermarking technology.
1.2.1 Digital Copyright Management of Digital Cinema
So far, the protection system for different content has been much. Such as satellite TV subscription, video game copy protection, based on the network content distribution [2], but these systems have an inquiry difference between the operating environment and the digital theater.
First, the value curve of the content is different. The digital film has the highest value after the previous release, and then the value is rapidly decline. This puts a relatively high security request for the previous issue of the film, and relatively low on the later stage.
Second, the participants of the digital theater are relatively more specific, and the quantity is small. The projector contains expensive optical equipment and complex anti-piracy technology equipment.
The purpose of piracy is to obtain a copy piece of unprotected works so that it can be disseminated through various channels. For example, by burning CD (VCD, DVD), now more through the Internet, is also the largest channel. Now the most common attack method is to use the hand-held camera recorded movies and then spread anything through the Internet.
1.2.2 Possible way to cause leakage
· In the distribution chain of the content, content leaks appear, such as technical attacks, an attacker attempts to extract the decrypted movie content from the legal projector, and the attacker tries to extract the certification key, so other devices can also Alternative dedicated projector.
· Attack encryption, decryption algorithm. However, this may not be large, because the public security encryption algorithm is practical inspection, and even if it is broken, it takes a long time, and the value of the video is not great.
· Attacks attacks the digital watermark fingerprint system through the joint attack. At present, there has been reported that a certain number of users jointly attack, which can remove the watermark fingerprint information embedded in the movie to obtain pirated works that do not contain watermark fingerprints.
· Others are factors: such as the discipline of internal personnel.
· This is the most common attack method through the pirated work recorded by the camera. If the quality of the attacker is recorded, it will bring huge losses to the Internet. 1.3 This article:
The first chapter is an introduction, briefly introduces the proposed and key issues of the digital theater, and the organizational structure and contributions herein.
The second chapter introduces the principles, main components and existing problems of the digital cinema copyright management system, and describes the copyright management system and related core technical solutions proposed by Microsoft Research Institute.
The third chapter introduces the digital watermarking technology applied in the digital cinema to study the high-capacity digital fingerprint watermark model based on orthogonal template. From the perspective of statistical analysis, the expansion spectrum is used to study high-capacity, robustness and irreparable digital watermarking algorithms. From theoretically analyzed, how to achieve maximum capacity, optimal detection effect, and The highest robustness. Two different image watermark algorithms are given, including: 1. High-capacity watermark algorithm based on spatial domain. Second, the watermark algorithm based on multi-scale wavelet coding. After fixing the standard wavelet transform, we got a non-standard formation, so that the algorithm can be incorporated into a general watermark frame, and the algorithm does not require the original image in the watermark detection.
The fourth chapter proposes an access control model based on digital fingerprint watermark, preventing the illegal propagation of digital content on the network to protect digital content. The basic principle is to first specify to embed the active digital watermark information in digital media content (image, video, audio, etc.), and then detect the extracted watermark information at the network node on the way of communication, and then according to the watermark information decision multimedia content transmitted in the network. Sex, thereby controlling the propagation of digital content in the network, and provides facts and clues for copyright protection.
The fifth chapter is concluded, including innovation points, conclusions, and digital watermark technology.
Chapter 2 Digital Cinema Copyright Management
A core problem in digital cinema construction is security issues, specific for common digital copyright management issues facing digital content. This paper mainly examines the digital cinema copyright management system proposed by Microsoft Research Institute Darko Kirovski et al. [3] and related core technical means.
2.1 Microsoft proposed digital theater copyright management system
This system consists of a set of security nodes that implement the function of digital copyright protection, which is synergistic by different participants.
2.1.1 Node function
The digital copyright management system is made of some mutual communication security nodes. The node is an abstract concept (which can be a projector), is an entity of the system, is used to securely store, and deliver content that requires protection. Nodes with permissions can access (such as display) a given content. Specifically, the function of the node is: i
· Authentication
· Rights Management (licensing))
· Content encryption and decryption (Content Encryption and Decryption)
· Fingerprinting of digital fingerprints
(1) Certification
Depending on the position in the distribution chain, a node can be used as a transmitter or a receiver. When as a transmitter, it must ensure that the receiver has the right to receive, in turn, when as a receiver, it must be proved to the transmitter is a legal recipient. This requires these nodes to have authentication. We use the public key encryption method, each node needs to save a private key, and contact the public key authentication system, implement basic public key operations (encrypted, decrypt, signature, and check). .
(2) Copyright Management and License Agreement
One of the main purposes of digital copyright management, that is when the content is distributed in electronic form, the content issuer can control the access rights of the content. This requires defining a special digital copyright language, and the content issuer can express the rules and conditions protocols accessed. Before anyone accesses the content, the digital copyright node must check if the other party complies with the agreement. A typical license agreement specifies access rights or action, such as playing or propagating to the next node. Each action is closely related to a set of conditions, which constitutes a set of control systems, only in line with specific conditions, nodes can have specific action capabilities. These restrictions require a safe counter or a safe clock. In addition, the license agreement can specify actions for content, such as operating actions such as embedding digital fingerprint watermarks. Other related license agreements are:
· The validity period of the agreement;
· Screen limit for a specific time;
· Execute the audit log, that is, automatically record the content header, time, span, etc. of each projector.
· Projector feature requirements (such as auditing features, safety features, digital water printing fingerprint recognition feature).
The protocol needs to be protected by cryptography technology. If you use digital signatures to ensure its integrity and confidentiality. The XRML copyright language has all the above functions.
(3) Encryption and decryption of content
As mentioned above, the node is a safe storage chamber and can access the stored content. The channel between nodes is unsafe, so it is necessary to protect the content of the encrypted decryption. For multimedia content encryption, it is impossible to use traditional strategies for text. To take into account the amount of multimedia content, selective encryption, and actual feasible policies must be combined with loss of compression coding, such as MPEG1 / 2/4, etc. This is a current research hotspot.
(4) Digital water printing fingerprint identification
The digital watermark fingerprint is an invisible information embedded in digital content, has robustness against general attack. Can be used to track pirated sources, can be used to control access to authentication. This article will examine the key issues of digital watermarking technology, proposing access control models based on digital watermarking technology, which effectively combines it in a copyright management system of digital theater.
2.1.2 Distribution Chain of Content
A typical distribution chain includes three major participants of the film manufacturer, publisher and theater. In the digital copyright management system proposed in [3], there are two possible distribution chains. Each participant is a node that has different permissions and access capabilities. The nodes communicate with each other through rules. The entire full system is a copyright management system.
Studio
Tier 1
Distrib.
Tier 2
Distrib.
Cinema
Film
USAGE DATA, PAYMENT
Studio
Tier 1
Distrib.
Tier 2
Distrib.
Cinema
Film
Access authorisation
(License Generation),
USAGE DATA, PAYMENT
Clearing
House
a)
b)
Figure 2-1. Two possible movies distribution chains.
2.2 Digital Image Information Encryption
The addition of the traditional cryptographic theory is developed. For the processing of the file to be encrypted, it is transmitted to secretly transferred, so that the illegal column in the network transmission process cannot obtain confidential information from it, reach the purpose of confidentiality. . Traditional encryption systems such as DES and IDEA, etc. are achieved based on the superimposed product password. In these methods, in order to ensure safety, it is generally mainly replaced by the key to a very complicated manner, and is difficult to achieve a fast additive, decryption algorithm for the multimedia data stream of the data amount. Since multimedia information has its own characteristics, we must combine the characteristics of multimedia information, and study encryption techniques suitable for multimedia information.
For analog television signals, it is often encrypted using a chaos. There is a chaos and timing in the simulation system, synchronous inhibition and full image inversion, random rows, chaos, timing reversed, chaos, line flat, line chaos, line score cutting Ratming and pixel chaos. For digital images and digital video data, due to their huge amount of data and autocorrelation, we can encrypt them in space (position space and color space of pixels), or encryption in transform domain space. .
For MPEG video streams, Mayles [4] proposes to simultaneously express the data bit flowing through MPEG as a normal data bit stream, and then encrypt / decrypts through the traditional DES algorithm. The disadvantage is that the amount of operation is large and does not meet the requirements of real-time. LEI TANG [5] The first proposes to integrate encryption / decryption processes into the MPEG video compression / decompression process. In this algorithm, a random scanning sequence is used as a key instead of a zigzag scanning sequence to rearrange the DCT transform coefficient to achieve an encryption. The calculation complexity of the algorithm is low, but its disadvantage is that the compression efficiency of MPEG has declined. C. SHI [6,7] proposed a fast MPEG video encryption algorithm called VEA (Video Encryption Algorithm). Its basic idea is to use a key control to randomly change the symbol bit of the DCT coefficient. During the decryption process, the effect of encryption is obtained by the reverse transformation of the IDCT. For each non-zero DCT coefficient, the encryption process only needs to complete the XOR operation between the current bits of the symbol bit and key control, the realization speed is quite fast, and does not affect the compression efficiency of MPEG.
For digital images, considering the large data quantity and autocorrelation of the digital image, encryption of the digital image can be expanded on the spatial domain (color space, position space), but also in the digital image conversion domain. (In the frequency domain). In the image encryption, the digital image has a non-negligible role, which is similar to the spatial domain of the digital image, such as the change of the classic password to the one-dimensional signal, or modifies the transform domain parameters of the digital image, so that the modified image Become a messy image, thus protecting the true content to be expressed in digital images.
2.3 Digital Image Information Hidden Technology
Digital image information hide mainly to study digital images information hiding technology, which mainly targets two-dimensional spaces of digital images (or 3D space based on digital video), which will require confidential information in the public image. It fully utilizes the confusion of the digital image itself to reach the camouflage confidential information, thus escaping the possible detectors to achieve the passage of secret information.
The information hidden examples are endless, from the ancient Chinese Tibetan poems to the raster system of Europe, from ancient Greek wax collection to German spy, etc. are typical examples. The wide application of multimedia technology provides a new field for the development of information hiding technology. From May 30th to June 1, 1996, the first international information hidden academic seminar was held in Newton University, the University of Cambridge, and marked an emerging cross-discipline - formal birth of information hidden [8] . Information hiding as the main means of concealed communication and intellectual property protection, is being widely studied.
Information hidden technology is mainly composed of two parts: (1) information embedding algorithm. It uses the key to implement secret information hidden. (2) Concealed information extraction / detection algorithm (detector). It detects / recover secret information from the hidden carrier. Under the premise of the unknown key, the third party is difficult to get or delete from the hidden carrier, and even discover secret information.
Information hidden technology has the following most basic features:
Transparency: After a series of hidden processing, the host information must have no obvious degradation, and the hidden information cannot be seen or heard, that is, the physiological sensory identification and computer detection cannot find other information in the host information. . Robust: To ensure that the host information after hiding the information is subject to possible processing and attack, without causing the hidden information loss.
Efficiency: whether it is acceptable to embedding the encoding and extracting the decoded time and space overhead.
Safety: Adjaver information, embedding algorithm, enhances the security of hidden information.
Adelson [9, 10] controls the sensitivity of the human vision to the spatial frequency domain of the digital image, and uses the high-band hidden information of the spatial frequency domain. Bender [11] improves the ADELSON method, encrypts confidential information using chaotic sequences, and then hides information. However, the defects of such algorithms are, they cannot endure the distortion introduced by the generic signal processing operation, such as noise overlay, lossless compression, etc.
Information hidden is an emerging cross-discipline, has a broad application background in the fields of computer, communications, and confidentiality, and information hiding technology is also researching from the vast science and technology workers. Digital watermarking technology, as the effectiveness of digital media copyright protection, as an important research branch of information hidden, has been widely studied and has been obtained.
2.4 Digital Watermarking Technology
The digitization of multimedia data provides great convenience for the access of multimedia information, and also greatly enhances the efficiency and accuracy of information expression. With the increasing popularity of the network, the exchange of multimedia information has reached an unprecedented depth and breadth, and its release form is increasing. People can post their own works through the Internet network, deliver important information, and conduct online trade. But its exposure is also very obvious: the infringement of the work is more easier, and the tamper is more convenient. How to make the convenience of the Internet network, but also effectively protect intellectual property rights and have been attached to people.
Digital Watermark is an effective way to achieve copyright protection, has become a hot spot in the field of multimedia information security research, and is also an important branch in the field of information hiding technology. It confirms the ownership of the data by embedding a secret information-watermark in raw data. The embedded watermark can be a paragraph, logo, serial number, etc. Watermark is usually invisible or inevailed, it is closely combined with raw data (such as image, audio, video data, etc.) and hides, becoming a part of the source data inseparable, and can undergo some non-destroy source data use value or commercial value The operation is survived.
In addition to the general characteristics of information hiding technology, digital watermarking technology has its own intrinsic features and research methods. For example, since information security is confidential, hidden information can be considered secure because the secret information has not been disclosed; however, in the digital watermark system, the loss of hidden information means copyright information Lost, thereby losing the function of copyright protection, this system is failed. Therefore, digital watermarking technologies must have strong robustness, safety and transparency.
Since 1990, research interest in digital watermark has been growing. At the 1998 International Image Treatment Conference, two topic discussions on digital watermarks were opened; the International Optical Engineering Society (SPIE) has held a multimedia Information Security and Digital Watermark Conference every year, and its conference is mainly About digital watermarking technologies. At present, the International Cambridge University, IBM Research Center, NEC University Institute, MIT, etc. have conducted extensive research; Domestic Tsinghua University, Peking University, Beijing University of Posts and Telecom, School of Science, North University of Technology, Zhejiang University , Defense Science and Technology, etc. are in-depth research on this technology.
Digital watermarking technology is a visible watermark and an invisible watermark (IMPERCEPTIBLE), the former, such as TV station, the latter, the latter, the latter, the embedded watermark is unable to see the naked eye, the digital watermark we refer Technology, if there is no particular indication, it means an invisible watermark technology. According to the anti-attack ability, it can be divided into robust watermarks. The former is mainly used for copyright protection and use tracking, the latter is mainly used for integrity certification; according to the watermark extraction For private watermarks, semi-public watermarks and publicmarks. Private watermark refers to extracting the watermark, when the original carrier image is required, the semi-public water printing does not require the original carrier image when extracting the watermark, and the public water is not required to extract the watermark, and the watermark is not required and the watermark is a meaningful information, such as a paragraph, one image Or trademark, one recording, etc.
