Source: - Bo Xiaochen Shen Lin Cheng Changwensen
I. Introduction
---- With the arrival of the information age, especially the popularity of the Internet, the problem of safety protection of information is increasing
prominent. The current information security technology is basically based on cryptographic theory, whether it is a traditional key system.
Or the public key system, its protection mode is the access to the control file, so that the file is encrypted into ciphertext, so that illegal users are not
Can interpret. However, with the rapid improvement of computer processing capacity, this is increasing the system secret by increasing the key length.
Level methods become increasingly unsafe.
---- On the other hand, multimedia technology has been widely used, requiring encryption, authentication and copyright protection
There are more and more data. Digital sound image data is essentially a digital signal, if you also pick this data
With a password encryption, its own signal attribute is ignored. In recent years, many researchers gave up
The technical route of the custom code, attempts to hide the sound image data with various signal processing methods, and will this technology
"Digital Watermark" for making multimedia.
Second, the method of writing - digital watermark
---- Digital Watermark technology refers to the number of signal processing in digitization
Including hidden tags in media data, this tag is usually invisible, only by dedicated detector or reading
Can be extracted. Digital watermarks are an important research direction of information hiding technology.
---- Information in embedded digital works must have the following basic characteristics to be referred to as digital watermarking:
a .. concealment: Embedding digital watermark in digital works will not cause obvious degradation, and it is not easy to be observed
feel.
b .. Hidden location security: Watermark information is hidden in data instead of file headers, file format transformation
Should not cause loss of watermark data.
c .. Robust: The so-called robustness refers to the number after experiencing a variety of unintentional or intentional signal processing.
Watermarking still maintains integrity or can still be accurately identified. Possible signal processing, including channel noise, filtering, number
/ Mode and mode / digital conversion, heavy sampling, shear, displacement, scale change, and lossy compression coding, etc.
---- In digital watermarking technology, the amount of watermarks and robustness of the watermark constitute a basic contradiction. Subjective
Speaking, the ideal watermark algorithm should be hidden in large amounts of data, but also resist various channel noise and signal deformation. however
In practice, these two indicators often do not implement simultaneously, but this does not affect the application of digital watermarking technology.
It is generally only one of the aspects of the actual application. If it is for concealing communication, the amount of data is obviously the most important
Since the communication method is extremely concealed, it is very likely that the enemy's tamper attack is small, so it is not the robustness.
high. However, for the guarantee data security, the situation is exactly the opposite, and various confidential data is facing theft and tampering.
The danger, so robustness is important. At this time, the requirements for hidden data are secondary.
---- The basic ideology of digital watermarking technologies originated from ancient neckout. The ancient Greece's Spartan has once
Revolution on ordinary wooden boards, fill in paraffin, as long as the refinement is rubbed with fire, after melting the paraffin,
To see secrets. I am afraid that the use of the most widely written method is prescribed by chemistry, milk, white peony, juice, etc.
When writing the role of the drug water. It can be said that most of the confidential communication means of human use is mostly a way to write instead of secret
code. However, compared with cryptographic technology, the method has never developed into an independent discipline, why, the main
If the lack of the necessary theoretical foundation is lacking.
---- Today, the development of digital technology is injecting new vitality into ancient neckout, and it brings new machines.
meeting. During the study of digital watermarking, the researchers have borrowed the idea of writing technology. Especially in recent years
The rise of the technical theory framework research, and more written a rigorous science brings hope. No doubt
Ask, write technology will be revived in the digital age.
Third, the category of digital watermark
---- Digital Watermarking technology can be divided from different angles.
----1. Divide by characteristics
---- The characteristics of the watermark can be divided into two categories of digital watermarks and fragile digital watermarks. Robust
Digital watermarks are mainly used to identify copyright information in digital works, such as authors, works, etc., which require embedded
Watermarks can withstand various common editing processing; fragile digital watermarks are mainly used for integrity protection, with robust watermarks
In contrast, fragile watermarks must be sensitive to changes in signals, and people can judge the number according to the state of fragile watermark.
Whether it is tampered with.
----2. Media division by watermark
---- According to the media attached to the watermark, we can divide the digital watermark into image watermark, audio watermark, depending on
Frequency watermark, text watermark, and grid watermark for three-dimensional grid model. With the development of digital technology, there will be more
A variety of digital media appears while producing corresponding watermarking technologies.
---- 3. Division according to the test process
---- Press the watermarking process to divide the digital watermark as a plaintext watermark and blind watermark. Ming text watermark inspection
The original data is required during the test, and the detection of blind watermarks only requires the key, and the original data is not required. Generally,
The robustness of Wenyin is relatively strong, but its application is limited by storage costs. Currently studied digital watermarks
Most are blind watermarks.
---- 4. Divide
---- Content by digital watermark can be divided into meaningful watermarks and unconscious watermarks. Meaningful watermark
It means that the watermark itself is also the encoding of a digital image (such as a trademark image) or a digital audio fragment; meaningless watermark
Only correspond to a serial number. The advantage of meaningful watermark is that if it is attacked or other causes, decoding
After the watermark is damaged, people can still confirm whether there is watermark by visual observation. But for the meaningless watermark,
If the decoded watermark sequence has several symbol errors, it can only be determined by the statistical decision to determine whether there is water in the signal.
Print.
---- 5. Divide by use
---- Different application requirements have made different watermarking techniques. According to the use of watermark, we can put digital water
Printing is a non-counterfeiting watermark, copyright protection watermark, tampering suggests watermark and concealed identification watermark.
---- Bill anti-counterfeiting watermark is a relatively special watermark, mainly used for printing tickets and electronic bills
Pseudo. In general, the manufacturer of counterfeit currency cannot be modified to the ticket image, so such as a scale transformation.
Wait signal editing operations are not considered. But on the other hand, people must consider the damage of the ticket, the pattern blur
Shape, and considering the requirements of rapid detection, digital watermarking algorithms for ticket security cannot be too complicated.
---- Copyright Identification Watermark is currently studied for a category of digital watermarks. Digital works are both goods and knowledge
Works, this duality determines the copyright identification watermark mainly emphasizes concealedness and robustness, and the requirements of the data volume
Little.
---- Tamper suggestion watermark is a fragile watermark, its purpose is to identify the integrity and authenticity of the host signal.
---- The purpose of hidden marking watermark is to hide the important label of confidential data to limit illegal users
The use of secret data.
---- 6. Positioned by watermark hidden location
---- Press the hidden position of the digital watermark, we can divide it into a time (empty) field digital watermark, frequency domain
Word watermark, time / frequency domain digital watermark and time / scale domain digital watermark.
---- Time (empty) Domain Digital Watermark is overlapping the watermark information directly on the signal space, and the frequency domain digital watermark,
Time / frequency domain digital watermark and time / scale domain digital watermarks are in DCT transform domains, time / frequency transform domains, and wavelets
Hide water in the transform domain.
---- With the development of digital watermarking technology, various watermark algorithms are endless, and the hidden position of watermark is no longer
It is limited to the above four types. It should be said that as long as a signal transformation is constituted, it is possible to hide water in its transform space.
Print.
Fourth, application prospects
---- The rapid development of multimedia technology and the popularity of the Internet have brought a series of political, economic, military and cultural issues, producing many new research hotspots. The following few issues have made digital watermarks.
Research Background.
----1. Intellectual property protection of digital works
---- Digital work (such as computer art, scanned image, digital music, video, 3D animation) copyright protection
Protection is the current hot problem. Due to the copy of the digital works, modification is very easy, and can be completely complete
The same, the original person has to adopt some ways to seriously damage the quality of the work to add copyright symbols, and this
A visible sign is easily tampered.
---- "Digital Watermark" utilized data hidden principle to make copyright symbols or not listening, neither damage
The product has reached the purpose of copyright protection. Currently, digital watermarking technology for copyright protection has entered the initial implementation.
During use, IBM has provided digital watermarking features in its "Digital Library" software, and Adobe is also
Its famous Photoshop software integrates Digimarc's digital watermark plug-in. However, seeking truth from facts,
At present, digital watermark products in the market are still immature, it is easy to destroy or crack, and the truly practical
there's still a long way to go.
----2. Bills in business transactions
---- With the development of high quality image input and output equipment, especially color spray with exceeding 1200DPI
Ink, laser printers and high-precision color copiers have made currency, checks, and other fakes for other notes
much easier.
---- According to US official report, only 40 million US dollars in 1997, high-precision color
The small-sized counterfeit banknote manufactured by the color printer accounts for 19%, which is 9.05 times in 1995. Currently, the United States, Japan
Books and the Netherlands have begun to study digital watermarking technologies for ticket security. Among them, Massachusetts Institute of Technology Media Laboratory
Entrusted by the US Treasury, it has begun to study the only one in each image of the color printer and the copy machine output.
, Invisible digital watermarks, can judge the watermark from the scanning ticket in real time in real time, quickly identify
Really pseudo.
---- On the other hand, in the process of transforming from traditional business to e-commerce, there will be a large excessive electricity.
Subfielders, scanned images such as various paper bills, etc. Even after the network security technology matures, various electronic bills
There are also some non-passable authentication methods. Digital watermarking technology can provide invisible certification for a variety of bills
Zhi, thereby greatly increase the difficulty of forgery.
---- 3. Hidden identity and tampering prompt of sound image data
---- The identification information of the data is often more confidential than the data itself, such as the shooting date of the remote sensing image,
/ Latitude, etc. Data without identification information sometimes can't be used, but directly mark these important information in the original
The initial file is very dangerous. Digital watermarking technology provides a way to hide the logo, identify information on the original file
It is not seen that only through special reading procedures can be read. This approach has been disclosed abroad
The sense image database is used.
---- In addition, tampering prompts are also a very important job. Existing signal splicing and mosaic technology
Can be "shifting flowers" instead of people, so how to prevent tampering against images, recording, video data
Hash is an important research topic. Digital watermarking tamper is an ideal technical way to solve this problem, through
The status of hidden watermarks can determine whether the sound image signal is tampered with.
---- 4. Concealed communication and its confrontation
---- Information hidden technology depends on digital watermark not only provides non-password safety route, but also triggered
The revolution of the Internet intelligence warfare, has produced a series of new ways of operation, which has caused the weight of many countries.
Depend.
---- Network Intelligence War is an important part of the information war, and its core content is to keep confidential using public networks.
data transmission. So far, the research ideas in this area have not been able to break through the "document encryption" thinking. However, encrypted documents are often unordered, and it is easy to pay attention to attackers. Network multimedia skills
The extensive application of surgery makes a new idea using public networks with new ideas, using digital sound image signals.
In human visual, hearing redundancy, information hidden in various time (empty) domains and transform areas can be hidden, thus achieving hidden
Communication.
V. Research Dynamics
---- From the public published literature, the international research in digital watermarks has just begun, but due to
The introduction of large companies and the support of the US military and the Ministry of Finance, the development speed of this technology is very fast. 1998
Come, "IEEE Image Processing", "IEEE Meeting", "IEEE Communication Selection", "IEEE Consumer Electronics", etc.
Many internationally important journals organized digital watermarking technology special issues or special news reports.
---- A batch of research institutions and companies represented by the MIT Media Laboratory have been applied
Digital watermarking patents. In 1998, the US government report appeared in the first AD related image data hidden.
report. At present, agency that has supported or carried out digital watermark research has both government departments, and universities and well-known companies.
They include US Treasury, US Copyright Working Group, US Air Force Research Institute, US Army Research Lab, Germany
National Information Technology Research Center, Japan NTT Information and Communication System Research Center, Massachusetts Institute of Technology, Illinois
University, Minnesota University, Cambridge University, Lausanne Federal Institute of Technology, Spain Vigo University, IBM
Watson Research Center, Microsoft Cambridge Research Institute, Lucent Company Bel Lab, CA, Sony,
NEC Research Institute and the Netherlands Philips, etc.
---- From May 30 to June 1, 1996, the first international information hidden in the British Newton Institute of Cambridge
The Academic Seminar has been held since the Tibetan Seminar. Some important international conferences in SPIE and IEEE have also opened relevant special
question.
---- my country's academic community's response to digital watermarking technology is also very fast, there is a relatively large number of research
The agency is invested in this area. In order to promote research and should be in digital watermarking and other information hidden technology
In December 1999, Heorda, the unique academician of my country's information security, Zhou Zhongyi, academician, Cai Ji people, should
In combination with the research unit, the first information hidden academic seminar in my country was held. In January 2000, the country
The "863" Smart Machine Expert Group and the Chinese Academy of Sciences Automation Mode Identification State Key Laboratory Organization held digital watermarks
Academic Seminar, from the National Natural Science Foundation of China, National Information Security Evaluation Center, China Science
Institute, Beijing University of Posts and Telecommunications, Tsinghua University, Northern University of Technology, Shanghai Jiaotong University, Tianjin University
Learning, University of Science and Technology, Peking University, Beijing University of Science and Technology, Sun Yat-sen, Beijing Electronic Technology Application Research Institute, etc.
The expert scholars and researchers discussed key technologies of digital watermarks and reported their respective research results.
From this conference reaction, research in my country's related academic fields is far from the world level, and
Unique research ideas.
---- Currently, agency that has supported or carrying digital watermark research has both government departments, and universities and well-known enterprises.
Industry, including US Treasury, US Copyright Working Group, US Air Force Research Institute, US Army Research Lab,
German National Information Technology Research Center, Japan NTT Information and Communication System Research Center, Massachusetts Institute of Technology, Yili
University of Nos, Minnesota University, Cambridge University, Lausanne Federal Institute of Technology, Vigo, Spain, IBM
Watson Research Center, Microsoft Cambridge Research Institute, Lucent Company Bel Lab, CA, Sony
Division, NEC Research Institute and the Netherlands Phillips.
---- From May 30 to June 1, 1996, the first international information hidden in the British Newton Institute of Cambridge
The Academic Seminar has been held since the Tibetan Seminar. Some important international conferences in SPIE and IEEE have also opened relevant special
question.
---- my country's academic community's response to digital watermarking technology is very fast, and there is a relatively large number of research institutions to invest in this area. In order to promote research and should be in digital watermarking and other information hidden technology
In December 1999, Heorda, the unique academician of my country's information security, Zhou Zhongyi, academician, Cai Ji people, should
In combination with the research unit, the first information hidden academic seminar in my country was held. In January 2000, the country
The "863" Smart Machine Expert Group and the Chinese Academy of Sciences Automation Mode Identification State Key Laboratory Organization held digital watermarks
Academic Seminar, from the National Natural Science Foundation of China, National Information Security Evaluation Center, China Science
Institute, Beijing University of Posts and Telecommunications, Tsinghua University, Northern University of Technology, Shanghai Jiaotong University, Tianjin University
Learning, University of Science and Technology, Peking University, Beijing University of Science and Technology, Sun Yat-sen, Beijing Electronic Technology Application Research Institute, etc.
The expert scholars and researchers discussed key technologies of digital watermarks and reported their respective research results.
From this conference reaction, research in my country's related academic fields is far from the world level, and
Unique research ideas.
