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Discussion on the digital watermarking technology in electronic reading business applicationsAbstract: the business era, the market competition is fierce day by day. Have broad prospects of electronic reading business may become the carrier of new profit growth point. Digital watermark technology in electronic reading content copyright protection of some of the application, make a preliminary study and discussion, and puts forward some suggestionsKey words: digital watermarking; copyright protection of electronic reading;PrefaceSince China telecom carrier recombination and 3G licences, the domestic telecommunication market competition is intense with each passing day. Facing market competition pressure, how to play their own advantages to gain competitive advantage, has become the major operators must solve the problem.In the telephone business is gradually replacing mobile communication, broadband market is nearing saturation, the traditional mobile voice revenue ARPU values in the great pressure of competition is also very difficult to have the breakthrough of the severe form, as an emerging business electronic reading become carriers of potential revenue growth.Electronic reading, is defined in PC, laptop, mobile phone and other portable electronic terminal reading novels, newspapers, magazines and pictures and other traditionally printed on paper carrier content reading. Compared with traditional way of reading, reading in the acquisition mode, distribution channels, sales management, payment means and environmental protection has natural advantage. With the 3G network of perfection and the mobile phone terminal screen, intelligent development trend, relying on more than 700000000 of mobile phone users, electronic reading have a broad market prospect.Electronic reading business core content is the use of the traditional means of communication to provide rich multimedia resources. At present, China's copyright protection situation is not optimistic, the literature works of infringement acts have occurred. Electronic reading success, largely dependent on the copyright management. Therefore, for copyright protection and digital watermarking technology in electronic reading business will play a very positive role.1 digital watermark1.1 What is the digital watermarking technologyDigital watermark technology is through a certain algorithm will landmark information directly embedded into the multimedia content, but not affect the original content value and use, and can not be aware of the perceptual system or pay attention to, only through a special detector or reader to extract. Digital watermarking technique can distinguish whether the object is under protection, monitoring of the protected data transmission, authentication and illegal copy, resolve copyright disputes, and to provide evidence to the court.Copyright protection digital watermarking to requirements1) validity: in copyright protection digital watermarking embedded content shouldhave authority, that is to say should be able to show that the carrier file ownership is recognized; 2): a robust watermarking anti-attack ability; 3) capacity: refers to embed information in the file number; 4) imperceptibility: refers to the embedded watermark information file with the original documents should be almost the same or does not influence the normal use of the files, but also users can not feel the existence of watermark.2 Digital watermarking technology in application of electronic readingDigital watermarking of a series of technical characteristics show that, in the rapid development of the electronic reading service, digital watermarking will be widely used.For image, video watermarking algorithmDiscrete cosine transform digital watermarking is often used as a basic transformation. First introduced the definition of discrete cosine transform:On digital image,The two dimensional DCT transform is defined as:Two dimensional inverse DCT transform ( IDCT ) is defined as:By 3.2 the original image can be expressed as, for a series of weightsWhen a pair of pixels in an image matrix after discrete cosine transform, the frequency domain matrix in left corner element value maximum, for the DC component, representing the whole image of the average brightness; while the remainder of each element value according to the corner element for fixed-pointtriangle lateral snaking arranged successively, representing the image low frequency, medium frequency components and high frequency components.Cox presents a global DCT domain watermarking algorithm:Selection of sequences of X = x1, x2, ... , xn as watermark, where Xi is satisfy the Gauss distribution of N (0, 1) of a random number. The algorithm first uses the discrete cosine transform of the original image I is transformed into the frequency domain, using the D representation of the data obtained. From the coefficient of D select n most important frequency component, consisting of sequences of V = V1,v2, ... , VN, in order to improve the robustness of image compression.Get the watermark array and frequency domain array, using the formula: Vi=vi ( 1+α XI ) digital watermark is embedded into the frequency domain array carrying watermark information, get new frequency domain array sequence of V = V1, v2, ... , VN, then the V' of each element in the frequency domain matrix D in the corresponding position of the V element replacement out, get a new frequency domain matrix D, the D inverse discrete cosine transform be containing the watermark watermark image I. In the watermark image I* for watermark detection, the whole process is the reverse process of embedding process almost. The first is to I* through DCT to obtain the frequency domain array sequence of V* = v1*, v2*, ... , vn*, then according to the formula Vi=vi ( 1+α XI ) inverse formula one watermark sequence of X* = x1*, x2*, ... , xn*, then calculate the watermark with the original watermark correlation of X* X.The algorithm is robust, can resist including scaling, JPEG compression, shear and jitter, printing and copy - scanning, image processing, and then embeddingMulti-watermarking, also can resist attacks multiple users, is a very effective watermarking algorithm.2.2 text digital watermarkingWith the picture or video files, text files without too much redundant information space, so the text based watermarking technique is far less than the image or video. Commonly used text watermarking is based mainly on the fixed format text watermarking. Commonly used methods: Based on the spacing of information representation, based on the word spacing information representation method and based on the character attribute information representation. In actual use, can these three kinds of information hiding methods combination.Based on the fixed format text watermarking, its biggest weakness is to retain the text but change the text format of soft copy sensitive. In order to solve this problem, people put forward based on the text semantic watermarking technology, but thistechnique is difficult to realize and watermark extraction need to provide source file control, maneuverability is not strong.In the actual electronic reading, we will be able to distribute content using the format developers to provide tools for content set can not be copied ( word, PDF have this feature ), to avoid illegal user to destroy the watermark information. In addition, also can be a text scanning for picture format, using the discrete cosine transform technology to embed the watermark, and then provided to the user.3 SummaryIn an electronic reading business applications, digital watermarking technology mainly focuses on the identification of the infringement, also cannot prevent and stop the infringement occurred. And the robustness of digital watermarking algorithm can not completely meet the needs of. But with the continuous progress of watermarking algorithm, and with the use of CA technology and the encryption technology, digital watermarking technology in electronic reading areas will have more extensive application.。
The research on DCT-domain digital watermarking algorithm based on chaotic sequence数字水印技术作为加密技术的补充，是保护数字作品版权的一种重要手段，近年来已成为学术界研究的一个热点.针对图像的水印方案是最近几年研究的主流方向，本文重点研究了基于DCT域的图像数字水印的设计和实现方法。
第一章介绍了数字水印目前的研究现状；第二章介绍了本文所涉及的主要相关知识和技术；首先介绍了数字水印技术，着重介绍了数字水印技术的基本原理、特征、典型算法；第三章讨论选择MATLAB作为实现系统的工具的目的和优势以及系统环境配置；第四章为本论文的主要部分，是系统实现的具体过程。
数字水印技术是一个新兴的研究领域，还需进一步深入研究。
．Digital watermarking technology as encryption technology added ,is to protect the copyright of digital works an important means In recent years，academic studies have become a hot topic．Image Watermarking against the program in recent years is the main research direction. This paper focuses on a DCT-based image digital watermark design and implementation. Chapter I provide a digital watermark current status of research and simple description of the idea;The second chapter describes the knowledge and technology the paper mainly related; The theme of the thesis is the Domain digital image watermarking algorithm ,it complete the following main aspects：This paper describes digital watermarking technology ,discussion of the digital watermark technology concepts，features，and other related knowledge;The third chapter discusses optioning MATLAB as a tool to achieve the purpose and advantages and the environment of the system configuration;Chapter IV of the main thesis of this part is the specific process of the system implementation.Digital watermarking technology is a new area ,needs further in-depth study．。
量子计算中英文2019英文FROM BITS TO QUBITS, FROM COMPUTING TO QUANTUM COMPUTING: AN EVOLUTION ON THE VERGE OF A REVOLUTION IN THE COMPUTINGLANDSCAPEPi rjan Alexandru; Petroşanu Dana-Mihaela.ABSTRACTThe "Quantum Computing" concept has evolved to a new paradigm in the computing landscape, having the potential to strongly influence the field of computer science and all the fields that make use of information technology. In this paper, we focus first on analysing the special properties of the quantum realm, as a proper hardware implementation of a quantum computing system must take into account these properties. Afterwards, we have analyzed the main hardware components required by a quantum computer, its hardware structure, the most popular technologies for implementing quantum computers, like the trapped ion technology, the one based on superconducting circuits, as well as other emerging technologies. Our study offers important details that should be taken into account in order to complement successfully the classical computer world of bits with the enticing one of qubits.KEYWORDS: Quantum Computing, Qubits, Trapped Ion Technology, Superconducting Quantum Circuits, Superposition, Entanglement, Wave-Particle Duality, Quantum Tunnelling1. INTRODUCTIONThe "Quantum Computing" concept has its roots in the "Quantum Mechanics" physics subdomain that specifies the way how incredibly small particles, up to the subatomic level, behave. Starting from this concept, the Quantum Computing has evolved to a new paradigm in the computing landscape. Initially, the concept was put forward in the 1980s as a mean for enhancing the computing capability required tomodel the way in which quantum physical systems act. Afterwards, in the next decade, the concept has drawn an increased level of interest due to the Shor's algorithm, which, if it had been put into practice using a quantum computing machine, it would have risked decrypting classified data due to the exponential computational speedup potential offered by quantumcomputing [1].However, as the development of the quantum computing machines was infeasible at the time, the whole concept was only of theoretical value. Nowadays, what was once thought to be solely a theoretical concept, evolved to become a reality in which quantum information bits (entitled "qubits") can be stored and manipulated. Both governmental and private companies alike have an increased interest in leveraging the advantages offered by the huge computational speedup potential provided by the quantum computing techniques in contrast to traditional ones [2].One of the aspects that make the development of quantum computers attractive consists in the fact that the shrinkage of silicon transistors at the nanometer scale that has been taking place for more than 50 years according to Moore's law begins to draw to a halt, therefore arising the need for an alternate solution [3].Nevertheless, the most important factor that accounts for boosting the interest in quantum computing is represented by the huge computational power offered by these systems and the fact that their development from both hardware and software perspectives has become a reality. Quantum computing managed to surpass the computability thesis of ChurchTuring, which states that for any computing device, its power computation could increase only in a polynomial manner when compared to a "standard" computer, entitled the Turing machine [4].During the time, hardware companies have designed and launched "classical" computing machines whose processing performance has been improving over the time using two main approaches: firstly, the operations have been accelerated through an increased processing clock frequency and secondly, through an increase in the number of operations performed during each processing clock's cycle [5].Although the computing processing power has increased substantially after having applied the above-mentioned approaches, the overall gain has remained inaccordance with the thesis of Church-Turing. Afterwards, in 1993, Bernstein and Vazirani have published in [6] a theoretical analysis stating that the extended Church-Turing thesis can be surpassed by means of quantum computing. In the following year, Peter Shor has proved in his paper that by means of quantumcomputing the factorization of a large number can be achieved with an exponentially computing speedup when compared to a classical computing machine [7-9]. Astonishing as the theoretical framework was, a viable hardware implementation was still lacking at the time.The first steps for solving this issue have been made in 1995, when scientists have laid the foundations for a technology based on a trapped ion system [10] and afterwards, in 1999, for a technology employing superconducting circuits [11]. Based on the advancement of technology, over the last decades, researchers have obtained huge progress in this field, therefore becoming able to build and employ the first quantum computing systems.While in the case of a classical computing machine the data is stored and processed as bits (having the values 0 or 1), in the case of a quantum computingmachine, the basic unit of quantum information under which the data is stored and processed is represented by the quantum bits, or qubits that can have besides the values of 0 and 1, a combination of both these values in the same time, representing a "superposition" of them [12].At a certain moment in time, the binary values of the n bits corresponding to a classical computer define a certain state for it, while in the case of a quantumcomputer, at a certain moment in time, a number of n qubits have the possibility to define all the classical computer's states, therefore covering an exponential increased computational volume. Nevertheless, in order to achieve this, the qubits must be quantum entangled, a non-local property that makes it possible for several qubits to be correlated at a higher level than it was previously possible in classical computing. In this purpose, in order to be able to entangle two or several qubits, a specific controlled environment and special conditions must be met [13].During the last three decades, a lot of studies have been aiming to advance thestate of knowledge in order to attain the special conditions required to build functional quantum computing systems. Nowadays, besides the most popular technologies employed in the development of quantum computing systems, namely the ones based on trapped ion systems and superconducting circuits, a wide range of other alternative approaches are being extensively tested in complex research projects in order to successfully implement qubits and achieve quantum computing [14].One must take into account the fact that along with the new hardware architectures and implementations of quantum computing systems, new challenges arise from the fact that this new computing landscape necessitates new operations, computing algorithms, specialized software, all of these being different than the ones used in the case of classical computers.A proper hardware implementation of a quantum computing system must take into account the special properties of the quantum realm. Therefore, this paper focuses first on analyzing these characteristics and afterwards on presenting the main hardware components required by a quantum computer, its hardware structure, the most popular technologies for implementing quantum computers, like the trapped ion technology, the one based on superconducting circuits, as well as other emerging technologies. Our developed research offers important details that should be taken into account in order to complement successfully the classical computer world of bits with the enticing one of qubits.2.SPECIAL PROPERTIES OF THE QUANTUM REALMThe huge processing power of quantum computers results from the capacity of quantum bits to take all the binary values simultaneously but harnessing this vast amount of computational potential is a challenging task due to the special properties of the quantum realm. While some of these special properties bring considerable benefits towards quantum computing, there are others that can hinder the whole process.One of the most accurate and extensively tested theory that comprehensibly describes our physical world is quantum mechanics. While this theory offers intuitive explanations for large-scale objects, while still very accurate also at the subatomiclevel, the explanations might seem counterintuitive at the first sight. At the quantum level, an object does not have a certain predefined state, the object can behave like a particle when a measurement is performed upon it and like a wave if left unmeasured, this representing a special quantum property entitled wave-particle duality [15].The global state of a quantum system is determined by the interference of the multitude of states that the objects can simultaneously have at a quantum level, the state being mathematically described through a wave function. Actually, the system's state is often described by the sum of the different possible states of its components, multiplied by a coefficient consisting in a complex number, representing, for each state, its relative weight [16, 17]. For such a complex coefficient, by taking into consideration its trigonometric (polar) form, one can write it under the form Aew = A(cos6 + i sind), where A > 0 represents the module of this complex number and is denoted as the "amplitude", while в represents the argument of the complex number, being denoted as "the phase shift". Therefore, the complex coefficient is known if the two real numbers A and в are known.All the constitutive components of a quantum system have wave-like properties, therefore being considered "coherent". In the case of coherence, the different states of the quantum components interact between them, either in a constructive manner or in a destructive one [1]. If a quantum system is measured at a certain moment, the system exposes only a single component, the probability of this event being equal to the squared absolute value of the corresponding coefficient, multiplied by a constant. If the quantum system is measured, from that moment on it will behave like a classical system, therefore leading to a disruption of its quantum state. This phenomenon causes a loss of information, as the wave function is collapsed, and only a single state remains. As a consequence of the measurement, the wave function associated to the quantum obj ect corresponds only to the measured state [1, 17].Considering a qubit, one can easily demonstrate that its quantum state could be represented by a linear superposition of two vectors, in a space endowed with a scalar product having the dimension 2. The orthonormal basis in this space consists of thevectors denoted as |0 >= [Jj and |1 >= [°j. If one considers two qubits, they could be represented as a linear combination of the 22 elements of the base, namely the ones denoted as .... Generally, in the case of n qubits, they could be represented by a superposition state vector in a space having the dimension 2n [2].Another special property of the quantum realm consists in the entanglement, a property that has the ability to exert a significant influence on quantumcomputing and open up a plethora of novel applications. The physical phenomenon of quantum entanglement takes place when two (or more) quantumobjects are intercorrelated and therefore the state of a quantum object influences instantaneously the state(s) of the other(s) entangled quantum object(s), no matter the distance(s) between these objects [16].Another important quantum mechanical phenomenon that plays a very important role in quantum computing is quantum tunneling that allows a subatomic particle to go through a potential barrier, which otherwise would have been impossible to achieve, if it were to obey only the physical laws of classical mechanics. An explanation of this different behavior consists in the fact that in quantum mechanics the matter is treated both as waves and particles, as we have described above, when we have presented the wave-particle duality concept [15].The Schrödinger equation describes the variation of the wave function, taking into account the energy environment that acts upon a quantum system, therefore highlighting the way in which this quantum system evolves. In order to obtain the mathematical description of the environment, of the energies corresponding to all the forces acting upon the system, one uses the Hamiltonian of the quantum system. Therefore, the control of a quantum system can be achieved by controlling its energy environment, which can be obtained by isolating the system from the external forces, and by subjecting the system to certain energy fields as to induce a specific behavior. One should note that a perfect isolation of the quantum system from the external world cannot be achieved, therefore in practice the interactions are minimized as much as possible. Over time, the quantum system is continuously influenced to a small extent by the external environment, through a process called "decoherence",process that modifies the wave function, therefore collapsing it to a certain degree [1].Figure 1 depicts the main special properties of the quantum realm, which, when precisely controlled, have the ability to influence to a large extent the performance of a quantum computer implementation, and open up new possibilities for innovation concerning the storing, manipulation and processing of data.In the following, we analyze a series of hardware components and existing technologies used for developing and implementing quantum computers.3.AN OVERVIEW OF THE NECESSARY HARDWARE AND OF THE EXISTING TECHNOLOGIES USED IN THE IMPLEMENTATIONS OF QUANTUM COMPUTERSA proper hardware architecture is vital in order to be able to program, manipulate, retrieve qubits and overall to achieve an appropriate and correct quantumcomputer implementation. When implementing a quantum computer at the hardware level, one must take into account the main hardware functions, a proper modularization of the equipment along with both similarities and differences between quantum and classic computer implementations. Conventional computers are an essential part in the successful implementation of a quantum computer, considering the fact that after having performed its computation, a quantumcomputer will have to interact with different categories of users, to store or transmit its results using classic computer networks. In order to be efficient, quantum computers need to precisely control the qubits, this being an aspect that can be properly achieved by making use of classic computing systems.The scientific literature [1, 18, 19] identifies four abstract layers in the conceptual modelling process of quantum computers. The first layer is entitled the "quantum data plane" and it is used for storing the qubits. The second layer, called "control and measurement plane", performs the necessary operations and measurement actions upon the qubits. The third layer entitled "control processor plane" sets up the particular order of operations that need to be performed along with the necessary measurement actions for the algorithms, while the fourth abstract layer, the "host processor", consists in a classical computer that manages the interface withthe different categories of personnel, the storage of data and its transmission over the networks.In the following, we present the two most popular technologies employed in the development of quantum computing systems, namely the ones based on trapped ion systems and superconducting circuits and, afterwards, other alternative approaches that are being extensively tested in complex research projects in order to successfully implement qubits and achieve quantum computing.By means of trapping atomic ions, based on the theoretical concepts presented by Cirac et al within [20], in 1995, Monroe et al [21] revealed the first quantumlogic gate. This was the starting point in implementing the first small scale quantum processing units, making it possible to design and implement a rich variety of basic quantum computing algorithms. However, the challenges to scale up the implementations of quantum computers based on the trapped ion technology are enormous because this process implies a synergy of complex technologies like coherent electronic controllers, laser, radio frequency, vacuum, microwave [1, 22].In the case of a quantum computer based on the trapped atomic ions technology, the qubits are represented by atomic ions contained within the quantum data plane by a mechanism that keeps them in a certain fixed location. The desired operations and measurement actions are performed upon the qubits using accurate lasers or a source of microwave electromagnetic radiation in order to alter the states of the quantum objects, namely the atomic ions. In order to reduce the velocity of the quantum objects and perform measurements upon them, one uses a laser beam, while for assessing the state of the ions one uses photon detectors [14, 23, 24]. Figure 2 depicts an implementation of the quantum trapping atomic ions technology.Another popular technology used in the development and implementation of quantum computers is based on superconducting quantum circuits. These quantum circuits have the property of emitting quantized energy when exposed to temperatures of 10-3K order, being referred in the literature as "superconducting artificial atoms" [25]. In contrast to classic integrated circuits, the superconducting quantum circuits incorporate a distinctive characteristic, namely a"Josephson junction" that uses wires made of superconducting materials in order to achieve a weak connection. The common way of implementing the junction consists in using an insulator that exposes a very thin layer and is created through the Niemeyer-Dolan technique which is a specialized lithographic method that uses thin layers of film in order to achieve overlapping structures having a nanometer size [26].Superconducting quantum circuits technology poses a series of important advantages, offering red3uced decoherence and an improved scale up potential, being compatible with microwaves control circuits, operating with time scales of the nanosecond order [1]. All of these characteristics make the superconducting quantum circuits an attractive and performant technique in developing quantum computers. A superconducting quantum circuit developed by D-Wave Systems Inc. is depicted in Figure 3.In order to overcome the numerous challenges regarding the scaling of quantum computers developed based on trapped ion systems and superconducting circuits, many scientists focus their research activity on developing emerging technologies that leverage different approaches for developing quantumcomputers.One of the alternatives that scientists investigate consists in making use of the photons' properties, especially of the fact that photons have a weak interaction between each other and also with the environment. The photons have been tested in a series of quantum experiments and the obtained results made the researchers remark that the main challenge in developing quantum computers through this approach is to obtain gates that operate on spaces of two qubits, as at the actual moment the photons offer very good results in terms of single qubit gates. In order to obtain the two-qubit gates, two alternative approaches are extensively being investigated as these have provided the most promising results.The first approach is based on operations and measurements of a single photon, therefore creating a strong interaction, useful in implementing a probabilistic gate that operates on a space of two qubits [1]. The second alternative approach employs semiconductor crystals structures of small dimensions in order to interact with the photons. These small structures can be found in nature, case in which they are called"optically active defects", but can also be artificially created, case in which they are called "quantum dots". An important challenge that must be overcome when analyzing quantum computers based on photons is their size. Until now, the development of this type of computers has been possible only for small dimensions, as a series of factors limit the possibility to increase the dimensions of photon quantum computers: the very small wavelengths of the photons (micron-size), their very high speed (the one of the light), the direction of their movement being along a certain dimension of the optical chip. Therefore, trying to significantly increase the number of qubits (represented by the photons) proves to be a difficult task in the case of a photonic device, much more difficult than in the case of other systems, in which the qubits are located in space. Nevertheless, the evolution of this emerging technology promises efficient implementations in the near future [27].Another technology that resembles the one of "trapping atomic ions" for obtaining qubits consists in the use and manipulation of neutral atoms by means of microwave radiation, lasers and optics. Just like in the case of the trapping atomic ions technology, the "cooling" process is achieved using laser sources. According to [1, 28], in 2018 there were implemented successfully quantum systems having 50 qubits that had a reduced space between them. By means of altering the space between the qubits, these quantum systems proved to be a successful analog implementation of quantum computers. In what concerns the error rates, according to [29], in 2018 there have been registered values as low as 3% within two-qubit quantum systems that managed to isolate properly the operations performed by nearby qubits. Since there are many similarities between the two technologies, the scaling up process faces a lot of the problems of the "trapping atomic ions" technology. However, the use of the neutral atoms technology offers the possibility of creating multidimensional arrays.A classification of semiconductor qubits is made according to the method used to manipulate the qubits that can be achieved either by photon manipulation or by using electrical signals. Quantum dots are used in the case of semiconductor qubits that are gated by optical means in order to assure a strong coupling of the photons while in the case of semiconductor qubits manipulated via electrical signals, voltages are usedupon lithographically metal gates for manipulating the qubits [1]. This quantum technology, although being less popular than other alternatives, resembles the existing classical electronic circuits, therefore one might argue that it has a better chance in attracting considerable investments that eventually will help speed up the scaling up process of quantum computers implementation.In order to scale up qubits that are optically gated, one needs a high degree of consistency and has to process every qubit separately at the optical level. In [30], Pla et al. state that even if the qubits that are gated electrically can be very dense, the material related problems posed not long-ago serious quality problems up to single qubits gates level. Although the high density provided by this type of quantum technology creates opportunities for integrating a lot of qubits on a single processor, complex problems arise when one has to manipulate this kind of qubits because the wiring will have to assure an isolation of the control signals as to avoid interference and crosstalk.Another ongoing approach in developing quantum computers consists in using topological qubits within which the operations to be performed upon are safeguarded due to a microscopically incorporated topological symmetry that allows the qubit to correct the errors that may arise during the computing process [1]. If in the future this approach materializes, the computational cost associated with correcting the quantum errors will diminish considerably or even be eliminated altogether. Although this type of technology is still in its early stages, if someday one is able to implement it and prove its technical feasibility, the topological quantum computers will become an important part of the quantum computing landscape.4. CONCLUSIONSQuantum computing represents a field in a continuous evolution and development, a huge challenge in front of researchers and developers, having the potential to influence and revolutionize the development of a wide range of domains like the computing theory, information technology, communications and, in a general framework, regarding from the time perspective, even the evolution and progress of society itself. Therefore, each step of the quantum computers' evolution has thepotential to become of paramount importance for the humanity: from bits to qubits, from computing to quantum computing, an evolution on the verge of a revolution in the computing landscape.中文从比特到量子比特，从计算到量子计算：计算机革命的演变抽象“量子计算”的概念已发展成为计算领域的一个新范例，具有极大地影响计算机科学领域和所有利用信息技术的领域的潜力。
一种新的基于Legendre混沌神经网络的数字水印算法韩宝如;覃学峰;李文锋【摘要】In order to protect medical image information,this paper presents a new algorithm of medical volume data digital watermarking based on Legendre chaotic neural network.It integrates Legendre chaotic neural network,three-dimensional discrete Fourier transformation and zero-watermarking.On the one hand, a novel Legendre chaotic neural network is used to generate a chaotic sequence with a pseudo-random sequenc for scrambling the original watermark image.On the other hand,zero-watermarking is constructed in the three-dimensional discrete Fourier transforming domain of medical volume data.The simulation results show that the digital watermarking algorithm not only has good robustness,but also good security and confidentiality.%为了保护医学图像信息,提出一种新的基于Legendre混沌神经网络的医学体数据数字水印算法,将Legendre混沌神经网络、三维离散傅里叶变换和零水印有机地结合在一起.一方面,使用一种新型的Legendre混沌神经网络产生具有伪随机性的混沌序列进行置乱原始水印图像;另一方面,在医学体数据的三维离散傅里叶变换域上构造零水印,以提高数字水印的抗攻击能力.仿真结果表明,该数字水印算法不仅具有很好的鲁棒性,而且具有很好的安全性和保密性.【期刊名称】《苏州市职业大学学报》【年(卷),期】2015(026)004【总页数】6页(P1-6)【关键词】Legendre混沌神经网络;三维离散傅里叶变换;医学体数据【作者】韩宝如;覃学峰;李文锋【作者单位】海南软件职业技术学院电子工程系,海南琼海571400;海南软件职业技术学院电子工程系,海南琼海571400;海南软件职业技术学院电子工程系,海南琼海571400【正文语种】中文【中图分类】TP317.4随着科学技术的发展，医疗行业的数字信息越来越重要.医学信息的数字化为医学信息的储存和传输带来极大便利的同时，也存在恶意攻击、篡改、非法占有等严重的安全性问题[1-2].现今的加密方法和访问控制已经很难满足医学图像的信息安全要求，寻求新的信息安全技术措施己迫在眉睫.在医学领域，医学图像是医生获取患者生理疾病信息的重要依据，细小的改变都有可能导致严重的后果.传统上对患者的病理医学数据质量要求极其严格，往往不允许做任何改动[3].医学图像数字水印技术(medical image watermarking，MIW)，是解决这一难题的一种有效方法[4].将具有特定含义的标识信息嵌入到载体医学图像，能实现医学图像的真实性和完整性认证，电子病历 EPR(electronic patientrecord)隐藏和版权保护.其特有的鲁棒性和安全性保证了在经历信息交流过程中的数据处理后，仍能完整可靠地提取水印标志，对医学图像的保护提供了有效的手段.最初数字水印技术是用于互联网上的数字媒体的版权保护[5-7]，现在利用数字水印的不可见性、鲁棒性等特点，可以把病人的个人信息隐藏在其医学图像中，以保证在互联网上的安全传输.为了保护医学图像的安全，人们提出了许多传统的加密算法[8-11].利用混沌神经网络产生具有伪随机性的混沌序列，基于混沌序列对初始值极其敏感的特性[12]，提出一种基于Legendre混沌神经网络的三维医学体数据数字水印算法.此方法能够适应医学图像体数据特点，能抵抗很强的攻击，具有很强的鲁棒性，采用混沌神经网络置乱具有很好的安全性.定义Legendre多项式是定义在[-1，1] 上关于权函数P(x)=1的n次Legendre正交多项式.混沌神经网络结构如图1所示，设Legendre混沌神经网络第一层的权值为wj，Legendre混沌神经网络第二层的权值为cj，隐层神经元采用Legendre正交多项式作为激励函数.隐层神经元的输入为netj=wjx，j=0，1，2，…，n.隐层神经元输出为一组Legendre正交多项式Pj(netj)，j=0，1，2，…，n，可由式(1)递推求得.所以，Legendre混沌神经网络的输出为设x1=y(P-1)，x2=y(P-2)，…，xm=y(P-m)；训练样本为(Tt，dt)，t=1，2，…，l.l为样本数目，Legendre混沌神经网络的输入为Tt=(x1t，x2t，…，xmt)，dt为Legendre混沌神经网络的期望输出.该混沌神经网络采用BP算法获得网络权值，其公式为三维离散傅里叶变换(3D-DFT)原理是通过时域信号向频域信号的转变，将原本具有强相关性的信号集中分布在某一特定区域，通过消除数据的空间冗余达到压缩目的，其公式为式中：f(x，y，z)是数据值；F(u，v，w)是3D-DFT变换系数.三维离散傅里叶反变换(3D-IDFT)公式为式中：f(x，y，z)为空间域采样值；F(u，v，w)为频率域采样值.由于零水印利用图像的重要特征构造水印信息，而不是修改原始图像的特征，因此在医学图像的版权保护中使用零水印.基于Legendre混沌神经网络的三维医学体数据，数字水印算法流程如图2所示.为了验证该数字水印算法的性能，利用Matlab2010a软件对该算法进行仿真.医学体数据采用Matlab2010a软件自带的医学体数据，其大小为128×128×27.为了测试该数字水印算法的抗攻击能力，依次进行了中值滤波[5×5]攻击、垂直下移攻击、顺时针旋转攻击和x轴方向剪切攻击.相关仿真结果如图3、图4、图5和图6所示.从各图中可以看出，在攻击下，提取的水印图像清晰可见，并且相关系数都很高.因此本文提出的数字水印算法具有很强的抗攻击能力，并且实现了水印的盲检测.由于水印图像的置乱采用了Legendre混沌神经网络，产生具有伪随机性的混沌序列，密钥量大，实现了一次一密，难以破解，提高了该数字水印算法的安全性.本研究与文献[13]的水印算法都是体数据数字水印算法，从仿真结果看，各水印算法都能很好地抵抗各种攻击.但是本研究的体数据来源于二维医学图像切片数据，而文献[13]的体数据来源于三维模型，因此嵌入的水印有所不同.文献[13]的水印算法是把水印嵌入到三维体数据的傅里叶变换域，而本研究的数字水印算法是把水印嵌入到每个二维医学图像切片.与文献[13]水印算法相比，本研究的数字水印算法简单易实现，水印的嵌入和提取具有快捷性且计算量小的特点.充分利用国内外相关领域的研究成果，以医学体数据的数字水印作为研究对象，研究具有鲁棒性的零水印技术，提出了一种医学体数据数字水印算法.该算法基于混沌神经网络将图像的特征提取和零水印技术有机地结合在一起，实现了对医学图像信息的保护，对医疗信息产业的发展具有显著的经济效益和社会效益.【相关文献】[1] KAUR S，FAROOQ O，SINGHAL R，et al.Digital watermarking of ECG data for secure wireless communication[C]//Proc of the 2010 IEEE International Conference on Recent Trends in Information，Telecommunication and Computing.Tunisia：2010：140-144. [2] NAVAS K A，SASIKUMAR M.Survey of medical image watermarkingalgorithms[C]//Proc of the 4th Sciences of Electronic Technologies of Information and Telecommunications International Conference.Tunisia：2007：25-29.[3] COATRIEUX G，MAITRE H，SANKUR B.Strict integrity control of biomedicalimages[C]//Proc of the International Society for Optical Engineering(SPIE) on Electronic Imaging，Security and Watermarking of Multimedia Contents.Tunisia：2001：229-240. [4] NAVAS K A， SASIKUMAR M.Survey of medical image watermarkingalgorithms[C]//Proc of the 4th International Conference，Sciences of Electronic，Technologies of Information and Telecommunications.Tunisia：2007：25-29，[5] COATRIEUX G，MAITRE H ，SANKUR B，et al.Relevance of watermarking in medical Imaging[C]//In Proc.IEEE Int.Conf.ITAB.Tunisia：2000：250-255.[6] 王鑫，聂春燕.混沌同步技术在保密通信中的应用[J].长春大学学报：自然科学版，2011，21(4)：25-28.[7] 黄继武，谭铁牛.图像隐形水印综述[J].自动化学报，2000，25(5)：643-653.[8] COUMOU D J，SHANNA G.Insertion，deletion codes with feature based embedding：A new paradigm for watermark sychronization with applications to speech watermarking[J].IEEE Transaction Son Information Forensics and Security，2008，3(2)：153-165.[9] 曹光辉，胡凯，佟维. 基于Logistic均匀分布图像置乱方法[J]. 物理学报，2011，60(11)：125-132.[10] 吴戈. 基于混沌加密和连词替换的文本水印算法[J]. 长春大学学报：自然科学版，2011，21(6)：16-18.[11] 曹光辉，胡凯. 基于混沌序列加权抽样和排序变换的图像置乱[J]. 北京航空航天大学学报，2013，39(1)：67-72.[12] 邹阿金，罗移祥. Legender神经网络建模及股票预测[J]. 计算机仿真，2005(11)：241-242.[13] VASSILIOS S，IOANNIS P.Watermarking digital 3D volumes in the discrete fourier transform domain[J].IEEE Transactions on Multimedia，2007，9 (7)：1373-1383.。
量子科技的应用作文英语Exploring the Quantum Frontier: Applications of Quantum Technology。
In the vast landscape of technological advancement, one realm stands out as both mysterious and promising: quantum technology. Harnessing the peculiar behaviors of quantum mechanics, quantum technology has the potential to revolutionize various fields, from computing to communication and beyond. In this essay, we will delve into the fascinating world of quantum technology, exploring its applications and envisioning its impact on the future.Quantum Computing: Unlocking Unprecedented Power。
At the forefront of quantum technology lies quantum computing, a paradigm-shifting approach to computation. Traditional computers rely on binary bits, which can exist in one of two states: 0 or 1. In contrast, quantum computers leverage quantum bits, or qubits, which can existin multiple states simultaneously due to the principle of superposition. This allows quantum computers to perform vast numbers of calculations simultaneously, leading to exponential increases in processing power.One of the most promising applications of quantum computing is in the field of cryptography. Current encryption methods, such as RSA, rely on the difficulty of factoring large numbers to ensure security. However, quantum computers could theoretically break these encryption schemes in a fraction of the time it would take traditional computers. Conversely, quantum cryptography offers a new paradigm for secure communication, utilizing the principles of quantum mechanics to enable unhackable encryption keys.Quantum Communication: The Dawn of Unbreakable Encryption。
l开头的创新的英文单词
一些以L开头的创新的英文单词包括:
1. "Laser"（激光）指一种通过受激辐射产生的高强度光束来进行加工、测量、通信等的装置或技术。
2. "Lithium-ion"（锂离子）指一种常见的充电电池技术，用于各种电子设备和汽车。
3. "Lidar"（激光雷达）指一种用激光来测量距离、速度和其他特性的技术，常用于自动驾驶汽车和地图制作。
4. "Low-carbon"（低碳）指一种环保的生产或生活方式，通过减少碳排放来降低对气候变化的影响。
5. "Lattice cryptography"（点阵密码学）指一种新兴的加密技术，利用数学上的点阵结构来保护数据安全。
这些单词都代表着不同领域的创新技术和概念，它们在科学、工程、环保和其他领域都有重要的应用和意义。
blindwatermark使用Blindwatermark是一种常用的数字图像水印技术，它可以在图像中嵌入不可见的信息，以确认图像的版权和完整性。
与传统的数字图像水印技术相比，Blindwatermark有更高的容忍度和更强的鲁棒性。
以下是一些与Blindwatermark相关的参考内容。
1. "Digital Image Watermarking Techniques: A Comprehensive Review" - 这篇论文对数字图像水印技术进行了全面的综述，包括Blindwatermark在内。
它讨论了不同的数字图像水印算法，并对它们的优缺点进行了比较和分析。
2. "BlindWaterMarking Algorithm for Image Authentication" - 这篇研究论文提出了一种基于Blindwatermark的图像认证算法。
它介绍了该算法的原理和实现细节，并对算法的性能进行了评估。
3. "A Robust Blind Watermarking Scheme Based on Discrete Wavelet Transform and Singular Value Decomposition" - 这篇论文提出了一种基于离散小波变换和奇异值分解的鲁棒性Blindwatermark方案。
它讨论了该方案的安全性和抗攻击能力，并进行了实验验证。
4. "Blind Watermarking for Image Tampering Detection and Recovery" - 这篇论文介绍了一种基于Blindwatermark的图像篡改检测和恢复方法。
它详细说明了该方法的步骤和流程，并通过实验结果验证了算法的有效性。
5. "A Survey on Digital Watermarking Techniques and its Applications" - 这篇综述性文章对数字水印技术及其应用进行了调研和总结。
一种新型的量子水印策略张伟伟12，高飞1，刘斌1，贾恒越1，温巧燕1，陈晖31北京邮电大学网络与交换技术国家重点实验室，北京 1008762信息安全国家重点实验室(中国科学院软件研究所)，北京1001903现代通信国家重点实验室，成都，610041摘要：随着量子计算机和量子网络的发展，量子数据的安全越来越重要。
量子水印是一种可以将包括身份信息等的不可见信号嵌入到包括音频，视频和图像等的量子多媒体数据中，起到版权保护的作用。
本文提出一种基于灵活量子图像表示的的新型水印策略。
之前提出的策略（唯一的一个基于量子图像的策略）只能用来验证载体图像的拥有者是否为所已知的身份。
与其相比，本文提出的策略能够找出真正的版权所有者，并且除版权所有者以外的任何人都不能清除或提取除水印图像。
关键词：量子计算，量子图像，量子水印中图分类号：O59A Novel Watermark Strategy For QuantumImagesWei-Wei Zhang12，Fei Gao1，Bin Liu1，Heng-Yue Jia1，Qiao-Yan Wen1，HuiChen31the State Key Laboratory of Networking and Switching Technology,Beijing University ofPosts and Telecommunications,Beijing1008762the State Key Laboratory of Information Security(Institute of Software,Chinese Academyof Sciences),Beijing1001903Science and Technology on Communication Security Laboratory,Chengdu,610041 Abstract:With the development of quantum computer and quantum network,the securityof quantum data becomes more and more important.Quantum watermarking is the technique which embeds the invisible quantum signal such as the owner’s identification into quantum multimedia data(such as audio,video and image)for copyright protection.In this paper,a novel watermark strategy for quantum images is proposed based onflexible representation for quantum images(FRQI).Compared with the former strategy(only one based on quantum 基金项目：NSFC(Grant Nos.61170270,61100203,60903152,61003286,60821001),NCET(Grant No.NCET-10-0260),SRFDP(Grant Nos.200800131016,20090005110010),Beijing Natural Science Foundation(Grant No.4112040),the Fundamental Research Funds for the Central Universities(Grant Nos.BUPT2011YB01,BUPT2011RC0505, 2011PTB-00-29,2011RCZJ15),Science and Technology on Communication Security Laboratory Foundation(Grant No.9140C110101110C1104).作者简介：Zhang Wei Wei（1987-），female，Master Student，major research direction：quantum key distribution, quantum secret sharing,and quantum images processing.Correspondence author：Gao Fei（1980-），male，professor，major research direction：quantum key distribution,quantum secret sharing,and quantum secure direct communication.images)which can only be used to verify the identity of the true owner of a carrier image,the proposed method can also be used tofind out who is the real owner.And it is impossible for anyone except the copyrighter to clear offor extract the watermark images.Key words:Quantum computation,Quantum image,Quantum watermarking.0IntroductionTHE high integration of the traditional computer has resulted in the appearing of quan-tum effects which greatly restricts the development of the classic computer.Recently,the quantum computer(QC)and the quantum network are developing rapidly.In2001,IBM de-veloped the world’sfirst7-qubit QC to give a demonstration.In2007,D-wave corporation in Canada announced that they hadfinished the16-qubit commercial QC for thefirst time and it was improved to48-qubit in2008.In2011,D-wave announced their achievement of 128-qubit commercial QC.The company had set goals for developing1024-qubit QC and pro-posed QC’s further application(such as releasing the quantum computing software system, providing interface for application program including SQL Prolog Lisp etc,developing the on-line commercial computation service).D-wave’s development implies that the principle of quantum computer has been matured and the practical technology also has made substantial progress.In the meantime,the quantum networks areflourishing.In2004,Raytheon BBN Technologies and Harvard university cooperatively constructed a quantum cryptography net-work Defense Advanced Research Projects Agency(DARPA)and successfully accomplished the mutual connection using the communication opticalfiber.Secure communication based on quantum cryptography(SECOQC)network was accomplished in2008,which was cooperatively fulfilled by41research institutions and enterprises from the European Union,Switzerland and Russia.In2010,based on the latest QKD technology,the Tokyo QKD network making use of JGN2plus(Japan’s Gigabit Network)was configured as a star network.This network con-nected the JGN2plus operation center in Otemachi with National Institute of Information and Communications Technology(NICT)’s Headquarter in Koganei as well as Tokyo University in Hongo and NICT’s research facility in Hakusan.With the development of quantum computer and quantum network,the security of quan-tum data becomes more and more important.Cryptography is the approach to protect data’s secrecy in public environment.As we know,the security of most classical cryptosystems is based on the assumption of computational complexity.But this kind of security is susceptible to the strong ability of quantum computation[1],[2].It means that many existing cryptosys-tems’s security will be threatened by quantum computer.Fortunately,this difficulty can be overcome by quantum cryptography[3],[4].Different from its classical counterpart,the secu-rity of quantum cryptography is assured by physical principles such as Heisenberg uncertaintyprinciple and quantum no-cloning theorem.Recently,quantum cryptography has obtained a great deal of attentions because it can stand against the threat from an attacker with the abil-ity of quantum computation.Quite a few branches of quantum cryptography develops greatly in recent years,including quantum key distribution(QKD)[5]-[10],quantum secret sharing (QSS)[11]-[13],quantum secure direct communication(QSDC)[14]-[18],quantum identity authentication[19]-[21],and so on.Different from cryptography,which is used to protect the secrecy of the message’s content, steganography aims at hiding the existence of message.Quantum watermarking is a kind of steganography,which is used to embed some symbolic quantum information into quantum multimedia content.It will not affect the usage of multimedia and others cannot feel the watermark’s existence.The watermark in the carrier is used to protect the copyright.Compared with theflourishing quantum cryptography,quantum steganography is still in its infancy.Images are good carriers and always used in steganography.Recently,a few strategies for quantum images’storing and retrieving have been proposed[22],[26],[27].Based on the presentations of quantum images,Le et al.proposed the strategies for quantum images’geometric transformations[25],[28]-[30].Besides,some quantum watermarking schemes[23], [24],[25],[32]were proposed,where[24]is the only andfirst one based on quantum images. But a significant limitation is that the proposed schemes in[24]based on quantum images can only be used to vertify the identity of carrier image’s true owner.That means we can only find out someone is using illegal carrier image,but we can notfind out where his/her images come from.This is a real limitation in practical application.In this paper,we propose a novel quantum watermarking strategy which is more universal,in the sense that it can be used to find out who is the real owner(or who leaks the carrier images to the illegal users)according to the watermark extracted from the carrier image.The rest of this paper is organized as follows.The next section introduces quantum information[31],theflexible representation of quantum images(FRQI)[27],which will be used in the following sections,and the watermarking scheme proposed by Le et al..In section III,we describe our quantum watermarking strategy detailedly and present the results and analysis of simulation-based experiments to demonstrate the realization of the watermarked carrier image. Finally,a short conclusion is given in Section IV.1Preliminaries1.1Quantum informationA quantum computer is a device for computations that makes direct use of quantum mechanical properties.Quantum computation and quantum information are based on the fundamental concept,the quantum bit,or qubit for short.Just like there exist a classical bit图1:Bloch sphere representation of a qubit|ψ⟩=cosθ2|0⟩+e iφsinθ2|1⟩[31].either0or1,a qubit also has a state.Their difference is that a qubit can be in any linear combinations of state|0⟩or|1⟩.It is often called superpositions:|ψ⟩=α|0⟩+β|1⟩.The numberαandβare complex numbers,and satisfy|α|2+|β|2=1.The computational basis states|0⟩and|1⟩form an orthonormal basis for a special vector space.We can think the qubit as the following geometric representations,which can be rewrite as the form of qubit as follows:|ψ⟩=cosθ2|0⟩+e iφsinθ2|1⟩,where theθandφare real numbers and define a point on theunit three–dimensional sphere,as shown in Fig.1.In principle,there are infinitely many points on the unit sphere,so that one could store an entire text of Shakespear in the infinite binary expansion ofθ[31].1.2Flexible representation of quantum imagesBased on the human perception of vision and the classical images’pixel representation, theflexible representation for quantum images(FRQI),a representation for quantum images, was proposed in[27].FRQI contains the color information and corresponding position of every pixel in image.According to the FRQI,a quantum image’s representation can be written as the form shown below.|c i⟩=n−1,where|0⟩,|1⟩are2-D computational basis quantum states,(θ0,θ1,...,θ22n−1)is the vector of angles encoding colors,and|i⟩,for i=0,...,22n−1,are(22n−1)-D computational basis.There图2:A simple image and its FRQI state:|I⟩=1[(cosθ0|0⟩+sinθ0|1⟩)⊗|00⟩+(cosθ1|0⟩+2sinθ1|1⟩)⊗|01⟩+(cosθ2|0⟩+sinθ2|1⟩)⊗|10⟩+(cosθ3|0⟩+sinθ3|1⟩)⊗|11⟩][24]are two parts in the FRQI of an image:c i and|i⟩,which encode information about the colors and their corresponding positions in the image,respectively.For2-D images,the location information encoded in the position qubit|i⟩includes two parts:the vertical and horizontal coordinates.For preparing quantum images in2n-qubit systems,or n-sized images,the vector|i⟩=|y⟩|x⟩=|y n−1y n−2...y0⟩|x n−1x n−2...x0⟩,|y i⟩|x i⟩∈{0,1},for every i=0,1,...,n,(y n−1,y n−2,...,y0)encodes thefirst n-qubit along the vertical location and(x n−1,x n−2,...,x0)encodes the second n-qubit along the horizontal axis.An example of a 2×2FRQJ image is shown in Fig.2.In[27],[28]-[30],[33],the methods for storing and retrieving quantum images are proposed.1.3Le et al.’s strategy based on restricted geometric transformationsIn[24],Le et al.proposed an algorithm for watermarking and authentication of quantum images based on restricted geometric transformations(including two-point swapping,the verti-calflip,the horizontalflip,the coordinate swap operations).It is a great progress for quantum images processing that they utilize the restricted variants(of the quantum versions)[28]of these transformations as the basic resources of the watermark embedding and authentication circuits.These procedures are available for the various stages by the copyright owners and users of the published(watermarked)images.The copyright owner has access to both the classical and quantum versions of the image and watermark signal.The end-users on their parts are图3:The outline of Le et al.’s watermark authentication procedure[24].restricted to only the published quantum versions of the watermarked images.The outline of quantum watermark image’s embedding procedure consists of two parts: thefirst part decides the watermark map with the classical versions of carrier and watermark images as input,the second part transforms the watermark map into quantum circuit accord-ing to a simple mapping between the map’s value(0,1or-1)and the quantum geometric transformations.The watermark authentication procedure,whose outline is shown in Fig.3,is only available to the copyright owner.He/she uses the inverse watermark-embedding circuit (comprising of the same gate sequence as the watermark-embedding circuit but in the reverse order)to authenticate the true ownership of an embedded carrier image.That means if the copyright owner want to authenticate some embedded carrier image,he/she has to know which watermark image is in the carrier image,i.e the unique embedding circuit.Therefore this scheme can only be used to verify the identity of a true owner of the carrier image.In this scheme,the copyrighters can onlyfind out someone is using illegal images,but they can not find out where his/her images come from.This is a real limitation in practical application.2Quantum watermark embedding and extracting procedureOur watermark embedding procedure is based on the idea that making a subtle change to the carrier image according to the watermarking image.The embedded carrier image and the original carrier image are indistinguishable by naked eyes.The extracting procedure can only be executed by the embedder,because the key used to decide the position of watermark and the original carrier image is only known to the embedder.2.1The embedding procedure of quantum watermark imageAs we known,an image consists of many pixels which are all pure colors.According to the FRQI,a pixel’s color in a quantum image can be written as I(θ)=cosθ|0⟩+sinθ|1⟩,where θrepresents the color of the pixel.The outline of the embedding procedure is shown in Fig.4.图4:The outline of watermark image’s embedding procedure.The concrete procedure is as following:(1)If the watermark image’s size is less than the carrier’s image,the embedder should polish it to the size of carrier image.Concretely,the embedder randomly cover the carrier image with the watermark image.The area in watermark image corresponding to the exposed region in carrier image is replenished with the corresponding pixels in the carrier image,thus the watermark image is the same size with the carrier image.Here the white pixels’position are only known to embedder.(2)The embedder produces a sequence of key k(unique to the carrier image).This key will be used to determine the position that the watermark image’s pixel will be embedded,and it is only known to the embedder.Specifically,if k=0the watermark image’s pixel is embedded in the cosine part,otherwise the sine part.(3)The embedder embeds the watermark image into the carrier image according to the following method,which makes a subtle change to the Taylor series expression of the carrier image’s pixels.The Taylor series of cos x and sin x iscos x=1−x22!+x44!−...+(−1)k x2k(2k)!+...(−∞<x<+∞)sin x=x−x33!+x55!−...+(−1)k−1x2k−1(2k−1)!+...(−∞<x<+∞)Assume the watermark image’s pixel is cosφ|0⟩+sinφ|1⟩.If the key in step(2)is0,the original pixel is approximated withα|0⟩+β|1⟩,whereα=cosθ=1−θ22!+θ44!−θ66!,β=√thus the pixel embedding watermark’s pixel isα′|0⟩+β′|1⟩,hereα′=cosθ′=1−θ22!+θ44!−φ66!,β=√1−α′2If the key in step(2)is1,the original pixel is approximated withα|0⟩+β|1⟩,where图5:The outline of watermark image’s extracting procedure.β=sin θ=θ−θ33!+θ55!−θ67!,α=√1−β2thus the embedding watermark’s pixel is α′|0⟩+β′|1⟩,hereβ′=sin θ′=θ−θ33!+θ55!−φ67!,α′=√1−β′2(4)Implement the above three steps for every carrier image’s pixel and watermark image’s pixel.2.2Quantum watermark image’s extracting procedureIn our scheme,the watermark extracting procedure is only available to the copyright owner (the embedder).He/She uses the key and the original carrier image to extract the watermark image from an embedded carrier image according to the extracting procedure (see Fig.5).Assume the color of the original carrier image’s pixel is I (θ)=cos θ|0⟩+sin θ|1⟩,the color of the embedded carrier image’s pixel is α′|0⟩+β′|1⟩.The concrete steps are as following:(1)According to the key (unique to the carrier image),the embedder get the position of watermark image’s every pixel.(2)If the key in step (1)is 0,the extracted watermark pixel is cos φ′|0⟩+sin φ′|1⟩,whereφ′=((1−θ22!+θ44!−α′)×6!)16If the key in step (1)is 1,the extracted watermark pixel is cos φ′|0⟩+sin φ′|1⟩,where φ′=((θ−θ33!+θ55!−β′)×7!)17(3)Implement the above two steps for every pixel of the embedded carrier image and get every pixel of the watermark image.2.3Simulations of quantum watermark embedding and extracting pro-cedureDue to the condition that the physical quantum hardware is not affordable for us to execute our protocol,we just make the simulations of the input quantum carrier images and watermark images.The tools needed and results obtained in our simulation experiments are presented and reviewed in this section.MATLAB(MATrix LABoratory)is a useful software tool for matrix manipulations,plot-ting of functions and data,implementation of algorithms,creation of user interfaces,and in-terfacing with programs.It isflexible in the representation and manipulation of large arrays of vectors and matrices.Because it is reasonable to treat the quantum images as large matrices and the transformations as matrix computations.Therefore,MATLAB is suitable to simulate quantum states(such as quantum images),although it has some limitations in simulating the image of huge size.MATLAB’s Image Processing Toolbox provides a comprehensive set of reference-standard algorithms and graphical tools for image processing,analysis,visualisation, and algorithm development.By using MATLAB,quantum images and their transformations can be effectively simulated[24].We demonstrate our quantum watermark embedding and ex-tracting procedure with a classical computer with Intel(R)Core(TM)2Duo CPU E75002.93 GHz,1.98GB Ram equipped with the MATLAB2009a environment.The peak-signal-to-noise ratio(PSNR),being one of the most used metrics in classical images for comparing thefidelity of a watermarked image with its original version,will be used as our watermarked image eval-uation metric by transforming the quantum images into classical forms,though there may be some influence on the results.It is most easily defined via the mean squared error(MSE),which for two m×n monochrome images(the original carrier image I and its watermarked version K) is defined asMSE=1mnm−1∑i=0n−1∑j=0[(I(i,j)−K(i,j))2]The PSNR is defined byP SNR=20log10(MAX I √MSE)Here,MAX I is the maximum possible pixel value of the image[24].2.3.1Simulation of gray imagesIn the simulation,we use256×256images of different types as carrier images and water-mark images.In Fig.6,a part of the embedded carrier images are shown at left and the right图6:The left are embedded carrier images.The right are extracted watermark images from the left.side is the watermark images extracted from the corresponding left images.And the PSNR is presented in Table I.表1:gray images’s PSNRcarrier image watermark image PSNRaerial sailboat50.8418baboon lena63.4885boat pepper63.5384lena baboon64.8810pepper boat64.2690sailboat aerial56.33472.3.2Simulation of color imagesIn the simulation,we use756×504and768×512images of different types and colors as carrier images and watermark images.In Fig.7,a part of the embedded carrier images are at left and the right side is the watermark images extracted from the corresponding left images. And the PSNR is presented in Table II.2.3.3AnalysisFrom Fig.6,Fig.7,Table I and Table II,we can see that the watermark image’s embedding doesn’t affect the carrier image’s visual effect.And the PSNR is obviously higher than theaverage level of the classical algorithms.图7:The left are embedded carrier images.The right are extracted watermark images from the left.表2:color images’s PSNRcarrier image watermark image PSNRsea lake78.6989green tree bar57.2443dancers building68.5769house boat76.6030temper huts76.0906mural wall infinitywall mural78.9717Due to the Minute changes to the original carrier images,users of the carrier images will not feel the exist of watermark images.Because the unique key of carrier image,the original carrier image and the embedding algorithm are only known to the embedder,the illegal operations of clearing away or extracting the watermark image are impossible.3ConclusionIn this paper,a novel watermarking algorithm for images on quantum computers is pro-posed based 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