Logistic mapping encryption method for color coordinate modulation

Abstract

The invention relates to the technical field of image encryption, in particular to a Logistic mapping encryption method for color coordinate modulation. The method specifically comprises the following steps: exciting rare earth luminescent nanoparticles on a target object through a light source to generate a plurality of color coordinates; obtaining an initial value and a control parameter according to the plurality of color coordinates; constructing a one-dimensional chaotic mapping, obtaining a chaotic sequence based on the one-dimensional chaotic mapping, the initial value and the control parameter, and taking the chaotic sequence as a key stream; and taking the color coordinates as plaintext blocks, and encrypting the plurality of plaintext blocks through an AES symmetric encryption algorithm by using the key stream to obtain a to-be-transmitted ciphertext. According to the method, the calculation efficiency is improved, the usability and the safety of the encryption method are improved, and the problems that an error is caused by the internal instability of a chaotic system in an existing Logistic mapping encryption method and the encryption and decryption efficiency is influenced under the high iteration frequency are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of image encryption, and particularly relates to a Logistic mapping encryption method modulated by color coordinates. Background Art

[0002] The Logistic mapping, also known as the logistic map or parabola map, is a mathematical model, and its mathematical expression is: x(t + 1) = μx(t)(1 - x(t)); where x(t) represents a measure of the system state at time point t; μ represents the control parameter, which determines the dynamic behavior of the system.

[0003] The Logistic mapping can exhibit complex chaotic behaviors through simple iteration, which has significant advantages in the field of image encryption. It has a structural feature of high sensitivity, and a slight change in the initial value or parameter will lead to completely different sequence results, which can provide extremely high security for the encryption process. In addition, the deterministic chaotic characteristics exhibited by the Logistic mapping, although its behavior seems random, are actually completely determined, which will make the encryption process not only predictable but also reversible. Due to the simple calculation method of the Logistic mapping, it is easy to be implemented on various computing platforms, which further enhances the convenience and flexibility of the Logistic mapping in practical applications.

[0004] However, although the existing Logistic mapping encryption methods utilize some advantages of chaos theory, some methods in practical applications may overly rely on the chaotic characteristics of the Logistic mapping, thus not considering the requirements of predictability and stability in the application process. For example, in the Logistic mapping encryption process, due to the inherent instability of the chaotic system and the uncertainty of the initial value, even a slight change in the initial value, the encryption algorithm may produce tiny errors at high iteration times. This sensitivity to the initial value is a significant feature of the chaotic system and one of the reasons for the high-strength security of the chaotic encryption method. However, this sensitivity also brings the problem of error amplification. These errors will gradually accumulate during the decryption process and lead to decryption failure, thus seriously threatening the security of the encrypted information. In addition, a large amount of computing resources consumed at high iteration times may affect the encryption and decryption efficiency according to the characteristics. More seriously, some characteristics of the chaotic system may be exploited by attackers for predictive attacks to crack the encrypted information. This predictability not only weakens the security of the encryption method but also limits the application of the Logistic mapping encryption method in some scenarios with extremely high security requirements. Summary of the Invention

[0005] To solve the error problems caused by the inherent instability of the chaotic system and the uncertainty of the initial value in the existing Logistic mapping encryption method, as well as the problem of affecting the encryption and decryption efficiency at high iteration times, the purpose of the present invention is to provide a color coordinate modulation Logistic mapping encryption method.

[0006] To achieve the above object, the technical solution of the present invention is as follows.

[0007] The present invention provides a color coordinate modulation Logistic mapping encryption method, which is characterized by including the following steps:

[0008] Exciting rare earth luminescent nanoparticles on the target by a light source to generate multiple color coordinates; obtaining the initial value and control parameters according to the generated multiple color coordinates; constructing a one-dimensional chaotic mapping, and based on the one-dimensional chaotic mapping, the initial value and the control parameters, obtaining a chaotic sequence, and using the chaotic sequence as the key stream; taking the color coordinates as the plaintext blocks, then multiple color coordinates correspond to multiple plaintext blocks, and using the key stream to encrypt the multiple plaintext blocks through the AES symmetric encryption algorithm to complete the color coordinate modulation Logistic mapping encryption and obtain the ciphertext to be transmitted.

[0009] The present invention mainly generates multiple color coordinates under the excitation of a light source, obtains the initial value and control parameters according to the generated multiple color coordinates, performs iterative calculations based on the one-dimensional chaotic mapping to obtain a chaotic sequence, uses the chaotic sequence as the key stream, takes the color coordinates as the plaintext blocks, and encrypts the multiple plaintext blocks through the AES symmetric encryption algorithm using the key stream to obtain the ciphertext to be transmitted.

[0010] The present invention analyzes the control parameters to determine that the control parameter values can generate the required chaotic behavior, and at the same time uses multiple color coordinates to obtain a relatively accurate initial value to maintain the system stability, thereby avoiding the error problems caused by the inherent instability of the chaotic system and the uncertainty of the initial value.

[0011] Traditional encryption methods only increase the ability to encrypt information through ordinary iteration. However, the present invention takes multiple color coordinates as the plaintext blocks, associates the encryption algorithm with the color coordinates, and can achieve the information encryption ability with fewer iterations. While improving the calculation efficiency, it also improves the encryption and decryption efficiency, and solves the problem that the existing Logistic mapping encryption method affects the encryption and decryption efficiency at high iteration times.

[0012] In addition, the present invention takes the excitation wavelength as a prerequisite for decryption, adds an additional security level, further improves the security of encryption and decryption, and improves the usability of the encryption method.

[0013] During the decryption process, the ciphertext to be transmitted, that is, the password book. Each ciphertext block can be regarded as an identification code. The key stream is used to decrypt multiple ciphertext blocks through the AES symmetric encryption algorithm to obtain multiple decrypted ciphertexts. For the material or product to be detected containing rare earth luminescent nanoparticles, multiple color coordinates can be generated through light source excitation, that is, multiple ciphertexts of the material or product to be detected are obtained. The multiple decrypted ciphertexts are compared with the multiple ciphertexts of the material or product to be detected. When the multiple decrypted ciphertexts match the multiple ciphertexts of the material or product to be detected, it is thus verified that the material or product to be detected matches the material or product decrypted from the ciphertext to be transmitted. The encryption algorithm of the present invention can be widely applied to the authenticity identification of materials or products.

[0014] Preferably, the method for obtaining the initial value is as follows:

[0015] The multiple generated color coordinates are calculated by the weighted average method to obtain the weighted average color coordinates; according to the weighted average color coordinates, the straight-line distance from the weighted average color coordinates to the origin is calculated; the straight-line distance from the weighted average color coordinates to the origin is used as the initial value.

[0016] Preferably, the weighted average color coordinates are set as (weight_x, weight_y); the calculation formula of the weighted average method is as follows:

[0017] where, x i is the abscissa value of the i-th color coordinate; y i is the ordinate value of the i-th color coordinate; ω’ i is the normalized weight of the i-th color coordinate; weight_x is the abscissa value of the weighted average color coordinates; weight_y is the ordinate value of the weighted average color coordinates.

[0018] Preferably, the calculation formula of the straight-line distance from the weighted average color coordinates to the origin is as follows:

[0019] where, weight_x is the abscissa value of the weighted average color coordinates; weight_y is the ordinate value of the weighted average color coordinates; Z 0 is the initial value.

[0020] Preferably, the control parameter is set as μ, then 3 < μ ≤ 4, which shows a chaotic mapping state.

[0021] Preferably, the mathematical expression of the one-dimensional chaotic mapping is:

[0022] Z n+1 = μZ n (1 - Z n ); where, Z n+1is the chaotic sequence value after the (n + 1)-th iteration; Z n is the chaotic sequence value after the n-th iteration; μ is the control parameter; n is the number of iterations; the one-dimensional chaotic map is constructed based on the Logistic map.

[0023] Preferably, the rare earth luminescent nanoparticles are NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles, where m% = 1% - 9%.

[0024] The present invention encrypts images through the Logistic map, calculates and determines an initial value based on multiple chromaticity coordinates, and the initial value is the average of the chromaticity coordinates corresponding to rare earth luminescent nanoparticles with different concentrations. Moreover, the excitation wavelength is used as a prerequisite for decryption, adding an additional security level to further improve the security of the encrypted image.

[0025] Preferably, the light source for exciting the NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles is a light source with an excitation wavelength of 271 nm or 980 nm.

[0026] Preferably, the NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles exhibit red emission peaks mainly at 593 nm and 615 nm in the fluorescence emission spectrum under 271 nm excitation, and emit green emission peaks at 525 nm and 540 nm under 980 nm excitation.

[0027] Preferably, the NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles are prepared by doping Yb 3+ , Er 3+ , Eu 3+ into the NaYF 4 matrix; the mass percentage of Yb 3+ in Yb 3+ , Er 3+ , Eu 3+ and Y 3+ is 20% of the total mass; the mass percentage of Er 3+ in Yb 3+ , Er 3+ , Eu 3+ and Y 3+The mass percentage of the total mass is 2%; Y 3+ accounts for Yb 3+ , Er 3+ , Eu 3+ and Y 3+ The mass percentage of the total mass is 69% - 77%.

[0028] Preferably, the target is a material or product containing rare earth luminescent nanoparticles.

[0029] Advantages of the present invention:

[0030] 1. The present invention analyzes control parameters to determine that the control parameter values can generate the desired chaotic behavior. At the same time, multiple color coordinates are used to obtain relatively accurate initial values to maintain system stability, thereby avoiding error problems caused by the inherent instability of the chaotic system and the uncertainty of the initial values. The present invention uses multiple color coordinates as plaintext blocks, associates the encryption algorithm with the color coordinates, and can achieve information encryption ability with fewer iterations. While improving the calculation efficiency, it also improves the encryption and decryption efficiency, and solves the problem that the existing Logistic mapping encryption method affects the encryption and decryption efficiency at high iteration times. In addition, the present invention takes the excitation wavelength as a prerequisite for decryption, adding an additional security level, further enhancing the security of encryption and decryption, and improving the usability of the encryption method.

[0031] 2. The present invention encrypts the initial values and control parameters, improving the encryption intensity. The combination of plaintext blocks and AES symmetric encryption realizes a secure data transmission and decryption process. The normalized modulation and encryption of color coordinates can significantly improve the security of encrypted images, making cracking more difficult. Description of the Drawings

[0032] Figure 1 is the X-ray diffraction pattern of NaYF 4 :Yb 3+ , Er 3+ , 1% Eu 3+ nanoparticles.

[0033] Figure 2 is the scanning electron microscope image of NaYF 4 :Yb 3+ , Er 3+ , 1% Eu 3+ nanoparticles.

[0034] Figure 3 is the energy dispersive spectrum of NaYF 4 :Yb 3+ , Er 3+ , 1% Eu 3+ nanoparticles.

[0035] Figure 4 is NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ The fluorescence emission spectrum of the nanoparticles under 271 nm excitation.

[0036] Figure 5 is NaYF 4 :Yb 3+ ,Er 3+ ,5% Eu 3+ The fluorescence emission spectrum diagram of the nanoparticles under 980 nm excitation.

[0037] Figure 6 is NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ The chromaticity coordinate diagram. Among them, (b) is a partial enlarged view of the part enclosed by the dashed line in (a).

[0038] Figure 7 is NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ The numerical diagram of 5 chromaticity coordinates.

[0039] Figure 8 is the connection diagram of the Logistic mapping iteration chaotic sequence values with different iteration times.

[0040] Figure 9 is the AES plaintext encryption flow chart.

[0041] Figure 10 is the plaintext block encryption flow chart.

[0042] Figure 11 is the encryption result diagram.

[0043] Figure 12 is the decryption flow chart. Specific implementation manners

[0044] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0046] In the following embodiments, the full English name of CIE is Commission Internationale de l'Éclairage, and its Chinese name is the International Commission on Illumination. The CIE chromaticity coordinate diagram is a coordinate diagram used to describe colors. The CIE chromaticity coordinates are abbreviated as chromaticity coordinates.

[0047] A plaintext block is a fixed-size data unit into which the original plaintext data, i.e., the data to be encrypted, is divided during the encryption process.

[0048] The full English name of AES symmetric encryption is Advanced Encryption Standard, and its Chinese name is the Advanced Encryption Standard. This is a common symmetric encryption algorithm that uses the same key for both encryption and decryption.

[0049] The Logistic map is a mathematical model that can exhibit complex chaotic behavior through simple iteration, which has significant advantages in the field of image encryption. It has a highly sensitive structural feature where a small change in the initial value or parameter will result in a completely different sequence of results, providing extremely high security for the encryption process. Secondly, the deterministic chaotic characteristics exhibited by the Logistic map, although its behavior seems random, are actually completely determined, making the encryption process not only predictable but also reversible.

[0050] The present invention optimizes the parameter process of Logistic map encryption, analyzes the parameter space, determines the parameter values that can generate the desired chaotic behavior while maintaining system stability, associates the encryption algorithm with chromaticity coordinates, and improves the usability and security of the encryption method while enhancing the computational efficiency.

[0051] The mathematical expression of the Logistic map is: Z n+1 = μZ n (1 - Z n ); where Z 0 is the initial value, μ is the control parameter; n is the number of iterations. For any n, Z n always lies between [0, 1], μ is an adjustable parameter, and to ensure that the mapped Z n always lies within [0, 1], then μ lies between [0, 4]. When different control parameters μ are changed, the equation of the Logistic map will exhibit different dynamic limiting behaviors, including fixed points, periods, and chaos. When n approaches infinity, i.e., the change situation of Z n is: always the same value, jumps between 2 or more values, and will never repeat but will equally likely take on values in a certain interval.

[0052] For the Logistic map, the typical value range of the control parameter μ is (0, 4]. Within this range, the behavior of the map changes with the value of μ:

[0053] When 0 < μ ≤ 1, the map exhibits fixed-point behavior.

[0054] When 1 < μ ≤ 3, the map may exhibit periodic behavior, but the length of the period increases with the increase of μ.

[0055] When 3 < μ ≤ 4, the map begins to exhibit chaotic behavior, especially when approaching 4, the chaotic behavior is most significant.

[0056] When the value of the control parameter approaches 4, it enters the chaotic map, reducing the calculation time. And encrypting the initial value and the control parameter improves the encryption strength. The combination of the plaintext block and the AES symmetric encryption realizes a secure data transmission and decryption process. The normalization modulation and encryption of the color coordinates can significantly improve the security of the encrypted image, making it more difficult to crack.

[0057] The technical solution of the present invention will be further described below through specific embodiments.

[0058] In the following embodiments, unless otherwise specified, the methods are all conventional methods; the reagents and materials, unless otherwise specified, can all be purchased on the market.

[0059] In the following embodiments, NaYF 4 :Yb 3+ ,Er 3+ ,m%Eu 3+ nanoparticles are upconversion multicolor rare earth luminescent nanoparticles with dual-mode excitation, mainly obtained by doping Yb 3+ ,Er 3+ ,Eu 3+ into the NaYF 4 matrix, where m% = 1% - 9%. The preparation method of NaYF 4 :Yb 3+ ,Er 3+ ,m%Eu 3+ nanoparticles is as follows:

[0060] Mix Y(NO 3 ) 3 ·6H 2 O with a concentration of 0.1 mol / L, Yb(NO 3 ) 3 ·6H 2 O with a concentration of 0.1 mol / L, and Er(NO 3 ) 3 ·6H2 O and Eu(NO with a concentration of 0.05 mol / L 3 ) 3 ·6H 2 O were stirred and dissolved at 45 °C to obtain a mixed solution.

[0061] 0.336 g of NaF was dissolved in 10 mL of deionized water to obtain an aqueous NaF solution, which was then added dropwise to the above mixed solution and stirred for 10 min. After that, the reaction solution was transferred to an autoclave and heated at 180 °C for 6 h. After the reaction was completed, it was washed repeatedly 3 times with ethanol and deionized water to obtain upconversion multi-color rare-earth luminescent nanoparticles with dual-mode excitation, denoted as NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles, where m% = 1% - 9%.

[0062] Table 1 Raw material dosage

[0063] Number <![CDATA[Y(NO 3 ) 3 ·6H 2 O]]> <![CDATA[Yb(NO 3 ) 3 ·6H 2 O]]> <![CDATA[Er(NO 3 ) 3 ·6H 2 O]]> <![CDATA[Eu(NO 3 ) 3 ·6H 2 O]]> a1 15.4 mL 4 mL 0.8 mL 0.4 mL a2 15 mL 4 mL 0.8 mL 1.2 mL a3 14.6 mL 4 mL 0.8 mL 2 mL a4 14.2 mL 4 mL 0.8 mL 2.8 mL a5 13.8 mL 4 mL 0.8 mL 3.6 mL

[0064] Table 2 Products prepared from different raw materials

[0065] Number Product a1 <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 1% Eu 3+ > a2 <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 3% Eu 3+ > a3 <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 5% Eu 3+ > a4 <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 7% Eu 3+ > a5 <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 9% Eu 3+ >

[0066] Figure 1 is the X-ray diffraction pattern of NaYF 4 :Yb 3+ ,Er 3+ ,1% Eu 3+ nanoparticles. Among them, PDF#77-2042 is the standard card data of cubic-phase NaYF 4 .

[0067] It can be seen from Figure 1 that all diffraction peaks have relatively high intensities. The prepared sample is in good agreement with the standard data, and no obvious impurities are detected, indicating that when doping Yb 4 , Er 3+ , Eu 3+ ions into the NaYF 3+ matrix, it has a relatively high phase purity. The samples are all crystallized in a cubic system with the space group FM-3M(225); for undoped NaYF 4 , the lattice parameters are determined to be 5.47×5.47×5.47. For NaYF 4 :Yb 3+ ,Er 3+ ,1% Eu 3+ nanoparticles, due to Yb 3+ , Er 3+ , Eu 3+The incorporation leads to the expansion of the unit cell volume, and it can be observed that the diffraction peaks shift towards lower angles.

[0068] The complete crystal structure is beneficial to reducing radiation loss, thereby enhancing the luminescence efficiency. The morphology of NaYF 4 :Yb 3+ ,Er 3+ ,1% Eu 3+ nanoparticles was observed by scanning electron microscopy, and the results are as Figure 2 shown. Figure 2 is the scanning electron microscopy image of NaYF 4 :Yb 3+ ,Er 3+ ,1% Eu 3+ nanoparticles.

[0069] As Figure 2 shown, the NaYF 4 :Yb 3+ ,Er 3+ ,1% Eu 3+ nanoparticles synthesized by the hydrothermal method have a uniform spherical morphology and a uniform size distribution, with a particle size of approximately 85 nm. The spherical structure indicates that the crystal preferentially grows along specific crystal directions during growth, forming a regular geometric shape.

[0070] Figure 3 is the energy-dispersive spectrum of NaYF 4 :Yb 3+ ,Er 3+ ,1% Eu 3+ nanoparticles. From Figure 3 the results, it can be seen that the display of all elemental characteristic peaks confirms the successful doping of Yb 3+ ,Er 3+ ,Eu 3+ ions.

[0071] Figure 4 is the fluorescence emission spectrum of NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles under 271 nm excitation. From Figure 4 it can be seen that the fluorescence emission spectrum shows red light emission peaks mainly at 593 nm and 615 nm, which is attributed to the electrons in 5 D 0 - 7 F 1 and 5 D 0 - 7 F 2Transitions between them. Under laser excitation, energy can prompt electrons to transition from the ground state to a higher excited state, and transfer the energy to Eu through a non-radiative energy transfer process 3+ Eu 3+ After receiving the energy, it transitions to the excited state, and then returns to the ground state through radiative transition, emitting strong characteristic visible light. At the same time, the emission intensity increases with the increase of Eu 3+ content, reaching the maximum value when m% = 5%, and then continuously decreasing due to concentration quenching. Therefore, it is determined that the optimal doping content of Eu 3+ is 5%, at which time the highest down-conversion luminescence effect can be obtained. Then, the up-conversion luminescence of NaYF 4 :Yb 3+ ,Er 3+ ,5% Eu 3+ nanoparticles was explored.

[0072] Figure 5 is the fluorescence emission spectrum of NaYF 4 :Yb 3+ ,Er 3+ ,5% Eu 3+ nanoparticles under 980 nm excitation. As Figure 5 , under 980 nm light radiation, Yb 3+ absorbs photons and transitions to 2 F 5 / 2 energy level. Through a non-radiative cross-relaxation process, Yb 3+ transfers the energy to Er 3+ , enabling Er 3+ to transition from 4 I 15 / 2 to a higher excited state, such as 4 I 11 / 2 , 4 I 9 / 2 etc. Er 3+ subsequently returns to the ground state energy level through radiative transition, emitting green emission peaks at 525 nm and 540 nm.

[0073] Next, take NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles, where m% = 1% - 9%, as rare earth luminescent nanoparticles, to further illustrate the color coordinate modulation Logistic mapping encryption method provided by the present invention.

[0074] As Figure 9 and Figure 10 , a color coordinate modulation Logistic mapping encryption method includes the following steps:

[0075] Step 1, prepare and obtain a material or product containing rare earth luminescent nanoparticles; excite the rare earth luminescent nanoparticles with a light source to generate multiple color coordinates.

[0076] Using NaYF 4 :Yb 3+ ,Er 3+ , m% Eu 3+ nanoparticles, where m% = 1% - 9%, as the main rare earth luminescent nanoparticles, prepare and obtain a material or product containing NaYF 4 :Yb 3+ ,Er 3+ , m% Eu 3+ nanoparticles; excite with a light source to obtain the color coordinates of NaYF 3+ with different doping contents of 4 :Yb 3+ ,Er 3+ , m% Eu 3+ nanoparticles. The light source for exciting NaYF 4 :Yb 3+ ,Er 3+ , m% Eu 3+ nanoparticles is a light source with an excitation wavelength of 271 nm or 980 nm. Among them, NaYF 4 :Yb 3+ ,Er 3+ , m% Eu 3+ nanoparticles show red light emission peaks mainly at 593 nm and 615 nm in the fluorescence emission spectrum under 271 nm excitation, and green light emission peaks at 525 nm and 540 nm under 980 nm excitation.

[0077] NaYF 4 :Yb 3+ ,Er 3+ , m% Eu 3+ nanoparticles are obtained by doping Yb 3+ , Er 3+ , Eu 3+ into the NaYF 4 matrix, where m% = 1% - 9%. The color coordinates are denoted as (x, y); the coordinates of the origin are denoted as (0, 0).

[0078] Figure 6 is the color coordinate diagram of NaYF 4 :Yb 3+ ,Er 3+ , m% Eu 3+ . Among them, (b) is a partial enlarged view of the part enclosed by the dashed line in (a). As Figure 6, when m% increases from 1% to 9%, the fluorescence color can be modulated in a jump manner and finally presents a light red state. Figure 6 The (b) diagram of Figure 6 shows Eu with different doping concentrations 3+ The chromaticity coordinate positions under 271 nm laser excitation. Eu with different doping concentrations 3+ The chromaticity coordinates under 271 nm laser excitation are shown in Table 3 and Figure 7 as follows. Figure 7 is NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ The numerical diagram of 5 chromaticity coordinates.

[0079] Table 3 Chromaticity coordinates of Eu with different doping concentrations 3+ under 271 nm laser excitation

[0080] Product Color coordinates <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 1% Eu 3+ > (0.6072，0.3892) <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 3% Eu 3+ > (0.5262，0.3839) <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 5% Eu 3+ > (0.5629，0.3571) <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ ,7%Eu 3+ > (0.5193，0.3553) <![CDATA[NaYF 4 :Yb 3+ ,Er 3+ , 9% Eu 3+ > (0.5398，0.3580)

[0081] Step 2, obtain the initial value and control parameters according to the generated multiple chromaticity coordinates.

[0082] The method for obtaining the initial value is as follows: calculate the generated multiple chromaticity coordinates by the weighted average method to obtain the weighted average chromaticity coordinate; calculate the straight-line distance from the weighted average chromaticity coordinate to the origin according to the weighted average chromaticity coordinate; use the straight-line distance from the weighted average chromaticity coordinate to the origin as the initial value.

[0083] The initial value is denoted as Z 0 ; the initial value is the average of multiple chromaticity coordinates. In the embodiment of the present invention, through five chromaticity coordinates and the weighted average method, the straight-line distance from each weighted average chromaticity coordinate to the origin is calculated as the initial value to be encrypted, so as to determine the initial value Z to be encrypted by the Logistic function mapping 0 .

[0084] Next, the data of the five chromaticity coordinates will be calculated to obtain the initial value Z to be encrypted 0 .

[0085] Step 2.1, set the ordinate of the chromaticity coordinate as the original weight, perform normalization calculation on the original weight to obtain the normalized weights of multiple chromaticity coordinates.

[0086] The normalization calculation formula of the chromaticity coordinate is as follows:

[0087] where ω i is the original weight, is the sum of all original weights, and ω' i is the normalized weight of the i-th chromaticity coordinate.

[0088] Through the above normalization process, the relative importance of each original weight during weighted averaging is ensured to be correct. The normalized weights of the five color coordinates are:

[0089] ω’ 1 = 0.3892 / 1.8335 ≈ 0.2122; ω’ 2 = 0.3839 / 1.8335 ≈ 0.2097; ω’ 3 = 0.3571 / 1.8335 ≈ 0.1949; ω’ 4 = 0.3553 / 1.8335 ≈ 0.1943; ω’ 5 = 0.3580 / 1.8335 ≈ 0.1959.

[0090] Step 2.2: Using the weighted average method, obtain the weighted average color coordinates based on the generated multiple color coordinates. The specific method is as follows: Using the weighted average method, perform a weighted average calculation on the normalized weights of the five color coordinates to obtain the value of the weighted average color coordinates.

[0091] Set the weighted average color coordinates as (weight_x, weight_y).

[0092] The calculation formula of the weighted average method is as follows:

[0093] where x i is the abscissa value of the i-th color coordinate; y i is the ordinate value of the i-th color coordinate; ω’ i is the normalized weight of the i-th color coordinate; weight_x is the abscissa value of the weighted average color coordinates; weight_y is the ordinate value of the weighted average color coordinates.

[0094] The calculated values of weight_x and weight_y are approximately 0.5053 and 0.4436 respectively.

[0095] It should be noted that the precision of the actually calculated values of weight_x and weight_y is too high. For the convenience of demonstration, the calculation is shown here by intercepting four decimal places.

[0096] Step 2.3: Calculate the straight-line distance from the weighted average color coordinates to the origin; use the straight-line distance from the weighted average color coordinates to the origin as the initial value.

[0097] The calculation formula for the straight-line distance from the weighted average color coordinates to the origin is as follows:

[0098] Among them, weight_x is the abscissa value of the weighted average color coordinate; weight_y is the ordinate value of the weighted average color coordinate; Z 0 is the initial value.

[0099] Substitute weight_x and weight_y into the calculation formula of the straight-line distance from the weighted average color coordinate to the origin, and calculate that the straight-line distance from the weighted average color coordinate to the origin is 0.4521. Take the straight-line distance from the weighted average color coordinate to the origin as the initial value to be encrypted, that is, Z 0 = 0.4521.

[0100] Step 2.4, determine the control parameter.

[0101] Set the control parameter to μ, then 3 < μ ≤ 4, showing a chaotic mapping state.

[0102] Generally, chaotic characteristics appear when the value of μ is close to 4. Therefore, when the value of the control parameter μ is close to 4, or μ = 4, a one-dimensional chaotic mapping generates a chaotic sequence. In the embodiment of the present invention, when the value of the control parameter μ is close to 4, or μ = 4, it will enter the chaotic mapping, reducing the calculation time.

[0103] Step 3, construct a one-dimensional chaotic mapping, and based on the one-dimensional chaotic mapping, the initial value, and the control parameter, obtain a chaotic sequence, and use the chaotic sequence as the key stream; use the color coordinate as the plaintext block, then multiple color coordinates correspond to multiple plaintext blocks, and use the key stream to encrypt the multiple plaintext blocks through the AES symmetric encryption algorithm to complete the Logistic mapping encryption of the color coordinate modulation, and obtain the ciphertext to be transmitted.

[0104] The mathematical expression of the one-dimensional chaotic mapping is:

[0105] Z n+1 = μZ n (1 - Z n ); among them, Z n+1 is the chaotic sequence value after n + 1 iterations; Z n is the chaotic sequence value after n iterations; μ is the control parameter; n is the number of iterations. The one-dimensional chaotic mapping is constructed based on the Logistic mapping.

[0106] Determine the initial value Z 0After that, by controlling the value of the parameter μ, the function mapping is made to enter the chaotic region. For example, when 3.5699456.. < μ ≤ 4, the mapping enters the chaotic region. Among them, 3.5699456.. is the Feigenbaum constant, and the Chinese name of the Feigenbaum constant is the Feigenbaum constant; it means the transition point from periodic behavior to chaotic behavior. Near this transition point, the system will exhibit extremely complex dynamic behaviors and is used to generate chaotic sequences.

[0107] The test data is that since the Logistic mapping does not enter the chaotic mapping state when μ = 3.7, the sequence may not exhibit chaotic characteristics. Usually, chaotic characteristics appear when the value of μ is close to 4. Therefore, when the value of the control parameter μ is close to 4 or μ = 4, the one-dimensional chaotic mapping generates a chaotic sequence.

[0108] In the embodiment of the present invention, by controlling the value of the parameter μ to be close to 4 or μ = 4, it will enter the chaotic mapping, reducing the calculation time.

[0109] For example, when the initial value is Z 0 = 0.4521 and the control parameter is μ = 4, substituting the initial value and the control parameter into the one-dimensional chaotic mapping equation Z n+1 = μZ n (1 - Z n ), iterative calculations are performed to generate a chaotic sequence. The following are the results of the first 10 iterative calculations:

[0110] Z 1 = 4×0.8543×(1 - 0.8543); Z 2 = 4×Z 1 ×(1 - Z 1 );......; Z 10 = 4×Z 9 ×(1 - Z 9 ).

[0111] Table 4 Iterative Chaotic Sequence Table of Logistic Mapping with Different Iteration Times

[0112]

[0113]

[0114] Figure 8 is the connection diagram of the iterative chaotic sequence values of the Logistic mapping with different iteration times.

[0115] Combined with Table 4 and Figure 8 It can be seen that due to the sensitivity of the chaotic sequence, even the initial value Z 0Minor changes will also result in significant differences in the chaotic sequence. Therefore, an approximate chaotic sequence is provided here. The actual chaotic sequence will depend on precise iterative calculations, with the actual number of iterations being higher than 10,000. So, the data of ten iterations is shown here for easy observation. In practical applications, more precise values should be used to avoid cumulative errors as the key stream.

[0116] Although existing Logistic map encryption methods utilize some advantages of chaos theory, some methods in practical applications may overly rely on the chaotic characteristics of the Logistic map, thus not considering the predictability and stability requirements during the application process. A large amount of computing resources may affect the encryption and decryption efficiency according to the characteristics at high iteration times. Therefore, in the embodiments of the present invention, by optimizing the parameter process of Logistic map encryption, through the analysis of parameters, it is determined which parameter values can generate the required chaotic behavior while maintaining system stability. The encryption algorithm is associated with color coordinates, improving the computing efficiency while enhancing the usability and security of the encryption method. For example, when the value of the control parameter μ is close to 4, or μ = 4, it will enter the chaotic map, reducing the computing time.

[0117] Figure 9 is the flowchart of AES plaintext encryption. Figure 10 is the flowchart of plaintext block encryption. Figure 9 The plaintext is the set of color coordinates {(0.6072, 0.3892), (0.5262, 0.3839), (0.5629, 0.3571), (0.5193, 0.3553), (0.5398, 0.3580)}. A plaintext block is a fixed-size data unit into which the original plaintext data, i.e., the data to be encrypted, is divided during the encryption process. Figure 9 and Figure 10 Plaintext blocks 1 to 5 respectively correspond to the five color coordinates. The plaintext blocks are encrypted according to the generated key. Figure 11 is the encryption result graph. Figure 12 is the comparison histogram of the original image and the encrypted image. Among them, (A) is the histogram of the original image; (B) is the histogram of the encrypted image.

[0118] In the embodiments of the present invention, image encryption is performed through the Logistic map. Based on the introduction of different Eu3+ contents and the corresponding chromaticity coordinates, an initial value is calculated and determined, and the initial value is the average of the color coordinates corresponding to the five concentrations. In the embodiments of the present invention, by encrypting the initial value and the control parameter, the encryption intensity is improved. The combination of plaintext blocks and AES symmetric encryption realizes a secure data transmission and decryption process. The normalized modulation and encryption of color coordinates can significantly improve the security of the encrypted image, making it more difficult to crack.

[0119] The decryption process is as follows:

[0120] During the decryption process, the ciphertext to be transmitted, which is also the password book, and each ciphertext block can be regarded as an identification code. The key stream is used to decrypt multiple ciphertext blocks through the AES symmetric encryption algorithm to obtain multiple decrypted ciphertexts. For the material or product to be detected containing rare earth luminescent nanoparticles, multiple color coordinates are generated by exciting the rare earth luminescent nanoparticles with a light source, that is, multiple ciphertexts of the material or product to be detected are obtained; the multiple decrypted ciphertexts are compared with the multiple ciphertexts of the material or product to be detected. When the multiple decrypted ciphertexts match the multiple ciphertexts of the material or product to be detected, it is thus verified that the material or product to be detected matches the material or product decrypted from the ciphertext to be transmitted. The encryption algorithm of the present invention can be widely applied to the authenticity identification of materials or products.

[0121] In the scenario, the excitation wavelength of 271 nm or 980 nm is the key factor affecting the luminescence color of the sample. Different excitation wavelengths will cause the sample to emit light of different colors, and these colors are related to the concentration of Eu 3+ ions doped in the sample. Therefore, at the beginning of decryption, a checkpoint is added to the system. When attempting to perform a decryption operation, the system first checks the current excitation wavelength. If the excitation wavelength does not meet the preset values, such as 271 nm or 980 nm, the decryption process will not be triggered.

[0122] The embodiment of the present invention takes the excitation wavelength as a prerequisite for decryption, adding an additional security level. Even if someone obtains the encrypted data and the key, without using the correct excitation wavelength, the information cannot be decrypted.

[0123] In the embodiment of the present invention, the acquisition of color coordinates requires excitation with a 271 nm or 980 nm light source. The excitation wavelength is determined by NaYF 3+ doped with different contents of Eu 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles. As Figure 4 and Figure 5 , NaYF 4 :Yb 3+ ,Er 3 + ,m% Eu 3+ nanoparticles show red emission peaks mainly at 593 nm and 615 nm in the fluorescence emission spectrum under 271 nm excitation; NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles emit green emission peaks at 525 nm and 540 nm under 980 nm excitation.

[0124] After using the correct excitation wavelength, perform the steps opposite to the AES encryption process for decryption.

[0125] When obtaining the key and all ciphertext blocks required for decryption, the same AES encryption mode as used during encryption needs to be used for the reverse operation. Each ciphertext block undergoes an operation to recover the data block using the same key. After completing the above decryption operation, the original plaintext information is obtained, thus completing the decryption.

[0126] For example, Figure 12 is the decryption flowchart. The usage mode mentioned above is the ECB cipher block mode. The full English name of ECB is Electronic Codebook, and the Chinese name is Electronic Cipher Book. As Figure 11 , the key is:?}\xa6\x89=\x14\xfc\x88>\x0f\x918>\xf6\xe0\xa9.

[0127] It should be noted that during the entire decryption process, for the secure transportation of key information and the security of ciphertext storage, prevent unauthorized access.

[0128] The receiving party uses its own RSA private key to decrypt the received RSA-encrypted AES key to obtain the decrypted key. Then, this decrypted key is used to decrypt the data to obtain the decrypted initial value and variables, as well as the color coordinates obtained from the reverse operation, and the coordinate image on the final color disk can be obtained.

[0129] In the above embodiments of the present invention, based on NaYF 4 :Yb 3+ ,Er 3+ ,m% Eu 3+ nanoparticles' efficient dual-mode emission characteristics and adjustable color coordinates, the potential applications in advanced information encryption in the visible-invisible region are prospected. To improve practicality and flexibility, an algorithm coding form and flexible encryption information features are designed. By optimizing the parameter process of Logistic map encryption, analyzing the parameter space, determining that the parameter values can generate the required chaotic behavior while maintaining system stability, associating the encryption algorithm with the color coordinates, while improving the calculation efficiency, the usability and security of the encryption method are improved.

[0130] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A color coordinate modulated Logistic mapping encryption method, characterized in that: The following steps are involved: The rare earth luminescent nanoparticles on the target object are excited by a light source to generate multiple color coordinates; Obtaining initial values ​​and control parameters based on the generated multiple color coordinates; Constructing a one-dimensional chaotic map, and obtaining a chaotic sequence based on the one-dimensional chaotic map, an initial value and a control parameter, and using the chaotic sequence as a key stream; Taking the color coordinates as the plaintext blocks, multiple color coordinates correspond to multiple plaintext blocks. The multiple plaintext blocks are encrypted by the AES symmetric encryption algorithm using the key stream to complete the Logistic mapping encryption of the color coordinate modulation to obtain the ciphertext to be transmitted.

2. The color coordinate modulated Logistic mapping encryption method according to claim 1, characterized in that: The method to obtain the initial value is as follows: The generated multiple color coordinates are calculated using a weighted average method to obtain a weighted average color coordinate; According to the weighted average color coordinates, the straight-line distance from the weighted average color coordinates to the origin is calculated; The straight-line distance from the weighted average color coordinate to the origin is taken as the initial value.

3. The color coordinate modulated Logistic mapping encryption method according to claim 2, characterized in that: Set the weighted average color coordinates to (weight_x, weight_y); The calculation formula of the weighted average method is as follows: Among them, x i is the abscissa value of the i-th color coordinate; y i is the ordinate value of the i-th color coordinate; ω' i is the normalized weight of the ith color coordinate; weight_x is the abscissa value of the weighted average color coordinate; weight_y is the ordinate value of the weighted average color coordinate.

4. The color coordinate modulated Logistic mapping encryption method according to claim 3, characterized in that: The calculation formula of the straight-line distance from the weighted average color coordinate to the origin is as follows: Among them, weight_x is the abscissa value of the weighted average color coordinate; weight_y is the ordinate value of the weighted average color coordinate; Z0 is the initial value.

5. The color coordinate modulated Logistic mapping encryption method according to claim 1, characterized in that: When the control parameter is set to μ, then 3<μ≤4, it manifests as a chaotic mapping state.

6. The color coordinate modulated Logistic mapping encryption method according to claim 4, characterized in that: The mathematical expression of one-dimensional chaotic mapping is: Z n+1 =μZ n (1-Z n ); Among them, Z n+1 is the chaotic sequence value after n+1 iterations; Z n is the chaotic sequence value iterated n times; μ is the control parameter; n is the number of iterations; the one-dimensional chaotic map is constructed based on the Logistic map.

7. The color coordinate modulated Logistic mapping encryption method according to claim 1, characterized in that: The rare earth luminescent nanoparticles are NaYF4:Yb 3+ ,Er 3+ ,m%Eu 3+ Nanoparticles, wherein m% = 1% to 9%.

8. The color coordinate modulated Logistic mapping encryption method according to claim 7, characterized in that: Excite the NaYF4:Yb 3+ ,Er 3+ ,m%Eu 3+ The light source of the nanoparticles is a light source with an excitation wavelength of 271 nm or 980 nm.

9. The color coordinate modulated Logistic mapping encryption method according to claim 7, characterized in that: The target object is a material or product containing rare earth luminescent nanoparticles.

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