An authentication system and method based on pseudo-random watermark superposition
By switching between the pseudo-random watermark overlay module and the authentication module in a wireless communication system, and combining the watermark overlay of messages and pilot signals, the vulnerability of identity authentication in wireless communication systems to attacks is solved, achieving efficient and secure identity authentication.
Patent Information
- Application Number
- CN202310227414.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-10
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2043-03-10
AI Technical Summary
Wireless communication systems are vulnerable to interception and spoofing attacks in identity authentication. Existing watermark overlay methods suffer from access delays and authentication uncertainties, making it difficult to achieve efficient and secure identity authentication.
A pseudo-random watermark overlay module is used to switch between messages and pilot signals to generate a random sequence and overlay the watermark signal. Combined with the authentication module, identity authentication is performed, which increases the uncertainty for attackers and improves security.
It achieves identity authentication with low false detection and low false alarm rates, improving the security and efficiency of the authentication scheme and reducing the difficulty of attacks.
Smart Images
Figure CN116489644B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of network security, in particular to a switching authentication system and method based on watermark superposition authentication in a network. BACKGROUND
[0002] The description in this section merely provides background information related to the present disclosure and does not constitute the prior art.
[0003] Due to the open broadcast nature of radio signal propagation and the use of standardized transmissions, wireless communication systems are highly susceptible to interception and spoofing attacks. Therefore, secure communication needs to verify whether the received message is sent by a legitimate agent, and to authenticate its identity. Therefore, identity authentication is mandatory in secure communication to ensure the legitimacy of both parties.
[0004] Physical layer authentication technology takes full advantage of the characteristics of the physical layer, superimposes authentication information, watermark signal, on the transmitted signal, so as to realize identity authentication without additional bandwidth and complex calculation. Message watermarking is to generate a watermark by hashing the transmitted message and the key, and to superimpose the watermark on the message according to the power allocation factor. The receiving end generates a watermark after recovering the data, and then authenticates the received information through the watermark. The authentication performance of message watermarking is good, but the method of superimposing watermark on the message needs channel estimation and message recovery before message authentication, resulting in a long access delay.
[0005] Pilot watermarking is to generate a watermark by hashing the pilot and the key, and then superimpose the watermark on the pilot signal. The receiving end generates a watermark using the pilot signal and authenticates the received information. The pilot watermarking method is easy for the receiving end to authenticate the transmitter without message recovery, and it is difficult for attackers to decode the tag watermark, enhancing the concealment of the authentication information. The watermark embedded in the pilot signal is also considered as interference to the channel estimation and equalization of the wireless communication system, but compared with message watermarking, this method does not need to recover the message, so it has the advantage of low delay.
[0006] The above introduction to the technical background is only to facilitate a clear and complete description of the technical solutions of the present application, and to facilitate the understanding of those skilled in the art. It cannot be considered that the above technical solutions are known to those skilled in the art just because they are described in the background section of the present application. SUMMARY
[0007] In order to solve the above-mentioned problems while utilizing the advantages of the message superimposed watermark and pilot superimposed watermark methods, and on this basis to improve the security of identity authentication, the application proposes a pseudo-random watermark superimposed authentication system and method for identity authentication. Based on the generated random sequence, the switching module is used to switch between the message superimposed watermark and pilot superimposed watermark authentication methods in real time. Based on the traditional watermark authentication scheme, the switching selection authentication scheme increases the uncertainty of the attacker to the authentication scheme, thereby further improving the security performance of the authentication scheme.
[0008] In order to achieve the above-mentioned purposes, the application adopts the following technical solutions:
[0009] An authentication system based on pseudo-random watermark superposition includes:
[0010] A pseudo-random watermark superposition module and an authentication module.
[0011] The pseudo-random watermark superposition module generates a random sequence based on a random seed, and superimposes the generated watermark signal on the transmitted pilot signal or message signal based on the sequence,
[0012] The authentication module switches the authentication mode of the watermark signal based on the sequence generated by the random seed and the generated watermark signal.
[0013] The application example proposes an authentication method using the above-mentioned system, which includes the following steps:
[0014] The pseudo-random watermark superposition module generates a watermark signal based on a key and the transmitted signal, and generates a pseudo-random watermark superposition sequence,
[0015] If the watermark superposition sequence represents message superimposed watermark, the pseudo-random watermark superposition module generates a watermark signal based on a key and a message signal, and superimposes the watermark signal on the message signal;
[0016] If the watermark superposition sequence represents pilot superimposed watermark, the pseudo-random watermark superposition module generates a watermark signal based on a key and a pilot signal, and superimposes the watermark signal on the pilot signal;
[0017] The authentication module performs identity authentication based on the same watermark signal and pseudo-random watermark superposition sequence.
[0018] In an embodiment, the pseudo-random watermark superposition module and the authentication module can generate the same pseudo-random watermark superposition sequence based on the same random number seed, which is used to determine the type of watermark signal that needs to be generated / authenticated.
[0019] In an embodiment, the generation method of the watermark signal of the transmitting device includes generating a pilot superimposed watermark signal and generating a message superimposed watermark signal,
[0020] The signal with pilot superimposed watermark includes:
[0021] 1) generating watermark t based on given pilot and key via hash function:
[0022] First, get the hash value S of pilot and key via hash function f(·) P =f(p,k); then convert the hash value S P from string to n-ary data; finally, intercept the n-ary data with the same specification as the pilot and perform corresponding modulation to obtain the superimposed watermark t.
[0023] 2) superimpose watermark on pilot signal based on preset superimposition coefficient: given pilot P, based on message m, generated watermark t and power allocation factor P t , the watermark signal X1=[P s *P+P t *t,m] can be generated.
[0024] In an embodiment, the signal with message superimposed watermark includes:
[0025] Generating watermark t based on given message and key via hash function,
[0026] Superimpose watermark on message signal based on preset superimposition coefficient: superimpose watermark on message signal based on preset superimposition coefficient: given pilot P, based on message m, generated watermark t and power allocation factor P t , the watermark signal X2=[P,P t *t+P s *m] can be generated.
[0027] In an embodiment, the authentication method of watermark signal by the receiving device includes: pilot superimposed watermark signal authentication and message superimposed watermark signal authentication,
[0028] The pilot superimposed watermark signal authentication includes:
[0029] Generating expected watermark t1 based on given pilot and key via hash function,
[0030] Based on the generated watermark and the received signal for authentication:
[0031] Given pilot P=(p1,p2,...,p L ), received information pilot part P r =(p 1r ,p 2r ,...,p Lr ),
[0032] First, get the hash value H r =P r *PH (P*P H ) obtain estimated channel H r where (·) H denotes conjugate transpose;
[0033] Then, the watermarked pilot signal P rt is recovered by
[0034] Secondly, the recovered watermark t r1 is obtained by rt = (P s - P t * P) / P r1
[0035] Finally, the authentication is performed based on the recovered watermark t r1 and the expected watermark t1.
[0036] If the inner product of the recovered watermark t r1 and the expected watermark t1 for each data block in the same frame (where T denotes transpose) is greater than a threshold value, denoted as τ > τ 01 , the verification is a legal device, otherwise, the verification is an illegal device.
[0037] In an embodiment, the message watermarked signal authentication includes:
[0038] Based on the received message, the message is recovered:
[0039] Given the pilot P, the received information pilot part P r and the received information message part M r are obtained.
[0040] First, the estimated channel H r is obtained by the pilot P and the received signal pilot part P r .
[0041] Then, the watermarked message signal M rt is recovered by
[0042] Finally, the correct transmission information m2 can be obtained by the receiver according to the recovered watermarked message signal M rt and the corresponding demodulation mode.
[0043] Based on the recovered message m2 and the key, the expected watermark t2 is generated by a hash function.
[0044] Based on the recovered watermarked message signal M rt and the recovered message m2, the watermark t r2 = (M rt - Ps *m2) / P t Get the watermark restored. r2 ;
[0045] Based on watermark recovery r2 Authenticate with the expected watermark t2:
[0046] If for each data block in the same frame, the watermark is recovered... r2 And the expected watermark t2 inner product (Where T represents the transpose) greater than a threshold is denoted as τ>τ 02 If the result is positive, the device is verified as legitimate; otherwise, it is verified as illegitimate.
[0047] In one embodiment, a pair of communication devices recover and verify each other's signals. If the received signal of each data block in the data frame of the device being authenticated and the statistical test value of the recovered watermark are greater than the threshold for watermark authentication, denoted as τ>τ0, then the device is authenticated as legitimate; otherwise, it is authenticated as an attacker.
[0048] In one embodiment, the device via
[0049] P MD (τ)=(P(τ>τ0|Φ1)) C and P FA (τ)=1-(P(τ>τ0|Φ0)) C
[0050] Calculate the theoretical false detection rate and theoretical false alarm rate of the watermark signal authentication method.
[0051] Where τ is the statistical estimate of the watermark signal, τ0 is the physical layer authentication threshold, Φ1 and Φ0 represent the attacker and the legitimate device, respectively, and C is the number of data blocks contained in each frame.
[0052] Beneficial effects
[0053] Compared with the prior art, the pseudo-random watermark overlay authentication scheme for identity authentication in this application combines the advantages of message overlay watermarking method and pilot overlay watermarking method, and can achieve more efficient and secure communication. Attached Figure Description
[0054] To more clearly illustrate the technical solutions in this disclosure or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0055] Figure 1A function flowchart of the switching authentication implementation of the embodiment of the present application;
[0056] Figure 2 A P Figure 1 A flowchart of the switching authentication implementation of the embodiment of the present application;
[0057] Figure 3 A P t The false alarm rate comparison results between different methods when the false alarm rate is 0.1;
[0058] Figure 4 A P t The false alarm rate comparison results between different methods when the false alarm rate is 0.1. DETAILED DESCRIPTION
[0059] The above scheme will be further described in combination with specific embodiments. It should be understood that these embodiments are used to illustrate the present application and do not limit the scope of the present application. The implementation conditions used in the embodiments can be further adjusted according to the specific manufacturer's conditions, and the implementation conditions not mentioned are usually the conditions in the conventional experiments.
[0060] The present application discloses an authentication system and method based on pseudo-random watermark superposition. The system includes a pseudo-random watermark superposition module, which generates a watermark signal based on a key and a transmission signal, and superimposes the watermark signal on a message signal and a pilot signal based on the generated pseudo-random watermark superposition sequence, greatly increasing the randomness of the identity authentication information and method and thus improving the security of the authentication scheme. The receiving end performs authentication based on the same pseudo-random watermark superposition sequence and watermark signal. This method improves the security of identity authentication and can be widely applied in wireless networks.
[0061] The present application discloses an authentication system based on pseudo-random watermark superposition, including a transmitting device and a receiving device, and identity authentication between the transmitting device and the receiving device. A pseudo-random watermark superposition module is placed in the transmitting device, and an authentication module is placed in the receiving device.
[0062] Next, the authentication method based on pseudo-random watermark superposition proposed by the present application will be described in combination with the accompanying drawings.
[0063] As Figure 1 and Figure 2 The flowchart of the authentication method based on pseudo-random watermark superposition is shown, which includes the following steps:
[0064] 1) Initialization: The initialization of the wireless communication system and the generation of system parameters, including:
[0065] 1-1 Determination of random number seed: The transmitting end and the receiving end determine the same random number seed in order to generate the same pseudo-random sequence subsequently;
[0066] 1-2 Determination of watermark superimposition power factor: the transmitting end and the receiving end determine the same watermark superimposition power factor, so that the receiving end more accurately restores the watermark signal;
[0067] 1-3 Determination of key and hash function: the transmitting end and the receiving end determine the same key and hash function, to ensure that the transmitting end and the receiving end generate the same watermark based on the same pilot signal or message signal.
[0068] 2) Pseudo-random watermark superimposition module: the pseudo-random watermark superimposition module includes random sequence generation and watermark signal generation.
[0069] 2-1 Pseudo-random watermark superimposition module generates a binary pseudo-random sequence (such as (i1, i2,..., in) based on a random number seed (such as s). K , where k represents the number of data blocks contained in a data frame, i k ∈{0,1}) is used to determine the type of watermark signal that needs to be generated. (such as 0 represents a pilot superimposed watermark signal, and 1 represents a message superimposed watermark signal.)
[0070] 2-2 Watermark generation: including generating a pilot superimposed watermark signal and generating a message superimposed watermark signal.
[0071] Generating a pilot superimposed watermark signal includes:
[0072] 2-3 Generating a watermark based on a pilot and a key and a hash function.
[0073] For example, given a pilot P, a key k, and a hash function f(·),
[0074] First, use the hash function f(·), such as the SHA-256 algorithm, to obtain the hash value of the pilot and the key: S P = f(p, k); then convert the hash value S P from a string to n-ary data (such as binary); finally, truncate the n-ary data of the same specification as the pilot and perform corresponding modulation (such as 2BPSK symbols represented by ±1, QPSK symbols represented by ±1, ±i) to obtain the superimposed watermark t1.
[0075] 2-4 Generating a pilot superimposed watermark signal using the watermark t1.
[0076] For example, given a message m, a watermark t1 generated based on a pilot P, and a power allocation factor P t , a watermark signal X1 = [P s *P + P t *t1, m] can be generated. Where * represents multiplication, [a, b] represents sequentially connecting a and b, P t is a watermark power allocation factor, satisfying and 1 > Ps P t >0.
[0077] The signal with message superimposed watermark includes:
[0078] 2-5 Generate watermark based on message and key and hash function.
[0079] For example, given message m, key k, hash function f(·),
[0080] The same as generating watermark based on pilot and key and hash function. First, use hash function f(·) to obtain the hash value of key and message m: S p =f(m,k); then convert the hash value S p from string to n-ary data; finally, intercept the n-ary data of the same specification as the message and perform corresponding modulation to obtain superimposed watermark t2.
[0081] 2-6 Generate message superimposed watermark signal using watermark t2.
[0082] For example, given pilot P, based on message m, generated watermark t2 and power allocation factor P t , the watermark signal X2=[P,P t *t2+P s *m] can be generated.
[0083] 3) Authentication module: the authentication module includes message type judgment and watermark signal authentication.
[0084] 3-1 Generate a binary pseudo-random sequence based on the same random number seed as the transmitting end, which is used to determine the watermark type of the received signal.
[0085] 3-2 Based on the determined signal watermark type, select the corresponding pilot superimposed watermark authentication or message superimposed watermark authentication mode.
[0086] Pilot superimposed watermark authentication includes:
[0087] 3-3 Generate expected watermark t1 based on pilot, key and hash function.
[0088] 3-4 Obtain recovered watermark t r1 based on the pilot and the pilot part of the received information.
[0089] For example, given pilot P=(p1,p2,...,p L ), the pilot part of the received information P r =(p 1r ,p 2r ,...,p Lr ).
[0090] First, H r =Pr *P H / (P*P H ) obtain the estimated channel H r , where (·) H denotes the conjugate transpose.
[0091] Then, the watermarked pilot signal P rt is recovered by .
[0092] Finally, the recovered watermark t r1 is obtained by rt = (P s -P t *P) / P r1 .
[0093] 3-5 Authentication based on the recovered watermark t r1 and the expected watermark t1.
[0094] If the inner product of the recovered watermark t r1 and the expected watermark t1 for each data block in the same frame (where T denotes the transpose) is greater than a threshold value, denoted as τ > τ 01 , then the device is verified as legal, otherwise it is verified as illegal.
[0095] Message watermarking authentication includes:
[0096] 3-6 Recover the message m2 based on the pilot and received information and generate the expected watermark t2:
[0097] Given the pilot P, the received information pilot part P r , and the received information message part M r .
[0098] First, the estimated channel H r is obtained by r using the pilot P and the received information pilot part P
[0099] Then, the watermarked message signal M rt is recovered by .
[0100] Second, the correct transmission information m2 is obtained by the receiving end based on the recovered watermarked message signal M rt and the corresponding demodulation method.
[0101] Finally, the expected watermark t2 is generated based on the recovered message m2, the key, and the hash function.
[0102] 3-7 Based on the recovered watermarked message signal M rt and the recovered message m2, the tr2 =(M rt -P s *m2) / P t Get the watermark restored. r2 ;
[0103] 3-8 Based on watermark recovery r2 Authenticate with the expected watermark t2.
[0104] If for each data block in the same frame, the watermark is recovered... r2 And the expected watermark t2 inner product If the value is greater than a threshold, it is denoted as τ>τ 02 If the device passes the verification, it is considered a legitimate device; otherwise, it is considered an illegitimate device. The device passes through P... MD (τ)=(P(τ>τ0|Φ1)) C and P FA (τ)=1-(P(τ>τ0|Φ0)) C Calculate the theoretical false detection rate and theoretical false alarm rate of the watermark signal authentication method, where Φ1 and Φ0 represent the attacker and the legitimate device, respectively, and C is the number of data blocks contained in each frame.
[0105] The proposed scheme will be evaluated through experimental simulation and numerical studies.
[0106] A. Experimental conditions:
[0107] A simulated authentication scenario is created by randomly positioning one transmitter, one receiver, and one attacker. The receiver moves randomly, with the distance between the receiver and transmitter increasing from 50m to 500m. The signal transmission power is P0 = 20dB, the receiver noise is -70dB, and the channel attenuation model is as follows. (Where d is the distance between the receiver and the transmitter / attacker, in meters), and the total signal strength P received by the receiver. rec =P0-P L (Unit: dB), pilot length 512, message length 1024, each frame contains 8 data blocks.
[0108] B. Experimental Procedure:
[0109] 1) The performance of message overlay watermarking and pilot overlay watermarking schemes was evaluated. A power allocation factor P was set. t =0.1, the traditional message overlay watermark authentication threshold is 512, and the traditional pilot overlay watermark authentication threshold is 256. In the pseudo-random watermark overlay scheme proposed in this application, the message overlay watermark authentication threshold is 140, and the pilot overlay watermark authentication threshold is 90.
[0110] 2) Compare the false alarm rate of the three methods of the disclosed scheme, message superimposed watermark authentication and pilot superimposed watermark. In different distance conditions, the three schemes are transmitted without superimposed watermark, and if the receiving end authenticates the legal, it is determined that the authentication is wrong, and finally the ratio of the number of authentication errors to the total number of authentication is taken as the experimental data of the system false alarm rate.
[0111] 3) Compare the authentication performance of legal users with distance changes between different methods. In different distance conditions, the corresponding legal authentication messages of the three schemes are transmitted, and if the receiving end authenticates the illegal, it is determined that the authentication is wrong, and finally the ratio of the number of authentication errors to the total number of authentication is taken as the experimental data of the system false alarm rate.
[0112] B. Experimental results:
[0113] From Figure 3 it can be seen that the scheme proposed in the present application alternately uses message superimposed watermark and pilot superimposed watermark, and requires that each frame of data block is authenticated, and the false alarm rate is lower than that of the traditional message superimposed watermark and pilot superimposed watermark. The reason is that the scheme requires that each frame of data block is authenticated, which increases the difficulty of attack for the attacker, and the alternating authentication scheme further increases the uncertainty of the attacker to the scheme. The scheme proposed in the present application can realize authentication with extremely low false alarm rate, and realizes reliable security authentication quality in identity authentication.
[0114] From Figure 4 it can be seen that the false alarm rate of the scheme proposed in the present application is lower than that of the traditional message superimposed watermark and pilot superimposed watermark. The false alarm rate of the scheme proposed in the present application is lower than that of the two traditional schemes, and has better authentication performance. The pseudo-random watermark superimposed authentication scheme has better performance in false alarm rate and false alarm rate, and realizes reliable security authentication quality in identity authentication.
[0115] As described above, the method of pilot superimposed watermark has low delay, but high false alarm rate, and the scheme of message superimposed watermark has low false alarm rate and false alarm rate, but high delay. Therefore, the scheme of the present application combines the two schemes, and improves the authentication unit from data block to data frame, and realizes the identity authentication meeting the security quality of service.
[0116] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent transformation or modification made in the spirit and essence of the present application should be covered within the protection scope of the present application.
Claims
1. An authentication system based on pseudo-random watermark overlay, characterized in that, include: Pseudo-random watermark overlay module and authentication module; The pseudo-random watermark overlay module generates a random sequence based on a random seed, and overlays the generated watermark signal onto the transmitted pilot signal or message signal based on the random sequence. The authentication module is used to generate a binary pseudo-random sequence to determine the watermark type of the received signal, and based on the determined watermark type, select the corresponding pilot superimposed watermark authentication or message superimposed watermark authentication, including the following steps: generating a signal for pilot superimposed watermark and generating a signal for message superimposed watermark; The signal that generates the pilot superimposed watermark includes: generating the watermark based on the pilot, key, and hash function; The watermark generation based on pilot P, key k, and hash function includes: First, use the hash function f(·) to obtain the hash value S of the pilot and the key. P =f(P,k); then hash value S P The string is converted into n-ary data; finally, the n-ary data with the same specifications as the pilot signal is extracted and modulated accordingly to obtain the superimposed watermark t1; Using watermark t1, a pilot-superimposed watermark signal is generated, including: Given a message m, generate a watermark t1 and a power allocation factor P based on the pilot P. t and P s Generate watermark signal X1 = [P s *P+P t *t1,m]; Where * indicates multiplication, P t and P s Let P be the watermark power allocation factor, satisfying P s 2 +P t 2 =1, and 1>P s ,P t >0.
2. The authentication system based on pseudo-random watermark overlay according to claim 1, characterized in that, The pseudo-random watermark overlay module and the authentication module generate the same pseudo-random watermark overlay sequence i1,i2,...,i based on the same random seed. K Where k represents the number of data blocks contained in a data frame, i k ∈{0,1} is used to determine the type of watermark signal that needs to be generated and authenticated.
3. The authentication system based on pseudo-random watermark overlay according to claim 1, characterized in that, The pseudo-random watermark overlay module generates a watermark signal based on the key and the transmitted signal, and generates a pseudo-random watermark overlay sequence. The authentication module performs identity authentication based on the same watermark signal and pseudo-random watermark overlay sequence as the pseudo-random watermark overlay module.
4. The authentication system based on pseudo-random watermark overlay according to claim 3, characterized in that, The authentication signal for generating the superimposed watermark in the pseudo-random watermark superposition module includes: generating a pilot superimposed watermark signal and generating a message superimposed watermark signal.
5. The authentication system based on pseudo-random watermark overlay according to claim 4, characterized in that, The signals that generate the pilot superimposed watermark include: 1) Generate a watermark based on a given pilot signal and key using a hash function: First, use the hash function f(·) to obtain the hash value S of the pilot signal and key. P =f(p,k), then the hash value S P The string is converted into n-ary data, the n-ary data of the same specification as the pilot signal is extracted and modulated accordingly to obtain the superimposed watermark t; 2) The watermark is superimposed onto the pilot signal based on a preset superposition coefficient: Using a given pilot P, and based on message m, the generated watermark t, and power allocation factor P t The watermark signal X = [P] is generated. s *P+P t *t,m]; Where * indicates multiplication, [a,b] indicates concatenating a and b in sequence, P t Let P be the watermark power allocation factor, satisfying P s 2 +P t 2 =1, and 1>P s ,P t >0.
6. The authentication system based on pseudo-random watermark overlay according to claim 4, characterized in that, The pseudo-random watermark overlay module generates the signal for message overlay watermarking, including: A watermark t is generated based on a given message and key using a hash function; Then, the watermark is superimposed onto the message signal based on a preset superposition coefficient: The watermark is superimposed on the message signal based on a preset superposition coefficient: given the pilot frequency P, based on the message m, the generated watermark t, and the power allocation factor P t Generate watermark signal X2 = [P, P t *t+P s *m].
7. An authentication method based on pseudo-random watermark overlay, characterized in that, The method includes the following steps: A pseudo-random watermark overlay module is used to generate a pseudo-random sequence and an overlaid watermark signal, which are then transmitted to the authentication module. The authentication module determines the signal watermark type and selects the corresponding pilot superimposed watermark authentication or message superimposed watermark authentication, including the following steps: Watermark generation: including signals that generate pilot superimposed watermarks and signals that generate message superimposed watermarks; The signal that generates the pilot-superimposed watermark includes: generating the watermark based on the pilot, key, and hash function, including: Given a pilot signal P, a key k, and a hash function f(·), First, use the hash function f(·) to obtain the hash value of the pilot and the key: S P =f(P,k); then hash value S P The string is converted into n-ary data; finally, the n-ary data with the same specifications as the pilot signal is extracted and modulated accordingly to obtain the superimposed watermark t1; Using watermark t1, a pilot-superimposed watermark signal is generated, including: Given a message m, generate a watermark t1 and a power allocation factor P based on the pilot P. t and P s Generate watermark signal X1 = [P s *P+P t *t1,m]; where * indicates multiplication, P t Let P be the watermark power allocation factor, satisfying P s 2 +P t 2 =1, and 1>P s ,P t >0; The signals that generate message-overlay watermarks include: watermark generation based on the message, key, and hash function; Given a message m, a key k, and a hash function f(·), Watermark generation based on pilot signals, keys, and hash functions: First, use the hash function f(·) to obtain the hash value of the key and message m: S p =f(m,k); then convert the hash value S p The string is converted into n-ary data; finally, the n-ary data of the same specification as the message is extracted and modulated accordingly to obtain the superimposed watermark t2; Generate a message superimposed with a watermark signal using watermark t2: Given a pilot frequency P, based on the message m, the generated watermark t2, and the power allocation factor P... t and P s Generate watermark signal X2 = [P, P t *t2+P s *m]; Authentication Module: The authentication module includes message type determination and watermark signal authentication, specifically used for: A binary pseudo-random sequence is generated based on the same random number seed as the transmitter to determine the watermark type of the received signal; Based on the determined signal watermark type, select the appropriate pilot superimposed watermark authentication or message superimposed watermark authentication method. Pilot overlay watermark authentication includes: Generate the expected watermark based on pilot signals, keys, and hash functions. 1; The watermark is recovered based on the pilot portion of the pilot and received information. r1 ; Given pilot frequency P = (p1, p2, ..., p L ), Pilot section for receiving information P r =(p 1r ,p 2r ,...,p Lr ); First, through H r =P r *P H / (P*P H Obtain the estimated channel H r ,in(·) H Indicates conjugate transpose; Then through Obtain the restored watermarked pilot signal P rt ; Finally, through t r1 =(P rt -P s *P) / P t Get the watermark restored. r1 ; Based on watermark recovery r1 Authentication with the expected watermark t1 includes: If for each data block in the same frame, the watermark is recovered... r1 and the expected watermark t1 inner product If the value is greater than a threshold, it is denoted as τ>τ 01 If the device passes the verification test, it is considered a legitimate device; otherwise, it is considered an illegitimate device.
8. The authentication method based on pseudo-random watermark overlay as described in claim 7, characterized in that, Before generating the pseudo-random sequence and overlaying the watermark signal, the following steps are also included: Initialization is performed to generate system parameters, including determining the random number seed, the watermark overlay power factor, and the key and hash function.
9. The authentication method based on pseudo-random watermark overlay as described in claim 7, characterized in that, The authentication module performs authentication using both pilot-signal watermarked signals and message-signal watermarked signals. Pilot-based watermarking signal authentication includes: Based on the given pilot and key, the expected watermark t1 is generated using a hash function. Authentication is performed based on the generated watermark and the received signal. Given pilot frequency P = (p1, p2, ..., p L ), Pilot section for receiving information P r =(p 1r ,p 2r ,...,p Lr First, through H r =P r *P H / (P*P H Obtain the estimated channel H r ,in(·) H Indicates conjugate transpose; then through Obtain the restored watermarked pilot signal P rt ; through t r1 =(P rt -P s *P) / P t Get the watermark restored. r1 ; Finally, based on the restoration of the watermark... r1 Authenticate with the expected watermark t1. If for each data block in the same frame, the watermark is recovered... r1 and the expected watermark t1 inner product If the value is greater than a threshold, it is denoted as τ>τ 01 If the result is positive, the device is verified as legitimate; otherwise, it is verified as illegitimate.
10. The authentication method based on pseudo-random watermark overlay according to claim 8, characterized in that, The authentication method for the message with superimposed watermark includes: Message recovery based on received messages: Through pilot P and the received signal pilot part P r Obtain the estimated channel H r , Then based on Restore watermarked message signal M rt , According to the message signal M rt And the corresponding demodulation method correctly recovers the transmitted message signal m2. Based on the recovered message signal and the key, the expected watermark t2 is generated using a hash function; Based on the recovered message signal M rt The message m2 and the recovery message are transmitted through t. r2 =(M rt -P s *m2) / P t Get the watermark restored. r2 Based on watermark recovery r2 Authenticate with the expected watermark t2. If for each data block in the same frame, the watermark is recovered... r2 And the expected watermark t2 inner product If the value is greater than a threshold, it is denoted as τ>τ 02 If the result is positive, the device is verified as legitimate; otherwise, it is verified as illegitimate.