Signature encryption method based on Beidou third-generation navigation satellite message authentication

Abstract

The invention provides a signature encryption method based on Beidou third-generation navigation message authentication, and belongs to the technical field of navigation signal processing. At present, a mainstream anti-spoofing attack scheme has the defect of high calculation time overhead due to the use of a traditional signature algorithm, and the anti-spoofing attack scheme only depends on signature authentication or MAC authentication, cannot cope with various spoofing attacks and has the problem of insufficient security. In the aspect of calculating time overhead by a signature algorithm, the method is based on an SM2 algorithm, a w-NAF scalar multiplication algorithm and a prime number table are adopted to optimize scalar multiplication operation, and a faster modular reduction and inverse element calculation method is obtained by using a Fermat's minimum theorem and SM2 prime number domain characteristics. In order to improve the safety, a signature, TESLA secret key and MAC triple authentication scheme is adopted, replay and generative spoofing attacks can be dealt with, a public key is updated by using a navigation message, and the situation that the equipment cannot update the secret key by using a certificate is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of navigation signal processing, and mainly relates to a navigation message encryption design and a message authentication protocol flow design under a deception attack. Background Art

[0002] Navigation technology is used in all aspects of human life. BeiDou Navigation Satellite System (BDS), one of the global navigation satellite systems, is a satellite navigation system independently developed and built by China, and has been widely used in different industries and fields in my country. However, due to the openness of BDS's civil navigation signals, the arrangement and modulation methods of its messages are public, and the navigation signals are not encrypted, making BDS civil navigation signals extremely vulnerable to spoofing attacks. Civilian receivers are extremely vulnerable to spoofing attacks by criminals because they use navigation messages without integrity protection measures. In order to prevent navigation spoofing attacks, anti-spoofing attacks have become the main research direction of navigation security, among which the technology of encrypting and authenticating navigation messages by encryption has become the mainstream of research. However, with the increase in spoofing attack methods, the current anti-spoofing attack scheme cannot meet higher security requirements due to the single encryption algorithm and authentication process. The defects are as follows:

[0003] 1. Traditional signature algorithms have high overhead

[0004] The current mainstream navigation message authentication scheme uses elliptic curve cryptography (ECC), mainly ECDSA and SM2 algorithms. Although the ECC algorithm, as an asymmetric encryption algorithm, is more secure than the symmetric encryption algorithm, it has a large overhead in computing and storage.

[0005] 2. Single certification process

[0006] The current mainstream authentication schemes only consider signatures or partial data encryption and decryption to ensure the security of electronic messages during the authentication process, and cannot cope with different types of deception attacks. Summary of the invention

[0007] In order to solve the performance and security problems of traditional signature algorithms with large computational time overhead and single authentication in mainstream anti-spoofing solutions, the present invention proposes a signature encryption method based on Beidou third-generation navigation satellite message authentication.

[0008] The present invention proposes a signature encryption method based on Beidou third-generation navigation satellite message authentication, and the technical solution includes:

[0009] Firstly, the Fast-SM2 algorithm optimized based on the SM2 signature algorithm is used to generate the signature and public and private key information of the message. Then, a triple authentication process based on the NMA and TESLA protocols is adopted, that is, signature authentication, TESLA key authentication and MAC authentication are performed on the navigation message received by the device in sequence. Finally, the signed public key is sent to the receiving device by satellite broadcasting for certificateless public key update.

[0010] Furthermore, the Fast-SM2 algorithm includes: using the w-NAF algorithm of the prime number table to perform scalar operations, using the characteristics of the SM2 elliptic curve prime field to reduce large integers, and using Fermat's little theorem to solve modular inverses.

[0011] Furthermore, the triple authentication process based on NMA and TESLA protocols includes: using Beidou navigation timestamp information and specific navigation parameters to generate TESLA keys, signatures and MAC information, and matching and authenticating the received telegram data at a certain time.

[0012] Furthermore, the TESLA key authentication includes: all satellites share the same key chain, but the keys sent by different satellites at the same authentication frame are inconsistent.

[0013] Furthermore, the public key distribution method includes: the recipient needs to complete registration at the ground control center to facilitate the recipient to decrypt the encrypted public key information transmitted by the navigation message.

[0014] The present invention proposes a signature encryption method based on Beidou third-generation navigation satellite message authentication. In terms of signature algorithm calculation time overhead, the present invention is based on the SM2 algorithm, uses the w-NAF scalar multiplication algorithm and prime number table to optimize its scalar multiplication operation, and uses Fermat's little theorem and SM2 prime field characteristics to obtain faster modular reduction and inverse element calculation methods. To improve security, the present invention adopts a signature, TESLA key and MAC triple authentication scheme, which can deal with replay and generative spoofing attacks, and uses navigation messages to update public keys to avoid the device being unable to use certificates to update keys. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram of an application scenario of a hybrid authentication solution provided by an embodiment of the present invention;

[0016] Figure 2 is a schematic diagram of a TESLA key generation process provided by an embodiment of the present invention;

[0017] Figure 3 Schematic diagram of the signature generation process provided by an embodiment of the present invention;

[0018] Figure 4is a schematic diagram of a MAC generation process provided by an embodiment of the present invention;

[0019] Figure 5 It is a schematic diagram of the D2 navigation message page and group distribution provided by an embodiment of the present invention;

[0020] Figure 6 is a schematic diagram of reserved bit allocation of subframe 1 provided in an embodiment of the present invention;

[0021] Figure 7 is a schematic diagram of reserved bit allocation of subframe 4 provided in an embodiment of the present invention;

[0022] Figure 8 It is a schematic diagram of a signature verification process provided by an embodiment of the present invention;

[0023] Fig. 9 is a schematic diagram of a TESLA key authentication process provided by an embodiment of the present invention;

[0024] Fig.10 It is a schematic diagram of the MAC authentication process provided by an embodiment of the present invention;

[0025] Fig.11 It is a schematic diagram of the receiving end authentication process provided by an embodiment of the present invention;

[0026] Fig.12 is a schematic diagram of replay attack detection provided by an embodiment of the present invention;

[0027] Fig.13 is a schematic diagram of generative deception attack detection provided by an embodiment of the present invention;

[0028] Fig.14 This is a comparison chart of signature times of different algorithms provided by an embodiment of the present invention;

[0029] Fig.15 This is a comparison chart of signature verification time using different algorithms provided by an embodiment of the present invention;

[0030] Fig.16 It is a comparison chart of authentication error rates under different authentication processes provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and embodiments.

[0032] The present invention proposes a signature encryption method based on Beidou third-generation navigation satellite message authentication, which solves the performance and security problems caused by the large computational time overhead of the traditional signature algorithm and the single authentication in the mainstream anti-spoofing scheme. In view of the problem of large computational overhead of the traditional signature algorithm, the present invention proposes a Fast-SM2 algorithm based on the SM2 signature algorithm, adopts the w-NAF algorithm of the prime number table for scalar operation, uses the characteristics of the prime number field of the SM2 elliptic curve to reduce large integers, and adopts Fermat's little theorem to solve the modular inverse element. The Fast-SM2 algorithm greatly improves the calculation rate of the SM2 algorithm in the signature and verification process. In view of the problem of the single authentication process, the present invention designs a hybrid authentication scheme based on the NMA and TESLA protocols. First, the encrypted information to be authenticated is generated, including the signature, TESLA key and MAC information. The generation of the encrypted information is completed in the ground control center and sent to the Beidou navigation satellite through the uplink together with the original navigation message. The receiver completes the signature authentication, TESLA key authentication and MAC authentication in sequence. After passing the triple authentication, it can be shown that the received navigation signal is authentic and can be used for timing and positioning calculations. At the same time, the encrypted public key information is broadcasted by satellite broadcasting to achieve certificateless public key update. In a preferred embodiment, the overall anti-spoofing navigation message authentication scheme is implemented from two perspectives: encryption algorithm design and authentication process.

[0033] Figure 1 The application scenario of the embodiment of the present invention is shown. The receiver first needs to register at the ground control center. The purpose of registration is mainly to exchange the identity information and public key information of the receiver and the ground control center. After the registration is completed, the ground control center establishes the legal identity of the receiver and obtains the public key of the receiver. Then the ground control center monitors a satellite in the space segment and generates the corresponding original navigation message data. The navigation message at this time does not have the ability to authenticate. Part of the data of the original navigation message is used to generate the TESLA key chain and MAC, and the generated TESLA key and MAC are stored in the reserved position of the Beidou satellite D2 navigation message. Secondly, the ground control station generates the public and private keys corresponding to the current satellite based on the Fast-SM2 signature algorithm (saved by the ground control station), and uses the satellite private key to sign the root key in the TESLA key chain, and the public key information of the satellite is encrypted by the public key of the receiver. Finally, the signature result and the encrypted satellite public key are stored in the reserved position of the D2 navigation message.

[0034] Beidou navigation satellites broadcast the navigation messages with authentication capabilities uploaded by the ground control center to all users, that is, both legitimate receivers and attackers can receive them. The receiver cannot establish a connection with the digital certificate authority, and thus cannot update the key through the digital certificate. At this time, the receiver uses its own private key to extract and decrypt the satellite public key stored in the navigation message, and then uses the public key to complete the signature verification, TESLA key authentication and MAC authentication in sequence. After the receiver completes all the authentication processes, it can solve the navigation data and perform the navigation task. If one of the authentications fails, it means that the received navigation signal may be subject to a spoofing attack, and the receiver immediately discards the signal that has not passed the authentication.

[0035] Step 1: Encrypted information generation process

[0036] The preferred implementation steps are as follows:

[0037] Step G01: Select a random number with a length of 128 bits as the initial key of the Tesla key chain, and calculate the remaining keys according to formula (1), and truncate each key to 128 bits. BDTj is the timestamp information of the Beidou satellite introduced to prevent replay attacks. SM3 Indicates that the SM3 algorithm is used as the hash function.

[0038]

[0039] Step G02: After concatenating the root key in the Tesla key chain with the BeiDou timestamp information and the corresponding satellite number, use the SM3 algorithm to preprocess the data, and use the Fast-SM2 algorithm to calculate the result to obtain the signature information.

[0040] Step G03: The present invention selects the ionospheric delay correction model parameters (IDCMP) in the navigation message as the core message data for generating MAC, and adopts the HMAC-SM3 algorithm to realize the generation of MAC.

[0041] Step 2: Encrypted information distribution process

[0042] Figure 5 , 6 7 shows the distribution method of the encrypted information in the navigation message in the embodiment.

[0043] The reserved bits in the D2 navigation message are subframe 1, subframe 4 and subframe 5. In the embodiment of the present invention, subframe 1 and subframe 4 are selected as the storage subframes for encryption information, and subframe 5 with too dispersed reserved bits is discarded. In order to ensure the continuity of the authentication process, the embodiment of the present invention divides the D2 navigation message of a superframe based on the broadcast period of subframe 1. The superframe can be divided into 12 groups, each of which contains 10 pages. Considering the capacity of the reserved bits of subframe 1 and subframe 4, the hybrid authentication scheme proposed in the embodiment of the present invention adopts the method of performing two authentications in one group to improve the accuracy of detection. At this time, page 1 and page 6 of each group are selected as authentication frames. The contents stored in the reserved bits of subframe 1 include signature, MAC and TESLA key. Among the three, the signature length is 512 bits, and the remaining 238 bits need to be allocated by MAC and TESLA keys. In the embodiment of this scheme, the length of the TESLA key chain is selected as 128 bits. The specific reasons will be explained in detail later. Then the length of MAC is 110 bits. The reserved bits of the entire period of subframe 4 are 780 bits in total, of which 512 bits are used to store the receiving party public key and the encrypted satellite public key information.

[0044] Step 3: Receiver authentication process

[0045] Figure 8 , 9 , 10 shows the authentication process of different encrypted information in the embodiment, and Fig.11 The overall authentication process for the receiver to obtain the navigation message is given, and the steps are as follows:

[0046] Step A01: The receiver receives the navigation message sent by the Beidou satellite and extracts the encrypted information and ciphertext, including the signature, TESLA key and MAC information. It uses its own private key to decrypt and obtain the satellite's public key.

[0047] Step A02: The receiver obtains the signature to be verified by subjecting the root key, timestamp and satellite number information in the extracted information to the same signature generation process, and compares the signature to be verified with the signature in the extracted information. If they match, the signature authentication is successful.

[0048] Step A03: The receiver calculates the extracted TESLA key through a one-way hash algorithm to obtain its subkey, and then compares the subkey with the TESLA key retained in the previous authentication frame. If the two are consistent, it means that the TESLA key authentication is successful.

[0049] Step A04: The receiver extracts the TESLA key of the current authentication frame, and compares the MAC value calculated by the HMAC-SM3 algorithm with the IDCMP stored in the previous authentication frame and the MAC stored in the previous authentication frame. If the two match, it means that the navigation information is complete.

[0050] Step A05: After the triple authentication of steps A02-A04, it is indicated that the navigation information is authentic and reliable and can be used for navigation and positioning. Otherwise, the currently received navigation message is discarded.

[0051] Step 4: Example testing process

[0052] The present invention conducts example tests on the scheme and gives the results in terms of security and performance.

[0053] Table 1 shows the test environment of the present invention.

[0054] Table 1 Experimental equipment parameters

[0055]

[0056] Fig.12 and Fig.13 This shows that the present invention has the ability to resist replay attacks and generative spoofing attacks. When verifying the ability to detect replay attacks, both the spoofing party and the receiving party can receive the navigation message sent by the satellite with ranging code number 59, and then the attacker repeats the received message to the target receiver. The attack test results are shown in Figure 2. Fig. 9 In the generative deception attack, this example designs two attack methods of different degrees. The first attack is that the deception party modifies all navigation message information based on the structure of the D2 navigation message. The experimental test results are shown in Fig.13 As shown in (a), another attack is that the cheater only modifies the important navigation message information, and keeps the other information content unchanged. The experimental test results are shown in Fig.13 (b) as shown.

[0057] In terms of performance testing, this example mainly analyzes the overhead of the signature algorithm and the authentication error rate. Fig.14 and Fig.15This is a comparison chart of different signature algorithms in the signature generation process and the signature verification process. This example tests 13 groups of data of different sizes, namely 32B, 64B, 128B, 256B, 512B, 1kB, 2kB, 4kB, 8kB, 16kB, 32kB, 64kB and 128kB. The example tests the time consumed by repeating the signature of these data 1000 times, and repeats the test 10000 times to take the average value. From the results, it is found that the Fast-SM2 algorithm proposed in the present invention has good performance not only in the signature process but also in the signature verification process. Fig.16 The performance of the present invention in terms of authentication error rate is given. Fig.16 There are 3 curves and 1 red straight line in it. The three curves represent different authentication processes. The red straight line represents the authentication error rate of 10-3. Usually, the authentication requirements are met only below the red line. Among the three curves, the T-1 curve represents the authentication signature only, the T-2 curve represents the authentication signature and TESLA key, and the T-3 curve represents the authentication signature, TESLA key and MAC. The AER curves of T-1, T-2, and T-3 are similar, indicating that the different authentication processes in the scheme have little effect on the authentication error rate, that is, the use of a triple authentication scheme has little effect on the performance of the overall scheme. Normally, the carrier-to-noise ratio of the navigation signal that can be received by the Beidou civilian receiver is about 45dBHz. In this scheme, the authentication error rate is less than 10-3 at 37.5dBHz (when there is a 7dBHz loss in the average carrier-to-noise ratio under normal circumstances). 3 , which can meet the needs of correct authentication.

[0058] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A signature encryption method based on Beidou third-generation navigation satellite message authentication, characterized in that: Firstly, the Fast-SM2 algorithm optimized based on the SM2 signature algorithm is used to generate the signature and public and private key information of the message. Then, a triple authentication process based on the NMA and TESLA protocols is adopted, that is, signature authentication, TESLA key authentication and MAC authentication are performed on the navigation message received by the device in sequence. Finally, the signed public key is sent to the receiving device by satellite broadcasting for certificateless public key update.

2. The signature encryption method based on Beidou third-generation navigation satellite message authentication according to claim 1 is characterized in that: The Fast-SM2 algorithm includes: using the w-NAF algorithm of the prime number table to perform scalar operations, using the characteristics of the SM2 elliptic curve prime field to reduce large integers, and using Fermat's little theorem to solve modular inverses.

3. The signature encryption method based on Beidou third-generation navigation satellite message authentication according to claim 1 is characterized in that: The triple authentication process based on NMA and TESLA protocols includes: using Beidou navigation timestamp information and specific navigation parameters to generate TESLA keys, signatures and MAC information, and matching and authenticating the received telegram data at a certain time.

4. The signature encryption method based on Beidou third-generation navigation satellite message authentication according to claim 1 is characterized in that: The TESLA key authentication includes: all satellites share the same key chain, but the keys sent by different satellites at the same authentication frame are inconsistent.

5. The signature encryption method based on Beidou third-generation navigation satellite message authentication according to claim 1 is characterized in that: The public key distribution method shown includes that the recipient needs to complete registration at the ground control center to facilitate the recipient to decrypt the encrypted public key information transmitted by the navigation message.

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