Lightweight network security protection method for intelligent control terminal of Internet of Things

Abstract

The invention provides a lightweight network security protection method for an intelligent control terminal of the Internet of Things, and aims to solve the problem of contradiction between security and real-time performance of resource-constrained equipment. According to the method, three core stages of equipment registration, bidirectional identity authentication and information encryption authentication are covered through layered architecture design. The method comprises the following steps: firstly, binding hardware characteristics and registration information by using physical unclonable functions (PUF) and HMAC to ensure that the identity of equipment is unique and credible; secondly, bidirectional identity authentication among the RTU, the LCS and the CCS is realized based on the PUF, the HMAC and the digital signature, and counterfeiting and replay attacks are prevented; and finally, symmetric encryption and asymmetric encryption are adopted to guarantee confidentiality, integrity and non-repudiation of communication data. According to the scheme, a timestamp and random number mechanism is introduced, the anti-attack ability is enhanced, the resource overhead and communication delay are optimized, the real-time requirement of the industrial Internet of Things is met, and the method is suitable for a distributed Internet of Things system in the fields of electric power, energy and the like and has the advantages of being efficient, safe and extensible.

Description

Technical Field

[0001] This invention relates to the field of Internet of Things (IoT) security technology, and specifically to a lightweight network security protection method for IoT smart control terminals. Background Technology

[0002] With the rapid development of the Internet of Things (IoT) technology, its applications in industrial control, smart grids, and energy management are becoming increasingly widespread. IoT systems typically consist of a large number of embedded terminal devices, such as Remote Terminal Units (RTUs), Programmable Logic Controllers (PLCs), and Intelligent Electronic Devices (IEDs). These devices are widely distributed and resource-constrained, with limited computing power, storage space, and communication bandwidth. Simultaneously, IoT devices require real-time transmission of data and control commands, placing high demands on communication latency and system response time. However, due to the open and distributed architecture of IoT systems, they face various security threats, including but not limited to data theft, tampering, forgery, man-in-the-middle attacks, and unauthorized device access.

[0003] Traditional network security measures, such as RSA encryption, SHA-256 hashing algorithm, and IPSec protocol, while providing high security, suffer from high algorithm complexity, high power consumption, and long processing times, making them unsuitable for the resource-constrained nature of IoT terminal devices. Furthermore, traditional solutions often lack differentiated designs for multi-level distributed architectures, failing to balance real-time performance and security requirements. Therefore, how to ensure the information security of IoT systems while reducing the resource overhead of security measures has become a pressing technical challenge.

[0004] Currently, some studies both domestically and internationally have proposed improvement solutions for the security protection of IoT terminal devices, but the following shortcomings still exist:

[0005] 1. High algorithm complexity: Traditional cryptographic algorithms, such as RSA and AES-256, are highly secure, but they are computationally intensive and inefficient, making them unsuitable for resource-constrained IoT devices.

[0006] 2. Lack of layered design: Most existing solutions do not consider the layered architecture characteristics of IoT systems and fail to dynamically adjust security policies according to communication levels, resulting in wasted resources or insufficient security.

[0007] 3. Single authentication mechanism: Most solutions rely solely on software-level authentication mechanisms, such as digital certificates or shared keys, which are vulnerable to cloning attacks or key leaks.

[0008] 4. Difficulty in balancing real-time performance and security: The transmission of control commands and status information in IoT systems has extremely high real-time requirements, while complex security measures may significantly increase communication latency and affect system performance.

[0009] 5. Insufficient resistance to attacks: Existing solutions still have certain shortcomings in preventing replay attacks and man-in-the-middle attacks, especially on resource-constrained devices where it is difficult to achieve efficient security protection. Summary of the Invention

[0010] To address the aforementioned issues, this invention provides a lightweight network security protection method for IoT smart control terminals. By integrating lightweight cryptographic algorithms, Physically Unclonable Functions (PUFs), and layered security architecture design, it overcomes the shortcomings of existing technologies in terms of resource consumption, real-time performance, and security, providing a practical solution for secure access and communication of terminal devices in scenarios such as Industrial IoT and smart grids.

[0011] The technical solution adopted in this invention is as follows:

[0012] A lightweight network security protection method for IoT smart control terminals, characterized in that the method includes the following steps:

[0013] Step 1 Device Registration: When a new device joins the system, it provides the server with registration information including identity identifier and region identifier. The hardware fingerprint is generated through PUF and combined with HMAC to bind the registration information, generating a unique and trusted identity.

[0014] Step 2: Two-way authentication: Only authenticated devices can participate in communication; the session key or shared parameters generated during the authentication process provide a secure foundation for subsequent encryption and authentication.

[0015] Step 3: Information Encryption and Authentication: Based on the authentication, the following steps are taken: Symmetric encryption or Asymmetric encryption protects the confidentiality, integrity, and non-repudiation of communication data.

[0016] Furthermore, in step 1, when the RTU (Remote Control Unit) registers the device with the LCS (Local Control Server), the following steps are included:

[0017] Step 1.1: When a new remote control terminal (RTU) joins the system, it needs to provide registration information to the local control server (LCS). The registration information includes: the IoT registration password (rpw) of the RTU and the area identifier (Sign). RTU Device Type RTU and registration date;

[0018] Step 1.2: LCS verifies the validity of the registration password rpw; if the verification is successful, a unique identifier (ID) is generated for the RTU. RTU If the verification fails, an alarm message will be returned.

[0019] Step 1.3: LCS calculates message authentication code H LCS And generate a random challenge signal C i LCS will H LCS ||ID RTU ||C i Send to RTU;

[0020] Step 1.4: The remote control terminal RTU receives H LCS ||ID RTU ||C i In the future, for

[0021] Sign RTU ||Type RTU ||Date is used for calculation and verification: if the verification passes, the ID is stored. RTU Meanwhile, the remote control terminal (RTU) uses its own PUF function to calculate the response value R. i The data is then sent to the LCS for storage; if the verification is inconsistent, an alarm message is sent to the local control server (LCS).

[0022] Furthermore, in Step 1.3, the local control server (LCS) uses the HMAC algorithm to calculate the message authentication code H. LCS And generate a random challenge signal C i The calculation formula is as follows:

[0023] H LCS =HMAC(Sign) RTU ||Type RTU ||Date);

[0024] In Step 1.4, the remote control terminal (RTU) receives H LCS ||ID RTU ||C i From now on, we will first focus on Sign. RTU ||Type RTU ||Date is used to calculate H′ according to the following formula LCS ;

[0025] H′ LCS =HMAC(Sign) RTU ||Type RTU ||Date);

[0026] If the verification passes, store the ID. RTU Meanwhile, the remote control terminal (RTU) uses its own PUF function to calculate the response value R. i =PUF(C i ), will ID RTU||(R i C i Send it to LCS for storage;

[0027] In the formula, H LCS Message authentication code generated for LCS; H′ LCS The message authentication code is recalculated for the RTU; HMAC is the hash message authentication code algorithm.

[0028] Furthermore, in step 1, when the local control server registers with the central control server:

[0029] Terminal devices in each regional IoT network are managed and controlled by the local control center server. When IoT control terminals are added after the regional IoT network is built, the local control server (LCS) needs to register with the central control center server (CCS). During registration, this paper chooses a manual-assisted method to assign identity IDs to the LCS. LCS And to store the identity IDs of each RTU in the IoT of this area. RTU and ID LCS Saved to CCS via a secure channel.

[0030] Furthermore, in step 2, the two-way authentication between the remote control terminal (RTU), the local control server (LCS), and the central control center server (CCS) includes the following steps:

[0031] Step 2.1.1: The remote control terminal (RTU) initiates an authentication request to the local control server (LCS), including: the RTU's identity ID. RTU Random number N1∈Z * The identity ID of the central control center server (CCS) CCS timestamp T R-S1 ;

[0032] Step 2.1.2: After LCS verifies the validity of the timestamp, it forwards the RTU's identity identifier and the new timestamp (ID) to CCS. RTU ||T L-S2 ;

[0033] Step 2.1.3: CCS verifies the timestamp and checks the ID. RTU The authenticity is verified, and if it passes, a random number N2∈Z is returned. * ;

[0034] Step 2.1.4: LCS generates verification information for RTU and CCS identity authentication respectively;

[0035] Step 2.1.5: RTU and CCS verify the information received in Step 5.

[0036] Furthermore, in Step 2.1.4, LCS generates verification information, including the following steps:

[0037] After receiving the message, LCS extracts the ID sequentially based on the message length. RTU N1, ID CCS and T R-S1 First, verify the timestamp to determine the received time T. L-S1 With the sending time T R-S1 Does the time difference satisfy T? L-S1 -T R-S1 ≤ΔT; If timestamp verification fails, authentication is terminated and an alarm is issued; If verification succeeds, LCS uses the identity identifier ID. RTU and ID CCS Search the database for the RTU's PUF parameter (ID). RTU C i ,R i HMAC is calculated using the shared key, and then the digital signature is calculated using the LCS private key.

[0038] H LCS1 =HMAC(ID) RTU ||R i ||N1||N3), S LCS1 =SIG(H LCS1 );

[0039] LCS selects a random number N4∈Z for ID CCS ||N2||N4 uses the shared key to generate the message authentication code H LCS2 And use the LCS private key to generate a digital signature S LCS2 The calculation process is as follows:

[0040] H LCS2 =HMAC(ID) CCS ||N2||N4), S LCS2 =SIG(H LCS2 );

[0041] Finally, LCS will ID RTU ||C i ||N3||S LCS1 ||T L-S5 Send to RTU,

[0042] ID CCS ||N2||N4||S LCS2 ||T L-S5 Send to CCS;

[0043] In the formula, ID RTU A unique identifier for the RTU; IDCCS N1 is a unique identifier for the CCS; N2 is a random number generated by the RTU to prevent replay attacks and increase the randomness of the protocol; N3 is a random number generated by the LCS to respond to the RTU's authentication request and verify the authenticity of the CCS; N4 is a random number generated by the LCS to participate in the authentication process between the RTU and the LCS; N5 is a random number generated by the LCS to participate in the authentication process between the LCS and the CCS; T L-S1 T is the timestamp when the LCS receives the RTU request; R-S1 The timestamp when the RTU sends the authentication request; T L-S5 The timestamp when LCS sends verification information to RTU or CCS; ΔT is the maximum allowed time difference; R i For the RTU's PUF function to the challenge signal C i The response value; C i Random challenge signals generated for LCS; H LCS1 H is the message authentication code calculated based on the shared key for LCS. LCS2 S is the message authentication code calculated based on the shared key for LCS; LCS1 Use private key pair for LCS H LCS1 The generated digital signature; S LCS2 Use private key pair for LCS H LCS2 The generated digital signature.

[0044] Furthermore, in Step 2.1.5, the RTU and CCS verification information includes the following steps:

[0045] After receiving the verification information, the RTU extracts the ID based on the length of each part of the content. RTU C i N3, S LCS1 and T L-S5 Each part; first, verify whether the timestamp satisfies T. R-S5 -T L-S5 ≤ΔT; then, the digital signature is decrypted using the LCS public key to obtain H. LCS1 Based on the PUF function of this device, in C i The output response value is calculated using the input stimulus as follows:

[0046] R i =PUF(C i ), H′ LCS1 =HMAC(ID) RTU ||R i ||N1||N3);

[0047] For ID RTU ||R i||N1||N3 use the HMAC algorithm to calculate H′ LCS1 H, recovered from digital signature LCS1 The system performs a comparison; if the comparison matches, the RTU has successfully authenticated the LCS; if the comparison does not match, the authentication has failed.

[0048] After receiving the information, CCS first verifies whether the timestamp of the information meets the T condition. C-S5 -T L-S5 ≤ΔT, using the public key of LCS to pair S LCS2 Decryption is performed to obtain the message authentication code H. LCS2 ; For ID CCS Perform HMAC calculations on ||N2||N4 to verify H′. LCS2 With H LCS2 Whether they match, the calculation formula is as follows:

[0049] H′ LCS2 =HMAC(ID) CCS ||N2||N4);

[0050] If the comparison matches, CCS has completed the identity authentication of LCS; if the comparison does not match, the identity authentication has failed.

[0051] RTU randomly selects input stimulus C i ′, calculate R based on the PUF function i ′, for C i ′||R i ′||N3||ID RTU HMAC is calculated to obtain H RTU3 and for H RTU3 The digital signature is calculated using the RTU's private key and appended to the message to generate verification information. The calculation formula is as follows:

[0052] R i =PUF(C) i ′), H RTU3 =HMAC(C i ′||R i ′||N3||ID RTU ), S RTU3 =SIG(H RTU3 );

[0053] RTU will Send to LCS;

[0054] CCS for N4||ID CCS HMAC is calculated to obtain H CCS4 And calculate its digital signature S CCS4After extracting the timestamp, the verification information N4||ID is generated. CCS ||S CCS4 ||T C-S10 The calculation formula is as follows:

[0055] H CCS4 =HMAC(N4||ID) CCS ), S CCS4 =SIG(H CCS4 );

[0056] CCS will use N4||ID CCS ||S CCS4 ||T C-S10 Send to LCS;

[0057] LCS separates C based on the different lengths of each part of the information. i ′、 ID RTU S RTU3 and T R-S9 First, verify whether the timestamp satisfies T. L-S9 -T R-S9 ≤ΔT; If timestamp verification fails, an alarm message is issued; if timestamp verification succeeds, then... Using R i XOR operation yields R i H′ is obtained by performing HMAC calculation. RTU3 H is obtained by decryption using the RTU public key. RTU3 Compared with H RTU3 With H′ RTU3 If they match, the authentication of the RTU is complete; if they do not match, the authentication fails. The calculation formula is as follows:

[0058] H′ RTU3 =HMAC(C i ′||R i ′||N3||ID RTU );

[0059] LCS separates N4 and ID based on the different lengths of each part of the information. CCS S CCS4 and T C-S10 First, verify whether the timestamp satisfies T. L-S10 -T C-S10 ≤ΔT; If timestamp verification fails, an alarm message is issued; If timestamp verification passes, H′ is calculated. CCS4 Use the CCS public key to restore the signature and obtain H. CCS4 Compared with H CCS4 With H′ CCS4If the match is consistent, the CCS identity authentication is complete; if the match is inconsistent, the identity authentication fails. The calculation formula is as follows:

[0060] H′ CCS4 =HMAC(N4||ID) CCS );

[0061] In the formula, ID RTU ID is the identifier for the RTU. LCS ID is the identifier for the LCS. CCS For the identity identifier of CCS; C i The input excitation signal for the PUF; R i For PUF to input stimulus C i The output response value; PUF() is the PUF function; HMAC() is the hash message authentication code; SIG() is the digital signature function, which signs the message using the private key; T x-Sy The timestamp marks the time of a certain step; ΔT is the maximum allowed time difference, used to determine whether the timestamp is valid; N x is a random number used to increase the randomness and anti-predictability of the protocol; E() / D() are symmetric encryption / decryption functions that use a shared key to encrypt or decrypt data; AE() / D'() are asymmetric encryption / decryption functions that use a public key to encrypt and a private key to decrypt, or vice versa.

[0062] Furthermore, in step 2, the two-way authentication between local control servers (LCS) in different regions includes the following steps:

[0063] Step 2.2.1: LCS i Select a random number N i ∈Z * Extract the local identity ID LCSi and Area identifier LCSi H is obtained by calculating H using HMAC. i Calculate the digital signature S using the local private key i Extract timestamp T i-S1 The calculation formula is as follows:

[0064] H i =HMAC(ID) LCSi ||Area LCSi ||N i ), S i =SIG(H i );

[0065] LCS i ID LCSi ||Area LCSi ||N i ||Si ||T i-S1 Send to LCS j ;

[0066] Step 2.2.2: LCS j Validate LCS i The identity authentication information is used to generate the identity authentication information on the client side;

[0067] LCS j After receiving the information, extract the ID. LCSi Area LCSi N i S i and T i-S1 Each section; extracting send and receive timestamps for verification T j-S1 -T i-S1 If ≤ΔT is satisfied; if not, proceed to LCS. i Issue an alarm message; if verification passes, the digital signature is restored using the public key to obtain H. i ; For the received ID LCSi ||Area LCSi ||N i Calculating HMAC using a shared key. i The calculation formula is as follows:

[0068] H i =HAMC(ID) LCSi ||Area LCSi ||N i );

[0069] Comparison H i With H i The system checks for consistency to verify the digital signature; if the verification passes, the LCS... j Completed LCS i Identity authentication;

[0070] LCS j Generate message authentication code H j and digital signatures j The calculation formula for this identity authentication information is as follows:

[0071] H j =HMAC(ID) LCSj ||Area LCSj ||N j ), S j =SIG(H j );

[0072] LCS j ID LCSj ||AreaLCSj ||N j ||S j ||T j-S4 Send to LCS i ;

[0073] Step 2.2.3: LCS i After receiving the message, verify the timestamp T. i-S4 -T j-S4 Does ≤ΔT satisfy the condition? Restore the digital signature S. j Get H j And calculate H j ′, by comparing H j With H j The system checks if the signature matches to verify the digital signature; if they match, then the LCS is executed. i Completed LCS j Identity authentication; the calculation formula is as follows:

[0074] H j =HAMC(ID') LCSj ||Area′ LCSj ||N j ′);

[0075] In the formula, LCS i For the local control server of region i; LCS j N is the local control server for region j; i For LCS i A randomly generated random number; N j For LCS j A randomly generated random number; ID LCSi For LCS i Identity identifier; ID LCSj For LCS j Identity identifier; Area LCSi For LCS i The area identifier; Area LCSj For LCS j The region identifier; H i For LCS i The message authentication code is calculated using HMAC; H j For LCS j The message authentication code is calculated using HMAC; S i For LCS i Use the private key to pair H i The digital signature of the computation; S j For LCS j Use the private key to pair H j The digital signature of the computation; T i-S1 Ti-S4 For LCS i Extracted timestamp; T j-S1 T j-S4 For LCS j Extracted timestamp; ΔT is the time window threshold.

[0076] Furthermore, in step 3, the information encryption and authentication between the remote control terminal (RTU) and the local control server (LCS) includes the following steps:

[0077] Step 3.1.1: RTU selects plaintext information M RTU Calculate message authentication code H using shared key RTU Using a symmetric encryption algorithm to target M RTU and H RTU C is obtained by performing encryption calculations. RTU Extract the timestamp T RTU Generate security information C RTU ||T RTU The calculation formula is as follows:

[0078] H RTU =HMAC(M RTU ), C RTU =E(M RTU ||H RTU );

[0079] RTU will transmit security information C RTU ||T RTU Send to LCS;

[0080] Step 3.1.2: After receiving the security information, LCS decrypts and verifies it;

[0081] LCS separates C based on information length. RTU and T RTU ;

[0082] First, verify the timestamp T. LCS -T RTU Check if ≤ΔT is satisfied; if the verification fails, reject the ciphertext C. RTU And send warning messages to the RTU and IoT control terminal central control center;

[0083] If the verification passes, M is obtained by decryption using the shared key of a symmetric cryptography algorithm. RTU ||H RTU , for M RTU Calculate the message authentication code H′ using the HMAC shared key RTU Compare H′ RTU and H RTU If they match, then accept the plaintext message M. RTUIf there is a discrepancy, the LCS will refuse to accept the plaintext and will send an alarm message to the RTU and the IoT control terminal central control center.

[0084] In the formula, M RTU Plaintext information sent to the RTU; H RTU C is a message authentication code generated based on the HMAC algorithm. RTU The encrypted ciphertext information; T RTU A timestamp appended to the RTU; ΔT is the maximum allowed time difference; H′ RTU The message authentication code is recalculated for LCS.

[0085] Furthermore, in step 3, the information encryption authentication between LCS and CCS includes the following steps:

[0086] Step 3.2.1: LCS generates plaintext information M LCS HMAC is calculated from the plaintext. LCS and for H LCS Calculate digital signature S LCS Asymmetric cryptography algorithm is selected for M LCS Perform encrypted calculations C LCS The calculation formula is as follows:

[0087] H LCS =HMAC(M LCS ), S LCS =SIG(H LCS ), C LCS =AE(M LCS );

[0088] LCS extracts timestamp T LCS , to securely transmit information C LCS ||S LCS ||T LCS Send to CCS;

[0089] Step 3.2.2: CCS decrypts and authenticates the received secure transmission information;

[0090] CCS separates C based on the length of each part of the content. LCS S LCS and T LCS ; Verify if the timestamp satisfies T CCS-S1 -T LCS-S1 If the verification fails, the ciphertext will not be decrypted, and an alarm will be sent to the LCS and IoT control terminal maintenance personnel; if the verification passes, the decryption process will proceed.

[0091] CCS uses a private key to decrypt C LCS Get M LCSAnd perform HMAC calculation to obtain H′ LCS The calculation formula is as follows:

[0092] H′ LCS =HMAC(M LCS );

[0093] CCS uses the LCS's signature public key to reconstruct the signature and obtain H. LCS Comparison of H′ LCS With H LCS If they match, the plaintext information has been authenticated and accepted; if they do not match, the CCS sends an alarm message to the LCS and IoT control terminal maintenance personnel.

[0094] In the formula, M LCS This is plaintext information, the raw data content generated by LCS; H LCS The message authentication code is used to verify the plaintext information M. LCS Calculated using the HMAC algorithm; S LCS For digital signature, it is for H LCS Generate using LCS private key signing; C LCS For ciphertext, it is the plaintext information M LCS Generated using an asymmetric encryption algorithm; T LCS The sending timestamp is the time recorded when the LCS sends the message; T CCS-S1 The receive timestamp is the time recorded when the CCS receives the message; ΔT is the maximum allowed time difference, which is the maximum allowed time interval from message sending to receiving; H′ LCS To recalculate the message authentication code, CCS processes the decrypted plaintext M. LCS Recalculated message authentication code; H LCS To restore the message authentication code obtained from the signature, CCS uses the LCS public key to verify the digital signature S. LCS The message authentication code obtained after restoration.

[0095] Compared with the prior art, the beneficial effects of the present invention are:

[0096] 1. Enhanced security for resource-constrained devices: Employing lightweight cryptographic algorithms such as HMAC, PRESENT, and ECC, along with the hardware feature PUF, significantly reduces computational, storage, and communication overhead, making it suitable for resource-constrained IoT terminal devices. Through differentiated encryption strategies, symmetric encryption is used... Asymmetric encryption is used for It meets both real-time requirements and ensures high security.

[0097] 2. Enhance Device Identity Trustworthiness: Utilize Physically Unclonable Function (PUF) to generate device hardware fingerprints, combined with HMAC binding registration information, to ensure each device has a unique and trustworthy identity, preventing device forgery or cloning. Through two-way authentication based on PUF, HMAC, and digital signatures, it effectively prevents man-in-the-middle attacks, replay attacks, and unauthorized device access.

[0098] 3. Achieve multi-layered, end-to-end security protection: This is based on the layered architecture of IoT smart control terminals. Differentiated security strategies are designed to balance the lightweight requirements of the edge layer and the high security requirements of the central layer. From device registration to two-way authentication and then to information encryption authentication, a complete security protection loop is formed, covering the entire communication link and avoiding security vulnerabilities in a single link.

[0099] 4. Optimize the balance between real-time performance and security: In The link employs symmetric encryption and HMAC mechanisms, significantly reducing encryption / decryption time and resource consumption, thus meeting the demands of real-time data transmission. Asymmetric encryption and digital signatures are used in the link to ensure the confidentiality, integrity and non-repudiation of critical information.

[0100] 5. Resistant to various network attacks: HMAC message authentication codes and digital signatures ensure that information is not tampered with or forged during transmission. The introduction of timestamps and random number mechanisms effectively prevents replay attacks and enhances the protocol's resistance to attacks. PUF hardware features and random numbers enhance the protocol's randomness, preventing attackers from cracking the system through prediction or analysis.

[0101] 6. Supports large-scale deployment and cross-regional collaboration: Supports two-way authentication between local control servers (LCS) in different regions, facilitating unified management and secure collaboration of cross-regional IoT systems. The solution is flexible in design, and security policies can be adjusted according to actual application scenarios, making it suitable for various industrial IoT scenarios such as power, energy, and smart manufacturing. Attached Figure Description

[0102] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0103] Figure 1 Diagram of a network security protection model for IoT control terminals;

[0104] Figure 2This is an overall flowchart of the lightweight network security protection method for IoT smart control terminals of the present invention;

[0105] Figure 3 This is a flowchart of the initial registration process for the device of the present invention;

[0106] Figure 4 This is a flowchart of the two-way identity authentication process of RTU, LCS and CCS in this invention;

[0107] Figure 5 For the present invention LCS i With LCS j Two-way authentication flowchart;

[0108] Figure 6 This is a schematic diagram of the RTU and LCS encryption authentication scheme of the present invention;

[0109] Figure 7 This is a flowchart illustrating the encrypted transmission process of RTU and LCS information in this invention.

[0110] Figure 8 This is a schematic diagram of the LCS and CCS information encryption and authentication scheme of the present invention;

[0111] Figure 9 This is a flowchart of the LCS and CCS information encryption and authentication process of the present invention. Detailed Implementation

[0112] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0113] To address the shortcomings in security protection for IoT terminal devices, this embodiment provides a lightweight network security protection method for IoT smart control terminals. This method covers three core components: device registration, two-way authentication, and information encryption authentication, and is implemented through a layered architecture. Achieve lightweight security protection to ensure confidentiality, integrity, identity trustworthiness, and non-repudiation during communication.

[0114] Due to the limited computing resources of embedded devices in systems such as the Internet of Things (IoT), Integral Chromium (ICS), and Radio Frequency Identification (RFID) tags, they cannot run resource-intensive, high-strength cryptographic algorithms. Therefore, lightweight cryptographic algorithms have become a hot research topic. Balancing security and lightweightness, numerous lightweight cryptographic algorithms have been designed, including lightweight symmetric cryptographic algorithms and lightweight hash functions.

[0115] (1) Lightweight Symmetric Cryptography Algorithms: Symmetric encryption algorithms refer to the use of the same key by the sender and receiver to encrypt and decrypt information. In recent years, various lightweight symmetric cryptography algorithms have emerged. There are two main design approaches for lightweight symmetric cryptography algorithms: one is based on improvements and simplifications of existing cryptographic algorithms, including the DESL algorithm, which is an improvement on the DES algorithm; the other is redesigned algorithm structures, including the PRESENT series and the KTANTAN series. Among the quantitative indicators of cryptographic algorithm implementation performance, the equivalent gate count of the algorithm implementation is of significant reference value and can measure the complexity of digital circuits. The table below shows a comparison of the hardware implementation performance of different series of symmetric cryptography algorithms.

[0116]

[0117] (2) Asymmetric cryptography algorithms: Compared with symmetric cryptography algorithms, asymmetric cryptography algorithms have higher security strength but slower encryption and decryption speeds, making them unsuitable for encrypting large amounts of data in resource-constrained environments. Currently, the most widely used asymmetric cryptography algorithms are the elliptic curve-based ECC encryption algorithm and the SM9 encryption algorithm, which are suitable for use in scenarios with high security requirements. The ECC encryption algorithm has a private key length of 160 bits, while the SM9 encryption algorithm has a private key length of 512 bits.

[0118] (3) Lightweight Hash Functions: Hash functions can calculate a fixed-length HMAC for information of arbitrary length, and are one-way; the information cannot be reconstructed from the HMAC. Hash functions have important applications in identity authentication and information integrity verification. Currently, the Hash functions designed for resource-constrained environments include LHash-64 and Quark series Hash functions. The hardware implementation performance comparison is shown in the table below:

[0119]

[0120] (4) Digital Signature Algorithms: Digital signature algorithms append a digital signature to plaintext information to ensure that the information cannot be tampered with, forged, or repudulated. The RSA digital signature algorithm is widely used in security protection, but due to its large computational load and slow processing speed, it is difficult to implement effectively in resource-constrained devices. The ECDSA and SM9 digital signature algorithms are relatively lightweight digital signature algorithms used in embedded devices. The ECDSA private key length is 256 bits, while the SM9 digital signature algorithm private key length is 512 bits.

[0121] (5) PUF function: The PUF function was proposed by Pappu et al. It is a hardware security primitive based on the process deviation characteristics in hardware manufacturing, and has the characteristics of being unclonable and unpredictable.

[47] The PUF function is shown in the following equation: R = PUF(C); where C and R are the input excitation and output response, respectively.

[0122] Non-cloning property: The same input stimulus will produce the same output response; different input stimulus will produce different output responses; the same input stimulus will produce different output responses when using different PUF inputs.

[0123] Unpredictability manifests as follows: given a set of stimulus and response pairs T = {(C i ,PUF(C i ))|i=1,2,...n}, based on the randomly input C x Unable to predict PUF(C) x ),and In the formula, C x This is a new input stimulus, not included in set T.

[0124] Based on the above research on multi-attribute decision-making strategies for lightweight network security protection measures, the basic principle of this lightweight network security protection method for IoT smart control terminals is as follows:

[0125] To ensure the network security of IoT control terminals, a network security protection model for IoT control terminals is established based on the system's structure and communication scenarios. Then, an overall network security protection scheme is designed for communication between devices at each layer in the model, including device registration, identity authentication, and information encryption authentication.

[0126] As can be seen from the previous analysis of the IoT control terminal structure, the IoT control terminal has a typical layered architecture, and the main equipment includes the central control server (CCS), the local control server (LCS), and terminal equipment such as RTU, PLC, and IED.

[0127] like Figure 1 As shown, the main communication scenarios of IoT control terminals include the following three categories:

[0128] (1) Terminal devices such as RTUs located at the IoT site send the information collected in real time to the LCS of the local IoT control center in the area via unicast.

[0129] (2) The LCS sends control commands and configuration parameters to terminal devices such as RTUs at the field device layer via multicast;

[0130] (3) The CCS performs initial registration and identity authentication for IoT LCS and RTU in each region before communication, and the operation and maintenance personnel of the central control center issue control commands to IoT devices at each layer.

[0131] like Figure 2As shown, this lightweight network security protection method for IoT smart control terminals includes the following steps:

[0132] Step 1 Device Registration: When a new device joins the system, it provides the server with registration information including identity identifier and region identifier. The hardware fingerprint is generated through PUF and combined with HMAC to bind the registration information, generating a unique and trusted identity.

[0133] like Figure 2 and Figure 3 As shown, during the device registration process in step 1, when a device in the IoT control terminal is added to the system for the first time, it needs to register its identity with the local control server of the IoT control terminal.

[0134] (1) The remote control terminal registers the device with the local control server:

[0135] Step 1.1: When a new RTU joins the system, it needs to provide registration information to the LCS, including the IoT registration password (rpw) of the RTU and the area identifier (Sign). RTU Device Type RTU And the registration date; where the registration password rpw is held by the IoT staff and entered into the RTU.

[0136] Step 1.2: LCS receives rpw||Sign RTU ||Type RTU After the Date field is set, the registration password must be verified first.

[0137] If successful, a unified format identity ID will be generated for the new device within the system. RTU ;

[0138] If the verification fails, an alarm message will be sent back to the on-site staff.

[0139] Step 1.3: For new devices that have passed the registration password, LCS uses the HMAC algorithm as follows to...

[0140] Sign RTU ||Type RTU ||Date Calculation Message Authentication Code H LCS And randomly select challenge signal C i ;

[0141] H LCS =HMAC(Sign) RTU ||Type RTU ||Date); where H is the date; LCS The message authentication code generated for LCS; HMAC is the hash message authentication code algorithm.

[0142] Finally, LCS will H LCS ||ID RTU ||C i Send to RTU.

[0143] Step 1.4: RTU receives H LCS ||ID RTU ||C i From now on, we will first focus on Sign. RTU ||Type RTU ||Date is used to calculate H′ according to the following formula LCS ;

[0144] H′ LCS =HMAC(Sign) RTU ||Type RTU ||Date); where H′ LCS The message authentication code is recalculated for the RTU.

[0145] Verify H′ LCS With H LCS If they match, then accept the ID. RTU And store it;

[0146] If the verification is inconsistent, an alarm message is sent to the LCS.

[0147] Then the RTU uses its own PUF function to calculate the challenge response R. i =PUF(C i ); and ID RTU ||(R i C i It is sent to LCS for storage.

[0148] (2) The local control server registers with the central control center server:

[0149] Terminal devices in each regional IoT network are managed and controlled by a local control center server. When IoT control terminals are added after the regional IoT network is built, the LCS (Local Control System) needs to register with the CCS (Central Control System). Because the information managed and transmitted by the LCS is important and has high security requirements, this paper chooses a manually assisted method to assign identity IDs to the LCS. LCS And to store the identity IDs of each RTU in the IoT of this area. RTU and ID LCS Saved to CCS via a secure channel.

[0150] Step 2 Two-way authentication: Only authenticated devices can participate in communication; the session key or shared parameters generated during the authentication process provide a security foundation for subsequent encryption and authentication.

[0151] like Figure 2 and Figure 4 As shown, in step 2, two-way authentication, the two-way authentication between the communicating parties is a key process in the security protection scheme between various devices in the IoT control terminal. Only after completing the two-way authentication process can each layer of devices transmit information in the IoT control terminal.

[0152] (1) Two-way authentication of RTU, LCS and CCS:

[0153] Step 2.1.1: The RTU sends an authentication request to the LCS;

[0154] RTU extracts its own identity ID. RTU Select random numbers N1∈Z * and CCS identity ID CCS Add timestamp T R-S1 Then generate the identity authentication request information ID. RTU ||N1||ID CCS ||T R-S1 This is sent to the LCS of the local IoT network. In the formula, N1 is a random number generated by the RTU, used to prevent replay attacks and increase the randomness of the protocol; Z... * T is the set of non-zero integers; L-S1 This is the timestamp when the LCS receives the RTU request.

[0155] Step 2.1.2: After LCS verifies the validity of the timestamp, it forwards the RTU's identity identifier and the new timestamp ID to CCS. RTU ||T L-S2 .

[0156] Step 2.1.3: CCS receives the ID RTU ||T L-S2 Next, the timestamp information is verified first, and the timestamp is compared with the received time T. C-S2 Does T satisfy? C-S2 -T L-S2 ≤ΔT; ΔT is the maximum permissible time difference.

[0157] If the requirements are met, verify the ID. RTU The authenticity is verified, and a random number N2∈Z is returned to LCS after successful verification. * N2 is a random number generated by CCS, used to respond to the RTU's authentication request and verify the authenticity of CCS.

[0158] Step 2.1.4: LCS generates verification information for RTU and CCS identity authentication respectively. The specific steps are as follows:

[0159] Step 2.1.4.1: After receiving the information, LCS extracts the IDs sequentially according to the information length. RTU N1, ID CCS and T R-S1 ID CCS The unique identifier for CCS; T R-S1 The timestamp when the authentication request was sent to the RTU.

[0160] First, the timestamp is verified to determine whether the time difference between the receiving time and the sending time satisfies T. L-S1 -T R-S1 ≤ΔT;

[0161] If the timestamp verification fails, the authentication process will be terminated and an alarm message will be issued.

[0162] If the verification is successful, LCS will use the identity ID. RTU and ID CCS Search the database for the RTU's PUF parameter (ID). RTU C i ,R i ); R i For the RTU's PUF function to the challenge signal C i The response value; C i Random challenge signals generated for LCS.

[0163] Then, HMAC is calculated based on the shared key, and the digital signature is calculated using the LCS private key, as shown in the following formula:

[0164] H LCS1 =HMAC(ID) RTU ||R i ||N1||N3), S LCS1 =SIG(H LCS1 );

[0165] In the formula, N3 is a random number generated by LCS, used in the identity authentication process between RTU and LCS; H LCS1 S is the message authentication code calculated based on the shared key for LCS; LCS1 Use private key pair for LCS H LCS1 The generated digital signature.

[0166] Step 2.1.4.2: LCS selects a random number N4∈Z, and performs an operation on ID. CCS ||N2||N4 uses the shared key to generate the message authentication code H LCS2 And use the LCS private key to generate a digital signature S LCS2 As shown in the following formula:

[0167] HLCS2 =HMAC(ID) CCS ||N2||N4), S LCS2 =SIG(H LCS2 );

[0168] In the formula, N4 is a random number generated by LCS, used in the identity authentication process between LCS and CCS; H LCS2 S is the message authentication code calculated based on the shared key for LCS; LCS2 Use private key pair for LCS H LCS2 The generated digital signature.

[0169] Finally, the LCS sends the generated verification information to both the RTU and the LCS:

[0170] LCS will ID RTU ||C i ||N3||S LCS1 ||T L-S5 Send to RTU;

[0171] LCS will ID CCS ||N2||N4||S LCS2 ||T L-S5 Send to CCS; T L-S5 The timestamp when LCS sends verification information to RTU or CCS.

[0172] Step 2.1.5: The RTU verifies the information received in Step 5. The specific steps are as follows:

[0173] Step 2.1.5.1: RTU verification information:

[0174] After receiving the verification information, the RTU extracts the ID based on the length of each part of the content. RTU C i N3, S LCS1 and T L-S5 Each part of the content; where ID RTU This serves as the identifier for the RTU.

[0175] First, verify whether the timestamp satisfies T. R-S5 -T L-S5 ≤ΔT;

[0176] Next, the digital signature is decrypted using the LCS public key to obtain H. LCS1 ;

[0177] Based on the PUF function of this device, in C i The output response value is obtained by taking the input stimulus as the input stimulus, as shown in the following formula:

[0178] Ri =PUF(C i ), H′ LCS1 =HMAC(ID) RTU ||R i ||N1||N3);

[0179] For ID RTU ||R i ||N1||N3 uses the HMAC algorithm in equation (3-9) to calculate H′ LCS1 H, recovered from digital signature LCS1 Compare;

[0180] If the comparison matches, then the RTU has successfully authenticated the LCS.

[0181] If the comparison does not match, the identity authentication fails.

[0182] If the comparison is consistent, the RTU randomly selects the input stimulus C. i ′, calculate R based on the PUF function i ′, for C i ′||R i ′||N3||ID RTU HMAC is calculated to obtain H RTU3 and for H RTU3 The digital signature is calculated using the RTU's private key and appended to the message to generate verification information. The calculation formula is as follows:

[0183] R i =PUF(C) i ′),H RTU3 =HMAC(C i ′||R i ′||N3||ID RTU ),S RTU3 =SIG(H RTU3 );

[0184] Finally, RTU will Send to LCS.

[0185] In the formula, PUF() is the PUF function; HMAC() is the hash message authentication code; SIG() is the digital signature function, which signs the message using the private key; T x-Sy The timestamp marks the time of a certain step; ΔT is the maximum allowed time difference, used to determine whether the timestamp is valid; N x It is a random number used to increase the randomness and anti-prediction ability of the protocol.

[0186] Step 2.1.5.2: CCS Verification Information:

[0187] After receiving the information, CCS first verifies whether the timestamp of the information meets the T condition. C-S5 -T L-S5 ≤ΔT, using the public key of LCS to pair S LCS2 Decryption is performed to obtain the message authentication code H. LCS2 As shown in the following formula:

[0188] H′ LCS2 =HMAC(ID) CCS ||N2||N4);

[0189] Then, for ID CCS Perform HMAC calculations on ||N2||N4 to verify H′. LCS2 With H LCS2 Are they consistent?

[0190] If the comparison matches, then CCS has completed the identity authentication of LCS;

[0191] If the comparison does not match, the identity authentication fails.

[0192] CCS for N4||ID CCS HMAC is calculated to obtain H CCS4 And calculate its digital signature S CCS4 After extracting the timestamp, the verification information N4||ID is generated. CCS ||S CCS4 ||T C-S10 The calculation formula is as follows:

[0193] H CCS4 =HMAC(N4||ID) CCS ), S CCS4 =SIG(H CCS4 );

[0194] CCS will use N4||ID CCS ||S CCS4 ||T C-S10 Send to LCS.

[0195] LCS separates C based on the different lengths of each part of the information. i ′、 ID RTU S RTU3 and T R-S9 ;

[0196] First, verify whether the timestamp satisfies T. L-S9 -T R-S9 ≤ΔT;

[0197] An alarm message will be issued if the timestamp verification fails.

[0198] If the timestamp verification passes, then... Using R i XOR operation yields R i H′ is obtained by performing HMAC calculation. RTU3 As shown in the following formula:

[0199] H′ RTU3 =HMAC(C i ′||R i ′||N3||ID RTU );

[0200] Then, H is obtained by decryption using the RTU public key. RTU3 Compared with H RTU3 With H′ RTU3 Are they consistent?

[0201] If they match, the authentication of the RTU is complete.

[0202] If the comparison does not match, the identity authentication fails.

[0203] LCS separates N4 and ID based on the different lengths of each part of the information. CCS S CCS4 and T C-S10 ;

[0204] First, verify whether the timestamp satisfies T. L-S10 -T C-S10 ≤ΔT;

[0205] If the timestamp verification fails, an alarm message will be issued;

[0206] If the timestamp verification passes, then calculate H′. CCS4 As shown in the following formula:

[0207] H′ CCS4 =HMAC(N4||ID) CCS );

[0208] If the timestamp verification passes, the signature is restored using the CCS public key to obtain H. CCS4 Compared with H CCS4 With H′ CCS4 If the match is consistent, the identity authentication for CCS is complete; if the match is inconsistent, the identity authentication fails.

[0209] In the formula, E() / D() is a symmetric encryption / decryption function that uses a shared key to encrypt or decrypt data; AE() / D'() is an asymmetric encryption / decryption function that uses a public key to encrypt and a private key to decrypt, or vice versa.

[0210] Through the implementation of the above process, this paper finally achieved pairwise identity authentication between the remote control terminal, the local control server, and the central control center server.

[0211] (2) Two-way authentication between LCSs in different regions:

[0212] Large-scale IoT systems typically divide the network into multiple regional IoT zones, each managed by a local control center. Other IoT control terminals include weather stations and booster stations. Two-way authentication is required before communication between the local control centers and between the local control centers and the weather and booster stations. Figure 5 The image shows the Local Control Server (LCS) for region i. i With the local control server LCS in region j j The two-way authentication process is described in detail below:

[0213] Step 2.2.1: LCS i Select a random number N i ∈Z * Extract the local identity ID LCSi and Area identifier LCSi H is obtained by calculating H using HMAC. i Calculate the digital signature S using the local private key i Extract timestamp T i-S1 The calculation formula is as follows:

[0214] H i =HMAC(ID) LCSi ||Area LCSi ||N i ), S i =SIG(H i );

[0215] Finally, LCS i ID LCSi ||Area LCSi ||N i ||S i ||T i-S1 Send to LCS j .

[0216] In the formula, LCS i N is the local control server for the i-th region; i For LCS i A randomly generated random number; ID LCSi For LCS i Identity identifier; Area LCSi For LCS i The region identifier; H i For LCSi The message authentication code is calculated using HMAC; S i For LCS i Use the private key to pair H i The digital signature of the computation; T i-S1 For LCS i The extracted timestamp.

[0217] Step 2.2.2: LCS j Validate LCS i The identity authentication information is used to generate the identity authentication information on the client side;

[0218] LCS j After receiving the information, extract the ID. LCSi Area LCSi N i S i and T i-S1 For each part of the content, extract the sending and receiving timestamps for verification. j-S1 -T i-S1 Does ≤ΔT satisfy the condition?

[0219] If the verification fails, then send a request to the LCS. i Issue an alarm message.

[0220] If the verification passes, the digital signature can be decrypted using the public key to obtain H. i For the received ID LCSi ||Area LCSi ||N i Calculating HMAC using a shared key. i ′, as shown in the following formula:

[0221] H i =HAMC(ID) LCSi ||Area LCSi ||N i );

[0222] Comparison H i With H i Whether they match, to verify the digital signature;

[0223] If the verification passes, then LCS j Completed LCS i Identity authentication.

[0224] The message authentication code and digital signature are generated as identity authentication information, and the calculation formula is as follows:

[0225] H j =HMAC(ID) LCSj ||Area LCSj ||Nj ), S j =SIG(H j );

[0226] LCS j ID LCSj ||Area LCSj ||N j ||S j ||T j-S4 Send to LCS i .

[0227] In the formula, LCS j N is the local control server for region j; j For LCS j A randomly generated random number; ID LCSj For LCS j Identity identifier; Area LCSj For LCS j The region identifier; H j For LCS j The message authentication code is calculated using HMAC; S j For LCS j Use the private key to pair H j The digital signature of the computation; T j-S1 For LCS j Extracted timestamp; ΔT is the time window threshold.

[0228] Step 2.2.3: LCS i After receiving the message, verify the timestamp T. i-S4 -T j-S4 Does ≤ΔT satisfy the condition? Restore the digital signature S. j Get H j And calculate H as shown in the following formula. j ′;

[0229] H j =HAMC(ID') LCSj ||Area′ LCSj ||N j ′);

[0230] By comparing H j With H j Whether they match, to verify the digital signature;

[0231] If they match, then LCS i Completed LCS j Identity authentication.

[0232] In the formula, T i-S4 For LCS iExtracted timestamp; T j-S4 For LCS j The extracted timestamp.

[0233] Through the above process, this paper completes the two-way authentication between local control servers in different regions.

[0234] Step 3: Information Encryption and Authentication: Based on the authentication, the following steps are taken: Symmetric encryption or Asymmetric encryption protects the confidentiality, integrity, and non-repudiation of communication data.

[0235] The preceding steps completed identity authentication before communication, preventing attackers from forging legitimate identities. However, during information transmission from IoT control terminals, information is vulnerable to tampering, theft, and forgery attacks, necessitating the addition of information encryption and authentication measures. The information transmitted in the IoT control terminal includes real-time data, alarm information, control commands, and configuration parameters. Real-time data and alarm information represent the operational status of the IoT network sent from field terminal devices to the local control center and the central control center. Control commands and configuration parameters represent command information sent from the central control center to the local control layer and field device layer. Therefore, step 3, information encryption and authentication, designs an information encryption and authentication scheme based on digital signatures and HMAC for communication between devices at different layers, as detailed below:

[0236] (1) Information encryption authentication between RTU and LCS:

[0237] like Figure 6 The diagram illustrates the RTU and LCS message encryption and authentication scheme. The RTU uses a symmetric encryption algorithm to encrypt the message, generating ciphertext, and then uses the HMAC algorithm to generate a message authentication code. Upon receiving the message, the LCS uses the shared key to decrypt it into plaintext, and then uses the same HMAC algorithm to generate a message authentication code on the received plaintext. This code is compared with the received message authentication code to verify the message's integrity.

[0238] like Figure 7 As shown, the specific process for information encryption authentication between RTU and LCS is as follows:

[0239] Step 3.1.1: RTU selects plaintext information M RTU Calculate message authentication code H using shared key RTU Using a symmetric encryption algorithm to target M RTU and H RTU C is obtained by performing encryption calculations. RTU Extract the timestamp T RTU Generate security information C RTU ||T RTU The calculation formula is as follows:

[0240] H RTU =HMAC(M RTU ), C RTU =E(M RTU ||H RTU );

[0241] RTU will transmit security information C RTU ||T RTU Send to LCS.

[0242] Step 3.1.2: After receiving the security information, LCS decrypts and verifies it.

[0243] LCS separates C based on information length. RTU and T RTU ;

[0244] First, verify the timestamp T. LCS -T RTU Does ≤ΔT satisfy the condition?

[0245] If the verification fails, the ciphertext C will be rejected. RTU And send warning messages to the RTU and IoT control terminal central control center;

[0246] If the verification passes, M is obtained by decryption using the shared key of a symmetric cryptography algorithm. RTU ||H RTU , for M RTU Calculate the message authentication code H′ using the HMAC shared key RTU Compare H′ RTU and H RTU If they match, then accept the plaintext message M. RTU If they are inconsistent, then M RTU There is a risk of tampering and forgery, so LCS refuses to accept plaintext and sends alarm information to the RTU and IoT control terminal central control center.

[0247] In the formula, M RTU Plaintext information sent to the RTU; H RTU C is a message authentication code generated based on the HMAC algorithm. RTU The encrypted ciphertext information; T RTU A timestamp appended to the RTU; ΔT is the maximum allowed time difference; H′ RTU The message authentication code is recalculated for LCS.

[0248] (2) LCS and CCS information encryption authentication:

[0249] The confidentiality and integrity requirements of information transmitted between LCS and CCS are high. Therefore, this paper chooses highly secure asymmetric encryption and digital signature measures to encrypt and authenticate the information.Figure 8 The diagram shows the information encryption and authentication schemes for LCS and CCS.

[0250] LCS uses the public key of an asymmetric cryptographic algorithm to encrypt the plaintext to obtain ciphertext, then uses a hash function to calculate the message digest, and uses the signing private key to calculate a digital signature from the digest. The ciphertext and digital signature are then sent to CCS.

[0251] After receiving the ciphertext and digital signature, CCS decrypts it using its private key to obtain the plaintext and calculates a message digest from the plaintext. It then uses the public key to reconstruct the digital signature to obtain the message digest again. By comparing the two message digests, CCS determines whether to accept the plaintext.

[0252] like Figure 9 As shown, the specific process for LCS and CCS information encryption authentication is as follows:

[0253] Step 3.2.1: LCS generates plaintext information M LCS HMAC is calculated from the plaintext. LCS and for H LCS Calculate digital signature S LCS Asymmetric cryptography algorithm is selected for M LCS Perform encrypted calculations C LCS The calculation formula is as follows:

[0254] H LCS =HMAC(M LCS ), S LCS =SIG(H LCS ), C LCS =AE(M LCS );

[0255] LCS extracts timestamp T LCS , to securely transmit information C LCS ||S LCS ||T LCS Send to CCS.

[0256] Step 3.2.2: CCS decrypts and authenticates the received secure transmission information:

[0257] CCS separates C based on the length of each part of the content. LCS S LCS and T LCS ; Verify if the timestamp satisfies T CCS-S1 -T LCS-S1 ≤ΔT.

[0258] If the verification fails, the encrypted text will be refused to be decrypted, and an alarm message will be sent to the LCS and IoT control terminal maintenance personnel.

[0259] If the verification passes, proceed with the decryption process, which is as follows:

[0260] CCS uses a private key to decrypt C LCS Get M LCS And perform HMAC calculation to obtain H′ LCS The calculation formula is as follows:

[0261] H′ LCS =HMAC(M LCS );

[0262] CCS uses the LCS's signature public key to reconstruct the signature and obtain H. LCS Comparison of H′ LCS With H LCS Are they consistent?

[0263] If they match, the plaintext message has been authenticated and accepted.

[0264] If there is a discrepancy, the plaintext information is at risk of being tampered with or forged, and the CCS will send an alarm message to the LCS and IoT control terminal maintenance personnel.

[0265] In the formula, M LCS This is plaintext information, the raw data content generated by LCS; H LCS The message authentication code is used to verify the plaintext information M. LCS Calculated using the HMAC algorithm; S LCS For digital signature, it is for H LCS Generate using LCS private key signing; C LCS For ciphertext, it is the plaintext information M LCS Generated using an asymmetric encryption algorithm; T LCS The sending timestamp is the time recorded when the LCS sends the message; T CCS-S1 The receive timestamp is the time recorded when the CCS receives the message; ΔT is the maximum allowed time difference, which is the maximum allowed time interval from message sending to receiving; H′ LCS To recalculate the message authentication code, CCS processes the decrypted plaintext M. LCS Recalculated message authentication code; H LCS To restore the message authentication code obtained from the signature, CCS uses the LCS public key to verify the digital signature S. LCS The message authentication code obtained after restoration.

[0266] This completes the process of encrypted information transmission between LCS and CCS.

[0267] In summary, this lightweight network security protection method for IoT smart control terminals proposes a multi-attribute decision-making strategy for lightweight network security protection measures. Based on the theoretical research of symmetric cryptography, asymmetric cryptography, hash functions, and digital signature algorithms, a network security protection scheme for communication between devices at different layers of the IoT control terminal is designed, including a system device initial registration scheme, a two-way identity authentication scheme based on PUF and digital signature, and an information encryption authentication scheme based on digital signature and HMAC. This achieves identity authentication before communication between devices and information encryption authentication during communication, ensuring the integrity, confidentiality, and non-repudiation of information.

[0268] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A lightweight network security protection method for IoT smart control terminals, characterized in that, This lightweight network security protection method for IoT smart control terminals includes the following steps: Step 1 Device Registration: When a new device joins the system, it provides the server with registration information including identity identifier and region identifier. The hardware fingerprint is generated through PUF and combined with HMAC to bind the registration information, generating a unique and trusted identity. Step 2: Two-way authentication: Only authenticated devices can participate in communication; the session key or shared parameters generated during the authentication process provide a secure foundation for subsequent encryption and authentication. Step 3: Information Encryption and Authentication: Based on the authentication, the following steps are taken: Symmetric encryption or Asymmetric encryption protects the confidentiality, integrity, and non-repudiation of communication data.

2. The lightweight network security protection method for IoT smart control terminals according to claim 1, characterized in that: In step 1, when the Remote Control Unit (RTU) registers the device with the Local Control Server (LCS), the following steps are included: Step 1.1: When a new remote control terminal (RTU) joins the system, it needs to provide registration information to the local control server (LCS). The registration information includes: the IoT registration password (rpw) of the RTU and the area identifier (Sign). RTU Device Type RTU and registration date; Step 1.2: LCS verifies the validity of the registration password rpw; if the verification is successful, a unique identifier (ID) is generated for the RTU. RTU If the verification fails, an alarm message will be returned. Step 1.3: LCS calculates message authentication code H LCS And generate a random challenge signal C i LCS will H LCS ||ID RTU ||C i Send to RTU; Step 1.4: The remote control terminal RTU receives H LCS ||ID RTU ||C i From now on, regarding Sign RTU ||Type RTU ||Date is used for calculation and verification: if the verification passes, the ID is stored. RTU Meanwhile, the remote control terminal (RTU) uses its own PUF function to calculate the response value R. i The data is then sent to the LCS for storage; if the verification is inconsistent, an alarm message is sent to the local control server (LCS).

3. The lightweight network security protection method for IoT smart control terminals according to claim 2, characterized in that: In Step 1.3, the Local Control Server (LCS) uses the HMAC algorithm to calculate the message authentication code H. LCS And generate a random challenge signal C i The calculation formula is as follows: H LCS =HMAC(Sign RTU ||Type RTU ||Date); In Step 1.4, the remote control terminal (RTU) receives H LCS ||ID RTU ||C i From now on, we will first focus on Sign. RTU ||Type RTU ||Date is used to calculate H′ according to the following formula LCS ; H′ LCS =HMAC(Sign RTU ||Type RTU ||Date); If the verification passes, store the ID. RTU Meanwhile, the remote control terminal (RTU) uses its own PUF function to calculate the response value R. i =PUF(C i ), will ID RTU ||(R i C i Send it to LCS for storage; In the formula, H LCS Message authentication code generated for LCS; H′ LCS The message authentication code is recalculated for the RTU; HMAC is the hash message authentication code algorithm.

4. The lightweight network security protection method for IoT smart control terminals according to claim 1, characterized in that: In step 1, when the local control server registers with the central control server: Terminal devices in each regional IoT network are managed and controlled by the local control center server. When IoT control terminals are added after the regional IoT network is built, the local control server (LCS) needs to register with the central control center server (CCS). During registration, this paper chooses a manual-assisted method to assign identity IDs to the LCS. LCS And to store the identity IDs of each RTU in the IoT of this area. RTU and ID LCS Saved to CCS via a secure channel.

5. The lightweight network security protection method for IoT smart control terminals according to claim 1, characterized in that: Step 2 involves two-way authentication between the remote control terminal (RTU), the local control server (LCS), and the central control center server (CCS), including the following steps: Step 2.1.1: The remote control terminal (RTU) initiates an authentication request to the local control server (LCS), including: the RTU's identity ID. RTU Random number N1∈Z * The identity ID of the central control center server (CCS) CCS timestamp T R-S1 ; Step 2.1.2: After LCS verifies the validity of the timestamp, it forwards the RTU's identity identifier and the new timestamp (ID) to CCS. RTU ||T L-S2 ; Step 2.1.3: CCS verifies the timestamp and checks the ID. RTU The authenticity is verified, and if it passes, a random number N2∈Z is returned. * ; Step 2.1.4: LCS generates verification information for RTU and CCS identity authentication respectively; Step 2.1.5: RTU and CCS verify the information received in Step 5.

6. The lightweight network security protection method for IoT smart control terminals according to claim 5, characterized in that: In Step 2.1.4, LCS generates verification information, including the following steps: After receiving the message, LCS extracts the ID sequentially based on the message length. RTU N1, ID CCS and T R-S1 First, verify the timestamp to determine the received time T. L-S1 With the sending time T R-S1 Does the time difference satisfy T? L-S1 -T R-S1 ≤ΔT; If timestamp verification fails, authentication is terminated and an alarm is issued; If verification succeeds, LCS uses the identity identifier ID. RTU and ID CCS Search the database for the RTU's PUF parameter (ID). RTU C i ,R i HMAC is calculated using the shared key, and then the digital signature is calculated using the LCS private key. H LCS1 =HMAC(ID RTU ||R i ||N1||N3),S LCS1 =SIG(H LCS1 ); LCS selects a random number N4∈Z for ID CCS ||N2||N4 uses the shared key to generate the message authentication code H LCS2 And use the LCS private key to generate a digital signature S LCS2 The calculation process is as follows: H LCS2 =HMAC(ID CCS ||N2||N4),S LCS2 =SIG(H LCS2 ); Finally, LCS will ID RTU ||C i ||N3||S LCS1 ||T L-S5 Send to RTU, with ID CCS ||N2||N4||S LCS2 ||T L-S5 Send to CCS; In the formula, ID RTU A unique identifier for the RTU; ID CCS N1 is a unique identifier for the CCS; N2 is a random number generated by the RTU to prevent replay attacks and increase the randomness of the protocol; N3 is a random number generated by the LCS to respond to the RTU's authentication request and verify the authenticity of the CCS; N4 is a random number generated by the LCS to participate in the authentication process between the RTU and the LCS; N5 is a random number generated by the LCS to participate in the authentication process between the LCS and the CCS; T L-S1 T is the timestamp when the LCS receives the RTU request; R-S1 The timestamp when the RTU sends the authentication request; T L-S5 The timestamp when LCS sends verification information to RTU or CCS; ΔT is the maximum allowed time difference; R i For the RTU's PUF function to the challenge signal C i The response value; C i Random challenge signals generated for LCS; H LCS1 H is the message authentication code calculated based on the shared key for LCS. LCS2 S is the message authentication code calculated based on the shared key for LCS; LCS1 Use private key pair for LCS H LCS1 The generated digital signature; S LCS2 Use private key pair for LCS H LCS2 The generated digital signature.

7. The lightweight network security protection method for IoT smart control terminals according to claim 6, characterized in that: In Step 2.1.5, the RTU and CCS verification information includes the following steps: After receiving the verification information, the RTU extracts the ID based on the length of each part of the content. RTU C i N3, S LCS1 and T L-S5 Each part; first, verify whether the timestamp satisfies T. R-S5 -T L-S5 ≤ΔT; then, the digital signature is decrypted using the LCS public key to obtain H. LCS1 Based on the PUF function of this device, in C i The output response value is calculated using the input stimulus as follows: R i =PUF(C i ),H′ LCS1 =HMAC(ID RTU ||R i ||N1||N3); For ID RTU ||R i ||N1||N3 use the HMAC algorithm to calculate H′ LCS1 H, recovered from digital signature LCS1 The system performs a comparison; if the comparison matches, the RTU has successfully authenticated the LCS; if the comparison does not match, the authentication has failed. After receiving the information, CCS first verifies whether the timestamp of the information meets the T condition. C-S5 -T L-S5 ≤ΔT, using the public key of LCS to pair S LCS2 Decryption is performed to obtain the message authentication code H. LCS2 ; For ID CCS Perform HMAC calculations on ||N2||N4 to verify H′. LCS2 With H LCS2 Whether they match, the calculation formula is as follows: H′ LCS2 =HMAC(ID CCS ||N2||N4); If the comparison matches, CCS has completed the identity authentication of LCS; if the comparison does not match, the identity authentication has failed. RTU randomly selects input stimulus C i ′, calculate R based on the PUF function i ′, for C i ′||R i ′||N3||ID RTU HMAC is calculated to obtain H RTU3 and for H RTU3 The digital signature is calculated using the RTU's private key and appended to the message to generate verification information. The calculation formula is as follows: R′ i =PUF(C′ i ),H RTU3 =HMAC(C′ i ||R′ i ||N3||ID RTU ),S RTU3 =SIG(H RTU3 ); RTU will Send to LCS; CCS for N4||ID CCS HMAC is calculated to obtain H CCS4 And calculate its digital signature S CCS4 After extracting the timestamp, the verification information N4||ID is generated. CCS ||S CCS4 ||T C-S10 The calculation formula is as follows: H CCS4 =HMAC(N4||ID CCS ),S CCS4 =SIG(H CCS4 ); CCS will use N4||ID CCS ||S CCS4 ||T C-S10 Send to LCS; LCS separates C based on the different lengths of each part of the information. i ′、 ID RTU S RTU3 and T R-S9 First, verify whether the timestamp satisfies T. L-S9 -T R-S9 ≤ΔT; If timestamp verification fails, an alarm message is issued; if timestamp verification succeeds, then... Using R i XOR operation yields R i H′ is obtained by performing HMAC calculation. RTU3 H is obtained by decryption using the RTU public key. RTU3 Compared with H RTU3 With H′ RTU3 If they match, the authentication of the RTU is complete; if they do not match, the authentication fails. The calculation formula is as follows: H′ RTU3 =HMAC(C i ′||R i ′||N3||ID RTU ); LCS separates N4 and ID based on the different lengths of each part of the information. CCS S CCS4 and T C-S10 First, verify whether the timestamp satisfies T. L-S10 -T C-S10 ≤ΔT; If timestamp verification fails, an alarm message is issued; If timestamp verification passes, H′ is calculated. CCS4 Use the CCS public key to restore the signature and obtain H. CCS4 Compared with H CCS4 With H′ CCS4 If the match is consistent, the CCS identity authentication is complete; if the match is inconsistent, the identity authentication fails. The calculation formula is as follows: H′ CCS4 =HMAC(N4||ID CCS ); In the formula, ID RTU ID is the identifier for the RTU. LCS ID is the identifier for the LCS. CCS For the identity identifier of CCS; C i The input excitation signal for the PUF; R i For PUF to input stimulus C i The output response value; PUF() is the PUF function; HMAC() is the hash message authentication code; SIG() is the digital signature function, which signs the message using the private key; T x-Sy The timestamp marks the time of a certain step; ΔT is the maximum allowed time difference, used to determine whether the timestamp is valid; N x is a random number used to increase the randomness and anti-predictability of the protocol; E() / D() are symmetric encryption / decryption functions that use a shared key to encrypt or decrypt data; AE() / D'() are asymmetric encryption / decryption functions that use a public key to encrypt and a private key to decrypt, or vice versa.

8. The lightweight network security protection method for IoT smart control terminals according to claim 1, characterized in that: Step 2 involves two-way authentication between local control servers (LCS) in different regions, including the following steps: Step 2.2.1: LCS i Select a random number N i ∈Z * Extract the local identity ID LCSi and Area identifier LCSi H is obtained by calculating H using HMAC. i Calculate the digital signature S using the local private key i Extract timestamp T i-S1 The calculation formula is as follows: H i =HMAC(ID LCSi ||Area LCSi ||N i ),S i =SIG(H i ); LCS i ID LCSi ||Area LCSi ||N i ||S i ||T i-S1 Send to LCS j ; Step 2.2.2: LCS j Validate LCS i The identity authentication information is used to generate the identity authentication information on the client side; LCS j After receiving the information, extract the ID. LCSi Area LCSi N i S i and T i-S1 Each section; extracting send and receive timestamps for verification T j-S1 -T i-S1 If ≤ΔT is satisfied; if not, proceed to LCS. i Issue an alarm message; if verification passes, the digital signature is restored using the public key to obtain H. i ; For the received ID LCSi ||Area LCSi ||N i Calculating HMAC using a shared key. i The calculation formula is as follows: H′ i =HAMC(ID LCSi ||Area LCSi ||N i ); Comparison H i With H i The system checks for consistency to verify the digital signature; if the verification passes, the LCS... j Completed LCS i Identity authentication; LCS j Generate message authentication code H j and digital signatures j The calculation formula for this identity authentication information is as follows: H j =HMAC(ID LCSj ||Area LCSj ||N j ),S j =SIG(H j ); LCS j ID LCSj ||Area LCSj ||N j ||S j ||T j-S4 Send to LCS i ; Step 2.2.3: LCS i After receiving the message, verify the timestamp T. i-S4 -T j-S4 Does ≤ΔT satisfy the condition? Restore the digital signature S. j Get H j And calculate H j ′, by comparing H j With H j The system checks if the signature matches to verify the digital signature; if they match, then the LCS is executed. i Completed LCS j Identity authentication; the calculation formula is as follows: H′ j =HAMC(ID′ LCSj ||Area′ LCSj ||N′ j ); In the formula, LCS i For the local control server of region i; LCS j N is the local control server for region j; i For LCS i A randomly generated random number; N j For LCS j A randomly generated random number; ID LCSi For LCS i Identity identifier; ID LCSj For LCS j Identity identifier; Area LCSi For LCS i The area identifier; Area LCSj For LCS j The region identifier; H i For LCS i The message authentication code is calculated using HMAC; H j For LCS j The message authentication code is calculated using HMAC; S i For LCS i Use the private key to pair H i The digital signature of the computation; S j For LCS j Use the private key to pair H j The digital signature of the computation; T i-S1 T i-S4 For LCS i Extracted timestamp; T j-S1 T j-S4 For LCS j Extracted timestamp; ΔT is the time window threshold.

9. The lightweight network security protection method for IoT smart control terminals according to claim 1, characterized in that: In step 3, the information encryption and authentication between the remote control terminal (RTU) and the local control server (LCS) includes the following steps: Step 3.1.1: RTU selects plaintext information M RTU Calculate message authentication code H using shared key RTU Using a symmetric encryption algorithm to target M RTU and H RTU C is obtained by performing encryption calculations. RTU Extract the timestamp T RTU Generate security information C RTU ||T RTU The calculation formula is as follows: H RTU =HMAC(M RTU ),C RTU =E(M RTU ||H RTU ); RTU will transmit security information C RTU ||T RTU Send to LCS; Step 3.1.2: After receiving the security information, LCS decrypts and verifies it; LCS separates C based on information length. RTU and T RTU ; First, verify the timestamp T. LCS -T RTU Check if ≤ΔT is satisfied; if the verification fails, reject the ciphertext C. RTU And send warning messages to the RTU and IoT control terminal central control center; If the verification passes, M is obtained by decryption using the shared key of a symmetric cryptography algorithm. RTU ||H RTU , for M RTU Calculate the message authentication code H′ using the HMAC shared key RTU Compare H′ RTU and H RTU If they match, then accept the plaintext message M. RTU If there is a discrepancy, the LCS will refuse to accept the plaintext and will send an alarm message to the RTU and the IoT control terminal central control center. In the formula, M RTU Plaintext information sent to the RTU; H RTU C is a message authentication code generated based on the HMAC algorithm. RTU The encrypted ciphertext information; T RTU A timestamp appended to the RTU; ΔT is the maximum allowed time difference; H′ RTU The message authentication code is recalculated for LCS.

10. The lightweight network security protection method for IoT smart control terminals according to claim 1, characterized in that: Step 3, the information encryption authentication between LCS and CCS, includes the following steps: Step 3.2.1: LCS generates plaintext information M LCS HMAC is calculated from the plaintext. LCS and for H LCS Calculate digital signature S LCS Asymmetric cryptography algorithm is selected for M LCS Perform encrypted calculations C LCS The calculation formula is as follows: H LCS =HMAC(M LCS ),S LCS =SIG(H LCS ),C LCS =AE(M LCS ); LCS extracts timestamp T LCS , to securely transmit information C LCS ||S LCS ||T LCS Send to CCS; Step 3.2.2: CCS decrypts and authenticates the received secure transmission information; CCS separates C based on the length of each part of the content. LCS S LCS and T LCS ; Verify if the timestamp satisfies T CCS-S1 -T LCS-S1 If the verification fails, the ciphertext will not be decrypted, and an alarm will be sent to the LCS and IoT control terminal maintenance personnel; if the verification passes, the decryption process will proceed. CCS uses a private key to decrypt C LCS Get M LCS And perform HMAC calculation to obtain H′ LCS The calculation formula is as follows: H′ LCS =HMAC(M LCS ); CCS uses the LCS's signature public key to reconstruct the signature and obtain H. LCS Comparison of H′ LCS With H LCS If they match, the plaintext information has been authenticated and accepted; if they do not match, the CCS sends an alarm message to the LCS and IoT control terminal maintenance personnel. In the formula, M LCS This is plaintext information, the raw data content generated by LCS; H LCS The message authentication code is used to verify the plaintext information M. LCS Calculated using the HMAC algorithm; S LCS For digital signature, it is for H LCS Generate using LCS private key signing; C LCS For ciphertext, it is the plaintext information M LCS Generated using an asymmetric encryption algorithm; T LCS The sending timestamp is the time recorded when the LCS sends the message; T CCS-S1 The receive timestamp is the time recorded when the CCS receives the message; ΔT is the maximum allowed time difference, which is the maximum allowed time interval from message sending to receiving; H′ LCS To recalculate the message authentication code, CCS processes the decrypted plaintext M. LCS Recalculated message authentication code; H LCS To restore the message authentication code obtained from the signature, CCS uses the LCS public key to verify the digital signature S. LCS The message authentication code obtained after restoration.

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