SSL VPN security gateway communication method fused with post quantum cryptography

Abstract

The invention discloses an SSL VPN security gateway communication method fused with a post quantum cryptography technology. Comprising the following steps: S1, a client and a server respectively configure a serial hybrid signature digital certificate containing an SM2 algorithm and a serial hybrid encryption digital certificate containing a PQC algorithm, and a corresponding PQC encryption key pair private key, a PQC signature key pair private key, an SM2 encryption key pair private key and an SM2 signature key pair private key; s2, newly adding a hybrid algorithm password suite using an SM2 algorithm and a PQC algorithm in a password suite list of the client, and forcibly jacking the priority of the hybrid algorithm password suite; and S3, a message structure in a handshake protocol is transformed to use a series hybrid encrypted digital certificate to realize that PQC algorithm processing is added on the basis of an original national cryptographic algorithm to realize quantum key negotiation resistance. According to the method, the PQC algorithm is added on the basis of the original national secret algorithm, and the handshake protocol is transformed, so that anti-quantum-attack key agreement and identity authentication can be realized, the communication security is remarkably improved, and meanwhile, the interoperability with the standard SSL VPN is kept.

Description

Technical Field

[0001] The present invention relates to the field of network security technology, and in particular to an SSL VPN security gateway communication method integrating post-quantum cryptography technology. Background Art

[0002] The handshake protocol in the classic SSL VPN technical specification involves the following process: a) Exchange hello messages to negotiate cipher suites, exchange random numbers, and decide whether to reuse the session; b) Exchange necessary parameters and negotiate the pre-master key; c) Exchange certificates or IBC information to verify the other party; d) Generate the master key using the pre-master key and the exchanged random number; e) Provide security parameters to the record layer; f) Verify the consistency of the security parameters calculated by both parties and the authenticity and integrity of the handshake process.

[0003] like Figure 1 As shown in the figure, the client sends a client hello message to the server. The server should respond with a server hello message; otherwise, a fatal error is generated and the connection is terminated. The client hello and server hello messages are used by the client and server to negotiate the SM2-based cryptographic algorithm, determine secure transmission capabilities, including the protocol version, session identifier, and cipher suite attributes, and generate and exchange random numbers. Following the client hello and server hello messages, the authentication and key exchange process begins, including the server certificate and server key exchange, and the client certificate and client key exchange.

[0004] After the server sends its Hello message, it sends its own Certificate message and a Server Key Exchange message. If the server needs to verify the client's identity, it sends a Certificate Request message to the client, followed by a Server Hello Completion message, indicating the end of the Hello message phase and awaiting a response from the client. If the server sends a Certificate Request message, the client responds with a Certificate message. The client then sends a Key Exchange message, the content of which depends on the key exchange algorithm negotiated between the client and server Hello messages. If the client sends a Certificate message, it also sends a digitally signed Certificate Verification message for the server to verify the client's identity.

[0005] Current SSL VPN systems commonly use public key algorithms such as SM2 and RSA for key negotiation. However, with the development of quantum computing, these algorithms are at risk of being cracked. While theoretical progress has been made in post-quantum cryptography (PQC), its application in practical network equipment like SSL VPNs still faces challenges such as protocol compatibility and performance optimization. Furthermore, existing technologies, such as the national encryption algorithm scheme defined in GM / T 0024, the "SSL VPN Technical Specification," do not yet address the requirements for quantum computing resistance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an SSL VPN security gateway communication method that integrates post-quantum cryptography technology to achieve key negotiation and identity authentication that is resistant to quantum attacks, thereby significantly improving communication security.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0008] A SSL VPN security gateway communication method integrating post-quantum cryptography technology, comprising the following steps: S1. The client and server are respectively configured with a concatenated hybrid signature digital certificate containing the SM2 algorithm and the PQC algorithm, a concatenated hybrid encryption digital certificate, and the corresponding PQC encryption key pair private key, PQC signature key pair private key, SM2 encryption key pair private key, and SM2 signature key pair private key; S2. Add a hybrid cipher suite using the SM2 and PQC algorithms to the client's cipher suite list and prioritize it. S3. By modifying the message structure in the handshake protocol to use a serial hybrid encrypted digital certificate, PQC algorithm processing is added to the original national secret algorithm to achieve quantum-resistant key negotiation.

[0009] Preferably, the PQC algorithm in step S1 includes but is not limited to a key encapsulation algorithm based on a lattice cryptographic mechanism: ML-KEM, and a digital signature algorithm based on a lattice cryptographic mechanism: ML-DSA; the PQC digital certificate used by the PQC algorithm is a standard X.509 format certificate, and a new OID identification hybrid algorithm is used in the PQC digital certificate; the public key value uses the PQC public key value and the SM2 public key value in series, with the PQC public key value in front and the SM2 public key value in the back; the signature value uses the PQC signature value and the SM2 signature value in series, with the PQC signature value in front and the SM2 signature value in the back.

[0010] Preferably, the hybrid algorithm cipher suite in step S2 is ECC_MLDSA_MLKEM_SM4_SM3, wherein ECC_MLDSA_MLKEM is a key exchange algorithm that combines the SM2 algorithm with the ML-DSA algorithm and the ML-KEM algorithm, SM4 is an encryption algorithm, and SM3 is a verification algorithm.

[0011] Preferably, step S3 includes performing PQC algorithm transformation on 7 types of messages in the handshake protocol, and the 7 types of messages include client hello message, server hello message, certificate message, server key exchange message, certificate request message, client key exchange message and certificate verification message.

[0012] Preferably, the client hello message adds a hybrid algorithm cipher suite ECC_MLDSA_MLKEM_SM4_SM3, whose value is {0xe0, 0x63}; the server hello message selects a hybrid algorithm cipher suite.

[0013] Preferably, the certificate format of the certificate message is a serial hybrid digital certificate, the serial hybrid digital certificate includes a serial hybrid signature digital certificate and a serial hybrid encryption digital certificate, the serial hybrid signature digital certificate contains the PQC signature key pair public key and the SM2 signature key pair public key, the serial hybrid encryption digital certificate contains the PQC encryption key pair public key and the SM2 encryption key pair public key.

[0014] Preferably, the signature processing of the server-side key exchange message adopts a double signature mechanism, specifically: the server signs the random numbers of both parties and the server-side encryption certificate, first using the PQC algorithm to sign, and then using the SM2 algorithm to sign.

[0015] Preferably, the certificate request message is set as a mandatory message, and the newly added sm2_pqc_sign certificate type requires the client to provide a serial hybrid signature digital certificate.

[0016] Preferably, the generation of the pre-master key of the client key exchange message includes: The client uses the server's PQC encryption key to generate a 32-byte shared key Ski and ciphertext Skic. Then, the 2-byte client_version, 14-byte random, and ciphertext Skic are concatenated, and the public key is encrypted using the server's SM2 encryption key and sent to the server. The client concatenates the 2-byte client_version, 14-byte random, and 32-byte Ski to form a 48-byte pre-master key. The process of the server obtaining the plaintext of the pre-master key includes: The server first uses the server SM2 encryption key to decrypt the outer layer of the private key to obtain client_version, random and Skic; Use the server's PQC encryption key to decrypt the private key to obtain Ski; Finally, concatenate client_version, random, and Ski to generate a 48-byte pre-master key.

[0017] Preferably, the certificate verification message is specifically: The client first uses the SM3 algorithm to hash all handshake messages from the client hello message to the certificate verification message; then uses the client's PQC signature key to sign the private key and the client's SM2 signature key to sign the private key respectively; then concatenates the PQC signature and SM2 signature, with the PQC signature first and the SM2 signature last; finally, writes the concatenated message into the certificate verification message and sends it to the server; After receiving the certificate verification message, the server needs to verify the client's dual signature, specifically including: the server uses the client's PQC signature key to verify the public key PQC signature, and then uses the client's SM2 signature key to verify the public key SM2 signature.

[0018] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is as follows.

[0019] By adding the PQC algorithm to the original national secret algorithm and modifying the handshake protocol, the present invention can achieve quantum attack-resistant key negotiation and identity authentication, significantly improving communication security while maintaining interoperability with standard SSL VPN. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the handshake message flow chart in the existing classic SSL VPN technical specifications; Figure 2 This is an architectural diagram of the SSL VPN security gateway system that applies the post-quantum cryptography technology of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] A SSL VPN security gateway communication method integrating post-quantum cryptography technology, comprising the following steps: S1. The client and server are respectively configured with a concatenated hybrid signature digital certificate and a concatenated hybrid encryption digital certificate containing the SM2 algorithm and the PQC algorithm, as well as the corresponding PQC encryption key pair private key, PQC signature key pair private key, SM2 encryption key pair private key, and SM2 signature key pair private key.

[0023] The PQC algorithm includes but is not limited to the key encapsulation algorithm based on the lattice cryptography mechanism: ML-KEM, and the digital signature algorithm based on the lattice cryptography mechanism: ML-DSA; the PQC digital certificate used by the PQC algorithm is a standard X.509 format certificate, and the PQC digital certificate uses a new OID to identify the hybrid algorithm; the public key value uses the PQC public key value and the SM2 public key value in series, with the PQC public key value in front and the SM2 public key value in the back; the signature value uses the PQC signature value and the SM2 signature value in series, with the PQC signature value in front and the SM2 signature value in the back.

[0024] The two participants in the handshake protocol: the client (Initiator) and the server (Responder) need to have a serial hybrid signature digital certificate, a serial hybrid encryption digital certificate and the corresponding PQC encryption key pair private key, PQC signature key pair private key, SM2 encryption key pair private key, and SM2 signature key pair private key. The client's PQC encryption key pair public key is included in the serial hybrid encryption digital certificate, recorded as EncPubKey I , the private key of the PQC encryption key pair is recorded as EncPriKey I The client's PQC signature key pair public key is included in the serial hybrid signature digital certificate, recorded as SignPubKey I , the private key of the PQC signature key pair is recorded as SignPriKey I The server's PQC encryption key pair public key is included in the serial hybrid encryption digital certificate, recorded as EncPubKey R , the private key of the PQC encryption key pair is recorded as EncPriKey R The server's PQC signature key pair public key is included in the serial hybrid signature digital certificate, recorded as SignPubKey R , the private key of the PQC signature key pair is recorded as SignPriKey R .

[0025] S2. Add a hybrid algorithm cipher suite using the SM2 and PQC algorithms to the client's cipher suite list and force it to the top of the priority list.

[0026] The hybrid algorithm cipher suite is ECC_MLDSA_MLKEM_SM4_SM3. ECC_MLDSA_MLKEM is a key exchange algorithm that combines the SM2 algorithm with the ML-DSA and ML-KEM algorithms. SM4 is the encryption algorithm, and SM3 is the verification algorithm.

[0027] S3. By modifying the message structure in the handshake protocol to use a serial hybrid encrypted digital certificate, PQC algorithm processing is added to the original national secret algorithm to achieve quantum-resistant key negotiation.

[0028] The handshake message process involves nine messages: ClientHello (client hello message), ServerHello (server hello message), Certificate (certificate message), ServerKeyExchange (server key exchange message), CertificateRequest (certificate request message), ServerHelloDone (server hello completion message), CertificateVerify (certificate verification message), ClientKeyExchange (client key exchange message), and Finished (handshake completion message). This step primarily involves modifying the PQC algorithm for seven messages in the handshake protocol: ClientHello, ServerHello, Certificate, ServerKeyExchange, CertificateRequest, CertificateVerify, and ClientKeyExchange. The formats and processing of other messages remain consistent with the GM / T 0024 "SSL VPN Technical Specification." Details are as follows: (1) ClientHello message The following new hybrid algorithm cipher suites are added: name Key Exchange encryption check value ECC_MLDSA_MLKEM_SM4_SM3 ECC_MLDSA_MLKEM SM4 SM3 {0xe0,0x63} (2) ServerHello message The server selects a cipher suite from the client's hello message, specifically a hybrid algorithm cipher suite.

[0029] (3) Certificate message The certificate format of the certificate message is a concatenated hybrid digital certificate. The concatenated hybrid digital certificate includes a concatenated hybrid signature digital certificate and a concatenated hybrid encryption digital certificate. The concatenated hybrid signature digital certificate contains the PQC signature key pair public key and the SM2 signature key pair public key. The concatenated hybrid encryption digital certificate contains the PQC encryption key pair public key and the SM2 encryption key pair public key.

[0030] (4) ServerKeyExchange message The server-side key exchange message signature process uses a dual signature mechanism. Specifically, the server-side signature of both random numbers and the server-side encryption certificate is first signed using the PQC algorithm and then signed using the SM2 algorithm. The calculation process is as follows: signed_params=PQC_SecKey_Sign(client_random|server_random|CERT_enc_r_b, SignPriKey R )|Asymmetric_Sign(client_random|server_random|CERT_enc_r_b,priv_r).

[0031] Among them, PQC_SecKey_Sign represents the PQC private key signature method; client_random is the random number generated by the client; server_random is the random number generated by the server; CERT_enc_r_b is the derived value of the server's PQC encryption certificate CERT_enc_r; Asymmetric_Sign represents the classic asymmetric signature algorithm; priv_r is the private key of the server's SM2 signature key pair.

[0032] The client uses the server's signature public key to verify the signature, first verifying the PQC algorithm signature, and then verifying the SM2 algorithm signature.

[0033] (5) CertificateRequest message In the SSL_VPN technical specification, this message is optional, but it is required to obtain the client's PQC algorithm certificate.

[0034] List of certificate types required from the client The certificate_types parameter needs to add a tandem hybrid signature digital certificate type (sm2_pqc_sign) to require the client to provide a tandem hybrid signature digital certificate.

[0035] (6) ClientKeyExchange message This message contains the pre-master key, which is generated as follows: Skic=PQC_PubKey_Enc(Ski, EncPubKey R ) PQCEncryptedPreMasterSecret=Asymmetric_Encrypt(client_version|random|Skic,pub_r); PreMasterSecret= client_version|random|Ski; Among them, client_version is 2 bytes, random is a 14-byte random number, Ski is a 32-byte shared key generated by PQC, and a total of 48 bytes of pre-master key are generated. Asymmetric_Encrypt represents classic asymmetric algorithm encryption, pub_r is the public key of the SM2 encryption key pair on the server, and PQC_PubKey_Enc represents the key encryption method based on PQC public key encryption.

[0036] Specifically: The client uses the server's PQC encryption key to generate a 32-byte shared key Ski and ciphertext Skic.

[0037] Then concatenate the 2-byte client_version, 14-byte random, and the ciphertext Skic, encrypt the public key with the server's SM2 encryption key, and send it to the server.

[0038] The client concatenates the 2-byte client_version, 14-byte random, and 32-byte Ski to form a 48-byte pre-master key.

[0039] The process of obtaining the plaintext pre-master key on the server includes: The server first uses the server SM2 encryption key to decrypt the outer layer of the private key to obtain client_version, random and Skic; Use the server's PQC encryption key to decrypt the private key to obtain Ski; Finally, concatenate client_version, random, and Ski to generate a 48-byte pre-master key.

[0040] (7) CertificateVerify message The certificate verification message is as follows: Signature=PQC_SecKey_Sign(SM3(Handshake),SignPriKey I )|Asymmetric_Sign(SM3(handshake-messages),priv_i).

[0041] Among them, Handshake refers to the logical set of all handshake protocol messages from ClientHello to the current message; handshake-messages is the binary data stream form of Handshake; priv_i is the private key of the client's SM2 signature key pair.

[0042] The client first uses the SM3 algorithm to calculate the hash value of all handshake messages from the client hello message to the certificate verification message; then uses the client PQC signature key to sign the private key and the client SM2 signature key to sign the private key respectively; then concatenates the PQC signature and SM2 signature, with the PQC signature in front and the SM2 signature in the back; finally, writes the concatenated message into the certificate verification message and sends it to the server.

[0043] The SM3 calculation covers all handshake-related messages from the client's hello message up to (but not including) this message (the encryption certificate must be included in the signature calculation), including the handshake message type and length fields. This is consistent with the SSL_VPN technical specification.

[0044] After receiving the certificate verification message, the server needs to verify the client's dual signature, specifically including: the server uses the client's PQC signature key to verify the PQC signature of the public key, and then uses the client's SM2 signature key to verify the SM2 signature of the public key The client and server use the pre-master secret key to calculate the master key and working key respectively, and the usage method is implemented according to the requirements of the standard specification.

[0045] An SSL VPN security gateway system integrating post-quantum cryptography technology is implemented based on an SSL VPN security gateway communication method integrating post-quantum cryptography technology. It is an upgrade and transformation based on the existing standard SSL VPN security gateway. The upgraded functions include: a handshake protocol integrating the SM2 algorithm and the PQC algorithm, and the import and export functions of PQC digital certificates.

[0046] The handshake protocol function that integrates the SM2 algorithm and the PQC algorithm mainly embeds the PQC algorithm in the existing technical specifications and uses a hybrid PQC algorithm digital certificate. The PQC algorithm digital certificate is a standard X.509 format certificate. The PQC digital certificate uses a new OID to identify the hybrid algorithm. The public key value uses the PQC public key value and the SM2 public key value in series, with the PQC public key value in front and the SM2 public key value in the back. The signature value uses the PQC signature value and the SM2 signature value in series, with the PQC signature value in front and the SM2 signature value in the back.

[0047] The import and export function of PQC digital certificates is mainly used to import hybrid PQC digital certificates and supporting private keys into the PQCSSL VPN security gateway, thereby performing key negotiation that integrates the SM2 algorithm and the PQC algorithm.

[0048] Combine Figure 2As shown, the system includes a database module, a password module, a device management service, an SSL VPN module and a key negotiation module, wherein the output end of the database module is connected to the input end of the device management service; the output end of the password module is connected to the input ends of the device management service, the SSL VPN module and the key negotiation module respectively; the output end of the key negotiation module is connected to the input end of the SSL VPN module; and the output end of the SSL VPN module is connected to the input end of the device management service.

[0049] The database module is a data storage module used to store data generated by the management system.

[0050] The cryptographic module includes classical cryptographic algorithms and post-quantum cryptographic algorithms. The classical cryptographic algorithms are used for classical static key management and logical implementation of classical cryptographic algorithms; the post-quantum cryptographic algorithms are used to implement post-quantum cryptographic algorithms, post-quantum key storage and use.

[0051] The device management service is a human-computer interaction module used to manage the SSL VPN security gateway's parameters, function enablement, and permissions. It connects to the database module to store data generated during operations. It also connects to the cryptography module to provide both classical and post-quantum cryptographic algorithms for the device management service.

[0052] The SSL VPN module, based on an open-source project, is primarily used to establish secure, encrypted communication tunnels over public networks. Its core functions include remote access (e.g., enabling employees to securely connect to the company intranet) and site-to-site connectivity (e.g., inter-regional network connectivity). It supports both TCP and UDP protocols, with UDP being the default for improved efficiency, and offers reliable traversal through NAT and firewall environments. Data encapsulation is achieved through virtual network adapters (TUN / TAP modes). TUN mode processes IP layer data, while TAP mode supports full Ethernet frame transmission, adapting to diverse scenarios.

[0053] The key negotiation module implements the handshake protocol, completing key negotiation and certificate verification. Compared to standard SSL VPN, the addition of the PQC algorithm to the existing national encryption algorithm improves the security of the SSLVPN key negotiation process while maintaining compatibility with SSL VPN protocol specifications, and also provides quantum-resistant features.

Claims

1. A SSL VPN security gateway communication method integrating post-quantum cryptography technology, characterized by: The following steps are involved: S1. The client and server are respectively configured with a concatenated hybrid signature digital certificate containing the SM2 algorithm and the PQC algorithm, a concatenated hybrid encryption digital certificate, and the corresponding PQC encryption key pair private key, PQC signature key pair private key, SM2 encryption key pair private key, and SM2 signature key pair private key; S2. Add a hybrid cipher suite using the SM2 and PQC algorithms to the client's cipher suite list and prioritize it. S3. By modifying the message structure in the handshake protocol to use a serial hybrid encrypted digital certificate, PQC algorithm processing is added to the original national secret algorithm to achieve quantum-resistant key negotiation.

2. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 1, characterized in that: The PQC algorithm in step S1 includes but is not limited to the key encapsulation algorithm based on the lattice cryptography mechanism: ML-KEM, and the digital signature algorithm based on the lattice cryptography mechanism: ML-DSA; the PQC digital certificate used by the PQC algorithm is a standard X.509 format certificate, and the new OID identification hybrid algorithm is used in the PQC digital certificate; The public key value is the concatenation of the PQC public key value and the SM2 public key value, with the PQC public key value in front and the SM2 public key value in the back; the signature value is the concatenation of the PQC signature value and the SM2 signature value, with the PQC signature value in front and the SM2 signature value in the back.

3. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 2, characterized in that: In step S2, the hybrid algorithm cipher suite is ECC_MLDSA_MLKEM_SM4_SM3, where ECC_MLDSA_MLKEM is a key exchange algorithm that combines the SM2 algorithm with the ML-DSA algorithm and the ML-KEM algorithm, SM4 is an encryption algorithm, and SM3 is a verification algorithm.

4. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 3 is characterized in that: The step S3 includes performing PQC algorithm transformation on 7 types of messages in the handshake protocol, the 7 types of messages including client hello message, server hello message, certificate message, server key exchange message, certificate request message, client key exchange message and certificate verification message.

5. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 4 is characterized in that: The client hello message adds a new hybrid algorithm cipher suite ECC_MLDSA_MLKEM_SM4_SM3, whose value is {0xe0, 0x63}; the server hello message selects a hybrid algorithm cipher suite.

6. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 4, characterized in that: The certificate format of the certificate message is a serial hybrid digital certificate, which includes a serial hybrid signature digital certificate and a serial hybrid encryption digital certificate. The serial hybrid signature digital certificate contains the PQC signature key pair public key and the SM2 signature key pair public key, and the serial hybrid encryption digital certificate contains the PQC encryption key pair public key and the SM2 encryption key pair public key.

7. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 4, characterized in that: The signature processing of the server-side key exchange message adopts a double signature mechanism, specifically: the server signs the random numbers of both parties and the server-side encryption certificate, first using the PQC algorithm to sign, and then using the SM2 algorithm to sign.

8. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 4, characterized in that: The certificate request message is set as a mandatory message, and the newly added sm2_pqc_sign certificate type requires the client to provide a serial hybrid signature digital certificate.

9. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 4, characterized in that: The generation of the pre-master key of the client key exchange message includes: The client uses the server's PQC encryption key to generate a 32-byte shared key Ski and ciphertext Skic. Then, the 2-byte client_version, 14-byte random, and ciphertext Skic are concatenated, and the public key is encrypted using the server's SM2 encryption key and sent to the server. The client concatenates the 2-byte client_version, 14-byte random, and 32-byte Ski to form a 48-byte pre-master key. The process of the server obtaining the plaintext of the pre-master key includes: The server first uses the server SM2 encryption key to decrypt the outer layer of the private key to obtain client_version, random and Skic; Use the server's PQC encryption key to decrypt the private key to obtain Ski; Finally, concatenate client_version, random, and Ski to generate a 48-byte pre-master key.

10. The SSL VPN security gateway communication method integrating post-quantum cryptography technology according to claim 4, characterized in that: The certificate verification message is specifically: The client first uses the SM3 algorithm to hash all handshake messages from the client hello message to the certificate verification message; then uses the client's PQC signature key to sign the private key and the client's SM2 signature key to sign the private key respectively; then concatenates the PQC signature and SM2 signature, with the PQC signature first and the SM2 signature last; finally, writes the concatenated message into the certificate verification message and sends it to the server; After receiving the certificate verification message, the server needs to verify the client's dual signature, specifically including: the server uses the client's PQC signature key to verify the public key PQC signature, and then uses the client's SM2 signature key to verify the public key SM2 signature.

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