Voice communication plaintext recognition method and system

Abstract

The application discloses a voice communication clearness and secrecy identification method and system, comprising the following steps: sending first key negotiation data frames to a peer end at a fixed time; receiving a first response message returned by the peer end, wherein the first response message is a normal response message or an abnormal response message; when the first response message is the normal response message, identifying a clearness and secrecy call based on the first response message; when the first response message is the abnormal response message, sending second key negotiation data frames to the peer end at a fixed time based on an encrypted random number returned by the peer end; receiving a second response message returned by the peer end, and identifying the clearness and secrecy call based on the second response message. The application is suitable for voice communication under a satellite network, is not only fast and reliable, but also does not need to modify a signaling interaction process of the network; and can realize synchronization of key acquisition states of two parties under a limited frame length condition through definition of two negotiation frames, and can realize connection of one end when the one end cannot acquire the key due to network reasons, thereby improving a connection rate.

Description

Technical Field

[0001] This invention relates to the field of network security communication technology, and specifically to a method and system for identifying confidentiality in voice communication. Background Technology

[0002] Satellite mobile communication, with its advantages of wide coverage and independence from geographical conditions, complements terrestrial communication systems and is widely used in areas where terrestrial communication systems are difficult to cover or where construction costs are too high. Current satellite communication technology has achieved capabilities for satellite mobile network voice, SMS, and low data transmission rates, enabling call quality at low data rates such as 2.4kbps.

[0003] In traditional encrypted voice communication designs, if the encrypted terminal uses a one-click keying method (i.e., when dialing, the user can choose to dial plaintext or encrypted text, and the called party automatically identifies the incoming call as either plaintext or encrypted), achieving rapid distinction between plaintext and encrypted calls for the called party is crucial. Related technologies often employ out-of-band methods for this determination. While out-of-band determination offers advantages such as speed and reliability, it requires modifying the network signaling interaction process—specifically, distinguishing between plaintext and encrypted calls within the signaling—leading to significant network modifications. Therefore, a more common approach is to use in-band determination methods, directly utilizing the voice protocol. This method is also known as in-band negotiation. However, compared to traditional 2G, 3G, and 4G networks, due to the unique characteristics of satellite channels and limitations in air interface rates, there are issues such as shorter negotiation frame lengths and susceptibility to frame loss. Often, network problems at one end prevent the acquisition of the key, resulting in the call being converted to plaintext, severely impacting the speed and efficiency of key negotiation.

[0004] In related technologies, Chinese invention patent application CN105992199A discloses a method for identifying encrypted and unencrypted voice communication. In this method, both parties in an encrypted voice communication terminal send key negotiation data frames to each other for identification. The system determines whether the key negotiation data frame is detected; if so, it is identified as encrypted speech; otherwise, it switches to plain speech. However, this patent, as a method for identifying encrypted and unencrypted communication using 2G / 3G / 4G networks, does not consider the impact of real-world network air interface rates, negotiation frame limitations, and frame loss on the solution in practical use. This solution cannot adapt to the characteristics of high latency, low bandwidth, and unreliable satellite connections; furthermore, the negotiation process only involves encrypted speech negotiation and does not consider the problem of the other end not obtaining the key due to relevant network factors, nor does it provide a corresponding solution. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to achieve synchronization of key acquisition status between the two parties through the definition of two negotiation frames under the condition of limited frame length in satellite network, and improve the encryption call connection rate and negotiation security.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] This invention proposes a method for identifying explicit and implicit encryption in voice communication. The method is applied to one end of a communication between two parties. After the encryption key is distributed to both parties by a key distribution center, the method includes the following steps:

[0008] The first key negotiation data frame is sent to the peer at regular intervals.

[0009] Receive a first response message returned by the peer, wherein the first response message is a normal response message or an abnormal response message;

[0010] When the first response message is a normal response message, the explicit / private call is identified based on the first response message;

[0011] When the first response message is an abnormal response message, based on the encrypted random number returned by the peer, a second key negotiation data frame is periodically sent to the peer;

[0012] Receive the second response message returned by the other end, and identify the explicit / implicit call based on the second response message.

[0013] In this invention, when two parties in an encrypted voice terminal negotiate the encryption key for the current call via a satellite channel, both parties send a first key negotiation data frame to the other for identification. If the other end returns a normal response message, the other end recognizes the first key negotiation data frame and directly performs plaintext / secret text call identification. If the other end returns an abnormal response message, the terminal that has already obtained the encryption key for the current call uses the encrypted random number returned by the other end during the first negotiation as a protection key to encrypt the current call key, obtains a second key negotiation data frame, and sends it to the other end. After receiving the second negotiation frame, the other end returns the corresponding receiving status and performs plaintext / secret text call identification processing. When two parties in an encrypted voice terminal negotiate the encryption key for the current call via a satellite channel, to meet the challenges of high latency, low bandwidth, and limited air interface resources of the satellite channel, the definition of two frames solves the problem of fast plaintext / secret text negotiation between the communicating parties under the satellite channel, with one message completing plaintext / secret text identification. If the other end fails to obtain the key due to network problems, the second frame message can be used to achieve secure key transmission, improving the connection rate.

[0014] Furthermore, the data structure of the first key negotiation data frame is as follows: frame sequence number | secret message identifier | secret message identifier CRC check bit | key ciphertext CRC check result, wherein the key ciphertext is obtained by encrypting the encryption key using a shared key agreed upon by both communicating parties and the secret message identifier as the initialization vector.

[0015] Further, receiving the first response message returned by the peer includes:

[0016] When the peer obtains the encryption key via the satellite channel, the message is verified, and a normal response message is returned when the verification is successful. The data format of the normal response message is: frame sequence number | verification random number | verification HMAC value | CRC check of this frame, where the verification random number is generated by the peer, and the verification HMAC value is obtained by performing HMAC calculation on the verification random number, the encrypted message identifier, and the agreed verification success value using the cryptographic algorithm and key negotiated by both parties.

[0017] If the peer fails to obtain the encryption key via the satellite channel, it returns the abnormal response message. The data format of the abnormal response message is: frame sequence number | encryption random number | agreed value for not obtaining the key | CRC check of this frame, wherein the encryption random number is generated by the peer and the agreed value for not obtaining the key is agreed upon in advance by both parties.

[0018] Furthermore, when the first response message is a normal response message, the HMAC operation is performed using the verification random number carried in the first response message, the encrypted identifier of the first key negotiation data frame, and the verification success agreement value, and the operation result is compared and verified with the HMAC value in the first response message.

[0019] If the verification passes, the call will be switched to a private call.

[0020] If the verification fails, the timing of sending the first key negotiation data frame to the peer will be repeated within the time threshold T.

[0021] Further, when the first response message is an abnormal response message, the step of periodically sending a second key negotiation data frame to the peer based on the encrypted random number returned by the peer in the abnormal response message includes:

[0022] When the first response message is an abnormal message, the second key negotiation data frame is obtained by encrypting the plaintext key, the shared key, and the encrypted random number in the first key negotiation data frame.

[0023] The second key negotiation data frame is sent to the peer terminal.

[0024] Further, receiving the second response message returned by the peer and identifying the explicit / implicit call based on the second response message includes:

[0025] If the second response message indicates successful verification, the call will be switched to a private call.

[0026] If the second response message indicates a verification failure, the second key negotiation data frame is sent to the peer repeatedly within the time threshold T.

[0027] Furthermore, the method also includes:

[0028] When the time for determining whether the communication is open or closed exceeds the time threshold T, the call will be converted to plaintext.

[0029] Furthermore, the present invention also proposes a voice communication confidentiality recognition terminal, the terminal comprising:

[0030] The first key negotiation module is used to periodically send the first key negotiation data frame to the other end.

[0031] The first response module is used to receive a first response message returned by the peer, wherein the first response message is a normal response message or an abnormal response message;

[0032] The first explicit / implicit call identification module is used to identify explicit / implicit calls based on the first response message when the first response message is a normal response message;

[0033] The second key negotiation module is used to periodically send a second key negotiation data frame to the peer based on the encrypted random number returned by the peer when the first response message is an abnormal response message.

[0034] The second response module is used to receive the second response message returned by the other end;

[0035] The second confidentiality identification module is used to identify confidential calls based on the second response message.

[0036] The advantages of this invention are:

[0037] (1) In this invention, when the two parties of the encrypted voice terminal negotiate the encryption key for this call through the satellite channel, in order to meet the conditions of high latency, low bandwidth and limited air interface resources of the satellite channel, the function of fast negotiation of explicit and implicit keys between the two parties under the satellite channel is solved by defining two frames. The explicit and implicit keys are identified in one message. If the other party fails to obtain the key due to network problems, the key can be securely transmitted through the second frame message, thereby improving the connection rate.

[0038] (2) This scheme is applicable to voice communication under satellite network. It is not only fast and reliable, but also does not require network modification of signaling interaction process. That is, it can realize the distinction between explicit and implicit voice communication without modifying the existing network. Moreover, it can realize the synchronization of key acquisition status between the two parties by negotiating the definition of the frame twice when the frame length is limited.

[0039] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating the voice communication explicit / implicit recognition method proposed in Embodiment 1 of the present invention;

[0041] Figure 2 This is a schematic diagram of the caller's identification process in Embodiment 1 of the present invention;

[0042] Figure 3 This is a schematic diagram of the called party's explicit / confidential identification process in Embodiment 1 of the present invention;

[0043] Figure 4 This is a schematic diagram of the voice communication confidentiality recognition system proposed in Embodiment 2 of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0045] like Figure 1 As shown, the first embodiment of the present invention proposes a voice communication encrypted identification method. The method is applied to one end of the communication between the two parties. After the encryption key is distributed to both parties by the key distribution center, the method includes the following steps:

[0046] S10. Timely send the first key negotiation data frame to the peer;

[0047] It should be noted that, in this embodiment, sending the first key negotiation data frame to the peer at regular intervals means sending the first key negotiation data frame to the peer every time interval t.

[0048] S20. Receive the first response message returned by the peer, wherein the first response message is a normal response message or an abnormal response message;

[0049] It should be noted that when the other end recognizes the first key negotiation data frame, that is, when the other end has obtained the encryption key for this call, a normal response message is returned; when the other end does not recognize the first key negotiation data frame, that is, when the other end has not successfully obtained the encryption key for this call, an abnormal response message is returned.

[0050] S30. When the first response message is a normal response message, identify the explicit / implicit call based on the first response message;

[0051] S40. When the first response message is an abnormal response message, based on the encrypted random number returned by the peer, send a second key negotiation data frame to the peer at regular intervals.

[0052] It should be noted that the exception response message carries the encrypted random number.

[0053] S50. Receive the second response message returned by the peer, and identify the explicit / implicit call based on the second response message.

[0054] It should be noted that the voice communication explicit / implicit identification method proposed in this embodiment is applied to one end of the communication between the two parties, which means it can be applied to either the calling party or the called party in the communication.

[0055] In this embodiment, the two communicating parties of the encrypted voice satellite terminal send a first key negotiation data frame to each other for identification. If the other end returns a normal response message, the other end recognizes the first key negotiation data frame and directly performs plaintext / secret call identification. If the other end returns an abnormal response message, the terminal that has already obtained the encryption key for this call uses the encrypted random number returned by the other end during the first negotiation as a protection key to encrypt the key for this call. The second key negotiation data frame is obtained from this encryption key and sent to the other end. After receiving the second negotiation frame, the other end returns the corresponding receiving status and performs plaintext / secret call identification processing. In this scheme, when the two parties of the encrypted voice terminal negotiate the encryption key for this call through the satellite channel, in order to meet the high latency, low bandwidth, and limited air interface resources of the satellite channel, the definition of two frames solves the function of fast plaintext / secret negotiation between the two communicating parties under the satellite channel, and a single message completes the plaintext / secret call identification. If the other end fails to obtain the key due to network problems, the second frame message can be used to achieve secure key transmission, improving the connection rate.

[0056] Moreover, it is suitable for voice communication under satellite networks. It is not only fast and reliable, but also uses the voice frame after the satellite call is connected for key negotiation. Therefore, it does not require modification of the signaling process of the original satellite network. It can achieve clear and confidential distinction in voice communication without modifying the existing network. In addition, it can achieve synchronization of key acquisition status between the two parties by defining the two negotiation frames when the frame length is limited, and achieve key transmission when one party's network is limited, thereby improving the connection rate.

[0057] In one embodiment, the data structure of the first key negotiation data frame is: frame sequence number | current call secret message identifier | secret message identifier CRC check bit | key ciphertext CRC check result, wherein the key ciphertext is obtained by encrypting the encryption key using a shared key agreed upon by both communicating parties and the secret message identifier as an initialization vector.

[0058] It should be noted that, for security reasons, this frame only sends the CRC check result of the key ciphertext.

[0059] Specifically, the frame sequence number is the sequence number of the current first key negotiation data frame, starting from 1 and with a maximum of M; the negotiation data field is the key negotiation data carried; the CRC check is used to verify the integrity of the frame sequence number and the negotiation data field; the length of the entire frame is no more than 18 bytes, and the key length required by commonly used national cryptographic algorithms is 16 bytes.

[0060] It should be noted that M is a natural number greater than 1, determined by the amount of data to be transmitted during key negotiation.

[0061] Specifically, the data structure of the first key negotiation data frame is shown in Table 1:

[0062] Table 1 First Key Negotiation Data Frame

[0063] Frame sequence number (1 byte) Password identifier (8 bytes) Identifier CRC checksum (4 bytes) Key ciphertext CRC check (4 bytes)

[0064] It should be noted that if the calling party or the called party has obtained the encryption key for this call, they will encapsulate the encrypted call identifier (8 bytes), the corresponding CRC check result (4 bytes), and the CRC check result of the key ciphertext (4 bytes) and send them as the first key negotiation data frame. The key ciphertext is encrypted using a fixed key and the encrypted call identifier agreed upon by both parties in advance as the initialization vector IV. The actual encryption process conforms to the one-time key principle.

[0065] In one embodiment, step S20: receiving the first response message returned by the peer, includes the following steps:

[0066] When the peer obtains the encryption key through the satellite channel, the normal response message returned by the peer is received. The data format of the normal response message is: frame sequence number | verification random number | verification HMAC value | CRC check of this frame, wherein the verification HMAC value is calculated by using the verification random number returned by this frame, the encrypted message identifier in S10, the verification result (i.e., the verification success agreed value), the cryptographic algorithm negotiated by both parties, and the key.

[0067] When the peer fails to obtain the encryption key via the satellite channel, the abnormal response message returned by the peer is received. The data format of the abnormal response message is: frame sequence number | encryption random number | agreed value for not obtaining key | CRC check of this frame.

[0068] Specifically, when the other end obtains the encryption key for this call, it verifies the encrypted message identifier and its CRC in the received first key negotiation data frame. The verification process is as follows: first, it compares the encrypted message identifier it obtained, mainly by comparing the encrypted message identifier and its corresponding CRC check bit; then, it uses the obtained encryption key plaintext combined with the algorithm, key agreed upon by both parties, and the successfully verified encrypted message identifier as an encryption vector for calculation; it calculates the CRC check value of the calculation result and compares it with the key ciphertext check value sent in the first frame; if they pass, it indicates that the verification of this frame has passed, and the normal response message is returned. The data structure of the normal response message is shown in Table 2.

[0069] Table 2 Normal Response Messages

[0070]

[0071] If the other end fails to obtain the encryption key for this call, the encrypted call identifier and its CRC in the first key negotiation data frame are verified. The encrypted call identifier and the CRC check value of the key ciphertext are saved. A random encrypted number, the key agreement value, and the CRC check value of this frame are randomly generated and fed back according to the abnormal response message. The data structure of the abnormal response message is shown in Table 3.

[0072] Table 3 Abnormal Response Messages

[0073]

[0074] In one embodiment, step S30: when the first response message is a normal response message, identifying a confidential call based on the first response message specifically includes the following steps:

[0075] S31. Perform format verification on the normal response message. The main verification method is: perform HMAC operation on the verification random number carried in the first response message, the secret message identifier of the first frame, and the verification success agreement value, and compare the operation result with the HMAC value in the first response message.

[0076] S32. If the verification passes, the call will be converted to a private call.

[0077] S33. If the verification fails, the timing of sending the first key negotiation data frame to the peer is repeated within the time threshold T.

[0078] In this embodiment, a threshold time T is set. Both communicating parties continuously send key negotiation data frames to each other for identification. It is determined whether the first key negotiation data frame is identified within time T. If so, it is identified as a secret message, and the communication is switched from the current frame to the secret message communication and the secret message key negotiation process is entered. Otherwise, it is switched to plaintext communication.

[0079] It should be noted that, based on the characteristics of the satellite domain, the normal connection time of the current satellite domain is about 15 seconds. Therefore, the time threshold T is set to 20 to 30 seconds. The first key negotiation data frame is continuously sent within the time threshold T to further ensure that the other party can receive the first key negotiation data frame.

[0080] In one embodiment, step S40: when the first response message is an abnormal response message, based on the encrypted random number returned by the peer, a second key negotiation data frame is periodically sent to the peer, specifically including the following steps:

[0081] S41. When the first response message is an abnormal message, the second key negotiation data frame is obtained by encrypting the plaintext key obtained by the terminal, the shared key agreed upon by both parties, and the encrypted random number fed back in the abnormal response message.

[0082] S42. Send the second key negotiation data frame to the peer.

[0083] Specifically, the data structure of the second key negotiation data frame is frame sequence number | key ciphertext, as shown in Table 4:

[0084] Table 4 Second Key Negotiation Data Frame

[0085] Frame sequence number (1 byte) Key ciphertext (16 bytes) Reserved

[0086] Furthermore, after receiving the second key negotiation data frame, the peer decrypts the ciphertext of the key in the second key negotiation data frame according to a shared key agreed upon by both parties and the encrypted random number fed back in the first frame error message, obtaining the plaintext of the key. It then calculates the ciphertext of the key based on the shared key and the secret key identifier agreed upon by both parties. The calculation result is compared with the CRC checksum of the ciphertext of the key in the first frame message of the terminal. If the checksum passes, the key verification is successful, and a verification success message is returned. If the checksum fails, the key verification fails, and a verification failure message is returned. The data structure of the returned second response message is: frame sequence number | ciphertext CRC checksum result | CRC checksum of this frame, as shown in Table 5.

[0087] Table 5 Second Response Message

[0088] Frame sequence number (1 byte) Key verification result (2 bytes) This frame's CRC checksum (4 bytes) Reserved

[0089] In one embodiment, step S50: receiving a second response message returned by the peer, and identifying a confidential call based on the second response message, includes the following steps:

[0090] If the second response message indicates successful verification, the call will be switched to a private call.

[0091] If the second response message indicates a verification failure, the second key negotiation data frame is sent to the peer repeatedly within the time threshold T.

[0092] In one embodiment, it is determined whether the second key negotiation data frame is identified within time T. If so, it is identified as a secret message, and the current frame is switched to secret message communication to enter the secret message key negotiation process; otherwise, it is switched to plaintext communication.

[0093] In one embodiment, when the calling party initiates a secure call between the two communicating parties, the timing of sending a first key negotiation data frame to the other party includes:

[0094] The voice frame sent by the called party to the calling party is a silence frame or a prompt voice frame.

[0095] In one embodiment, when the calling party initiates a plaintext call between the two communicating parties, during the plaintext / privatetext identification period, the voice frame sent by the called party to the calling party is a silence frame or a prompt voice frame.

[0096] It should be noted that the voice frames sent by the called party to the calling party, or the voice frames received by the calling party from the called party, are either silence frames or prompt tone voice frames. When the called party answers a plaintext call, the time for distinguishing between plaintext and key-key messages is short. During this time, the called party sends a silence frame or prompt tone voice frame to the first terminal to prevent the calling party making a plaintext call from hearing the howling sound of the called party directly playing the key negotiation data.

[0097] Furthermore, in encrypted voice communication, if the calling party is speaking in plaintext, that is, although the calling party has the function of encrypted voice communication, it has not made it encrypted, and there is no clear distinction between plaintext and encrypted, and it is assumed to be plaintext communication.

[0098] It should be noted that the encrypted communication terminal in-band explicit-private identification method proposed in this embodiment can simultaneously solve the explicit-private identification of both parties in the communication process, and the process is simple and efficient; moreover, it does not require any modification to the existing network. After the call is connected, the caller and the caller distinguish between explicit and confidential by judging whether there is confidential speech feature data in the received voice data.

[0099] The following two specific examples illustrate the explicit / implicit voice communication recognition process:

[0100] When the caller in an encrypted voice communication speaks in plaintext, the process of distinguishing between plaintext and encrypted voice communication is as follows: Figure 2 As shown:

[0101] (1) The calling party initiates a call and sends a key acquisition request to the key distribution center. The key distribution center (KDC) generates an encryption key Z and sends it to both parties via satellite channel. The key acquisition request carries information including the calling party's number, the called party's number, and the session identifier S.

[0102] (2) After the called party responds, the calling party begins in-band key state negotiation.

[0103] (3) Every t time interval, the calling party starts to negotiate and assemble the first key negotiation data frame and sends it to the called party.

[0104] (4) The calling party parses the first response message returned by the called party. If the parsing is successful, it is a normal response message (i.e., the called party also obtains the encryption key Z). The normal response message is then format-verified. If the verification is successful, the encrypted conversation is directly initiated. If the verification fails, step (3) is continued within the time threshold T. If the verification still fails within the time threshold T, the plaintext process is directly initiated.

[0105] (5) If the calling party parses the first frame response message of the called party and finds that it is an abnormal response (the other party has not obtained the encryption key for this call), then the calling party will start to negotiate and assemble the second key negotiation data frame every t time and send it to the called party.

[0106] (6) The calling party parses and verifies the second response message returned by the called party. If it passes, it directly converts the message to a secret key. If it fails, it reassembles the second key negotiation data frame within the time threshold T. If the parsing procedure is not completed within the time threshold T, it directly converts the message to plaintext.

[0107] When the caller in an encrypted voice communication is speaking in a secret mode, the voice communication secret / open communication identification process is as follows: Figure 3 As shown:

[0108] (1) The caller initiates a call by pressing the secret code.

[0109] (2) During the ringing phase, the key acquisition for this call is initiated via the satellite channel. The key acquisition is identified based on three parameters: the calling and called numbers, and the call identifier.

[0110] (3) Every t time, the called party starts to negotiate and assemble the first key negotiation data frame and sends it to the calling party.

[0111] (4) The called party parses the first response message returned by the calling party. If it is a normal response message (the calling party has also obtained the encryption key for this call), the normal response message is format-verified. If the verification passes, the encrypted call is directly entered. If the verification fails, step (3) is re-executed within the time threshold T. If the verification still fails within the time threshold T, the call is directly switched to plaintext processing.

[0112] (5) If the called party parses the first response message returned by the calling party and finds that it is an abnormal response (the calling party does not have an encryption key), then the called party will start to negotiate and assemble the second key negotiation data frame every t time and send it to the calling party.

[0113] (6) The called party parses and verifies the second response message returned by the calling party. If it passes, it directly converts the message to encryption. If it fails, it reassembles the second key negotiation data frame within the time threshold T. If the parsing process is not completed within the time threshold T, it directly converts the message to plain text.

[0114] In addition, such as Figure 4 As shown, the second embodiment of the present invention also proposes a voice communication confidentiality recognition terminal, the terminal comprising:

[0115] The first key negotiation module 10 is used to periodically send the first key negotiation data frame to the peer.

[0116] The first response module 20 is used to receive a first response message returned by the peer, wherein the first response message is a normal response message or an abnormal response message.

[0117] The first explicit / implicit call identification module 30 is used to identify explicit / implicit calls based on the first response message when the first response message is a normal response message;

[0118] The second key negotiation module 40 is used to periodically send a second key negotiation data frame to the peer based on the encrypted random number returned by the peer when the first response message is an abnormal response message.

[0119] The second response module 50 is used to receive the second response message returned by the other end;

[0120] The second confidentiality identification module 60 is used to identify confidential calls based on the second response message.

[0121] In this embodiment, the two communicating parties in the encrypted voice satellite terminal send a first key negotiation data frame to each other for identification. When the other end returns a normal response message, the other end recognizes the first key negotiation data frame and directly performs explicit / implicit call identification. When the other end returns an abnormal response message, the terminal that has already obtained the encryption key for this call uses the encrypted random number returned by the other end during the first negotiation as a protection key to encrypt the key for this call. The terminal then obtains a second key negotiation data frame and sends it to the other end. After receiving the second negotiation frame, the other end returns the corresponding receiving status and performs explicit / implicit call identification processing. This solution is applicable to voice communication under satellite networks. It is not only fast and reliable, but also does not require network modification of the signaling interaction process, meaning that explicit / implicit voice communication can be distinguished without modifying the existing network. Moreover, it can achieve synchronization of the key acquisition status of both parties through the definition of two negotiation frames when the frame length is limited, and in abnormal states, it can achieve secure and fast transmission of the encryption key for this call through the in-band channel. This allows encrypted voice to be achieved when only one party has the key, improving the encryption call connection rate.

[0122] In one embodiment, the data structure of the first key negotiation data frame is: frame sequence number | secret message identifier | secret message identifier CRC check bit | key ciphertext CRC check result, wherein the key ciphertext is obtained by encrypting the encryption key using a shared key agreed upon by both communicating parties and the secret message identifier as an initialization vector.

[0123] In one embodiment, the first response module 20 includes:

[0124] The first response unit is configured to receive the normal response message returned by the peer when the peer obtains the encryption key, wherein the data format of the normal response message is: frame sequence number | verification random number | verification HMAC value | CRC check of this frame;

[0125] The second response unit is used to receive the abnormal response message returned by the peer when the peer fails to obtain the encryption key, wherein the data format of the abnormal response message is: frame sequence number | encrypted random number | verification failure convention value | CRC check of this frame.

[0126] In one embodiment, the system further includes a first response message generation module, which, upon obtaining the encryption key for the current call, verifies the encrypted call identifier and the identifier CRC in the received first key negotiation data frame, verifies the CRC verification result of the key ciphertext of the first key negotiation data frame based on its own obtained key ciphertext, and if the verification is successful, directly feeds back the encrypted call identifier CRC verification result as a normal response message.

[0127] And when the encryption key for this call is not obtained, the encrypted call identifier and the identifier CRC in the first key negotiation data frame are verified, the encrypted call identifier and the key ciphertext CRC verification value are saved, and an encrypted random number, a verification failure convention value and the CRC verification value of this frame are randomly generated and fed back according to the abnormal response message.

[0128] In one embodiment, the first confidentiality identification module 30 includes:

[0129] The format verification unit is used to perform format verification on the normal response message. Specifically, it performs HMAC operation using the verification random number carried in the first response message, the secret code identifier of the first frame, the verification success agreement value, and the shared key agreed upon by both parties, and compares the operation result with the HMAC value in the first response message.

[0130] The first explicit / implicit distinction unit is used to convert the current call into a private call when the format verification unit outputs a verification pass result.

[0131] The second timing transmission unit is used to repeatedly execute the timing to send the first key negotiation data frame to the peer within a time threshold T when the output result of the format verification unit is that the verification fails.

[0132] In this embodiment, a threshold time T is set. Both communicating parties continuously send key negotiation data frames to each other for identification. It is determined whether the first key negotiation data frame is identified within time T. If so, it is identified as a secret message, and the communication is switched from the current frame to the secret message communication and the secret message key negotiation process is entered. Otherwise, it is switched to plaintext communication.

[0133] It should be noted that, in this embodiment, the time threshold T is set to 20 to 30 seconds based on the characteristics of the satellite field. The first key negotiation data frame is continuously sent within the time threshold T to further ensure that the other party can receive the first key negotiation data frame.

[0134] In one embodiment, the second key negotiation module 40 includes:

[0135] The second key negotiation data frame assembly unit is used to encrypt the key ciphertext, shared key and encrypted random number in the first key negotiation data frame when the first response message is an abnormal message, to obtain the second key negotiation data frame.

[0136] The second key negotiation data frame sending unit is used to send the second key negotiation data frame to the peer.

[0137] It should be noted that after the peer receives the second key negotiation data frame, it decrypts the ciphertext of the key in the second key negotiation data frame according to a shared key agreed upon by both parties and the encrypted random number fed back in the first frame error message to obtain the plaintext of the key. It then calculates the ciphertext of the key according to the shared key agreed upon by both parties and the secret call identifier. The calculation result is compared with the CRC check of the ciphertext of the key in the first frame message of the terminal. If the check passes, it means that the key check passes and a verification pass message is returned. If the check fails, it means that the key check fails and a verification fail message is returned. The data structure of the returned second response message is frame sequence number | ciphertext CRC check result | CRC check of this frame.

[0138] In one embodiment, the second confidential identification module 60 includes:

[0139] The second explicit / implicit distinction unit is used to convert the current call into an implicit call when the second response message indicates that the verification has passed.

[0140] The second timing sending unit is used to repeatedly execute the timing to send the second key negotiation data frame to the peer within a time threshold T when the second response message indicates a verification failure.

[0141] In one embodiment, it is determined whether the second key negotiation data frame is identified within time T. If so, it is identified as a secret message, and the current frame is switched to secret message communication to enter the secret message key negotiation process; otherwise, it is switched to plaintext communication.

[0142] It should be noted that other embodiments or implementation methods of the voice communication confidentiality recognition system described in this invention can refer to the above-described method embodiments, and will not be repeated here.

[0143] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0144] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0145] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for identifying explicit and implicit voice communication, characterized in that, The method is applied to one end of a communication between two parties. After the encryption key is distributed to both parties by the key distribution center, it includes the following steps: The first key negotiation data frame is sent to the peer at regular intervals. Receiving a first response message returned by the peer, wherein the first response message is a normal response message or an abnormal response message, includes: when the peer obtains the encryption key through the satellite channel, verifying the first key negotiation data frame, and returning the normal response message when the verification passes, wherein the data structure of the first key negotiation data frame is: frame sequence number | encrypted identifier | encrypted identifier CRC check bit | key ciphertext CRC check result, and the data format of the normal response message is: frame sequence number | verification random number | verification HMAC value | current frame CRC check, wherein the verification random number is generated by the peer, and the verification HMAC value is obtained by performing HMAC calculation on the verification random number, encrypted identifier, and verification success agreement value using the cryptographic algorithm and key negotiated by both parties; when the peer does not obtain the encryption key through the satellite channel, returning the abnormal response message, wherein the data format of the abnormal response message is: frame sequence number | encryption random number | agreement value for not obtaining the key | current frame CRC check, wherein the encryption random number is generated by the peer, and the agreement value for not obtaining the key is agreed upon in advance by both parties; When the first response message is a normal response message, the explicit / private call is identified based on the first response message; When the first response message is an abnormal response message, based on the encrypted random number returned by the peer, a second key negotiation data frame is periodically sent to the peer; Receive the second response message returned by the other end, and identify the explicit / implicit call based on the second response message.

2. The voice communication explicit / implicit recognition method as described in claim 1, characterized in that, The key ciphertext in the first key negotiation data frame is obtained by encrypting the encryption key using a shared key and a secret key identifier agreed upon by both communicating parties as an initialization vector.

3. The voice communication explicit / implicit recognition method as described in claim 1, characterized in that, When the first response message is a normal response message, identifying the explicit / implicit call based on the first response message includes: The HMAC operation is performed using the verification random number carried in the first response message, the encrypted identifier of the first key negotiation data frame, and the verification success agreement value, and the operation result is compared and verified with the verification HMAC value in the first response message. If the verification passes, the call will be switched to a private call. If the verification fails, the timing of sending the first key negotiation data frame to the peer will be repeated within the time threshold T.

4. The voice communication explicit / implicit recognition method as described in claim 2, characterized in that, When the first response message is an abnormal response message, based on the encrypted random number returned by the peer, a second key negotiation data frame is periodically sent to the peer, including: When the first response message is an abnormal message, the second key negotiation data frame is obtained by encrypting the key ciphertext, the shared key, and the encrypted random number in the first key negotiation data frame. Send the second key negotiation data frame to the peer.

5. The voice communication explicit / implicit recognition method as described in claim 1, characterized in that, Receiving the second response message returned by the peer, and identifying the explicit / implicit call based on the second response message, includes: If the second response message indicates successful verification, the call will be switched to a private call. If the second response message indicates a verification failure, the second key negotiation data frame is sent to the peer repeatedly within the time threshold T.

6. The voice communication explicit / implicit recognition method as described in claim 3 or 5, characterized in that, The method further includes: When the time for determining whether the communication is open or closed exceeds the time threshold T, the call will be converted to plaintext.

7. The voice communication explicit / implicit recognition method as described in claim 1, characterized in that, When the calling party initiates a secure call, the timing of sending the first key negotiation data frame to the other party includes: The voice frame sent by the called party to the calling party is a silence frame or a prompt voice frame.

8. The voice communication explicit / implicit recognition method as described in claim 1, characterized in that, When the calling party initiates a plaintext call, during the plaintext / confidentiality identification period, the voice frame sent by the called party to the calling party is a silence frame or a prompt voice frame.

9. A voice communication confidentiality recognition terminal, used to implement the voice communication confidentiality recognition method as described in any one of claims 1-8, characterized in that, The terminal includes: The first key negotiation module is used to periodically send the first key negotiation data frame to the other party after the key distribution center distributes the encryption key to both parties. The first response module is used to receive a first response message returned by the peer, wherein the first response message is a normal response message or an abnormal response message; The first explicit / implicit call identification module is used to identify explicit / implicit calls based on the first response message when the first response message is a normal response message; The second key negotiation module is used to periodically send a second key negotiation data frame to the peer based on the encrypted random number returned by the peer when the first response message is an abnormal response message. The second response module is used to receive the second response message returned by the other end; The second confidentiality identification module is used to identify confidential calls based on the second response message.

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