CN100394719C - A voice communication method on mobile ad hoc network - Google Patents

Abstract

The invention belongs to the technical field of communication network applications, and is a method for implementing voice communication on a mobile ad hoc network. In the case of dynamic configuration of IP addresses, the node addresses of the mobile ad hoc network are changeable. Effect of Address Change on Voice Communications. The steps of the method include: in the connection establishment stage, the real IP address currently used by the target node is obtained through a handshake process, and a random number is shared between the communication parties for authentication and encryption in the communication process. After completing the connection establishment and entering the conversation state, each party must periodically send encrypted address notification messages to the other party to inform the party of the current IP address used, so as to ensure that the address changes of the node can be updated in a timely manner. Inform the other party of the communication to realize the automatic switching of the voice communication, thereby improving the reliability of the communication.

Description

A voice communication method on mobile ad hoc network

technical field

The invention belongs to the technical field of communication network applications, in particular to a method for implementing voice communication on a mobile ad hoc network.

Background technique

Mobile Ad Hoc Network-MANET is a point-to-point self-creating, self-organizing and self-managing network with a highly dynamic topology, arbitrary movement of nodes, which enables free communication between nodes Without going through infrastructure such as base stations and access points. Literature [1] Ramanathan R, Redi J, "A Brief Overview of mobile Ad hoc Networks: Challenges and Directions", IEEE Communications Magazine, ^50th Anniversary Commemorative Issue[C], 2002. In MANET, the address of the communication node adopts the technology of automatic configuration, and the generated address is used by the node after confirming that it is unique in the Ad Hoc network to which it belongs through the process of repeated address detection. However, due to the mobility of nodes and networks, address conflicts often occur in MANET networks, resulting in changes in IP (Internet Protocol) addresses of nodes. For example, the mobile node A moves out of the transmission range of the MANET or the node temporarily loses contact with other nodes in the MANET network due to other reasons. During this period, node B joins the MANET group, it chooses the same IP address as node A, and no address conflict is found after duplicate address detection (because node A lost contact), so it declares that it has the same IP address as node A IP address. However, after a period of time, when node A moves back to the MANET network or eliminates the fault recovery and contact with other nodes in the group, node A and node B have duplicate addresses, and one of them must change its IP address . Another example is that two originally independent MANET networks become one MANET network due to mobile convergence. Because the two networks were originally separated from each other, there may be some duplicate addresses between them. In this way, when the two networks are merged, the problem of address conflict will appear, which makes some nodes have to change their own IP addresses. However, currently used voice communication VoIP (Voice over Internet Protocol) applications are based on fixed source and destination IP addresses, which do not take into account the change of addresses on MANET, so if they are applied to mobile In an ad-hoc network, when the address of the communication party changes, the voice communication will be wrongly maintained, and the node will conduct voice communication with the node that it does not want to communicate with, which will cause many security problems. For example: In MANET, nodes A and B are communicating by voice. At this time, due to the merger with another MANET network, an address conflict occurs between node A and node C, causing the IP address of node A to change from x to y. However, node B does not know this change, and the destination address of the voice packet sent from B to A still uses x, resulting in node B communicating with node C by mistake. In addition, as mentioned above, since the IP address of the communication device in the mobile ad hoc network is not fixed, it cannot use the IP address of each node to initiate a voice call like the VoIP application implemented on the fixed network. Instead, a communication ID is set for each device terminal, which uniquely marks a node, and voice calls are initiated between nodes through this communication ID. Before each voice call connection is established, the source node needs to access the name service module of the node. The name service module is responsible for maintaining a local database. The database contains a series of records, and each record contains a communication ID and IP Address correspondence. These records are saved from the previous call history of this node. However, the IP addresses recorded in the local database are just some historical information, which may not reflect the address currently used by the target node, because it is possible that the IP address of the target node has changed after the last call, so If this address is directly used to establish a voice call connection, it is likely to establish a call relationship with other nodes by mistake, which obviously violates the reliability requirements of our VoIP application, so we must check the validity of this address before the communication connection is established. verify.

In addition, in order to facilitate mutual authentication between communication nodes, reliability is improved. It is stipulated that each node generates the public key and private key information of the node, and discloses the public key of the node. Any two nodes that need to communicate with each other must know each other's public key.

Regarding how to obtain the real and legal public key on the MANET network, it can be pre-shared by both parties, or similar to the document [2] Asad Amir Pirzada, Chris McDonald, "Kerberos Assisted Authentication in Mobile Ad-hoc Network" , the method mentioned in 27th Australasian Computer Science Conference, Dunedin, New Zealand, January 18-22, 2004, but in the environment mentioned in [2], the address change is not considered, and the public key information is related to the node The IP address is bound, and in our implementation, the public key is bound to the constant communication ID of the node.

Contents of the invention

The purpose of the present invention is to provide a voice communication (VoIP) implementation method on the mobile ad hoc network, which can solve the address change problem on the mobile ad hoc network and eliminate its impact on VoIP applications.

The invention belongs to the application field of communication network, and proposes a VoIP application suitable for MANET. It ensures the reliability of voice communication on the mobile ad hoc network by increasing the handshake process before the connection is established, sharing random numbers between the communication parties, and transmitting encrypted address notification messages during the call, eliminating the need for MANET address changes. Bad effects of VoIP.

The present invention is based on the mobile ad hoc network (MANET), which is composed of notebook computers, personal digital assistants (PDA), vehicle-mounted stations and other mobile terminals with a highly dynamic topological structure, arbitrary movement of nodes, and point-to-point self-organization. Create, self-organize, self-manage networks. In this network, each node has a wireless network card, and the nodes are interconnected through wireless technology and communicate with each other in a multi-hop manner. In addition, each node is also equipped with a sound card device, which can perform codec processing on voice signals and other corresponding work.

In order to support voice communication, the node must first initialize the sound card and the network card, and then send the control data packet by driving the network card to perform the handshake process before the connection is established. After the connection is established, the communication node drives the sound card to collect, encode and decode the voice signal to receive and play the sound, and sends the encoded and compressed voice data packets through the network card to realize the voice communication between nodes.

The invention is based on the computer network communication, and realizes the voice communication of the nodes through the communication of the computer.

The invention provides a method for voice communication in a mobile ad-hoc network. The method comprises the following steps: each communication node maintains a local database, and the historical call records of the node are preserved in the database, and each record is <communication ID , the two-tuple of IP address>; when initiating a voice call, the source node first accesses the local database to find the historical record of the target node address, if it finds the historical record of the target node address, it sends a unicast to the recorded target node address Query the message to confirm the validity of the address. If the source node receives a reply message within the specified time indicating that the address is true and valid, then establish a communication connection based on this address; otherwise, send a broadcast query message to obtain the current address of the target node; in the above The unicast and broadcast query messages contain the random number generated by the source node for this voice call. The random number is encrypted with the public key of the target node. Only the target node can correctly decrypt the random number. The source node can identify the The authenticity of the reply message, and through a handshake process of sending query and reply messages between nodes, a random number is shared between the source node and the target node of this voice communication, which can be used as a communication process The encryption key and authentication basis in the communication; during the call process after the communication connection is established, the communication parties periodically send address notification messages to each other, and the address notification messages are encrypted using the random number negotiated in the handshake stage as the key, including the serial number Field and random number field, when the address of a node changes, the node will send the changed address to the other party in a timely manner through the address notification message, and the other party will cancel the original connection established on the old address after decrypting the message and switch to the new address In addition, when one party does not receive a new and correct address notification message from the other party within the specified time, the current voice communication connection will be released to ensure that even if the addresses of both parties to the communication change at the same time, the communication The connection will also be released in time, so as to avoid voice communication from being wrongly maintained for a long time and improve the reliability of voice communication.

The realization of the present invention relies on following two preconditions:

First of all, because the IP address of the communication device terminal is not fixed in the mobile ad hoc network, the IP address cannot be used to initiate a call. Instead, a communication ID is set for each communication terminal, and this communication ID is used to initiate a voice call. The communication ID is globally unique (that is, it is not repeated for nodes in different MANET networks), and is constant. It uniquely identifies a node and must be easy for the user to remember. Correspondence IDs are issued by a centralized agency.

Secondly, in order to facilitate mutual authentication between nodes and improve reliability. It is stipulated that each node generates the public key and private key information of the node, and discloses the public key of the node. Any two nodes that need to communicate with each other must know each other's public key.

The present invention is a kind of voice communication system on the mobile ad hoc network, and its realization method is as follows:

In MANET, when a node wants to initiate a call to another node, it first needs to generate a 32-bit random number and encrypt it with the public key of the target node. The generation of random numbers provides guarantee for the authentication and encryption in the communication process later. Next, the source node accesses the local name service module to obtain the IP address of the target node. The name service module is responsible for maintaining a local database, which contains a series of records, and each record contains a correspondence between a communication ID and an IP address. These records are all saved from the previous call history of this node. However, these historical records may not necessarily reflect the address currently used by the target node, because it is possible that the IP address of the target node has changed after the last call ended. Therefore, the address returned from the name service module cannot be directly used to establish a voice communication connection, but the accuracy of the address returned by the name service module must be verified through a unicast query message before attempting to establish a connection. If there is no address record about the target node in the local database and the name service module returns empty, then a broadcast query message must be sent to obtain the IP address of the target node.

The voice call source node sends a unicast query message to the address returned by the name service module. The format is as follows.

0 3 16 31

++++++++++++++++++++++++++++++++++++++++++++++++++

+ Type + Reserved + Serial Number +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ random number (encryption) +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+ Source Address +

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+ Destination Address +

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+                              

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+ Destination communication ID +

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

The 3-bit type field indicates the type of the message, and the type value of the unicast query message is 0. The 16-bit serial number marks this query, because a node may have sent multiple query messages, so a field is needed to indicate this time Query, the value of this field is incremented by 1 each time the source node sends a query request. The random number field places the encrypted "random number" generated by the source node for this call. The source address and destination address fields mark the source IP address and destination IP address of the query message respectively. (IPv4 address 32 bits, IPv6 address 128 bits) Two communication ID fields respectively record the communication IDs of the source node and the destination node.

When the unicast query message reaches the destination address, the node checks the "destination communication ID" field in the unicast query message, compares it with the communication ID of the node, and then sends a reply message to the communication source node. The format is as follows.

0 3 16 31

++++++++++++++++++++++++++++++++++++++++++++++++++

+ Type + Reserved + Serial Number +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ random number (encryption) +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+ Source Address +

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+ Destination Address +

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

The 3-bit type field indicates the type of the message, and the type value of the unicast query reply message is 1. The sequence number marks the query, which is copied from the corresponding query message, indicating which query request was answered. The source address and destination address fields mark the source IP address and destination IP address of the reply message respectively. If the communication ID of this node matches the value of the "destination communication ID" field in the unicast query message, use the private key of the node to decrypt the encrypted "random number" in the unicast query message to obtain the plain text of the random number, and then use The public key value of the node corresponding to the "source communication ID" specified in the unicast query message encrypts the plaintext of the random number, and puts the result in the encrypted "random number" field of the reply message. Conversely, if the communication ID of the local node does not match the value of the "destination communication ID" field in the unicast query message, simply fill the encrypted "random number" field in the reply message with all "0".

If the source node receives the reply message within the specified time (the type value of the unicast query reply message is 1), it uses its own private key to decrypt the encrypted "random number" in the reply message to obtain the plaintext of the random number, if the plaintext If it is the same as the random number generated by the source node for this call, the authentication of the destination node is completed, and the handshake ends. At this point, the call connection can be established with the destination address specified in the unicast query message. If the source node does not receive the reply message within the specified time, or the random number plaintext obtained by decrypting the encrypted "random number" field in the reply message with the private key is different from the random number generated by the source node for this call, then prove The address information of the target node originally obtained from the local database has become invalid, and the source node of the voice communication must obtain the corresponding address information by sending a broadcast query message.

The format of the broadcast query message is exactly the same as that of the unicast query message. Only the broadcast address is filled in the destination address field in the broadcast query message, and it is sent to every node in the MANET. In addition, for the broadcast query message, its type value is 2. (The type value of the unicast query message is 0)

After receiving the broadcast query message, each node in the MANET network checks whether its own communication ID is the same as the value of the "destination communication ID" field in the query message. If they are the same, it indicates that it is the target node of the voice call, and it will You must send a reply message telling yourself which IP address you are currently using.

The format of the broadcast query reply message is exactly the same as that of the unicast query reply message. The 3-bit type field indicates the type of the message, and the type value of the broadcast query reply message is 3. The sequence number marks the query, which is copied from the corresponding broadcast query message, indicating which query request was answered. The source address and destination address fields mark the source IP address and destination IP address of the reply message respectively. Finally, use the private key of this node to decrypt the encrypted "random number" in the broadcast query message to obtain the plaintext of the random number, and then use the public key value of the node corresponding to the "source communication ID" specified in the broadcast query message to encrypt the plaintext of the random number , and put the encrypted ciphertext in the encrypted "random number" field of the reply message.

After receiving the reply message, the query node decrypts the encrypted "random number" of the reply message with its own private key to obtain the plaintext of the random number, and then compares it with the random number generated by itself. If the two are the same, it means the reply message Indeed, it was sent from the destination node of the voice communication, because only this node can correctly decrypt the encrypted "random number" in the query message. Like this, the source node of voice communication has just obtained the current IP address of the target node (indicated in the source address field of the reply message), and it just uses this address information to update the local database, and then establishes a call connection on this address. If the result of the random number comparison is not the same, the reply message is discarded. If the query node does not receive a correct reply message within the prescribed time, it will consider that the target node of the voice call is not online at present, and the voice call process ends.

When the communication parties obtain each other's IP addresses and establish a call connection, they enter the voice call state. During the call, the addresses of the two communicating parties may still change due to various reasons. Therefore, some mechanism must be adopted so that the voice communication will not be wrongly maintained when the address of the node is changed. We require the communication parties to periodically send control data packets indicating the current address information while sending and receiving voice data packets. The format is as follows.

0 3 16 31

++++++++++++++++++++++++++++++++++++++++++++++++++

+ Type + + Reserved +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ Serial Number (encrypted) +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ + +

+ Current address (encrypted) +

+ + +

++++++++++++++++++++++++++++++++++++++++++++++++++

+ random number (encryption) +

++++++++++++++++++++++++++++++++++++++++++++++++++

The 3-bit type field indicates the type of the message, and the type value of the address notification message is 4. The 32-bit serial number is used to resist replay attacks and out-of-order arrival. The current address field is used to indicate the IPv4/IPv6 address currently used by the node. The random number field records the random number generated during the handshake process before the communication connection is established, and it plays a role of authentication. The contents of the last three fields are transmitted in the form of ciphertext during actual transmission.

When one party in the voice communication receives the address notification message in cipher text form from the other party, it first decrypts the message to check whether the random number field is the random number generated during the handshake. If not, the message is discarded; if it is, it means that the message is indeed sent from the other party of the communication, because only the two parties involved in the voice communication know the random number. Next, check the message sequence number to determine whether the message is new, if not, discard the message; if yes, check whether the value of the "current address" field is the IP address in use, if not, indicate the other party to the communication The address of the IP address has changed, so the original communication connection established on the old address will be released, and a new voice communication connection will be established on the changed IP address instead.

We stipulate that the communication parties periodically send the above address notification messages, and the serial number is incremented by 1 every time a message is sent. When the communication terminal does not receive any new correct address notification message from the other party within the specified time, it will release the existing voice communication connection.

In summary, the overall steps of the implementation method of voice communication (VoIP) on the mobile ad hoc network of the present invention are as follows:

Step S1: The source node of the voice communication generates a 32-bit random number, and encrypts it with the public key of the target node of the voice communication;

Step S2: The source node accesses the name service module, and the name service module queries the local database. If the corresponding record is found, it returns the IP address of the target node and enters S3. If no corresponding record is found, enters S9;

Step S3: The source node sends a unicast query message to the IP address returned by the name service module to confirm the validity of the address and start the timer at the same time; the unicast query message contains the encrypted random number generated by S1;

Step S4: After the unicast query reaches the destination address, the corresponding node compares the communication ID (Identifier) of the node with the "destination communication ID" field in the query message. If they are the same, go to S5; otherwise, go to S6;

Step S5: The node decrypts the encrypted random number in the unicast query message with its own private key to obtain the plaintext of the random number, and then encrypts the random number with the public key value of the node corresponding to the "source communication ID" specified in the unicast query message. The plaintext of the random number, and put the result in the unicast query reply message, and enter S7;

Step S6: The node fills the encrypted "random number" field in the unicast query reply message with all "0"s;

Step S7: the node sends a unicast query reply message to the source node of the voice call;

Step S8: If the source node receives the unicast query reply message within the specified time, it uses the private key of this node to decrypt the encrypted random number in the reply message, and compares it with the random number generated in S1, if the result of the comparison is the same , then use the IP address returned by the name service module as the destination address of the voice call, and transfer to S13; if the comparison results are different, discard the reply message and enter S9; if the source node does not receive the unicast query reply message within the specified time , enter S9;

Step S9: the source node sends a broadcast query message to the Mobile Ad Hoc Network-MANET, and starts the timer at the same time, and the broadcast query message contains the encrypted random number generated in S1;

Step S10: After receiving the broadcast query message, each node in the MANET checks its own communication ID. If it is the destination node of the call, it decrypts the encrypted random number in the broadcast query message with its own private key to obtain the random number. Then use the public key value of the node corresponding to the "source communication ID" specified in the broadcast query message to encrypt the plaintext of the random number, put the result in the broadcast query reply message, and then send a broadcast to the source node of the voice call Query reply message;

Step S11: The source node listens to the port. If it receives a broadcast query reply message before the timer expires, it uses its private key to decrypt the encrypted random number in the reply message, and compares it with the random number generated in S1. If If the comparison results are the same, update the local database with the source address of the reply message, and use this address as the destination address of the voice call, and transfer to S13; if the comparison results are different, discard the reply message and continue to listen; if the timer expires , enter S12;

Step S12: The source node thinks that the target node of this voice call is not online, and the call process ends with an error type of "not online";

Step S13: After the source node obtains the accurate IP address currently used by the target node in S8 or S11, establish a voice communication connection with the target node on this address;

Step S14: After the communication connection is established and enters the call state, each party needs to periodically send an encrypted address notification message to the other party to inform the party of the current address information;

Step S15: When one party receives the address notification message from the other party, it first decrypts the message, and checks whether the random number field is the random number shared when the connection is established; if not, discard the message; The message does come from the other side of the communication; then only if the check is successful then check the message sequence number to see if the message is new, if not discard the message, if so check the "Current Address" field's Is the value the destination IP address being used? If not, it means that the address of the other party has changed, so the communication connection established on the old address will be released, and a new voice communication will be established on the changed IP address. connect;

Step S16: When one party to the communication does not receive any new correct address notification message sent from the other party within the specified time (generally 3-10 address notification message sending cycle), it will release the existing address notification message. voice communication connection.

Implementation details:

1. The asymmetric encryption algorithm RSA is used in the handshake phase, and in order to reduce the generation time of large prime numbers

Only 8-bit keys are used.

2. When a node sends a unicast or multicast query message, if it does not receive a response within 2 seconds, it starts the corresponding timeout operation. The setting of this time value is closely related to factors such as network scale and node processing speed.

In general, it can be calculated according to the following formula:

WAIT_TIME=4 ^* NODE_PROCESS_TIME ^* NET_DIAMETER

WAIT_TIME: Waiting time.

NODE_PROCESS_TIME: Node processing time, which is the sum of the time for the node to process and forward the message, generally 40ms.

NET_DIAMETER: The maximum number of hops between two nodes in MANET, which is related to the network scale.

3. During the communication process, the VoIP communication node sends an address notification message to the other party every 5 seconds. Considering the efficiency of encryption and decryption, the symmetric encryption algorithm RC4 is used to encrypt the address notification message, and the key used by the RC4 algorithm is the random number generated during the handshake phase.

4. It is stipulated that when one party of the communication does not receive a new correct address notification message from the other party within 30 seconds, it will cut off the current voice communication connection.

Comparing the present invention with the traditional VoIP processing mechanism, we can find out that the present invention has the following advantages obviously:

1. Before the voice communication connection is established, a random number is shared between the communication parties through a handshake process. Because the random numbers are all sent in the form of ciphertext, other nodes in the MANET do not know the random numbers, and the random numbers can be used as the basis for the mutual authentication of the two parties in the voice communication.

2. We did not directly use the 'address returned from the local database to establish a communication connection, but tried to confirm its validity through a unicast query before using it, so as to improve the reliability of voice communication.

3. Using the address information stored in the local database to send unicast queries instead of obtaining the IP address of the target node through broadcasting each time can reduce the broadcast storm of the mobile ad hoc network and save bandwidth resources.

4. During the communication process, when the address of a node changes, it will promptly notify the other party of the new address through the address notification message. After the other party decrypts the address notification message, it can cancel the original communication connection established on the old address, and instead establish a new voice communication connection on the new address, so that the voice communication process can be automatically switched to the new address. Because the address notification message contains a random number field, and this random number is only shared by the two parties in the voice communication, so when one party decrypts the plaintext of the address notification message, if it sees a correct value of the random number, it can It is determined that the address notification message is indeed sent from the other party of the communication, and the random number field in the address notification message plays an authentication role. After adding the sequence number field in the address notification message, it can not only resist the replay attack, but also solve the problem of the out-of-order arrival of the address notification message in the packet network, that is, if the sequence number value of the address notification message after this decryption If it is less than or equal to the sequence number value of the previous correctly received address notification message, it proves that this address notification message is an old message and can be simply discarded.

5. During the communication process, if the addresses of the communicating parties change one or more times in turn, the voice communication connection can still be maintained correctly according to the above method.

6. During the communication process, if the addresses of both parties to the communication change at the same time at a certain moment, although the address notification messages sent by both parties cannot reach the other party, because we stipulate that when one party communicates within the specified time (30 seconds) When it does not receive any new correct address notification message from the other party, it will release the existing voice communication connection, so after a period of time, each party will not receive the correct address from the other party. The connection is released by notifying the message, so that the voice communication will not be wrongly held for a long time, and the reliability is improved.

Description of drawings

FIG. 1 is a flow chart of processing before a voice call source node establishes a call connection.

Fig. 2 is a flow chart of the communication node processing the received address notification message during the call.

Detailed ways

The processing steps of each event in Figure 1 are as follows:

Step S1.1: The source node of the voice call generates a 32-bit random number, and encrypts it with the public key of the target node of the voice communication;

Step S1.2: The source node accesses the name service module, and the name service module queries the local database;

Step S1.3: If the corresponding record is found in the local database, return the IP address of the target node and go to S1.4, if no corresponding record is found, go to S1.10;

Step S1.4: The source node sends a unicast query message to the IP address returned by the name service module to confirm the validity of the address and start the timer at the same time. The unicast query message contains the encrypted random number generated by S1.1 ;

Step S1.5: If the source node receives the reply message within the specified time, go to S1.6; otherwise, go to S1.10;

Step S1.6: The source node decrypts the encrypted random number in the reply message with its private key;

Step S1.7: Compare the decrypted random number with the random number generated by the node in S1.1, if the comparison result is the same, go to S1.8; if the comparison result is different, go to S1.9;

Step S1.8: use the IP address returned by the name service module as the target address of the voice call; enter S1.18;

Step S1.9: Discard the reply message;

Step S1.10: The source node sends a broadcast query message to the MANET network and starts a timer at the same time. The broadcast query message contains the encrypted random number generated in S1.1;

Step S1.11: The source node listens to the port. If there is a broadcast query reply message before the timer expires, enter S1.13; if the timer expires, enter S1.12;

Step S1.12: The target node is offline, and the voice call process ends;

Step S1.13: The source node decrypts the encrypted random number in the reply message with its private key;

Step S1.14: Compare the decrypted random number with the random number generated by the node in S1.1, if the comparison result is the same, go to S1.16; if the comparison result is different, go to S1.15;

Step S1.15: Discard the reply message and return to S1.11;

Step S1.16: Utilize the source IP address of the reply message to update the local database;

Step S1.17: use the source IP address of the reply message as the target address of the voice call;

Step S1.18: Establish a voice call connection according to the target address obtained in S1.8 or S1.17.

The processing steps of each event in Figure 2 are as follows:

Step S2.1: The communication node receives the address notification message;

Step S2.2: The communication node uses the random number negotiated in the connection establishment phase as a key to decrypt the address notification message;

Step S2.3: Check the value of the random number field, if it is the same as the random number shared by both communication parties in the connection establishment phase, go to S2.4, otherwise, go to S2.7;

Step S2.4: Check the serial number field, if it is a new message (this value is greater than the serial number of the address notification message received correctly last time), record the serial number value to replace the address received correctly last time Notify the serial number value of the message, enter S2.5, otherwise, enter S2.7;

Step S2.5: Check the current address field, if it is found that the IP address of the other party has changed, go to S2.6, otherwise, go to S2.7;

Step S2.6: cut off the voice communication connection on the old address, and then establish a new voice communication connection on the changed IP address, and end this process;

Step S2.7: Discard the message.

Claims (4)

1. A voice communication method in a mobile ad-hoc network, characterized in that the method comprises the following steps: each communication node maintains a local database, and the historical call record of this node is preserved in the database, and each record is < Two-tuple of communication ID, IP address>; When initiating a voice call, the source node first accesses the local database to find the historical record of the target node address. If the historical record of the target node address is found, it sends a unicast query message to the target node address in the record to confirm the validity of the address , if the source node receives a reply message within the specified time indicating that the address is true and valid, then establish a communication connection based on this address; otherwise, send a broadcast query message to obtain the current address of the target node; the above unicast and broadcast query messages include The random number generated by the source node for this voice call is encrypted with the public key of the target node. Only the target node can correctly decrypt the random number. The source node can use this random number to identify the authenticity of the reply message. In the handshake process of sending query and reply messages between nodes, a random number is shared between the source node and the target node of this voice communication, which is used for the encryption key and authentication basis in the communication process; During the call process after the communication connection is established, the communication parties periodically send address notification messages to each other. The address notification messages are encrypted using the random number negotiated in the handshake phase as the key, including the sequence number field and the random number field. When a node If the address of the node changes, the node will send the changed address to the other party in a timely manner through the address notification message, and the other party will cancel the connection established on the old address after decrypting the message and establish a voice communication connection on the new address; In addition, when one party does not receive a new and correct address notification message from the other party within the specified time, the current voice communication connection will be released to ensure that even if the addresses of both communication parties change at the same time, the communication connection will be released in time , to avoid voice communication being wrongly maintained for a long time, and improve the reliability of voice communication. 2. the voice communication method in the mobile ad hoc network according to claim 1, wherein the voice call source node initiates a voice call, and the step of establishing a communication connection comprises: Step S1.1: The source node of the voice call generates a 32-bit random number, and encrypts it with the public key of the target node of the voice communication; Step S1.2: The source node accesses the name service module, and the name service module queries the local database; Step S1.3: If the corresponding record is found in the local database, return the IP address of the target node and go to S1.4, if no corresponding record is found, go to S1.10; Step S1.4: The source node sends a unicast query message to the IP address returned by the name service module to confirm the validity of the address and start the timer at the same time. The unicast query message contains the encrypted random number generated by S1.1 ; Step S1.5: If the source node receives the reply message within the specified time, go to S1.6; otherwise, go to S1.10; Step S1.6: The source node decrypts the encrypted random number in the reply message with its private key; Step S1.7: Compare the decrypted random number with the random number generated by the node in S1.1, if the comparison result is the same, go to S1.8; if the comparison result is different, go to S1.9; Step S1.8: use the IP address returned by the name service module as the target address of the voice call; enter S1.18; Step S1.9: Discard the reply message; Step S1.10: The source node sends a broadcast query message to the MANET network and starts a timer at the same time. The broadcast query message contains the encrypted random number generated in S1.1; Step S1.11: The source node listens to the port. If there is a broadcast query reply message before the timer expires, enter S1.13; if the timer expires, enter S1.12; Step S1.12: The target node is offline, and the voice call process ends; Step S1.13: The source node decrypts the encrypted random number in the reply message with its private key; Step S1.14: Compare the decrypted random number with the random number generated by the node in S1.1, if the comparison result is the same, go to S1.16; if the comparison result is different, go to S1.15; Step S1.15: Discard the reply message and return to S1.11; Step S1.16: Utilize the source IP address of the reply message to update the local database; Step S1.17: use the source IP address of the reply message as the target address of the voice call; Step S1.18: Establish a voice call connection according to the target address obtained in S1.8 or S1.17. 3. the voice communication method in the mobile ad-hoc network according to claim 1, wherein the step of communicating node processing the address notification message received during the call comprises: Step S2.1: The communication node receives the address notification message; Step S2.2: The communication node uses the random number negotiated in the connection establishment phase as a key to decrypt the address notification message; Step S2.3: Check the value of the random number field, if it is the same as the random number shared by both communication parties in the connection establishment phase, go to S2.4, otherwise, go to S2.7; Step S2.4: Check the serial number field. If it is a new message and the value is greater than the serial number of the address notification message received correctly last time, record the serial number value to replace the address notification message received correctly last time The serial number value of the message, enter S2.5, otherwise, enter S2.7; Step S2.5: Check the current address field, if it is found that the IP address of the other party has changed, go to S2.6, otherwise, go to S2.7; Step S2.6: cut off the voice communication connection on the old address, and then establish a new voice communication connection on the changed IP address, and end this process; Step S2.7: Discard the message. 4. the voice communication method in the mobile ad hoc network according to claim 1, characterized in that the method specifically comprises: Step S1: The source node of the voice communication generates a 32-bit random number, and encrypts it with the public key of the target node of the voice communication; Step S2: The source node accesses the name service module, and the name service module queries the local database. If the corresponding record is found, it returns the IP address of the target node and enters S3; if no corresponding record is found, enters S9; Step S3: The source node sends a unicast query message to the IP address returned by the name service module to confirm the validity of the address and start a timer at the same time; the unicast query message contains the encrypted random number generated in step S1; Step S4: After the unicast query reaches the destination address, the corresponding node compares the communication ID of the node with the "destination communication ID" field in the query message, and if they are the same, go to S5; otherwise, go to S6; Step S5: The node decrypts the encrypted random number in the unicast query message with its own private key to obtain the plaintext of the random number, and then encrypts the random number with the public key value of the node corresponding to the "source communication ID" specified in the unicast query message. The plaintext of the random number, and put the result in the unicast query reply message, and enter S7; Step S6: The node fills the encrypted "random number" field in the unicast query reply message with all "0"s; Step S7: the node sends a unicast query reply message to the source node of the voice call; Step S8: If the source node receives the unicast query reply message within the specified time, it uses the private key of this node to decrypt the encrypted random number in the reply message, and compares it with the random number generated in S1, if the result of the comparison is the same , then use the IP address returned by the name service module as the destination address of the voice call, and transfer to S13; if the comparison results are different, discard the reply message and enter S9; if the source node does not receive the unicast query reply message within the specified time , enter S9; Step S9: the source node sends a broadcast query message to the mobile ad hoc network MANET, and starts a timer at the same time, the broadcast query message contains the encrypted random number generated in S1; Step S10: After receiving the broadcast query message, each node in the MANET checks its own communication ID. If it is the destination node of the call, it decrypts the encrypted random number in the broadcast query message with its own private key to obtain the random number. Then use the public key value of the node corresponding to the "source communication ID" specified in the broadcast query message to encrypt the plaintext of the random number, put the result in the broadcast query reply message, and then send a broadcast to the source node of the voice call Query reply message; Step S11: The source node listens to the port. If it receives a broadcast query reply message before the timer expires, it uses its private key to decrypt the encrypted random number in the reply message, and compares it with the random number generated in S1. If If the comparison results are the same, update the local database with the source address of the reply message, and use this address as the destination address of the voice call, and transfer to S13; if the comparison results are different, discard the reply message and continue to listen; if the timer expires , enter S12; Step S12: The source node thinks that the target node of this voice call is not online, and the call process ends with an error type of "not online"; Step S13: After the source node obtains the accurate IP address currently used by the target node in S8 or S11, establish a voice communication connection with the target node on this address; Step S14: After the communication connection is established and enters the call state, each party needs to periodically send an encrypted address notification message to the other party to inform the party of the current address information; Step S15: When one party receives the address notification message from the other party, it first decrypts the message, and checks whether the random number field is the random number shared when the connection is established; if not, discard the message; The message does come from the other side of the communication; then only if the check is successful then check the message sequence number to see if the message is new, if not discard the message, if so check the "Current Address" field's Is the value the destination IP address being used? If not, it means that the address of the other party has changed, so the communication connection established on the old address will be released, and a new voice communication will be established on the changed IP address. connect; Step S16: When the communication party does not receive any new correct address notification message from the other party within the specified time, release the existing voice communication connection.

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