JP2006270431A - Call controller, terminal, their programs, and communication channel establishment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate a burden on a session management server concerning access control. <P>SOLUTION: A call controller establishes a communication channel by using third party call control between two terminals which are mutually authenticated with a session management device and connected to the session management device via respective encipher signaling channels. The call controller comprises: an encipher signaling channel establishing means for exchanging key information for encipher communication with the session management device, mutually performing authentication with the session management device, and establishing the encipher signaling channel with the session management device; and a call control means for transmitting a connection request message based on the third party call control to the two respective terminals via the encipher signaling channels. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for efficiently performing access control in a system that constructs a data channel between terminals using a session management server.

  An example of a system for establishing a channel between terminals via a session management server is shown in FIG. In the system shown in FIG. 1, a session management server 3 is installed between the terminal 1 and the terminal 2, and a data channel between the terminal 1 and the terminal 2 is established between the terminal 1 -session management server 3 -terminal 2. Signaling (signaling procedure) is executed, and after data channel construction, data communication is performed only between terminals without going through the session management server 3.

  First, a secure signaling channel for performing encrypted communication such as IPsec is established between the terminal 1 and the session management server 3 and between the session management server 3 and the terminal 2. Then, the terminals 1 and 2 are accessed to the session management server 3 through the secure signaling channels established between the terminal 1 and the session management server 3 and between the session management server 3 and the terminal 2, respectively. Signaling for establishing a data channel between the terminals 2 is executed. As a means for the above signaling, for example, the SIP protocol is used.

In the system shown in FIG. 1, the session management server 3 performs access control for permitting access only to a specific terminal. For this purpose, the session management server 3 has an access control list as shown in FIG. 2 in which each terminal can communicate with which terminal the terminal can communicate with. When a terminal transmits a connection request for another terminal to the session management server 3, the session management server 3 refers to the list of FIG. 2 to check whether the communication is permitted. The connection request is transferred to another terminal.
JP 2002-208921 A

  However, when the above technique is used for access control, if the number of terminals subject to access control becomes enormous, the load on the session management server 3 increases and the performance such as the user accommodation rate or processing speed decreases. There is a fear.

  If a building management system having 1000 cameras and 100 monitors as terminals connected to the session management server 3 is taken as an example, the list shown in FIG. 3 is required. In this case, permission entries (100,000 entries) of cameras 1 to 1000 (for 1000 cameras) are managed for each of 100 monitors, and monitors 1 to 100 (for 100 cameras) for each of 1000 cameras. ) Permission entries (100,000 entries) are managed, and a list of 200,000 entries in total is managed. Since this list is searched every time a connection request is received from the monitor or camera, the load on the session management server 3 increases.

  Furthermore, for example, when one monitor is added to the above configuration, it is necessary to add this monitor to each permission entry of 1000 cameras, and there is a problem that management is complicated.

  The present invention has been made in view of the above points, and an object thereof is to provide a technique for reducing the load on the session management server related to access control.

  The above problem is a terminal that establishes a communication channel with another terminal based on third party call control by a call control apparatus that is mutually authenticated with a session management apparatus and connected via an encrypted signaling channel. Exchange of key information for encrypted communication with the session management device, mutual authentication with the session management device, and establishment of an encrypted signaling channel with the session management device And a call control for receiving a connection request message including session information of the other terminal from the call control device and transmitting a response message including the session information of the own terminal to the call control device based on the third party call control. This can be solved by a terminal characterized by having information processing means.

  The terminal has recording means for recording identification information of the call control device as identification information of a reliable device, and the call control information processing means stores the identification information of the call control device in the recording means. The transmission source address of the connection request message included in the header part of the connection request message may not be compared with the address of the other terminal included in the session information of the other terminal. .

  The present invention also relates to a terminal that establishes a communication channel with another terminal based on third party call control by a call control apparatus that is mutually authenticated with a session management apparatus and connected via an encrypted signaling channel. An encrypted signaling channel for exchanging key information for encrypted communication with a session management apparatus, performing mutual authentication with the session management apparatus, and establishing an encrypted signaling channel with the session management apparatus And a call control information processing means for receiving a connection request message not including session information from the call control device and transmitting a response message including the session information of the terminal to the call control device based on the third party call control. It can also be configured as a terminal characterized by having.

  The terminal has recording means for recording the identification information of the call control device as identification information of a reliable device, and the call control information processing means stores the identification information of the call control device in the recording means. A source address included in a header part of the reception confirmation message based on the third party call control received from the call control information, and the other address in the session information of the other terminal included in the reception confirmation message. It is good also as not comparing with the address of a terminal.

  In addition, the present invention establishes a communication channel by using third party call control between two terminals that are mutually authenticated with a session management apparatus and connected with the session management apparatus through an encrypted signaling channel. The call control device exchanges key information for encrypted communication with the session management device, authenticates with the session management device, and establishes an encrypted signaling channel with the session management device. An encrypted signaling channel establishing means, and a call control means for transmitting a connection request message based on the third party call control to each of the two terminals via the encrypted signaling channel. It can also be configured as a call control device.

  In the call control device, whether or not the source address of the response message included in the header part of the response message to the connection request message matches the source address in the session information included in the response message It is good also as having the confirmation means which performs.

  The present invention can also be configured as a program for causing a computer to realize each means of the terminal and the call control device.

  The present invention also provides a communication system having a first terminal, a second terminal, a call control device, and a session management device connected to a network, wherein the first terminal is based on third party call control by the call control device. For establishing a communication channel between the session management apparatus and the second terminal, establishing an encrypted signaling channel between the session management apparatus and the first terminal, performing mutual authentication, and An encrypted signaling channel is established between the terminal and a mutual authentication, the encrypted signaling channel is established between the session management device and the call control device, and the mutual authentication is performed. The connection request message based on the third party call control is transmitted to the first terminal via the encrypted signaling channel, and the first request message is received. A terminal transmits a response message including its session information to the call control server via the encrypted signaling channel; and the call control server receiving the response message receives the response message via the encrypted signaling channel. A connection request message including the session information transmitted to the second terminal, and the second terminal receiving the connection request message transmits a response message including its session information via the encrypted signaling channel. And a call control server that has received the response message transmits a reception confirmation message including the received session information to the first terminal via the encrypted signaling channel. It may be configured as a method.

  According to the present invention, since the call control device mutually authenticated with the session management device and connected by the encrypted signaling channel performs the third party call control on the terminal, the communication channel between the terminals is established. The management device does not need to have an access control list for each terminal, and can establish a communication channel between terminals simply by having an access control list that permits communication between the call control device and the terminal. Therefore, even when the number of terminals is large, access control can be performed securely without increasing the load on the session management apparatus.

  Hereinafter, embodiments of the present invention will be described. Prior to that, a technique for constructing a secure data channel between terminals, which is a premise of the embodiments of the present invention, will be described.

  FIG. 4 shows the sequence. The sequence shown in FIG. 4 is based on a system configuration in which the terminal 1, the session management server 3, and the terminal 2 are connected to the IP network as shown in FIG.

  Each terminal includes a signaling function for performing signaling with the session management server 3, a function for performing data communication via a secure data channel, and an application for providing a desired service using the data communication. Yes.

  In addition, the session management server 3 includes a signaling function for performing signaling with each terminal, a connection policy control function for controlling connection permission between terminals, an authentication function for authenticating each terminal, an IP from the name of the terminal A name resolution function for acquiring an address, a database for storing IDs and passwords used for authentication, a database for storing names in association with IP addresses, and the like are provided. Further, a function equivalent to general DNS can be provided as a name resolution function.

  As shown in FIG. 4, in constructing a secure data channel between the terminal 1 and the terminal 2, first, a secure signaling channel is constructed between the terminal 1 and the session management server 3 and between the terminal 2 and the session management server 3, respectively. , Do name registration. Details are as follows.

  The ID and password of each of the terminals 1 and 2 are distributed to the session management server 3 in advance, and the ID and password of the session management server 3 are distributed to the terminals 1 and 2 in advance. First, key information used for encryption communication such as IPsec is exchanged between the terminal 1 and the session management server 3 (step 1). Thereafter, mutual authentication is performed by encrypting information including its own ID and password and transmitting it to the other party (step 2). After the authentication, a secure signaling channel (encrypted signaling channel) is established, and the terminal 1 registers the name and IP address with the session management server 3 using the channel (step 3). A similar sequence is executed between the terminal 2 that is the communication partner of the terminal 1 and the session management server 3, and the name and IP address of the terminal 2 are registered in the session management server 3 (steps 4, 5, and 6).

  Thereafter, a connection request from the terminal 1 to the terminal 2 is transmitted via the secure signaling channel (step 7). The connection request includes the name of the terminal 2 and session information (the address of the terminal 1, key information for encryption communication (information for generating the encryption key), etc.). The session management server 3 that has received the connection request checks that the terminal 1 is not lying with respect to the connection request from the terminal 1 (caller spoofing check), and further, using the access permission list, the terminal 1 and the terminal 2 Is checked (step 8), and if it is permitted, the IP address of the terminal 2 is obtained from the name of the terminal 2 by referring to the database using the name resolution function (step 9). Then, the connection request is transferred to the terminal 2 via the secure signaling channel (step 10). If communication between the terminal 1 and the terminal 2 is not permitted, the connection request for the terminal 1 is rejected. At this time, information regarding the terminal 2 is not transmitted to the terminal 1 at all.

  The terminal 2 that has received the connection request transmits a response message including its session information (key information for encryption communication, etc.) to the session management server 3 via the secure signaling channel as a response to the connection request (step 11). The session management server 3 performs the same policy control and the like as in step 8, and sends a response message to the terminal 1 (step 12).

  With this procedure, encrypted communication between the terminal 1 and the terminal 2 becomes possible. That is, a secure data channel is established and desired data communication is performed.

  As means for realizing the above sequence, a protocol based on SIP (session initiation protocol) can be used. In this case, a REGISTER request message can be used for establishing a secure signaling channel and registering a name, and an INVITE request message can be used for establishing a secure data channel between terminal 1 and terminal 2. Further, the sender spoofing check after step 7 can be performed as follows.

  The session management server 3 holds the name of the terminal 1, the IP address, the port number, and information (for example, IPsec SA) that identifies the connection of the secure signaling channel between the terminal 1 and the session management server 3. Therefore, the session management server 3 can grasp the name of the terminal 1 and the IP address of the terminal 1 from the connection information that has received the INVITE request message, and the From line (the message transmission source) in the INVITE request message. By comparing the name described in the name line) and the IP address described in the Contact line (line in which the IP address of the message transmission source is described), the name or IP address is spoofed. Judge that there is no.

  As shown in the sequence of FIG. 4, the fact that the secure signaling channel has been established through steps 1, 2, 4 and 5 indicates that mutual authentication has succeeded between the terminal and the session management server, and a trust relationship has been established. That is. Since such a relationship is established between the terminal 1 and the session management server 3 and between the terminal 2 and the session management server 3, the terminal 1 and the terminal 2 are also mutually reliable. From step 7 onward, it is possible to use a procedure that is simpler than the key exchange procedure used in general encrypted communication.

  Therefore, in the above sequence, an electronic signature that is troublesome to distribute a certificate is not attached to the SDP (session information). Instead, in order to check the validity of the SDP, the terminal 2 that has received the INVITE request message in Step 10 receives the Contact line in the header part of the INVITE request message and the c line in the SDP (the IP address of the communication partner of the session). (Ie, the IP address of the terminal 1 is described) and if they match, it is determined that the SDP is valid and the session is continued. A similar check is performed on the terminal 2 side that receives the 200 OK response message. Since the validity of the Contact line in the header part of the INVITE request message (no spoofing) is guaranteed on the system side (session management server side), it is confirmed that the SDP is normal by the simple check as described above. it can.

(Description of Embodiment of the Present Invention)
FIG. 5 shows the configuration of the communication system in the embodiment of the present invention. This communication system includes a SIP server 3 as a session management server 3, a call control server 4, and a terminal 1 and a terminal 2 that perform data communication via a data channel. Each device is connected to an IP network such as the Internet. Although a large number of terminals can be connected in practice, only the terminal 1 and the terminal 2 are shown in FIG.

  In the communication system shown in FIG. 5, first, each of the terminal 1, the terminal 2, and the call control server 4 establishes a secure signaling channel with the SIP server 3 in the same manner as the steps 1 to 3 in FIG. The name and IP address are registered in the SIP server 3. In this state, the authentication is successful between each terminal and the SIP server 3 and between the call control server 4 and the SIP server 3, and a trust relationship is established.

  As shown in FIG. 6, the SIP server 3 includes an access control list that allows only communication between the call control server and each terminal, and the call control server is based on access control that refers to the access control list. Performs call control (third party call control: 3PCC for short) necessary for data channel construction between the terminal 1 and the terminal 2, and a signaling sequence through the secure signaling channel is executed. A data channel between 1 and terminal 2 is established. Even if the number of terminals is the same as in the example shown in FIG. 3, the number of permitted entries (2200) in the access control list in FIG. 6 is a digit compared to the number of permitted entries (200,000) in the example in FIG. There are fewer differences.

(Overview of operation)
With reference to FIG. 5, an outline of an operation for constructing a data channel between the terminal 1 and the terminal 2 will be described. First, the call control server 4 calls the terminal 1 by transmitting an INVITE request message not including SDP (step 21), and the terminal 1 sends a response message to which the SDP including its own session information is added to the call control server 4. Return (step 22). The call control server 4 transmits an INVITE request message including the SDP to the terminal 2 (step 23), and the terminal 2 returns a response message to which the SDP including its own session information is added to the call control server 4 (step 24). The call control server 4 sends a confirmation message including the SDP to the terminal 1 (step 25). Thereby, the terminal 1 and the terminal 2 can acquire other session information, and can start data communication based on the session information.

  In the above procedure, since both the terminal 1 and the terminal 2 that receive the message including the SDP receive the message from the call control server 4, the Contact line and the c line in the SDP are different. . In the example described with reference to FIG. 4, the session is canceled if the Contact line and the c line in the SDP are different. However, in this embodiment, each terminal trusts the call control server 4 (specifically, The call control server 4 is recorded in the terminal as a trusted server), and the SDP sent from the call control server 4 recorded as the trusted server is trusted as it is, and the Contact line and the SDP The comparison check with the c line is not performed. Therefore, the session continues even if the Contact line is different from the c line in the SDP.

(Operation details)
Next, the operation of the system of the present embodiment will be described in detail with reference to the sequence chart of FIG.

  In the example of FIG. 7, the IP address of the call control server 4 is 172.16.0.1, the name is 3PCC @ abc. com, the IP address of the terminal 1 is 192.168.0.1, the name is UA1 @ abc. com, the IP address of the terminal 2 is 10.0.0.1, and the name is UA2 @ abc. com.

  Step 31) First, the call control server 4 adds From: 3PCC @ abc. com (name of the call control server 4), To: UA1 @ abc. com (name of the terminal 1), Contact: 172.16.0.1 (IP address of the call control server 4), and an INVITE request message not including the SDP description is transmitted to the terminal 1.

  The SIP server 3 that has received the INVITE request message confirms that the contents of the From line and the contents of the Contact line are indeed those of the call control server 4 in the same manner as in the caller spoofing check shown in FIG. To do. When the content of the From line or the content of the Contact line is different from that of the call control server 4, the session is canceled.

  Further, the SIP server 3 refers to the access control list shown in FIG. 6, confirms that communication from the call control server 4 to the terminal 1 is permitted, and transfers the INVITE request message to the terminal 1.

  Step 32) The terminal 1 that has received the INVITE request message has the header: From: 3PCC @ abc. com (name of the call control server 4), To: UA1 @ abc. com (name of terminal 1), Contact: 192.168.0.1 (IP address of terminal 1) and SDP (c = 192.168.0.1 (IP address of terminal 1) including its own session information 200 OK response message including “)” is transmitted to the call control server 4.

  With respect to the response message, the SIP server 3 checks that the contents of the To line and the contents of the Contact line are indeed those of the terminal 1 in the same manner as in the caller spoofing check shown in FIG. The contents of the SDP including line c are not confirmed because they may be encrypted.

  Step 33) Upon receiving the 200 OK response message, the call control server 4 confirms that the contents of the Contact line and the contents of the c line are the same (192.168.0.1: IP address of the terminal 1), Confirm that the terminal 1 is not lying about the contents of the SDP.

  Then, the call control server 4 includes “From: 3PCC @ abc. com (name of the call control server 4), To: UA2 @ abc. com (name of terminal 2), Contact: 172.16.0.1 (IP address of call control server 4) and SDP received from terminal 1 (c = 192.168.0.1 (IP of terminal 1) An INVITE request message including the address) is transmitted to the terminal 2.

  The SIP server 3 that has received the INVITE request message confirms that the contents of the From line and the contents of the Contact line are indeed those of the call control server 4. The contents of the SDP including line c are not confirmed because they may be encrypted. Further, the SIP server 3 refers to the access control list, confirms that communication from the call control server 4 to the terminal 2 is permitted, and transfers the INVITE request message to the terminal 2.

  Step 34) The terminal 2 receives the INVITE request message. What is the IP address of the Contact line (172.16.0.1: IP address of the call control server 4) of this INVITE request message and the IP address of the c line (192.168.0.1: IP address of the terminal 1) Different. In such a case, in the sequence shown in FIG. 4, the terminal detects this and stops the session.

  On the other hand, in the present embodiment, the call control server 4 confirms that the IP address of the c line is indeed that of the terminal 1, and the mutual authentication between the terminal 2 and the call control server 4 Since the trust relationship is established and the terminal 2 can trust the call control server 4, the terminal 2 continues the session without performing a comparison check between the IP address of the Contact line and the IP address of the c line. More specifically, the name of the call control server 4 is recorded as a reliable server in the terminal 2 in advance, and the SDP included in the message received from the recorded server is compared with the Contact line and the c line. Will not be performed.

  Subsequently, the terminal 2 adds From: 3PCC @ abc. com (name of the call control server 4), To: UA2 @ abc. com (name of terminal 2), Contact: 10.0.0.1 (IP address of terminal 2), 200 OK with SDP including c = 10.0.0.1 (IP address of terminal 2) A response message is transmitted to the call control server 4.

  The SIP server 3 that has received the 200 OK response message confirms that the contents of the To line and the contents of the Contact line are indeed those of the terminal 2, and transfers the message. The contents of the SDP including line c are not confirmed because they may be encrypted.

  Step 35) Upon receiving the 200 OK response message, the call control server 4 confirms that the contents of the Contact line and the contents of the c line are the same (10.0.0.1: IP address of the terminal 2), It is confirmed that the terminal 2 is not lying about the contents of the SDP.

  Then, the call control server 4 includes “From: 3PCC @ abc. com (name of the call control server 4), To: UA1 @ abc. com (name of terminal 1), Contact: 172.16.0.1 (IP address of call control server 4), and SDP received from terminal 2 (c = 10.0.0.1 (IP of terminal 2) ACK request message having the address) is transmitted toward the terminal 1. An ACK request message is also transmitted to the terminal 2.

  The SIP server 3 that has received the ACK request message transmitted to the terminal 1 confirms that the contents of the From line and the contents of the Contact line are those of the call control server 4 and transfers the message. The contents of SDP are not confirmed because they may be encrypted. Therefore, even if the contents of the Contact line and the contents of the c line are different, the session is continued without discarding the message.

  The terminal 1 that has received this ACK request message records the call control server 4 in advance as a reliable server, and performs a comparison check between the Contact line and the c line as in the case of the terminal 2 that has received the INVITE request message. Absent. Then, data communication is started between the terminal 1 and the terminal 2 by establishing a session for the IP address described in the c line.

(Functional configuration of each device)
Next, the functional configuration of each device in the present embodiment will be described with reference to FIG.

  The SIP server 3 authenticates each terminal and call control server using a SIP proxy 31 that performs processing for transferring a call (message), a SIP registrar 32 that performs name registration, an ID, a password, or a certificate. The authentication module 33 includes an encryption module 34 for performing encrypted communication such as IPsec.

  Each terminal has an application for communication on a secure data channel, a SIP function unit 12 including a function for performing signaling based on third party call control and a function for issuing a REGISTER message, an ID, a password, or a certificate. It has an authentication module 13 for authenticating the SIP server 3 and an encryption module 14 for performing encrypted communication such as IPsec.

  The call control server 4 includes an application 41 that controls the start of third-party call control, a SIP function unit 42 that includes a function that performs signaling based on third-party call control, and a function that issues a REGISTER message. , An authentication module 43 that performs authentication of the SIP server 3 using a password or a certificate, and an encryption module 44 that performs encrypted communication such as IPsec.

  Each function of the SIP server 3, each terminal 1, 2 and the call control server 4 is realized by a program, and each means of each device in the present invention is realized by a program and hardware resources of a computer. It is what has been. The terminals 1 and 2 are computers such as general PCs including storage devices such as CPUs, memories, and hard disks, mobile devices, cameras, and the like. The terminal function can be realized. The terminal may be a digital home appliance. Each of the SIP server 3 and the call control server 4 is realized by installing a program in a computer having a storage device or the like.

(Application examples)
FIG. 9 shows a first application example. In the example shown in FIG. 9, the terminal in the configuration of FIG. 5 is a home appliance, and the call control server 4 is a mobile phone. In such a system, it is possible to safely control various communications between home appliances by only setting the SIP server to allow communication between all home appliances and mobile phones. . In this case, it can be considered that the cellular phone has a role as a master key. Examples of mobile phone applications include those that start communication between home appliances selected by a user's operation, and those that start communication between predetermined home appliances at a preset time.

  When such a third party call control function is not used, it is very cumbersome because the user has to make settings such as permitting communication between the camera and the TV one by one in the SIP server. By introducing the third party call control function, safe control can be performed with simple settings.

  FIG. 10 shows a second application example. The example shown in FIG. 10 is an example of realizing anonymous communication within a trusted group. In the system of the present embodiment, the reliable call control server 4 makes a call on behalf of the user's terminal. Therefore, the name of the call control server 4 is only entered in the From line in the call control message transmitted to each user terminal, and the names of other users are not entered. Since only the name of the terminal itself that receives the call control message is entered, secure anonymous communication between users as shown in FIG. 10 can be realized.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims. Moreover, although SIP is used in the embodiments of the present invention, the present invention is not limited to SIP. For example, HTTP can be used instead of SIP.

It is a figure which shows the example of the system which constructs | assembles a channel between terminals via a session management server. It is a figure which shows the example of an access control list. It is a figure which shows the example of an access control list. It is a figure for demonstrating the technique which performs a secure data channel construction between terminals. It is a figure which shows the structure and sequence outline | summary of a communication system in embodiment of this invention. It is a figure which shows the example of an access control list. It is a figure which shows the process sequence in the system of embodiment of this invention. It is a figure which shows the function structure of each apparatus in embodiment of this invention. It is a figure which shows the 1st application example. It is a figure which shows the 2nd application example.

Explanation of symbols

1, 2 Terminal 3 Session management server, SIP server 4 Call control server 11, 41 Application 12, 42 SIP function unit 13, 33, 43 Authentication module 14, 34, 44 Encryption module 31 SIP proxy 32 SIP registrar

Claims (10)

A terminal that establishes a communication channel with another terminal based on third party call control by a call control device that is mutually authenticated with a session management device and connected via an encrypted signaling channel,
An encrypted signaling channel establishment means for exchanging key information for encrypted communication with a session management device, performing mutual authentication with the session management device, and establishing an encrypted signaling channel with the session management device; ,
Call control information processing means for receiving a connection request message including session information of the other terminal from the call control device and transmitting a response message including session information of the own terminal to the call control device based on the third party call control And a terminal. The terminal has recording means for recording identification information of the call control device as identification information of a reliable device;
The call control information processing means, when the identification information of the call control device is recorded in the recording means, the source address of the connection request message included in the header part of the connection request message, and the other The terminal according to claim 1, wherein the terminal is not compared with the address of the other terminal included in the session information of the terminal. A terminal that establishes a communication channel with another terminal based on third party call control by a call control device that is mutually authenticated with a session management device and connected via an encrypted signaling channel,
An encrypted signaling channel establishment means for exchanging key information for encrypted communication with a session management device, performing mutual authentication with the session management device, and establishing an encrypted signaling channel with the session management device; ,
Call control information processing means for receiving a connection request message not including session information from the call control device based on the third party call control and transmitting a response message including session information of the terminal itself to the call control device. A terminal characterized by. The terminal has recording means for recording the identification information of the call control device as the identification information of a reliable device;
The call control information processing means includes a transmission included in a header part of a reception confirmation message based on the third party call control received from the call control information when the identification information of the call control device is recorded in the recording means. The terminal according to claim 3, wherein a comparison is not made between the original address and the address of the other terminal in the session information of the other terminal included in the reception confirmation message. A call control device for establishing a communication channel using two-party call control between two terminals that are mutually authenticated with a session management device and connected to the session management device via an encrypted signaling channel. And
An encrypted signaling channel establishment means for exchanging key information for encrypted communication with a session management device, performing mutual authentication with the session management device, and establishing an encrypted signaling channel with the session management device; ,
A call control device comprising: call control means for transmitting a connection request message based on the third party call control to each of the two terminals via the encrypted signaling channel.   Confirmation means for confirming whether or not the source address of the response message included in the header part of the response message to the connection request message matches the source address in the session information included in the response message The call control device according to claim 5. In a communication system having a first terminal, a second terminal, a call control device, and a session management device connected to a network, between the first terminal and the second terminal based on third party call control by the call control device A method for establishing a communication channel with
Establishing an encrypted signaling channel between the session management device and the first terminal, performing mutual authentication, establishing an encrypted signaling channel between the session management device and the second terminal, performing mutual authentication, Establishing an encrypted signaling channel between the session management device and the call control device and performing mutual authentication;
The call control apparatus transmits a connection request message based on the third party call control to the first terminal via the encrypted signaling channel, and the first terminal that has received the connection request message receives its session information. Sending a response message comprising: to the call control server via the encrypted signaling channel;
The call control server that has received the response message transmits a connection request message including the received session information to the second terminal via the encrypted signaling channel, and the second terminal that has received the connection request message Sending a response message including its session information to the call control device via the encrypted signaling channel;
The call control server receiving the response message includes a step of transmitting a reception confirmation message including the received session information to the first terminal via the encrypted signaling channel. Based on the third party call control by the call control device that is mutually authenticated with the session management device and connected via the encrypted signaling channel, causes the computer to execute processing for establishing a communication channel with another terminal. A program, a computer,
An encrypted signaling channel establishing means for exchanging key information for encrypted communication with the session management device, performing mutual authentication with the session management device, and establishing an encrypted signaling channel with the session management device;
A call control information processing means for receiving a connection request message including session information of the other terminal from the call control device based on the third party call control and transmitting a response message including its own session information to the call control device;
Program to function as. Based on the third party call control by the call control device that is mutually authenticated with the session management device and connected via the encrypted signaling channel, causes the computer to execute processing for establishing a communication channel with another terminal. A program, a computer,
An encrypted signaling channel establishing means for exchanging key information for encrypted communication with the session management device, performing mutual authentication with the session management device, and establishing an encrypted signaling channel with the session management device;
A call control information processing means for receiving a connection request message not including session information from the call control device based on the third party call control and transmitting a response message including its own session information to the call control device;
Program to function as. A computer performs processing for establishing a communication channel using third party call control between two terminals that are mutually authenticated with the session management device and connected to the session management device via an encrypted signaling channel. A computer program that
An encrypted signaling channel establishing means for exchanging key information for encrypted communication with the session management device, performing mutual authentication with the session management device, and establishing an encrypted signaling channel with the session management device;
Call control means for transmitting a connection request message based on the third party call control to each of the two terminals via the encrypted signaling channel;
Program to function as.

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