JP2014165795A - Ip telephone and communication method switchover method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable switchover to encryption communication between IP telephones having an encryption function without passing through a call control server.SOLUTION: An IP telephone includes: an audible sound transmitter for outputting a preset encryption communication request sound to an IP telephone on the reception side for encryption communication; an audible sound detector for monitoring the reception of the encryption communication request sound and outputting a switchover signal on detecting the encryption communication request sound; and an encryption processing unit for switching a circuit on receiving from a user an encryption request indicative of switchover to the encryption communication and the switchover signal, so that a sound caused by encryption key data is not output from a receiver when an identification signal and an encryption key are received as voice data, to share the encryption key and perform encryption processing using the shared encryption key.

Description

  The present invention relates to an IP telephone and a communication method switching method.

  2. Description of the Related Art In recent years, an IP (Internet Protocol) telephone system that has become widespread includes an IP telephone that communicates according to an IP system and a call control server that manages communication via the IP telephone.

  In this IP telephone system, in order to encrypt and communicate a call, the IP telephone on the transmission side has an encryption function for encrypting and transmitting communication information such as voice and data, and the IP telephone on the reception side decrypts it. It is necessary to have an encryption function. Further, it is necessary to hold key information for encryption in the IP telephones on the transmitting side and the receiving side for communication.

  In general, a method of passing through a call control server is used to identify whether or not a communication partner IP telephone has an encryption function and whether or not it holds key information. The call control server stores identification information in an SDP (Session Description Protocol) according to the SIP (Session Initiation Protocol) method, and transmits the identification information to an IP telephone on the communication partner side. Note that the key information may be shared not only by the identification but also by the IP telephones on both the transmission side and the reception side via the call control server. In this way, it can be identified that the IP telephone on the communication partner side has an encryption function, and it is identified that key information has been set and switched to encryption communication.

  However, in order to realize this method, the call control server has an identification information transmission function for the presence / absence of the encryption function of the IP telephone, an identification information transmission function for the presence / absence of encryption key setting, or an encryption key sharing function. It is assumed that it is compatible. Therefore, when the call control server does not have an identification information transmission function regarding the presence / absence of the encryption function of the IP telephone, does not have an identification information transmission function regarding the presence / absence of an encryption key, or does not have an encryption function sharing function. Even if the IP telephones on the transmission side and the reception side have an encryption function, encrypted communication cannot be performed. In addition, even if the call control server supports the transmission function of identification information for presence / absence of the encryption function of the telephone, the transmission function for presence / absence of key information, and the sharing function of key information, it is limited to the data length and format that can be transmitted. There can be. In such a case, encryption communication with a required encryption strength (encryption that is difficult to break) cannot be realized.

  Therefore, a method is conceivable in which IP telephones identify the presence or absence of an encryption function according to a protocol such as FTP (File Transfer Protocol) and directly share an encryption key.

  However, the IP telephone system is often provided with security such as a firewall in order to prevent system intrusion from the outside. In this case, only communication permitted by the call control server can be performed (Patent Literature). 1).

  Therefore, in the IP telephone system provided with security, only voice communication managed by the call control server is permitted, and therefore IP telephones cannot directly communicate with each other according to a protocol such as FTP.

  In such a case, a method may be considered in which identification information regarding the presence / absence of an encryption function, identification information regarding the presence / absence of an encryption key, and encryption key sharing information are stored in a VoIP voice packet and transmitted / received. However, if the IP phone on the receiving side does not have an encryption function, the identification information or the like is processed as an audio signal. Since the identification signal is not an audio signal, if it is processed as an audio signal, it will be output as noise.

JP 2006-50250 A

    In an IP telephone system in which the call control server does not have an encryption function and can only communicate with VoIP packets permitted by the call control server, an IP telephone with an encryption function and an IP telephone without an encryption function are mixed and the encryption function is When an IP telephone with no encryption function tries to communicate with a certain IP telephone, there is a problem that noise occurs in the IP telephone without the encryption function.

  Therefore, the main object of the present invention is to mix IP telephones with an encryption function and IP telephones without an encryption function in an IP telephone system in which the call control server does not have an encryption function and can only perform VoIP communication permitted by the call control server. Even so, it is an object of the present invention to provide an IP telephone and a communication method switching method capable of switching between encrypted communication and general communication without causing noise or the like in an IP telephone having no encryption function.

  In order to solve the above-mentioned problem, an invention relating to an IP telephone connected to a network and performing encrypted communication is configured to output an audible sound that outputs an encrypted communication request sound preset in the IP telephone to the communication partner when performing encrypted communication. When receiving the transmission unit, the audible sound detection unit that monitors the reception of the encrypted communication request sound and outputs a switching signal when the encrypted communication request sound is detected, and receives the encrypted communication request and the switching signal from the user When the identification signal for the presence / absence of the encryption function, the identification signal for the presence / absence of the encryption key, and the shared information of the encryption key are received as audio data, the circuit is switched so that the sound by the data such as the identification information is not output from the receiver. Cryptographic processing unit that identifies the presence / absence of a function, identifies the presence / absence of an encryption key, and performs encryption processing using the encryption key while sharing the encryption key when receiving encryption key sharing information , Characterized in that it comprises a.

  The invention relating to the method of switching the IP telephone connected to the network to the encrypted communication is a method of switching the communication from the IP telephone connected to the network to the encrypted communication. The audible sound sending procedure for outputting the encryption communication request sound set in advance to the IP telephone and the reception of the encryption communication request sound are monitored, and the audible sound that outputs the switching signal when the encryption communication request sound is detected Detection procedure, procedure for receiving an encryption request and switching signal indicating the start of encrypted communication from the user, and identification of the presence or absence of an encryption function when receiving an encrypted communication request sound as voice data from the IP telephone on the communication partner side The receiving circuit on the receiving side is switched so that the sound of the information, the identification information on the presence / absence of the encryption key, or the data of the shared information on the encryption key is not output from the receiver on the receiving side. Procedures for starting encrypted communication with IP phones with encryption function, procedures for starting general communication (not encryption communication) with IP phones without encryption function, and encryption key when receiving encryption key shared information And a procedure for starting the sharing process.

  According to the present invention, the identification information on the presence or absence of the encryption function, the identification information on the presence or absence of the encryption key, or the encryption key sharing information is transmitted as voice data, and the voice based on the identification information and the encryption key sharing information is transmitted from the receiver. Since it is not output, even in an IP phone system in which an IP phone with an encryption function and an IP phone without an encryption function coexist, an IP phone without an encryption function does not generate noise, Switching to communication can be realized without going through the call control server.

It is a block diagram of the IP telephone system concerning this invention. It is a flowchart which shows the communication procedure in an IP telephone. It is a flowchart which shows the communication procedure in the case where key information is preset. It is a flowchart which shows the communication procedure in the case where the encryption key is not set previously.

  A first embodiment of the present invention will be described. FIG. 1 is a configuration diagram of an IP telephone system to which an IP telephone according to the present invention is connected. FIG. 1 shows a case where two IP telephones, IP telephone 2A (2) and IP telephone 2B (2), are connected to a network 20 such as an IP network. Dare to add that.

  The IP telephone 2 includes a receiver 11 (11A, 11B), a digital / analog converter 12 (12A, 12B), an encryption processing unit 13 (13A, 13B), an audible sound detector 17 (17A, 17B), and an audible sound transmitter 16. (16A, 16B), the IP-IF unit 18 (18A, 18B) and the like are the main components.

  The cryptographic processing unit 13 includes a switch unit 21 (21A, 21B), a cryptographic response unit 22 (22A, 22B), a cryptographic key output unit 23 (23A, 23B), and a cryptographic processing unit 24 (24A, 24B). .

  Since the IP telephone 2A and the IP telephone 2B have the same configuration, in the following description, the IP telephone 2A is described as a transmitting telephone, the IP telephone 2B is described as a receiving telephone, and the configuration and operation are simply described for the IP telephone 2. In some cases, a general number is used.

  The receiver 11 is a combination or handset of a microphone and a speaker used for voice input or voice output.

  The digital / analog converter 12 converts a signal format (digital / analog). That is, an analog voice signal from the receiver 11 is converted into a digital signal and output to the IP-IF unit 18 side, and a digital signal from the IP-IF unit 18 side is converted into an analog signal and output to the receiver 11. Process.

  The audible sound sending unit 16 performs processing for outputting a cipher communication request sound to the receiving-side telephone 2B when performing cipher communication.

  The audible sound detection unit 17 detects whether or not a preset audio signal (encrypted communication request sound) is included in the communication signal from the receiving telephone 2B, and the encrypted communication request sound is included. If it is, the switching signal G2 is output to the cryptographic processing unit 13.

  The switch unit 21 of the cryptographic processing unit 13 includes two switches that operate synchronously based on the switching signal G2 from the audible sound detecting unit 17, and the communication signal includes the cryptographic response unit 22, the cryptographic key output unit 23, and the cryptographic processing unit 24. Switch whether or not to go through. The mode in which the communication signal passes through the encryption response unit 22, the encryption key output unit 23, and the encryption processing unit 24 is the encryption mode.

  The cryptographic response unit 22 outputs an identification response signal indicating the presence or absence of the cryptographic function when responding to the cryptographic communication request for the cryptographic communication request.

  The encryption key output unit 23 outputs an encryption key used for encrypted communication and shares the encryption key. If the encryption key is already shared, the encryption key is not output.

  The encryption processing unit 24 performs encryption / decryption processing of communication data transmitted / received using the shared encryption key.

  The IP-IF converter 18 performs an interface with the network 20 and transmits / receives IP packets.

  Next, a communication procedure in the IP telephone 2 having such a configuration will be described with reference to a flowchart shown in FIG.

  Step SA1: First, the transmitting side telephone 2A calls the receiving side telephone 2B. When the receiving telephone 2B answers in response to this call, the line is established.

  Steps SA2 to SA3: When line connection is established between the transmitting telephone 2A and the receiving telephone 2B, or when an encryption switching operation or the like is controlled after a general call (in normal mode), the encryption is performed. The request G1 is input to the cryptographic processing unit 13A and the audible sound sending unit 16A.

This encryption request G1 is automatically output after the line is connected, or is output by pressing a predetermined key such as a function key or a numeric keypad provided on the transmitting telephone 2A and the receiving telephone 2B. The
That is, when the user of the transmitting side telephone 2A desires encrypted communication or the receiving side telephone 2B responds to encrypted communication, the encryption request G1 is transmitted to the encryption processing unit 13A and the audible sound by pressing the key. Is output to the unit 16. Of course, such processing may be performed by control units (not shown) of the transmitting telephone 2A and the receiving telephone 2B.

  Step SA4: When the audible sound sending unit 16A receives the encryption request G1, the audible sound sending unit 16A sends an encrypted communication request sound that is a predetermined audible sound. Thereafter, the transmission side telephone 2A switches the communication mode to the encryption mode, and shifts to a response waiting state from the reception side telephone 2B. This encryption mode is a mode in which a communication signal passes through the encryption processing unit 13.

  The encryption communication request sound is an audio signal that informs the receiving telephone 2B that encryption communication is desired. The frequency of the encryption communication request sound can be exemplified by a single frequency sound, but is not limited to the single frequency. The condition for the encrypted communication request sound may be a sound that the user of the receiving telephone 2B who hears the encrypted communication request sound does not feel uncomfortable and can be surely recognized.

  An example of such a sound is a DTMF (Dual-Tone Multi-Frequency) signal sound. Further, it may be a guidance sound such as “I would like encrypted communication” or “I will send an encryption key” instead of a single sound, or a specific melody sound or music sound.

  Step SA5: At this time, the audible sound detection unit 17B monitors whether or not the encrypted communication request sound is included in the communication signal from the transmission side telephone 2A, and when the encrypted communication request sound is detected, the switching signal G2 is output to the cryptographic processing unit 13B. Note that the receiving telephone 2B may not have an encryption communication function. Therefore, the process can be divided into a case where the receiving side telephone 2B is not provided with the encryption communication function (step SA6 to step SA7) and a case where it is provided (step SA8 to step SA12).

  Steps SA6 and SA7: If the receiving side telephone 2B does not have the encryption communication function, it cannot respond to the encryption communication even if the encryption communication request sound is detected (such a telephone does not have an encryption mode). . In this case, the process proceeds to step SA6. Even if the receiving side telephone 2B does not have the encryption communication function, the user can hear the encryption communication request sound, but the encryption communication request sound is not an unpleasant sound as described above. There will be no trouble.

  If communication is not possible unless encrypted communication is possible (in the case of a system in which a call in the normal mode is not permitted), the normal mode communication in step SA7 is not performed, and the process proceeds to line disconnection in step SA13.

  Steps SA8 and SA9: Based on the switching signal G2, the switch unit 21B switches the communication mode to the encryption mode, outputs a response signal to the encryption request, and stops outputting the voice signal to the receiver.

  Step SA10: If the receiving telephone 2B has the encryption communication function, it is determined whether or not the encryption key is already shared. At this time, if the encryption key is already shared, the process proceeds to step SA12. The user does not need to operate the function key or the like to output the encryption request G1 to the encryption processing unit 13B, but the switching signal G2 is input to the encryption processing unit 13B. Therefore, the switch unit 21B switches the communication mode to the encryption mode based on the switching signal G2.

  Step SA11: If the encryption key is not shared, the encryption key is shared with the other party's telephone, and the key for encryption communication is shared. The encryption key not only transmits a single piece of data, but can also be shared according to a DH (Diffie-Hellman) key exchange method.

  Step SA12: Then, the transmission side telephone 2A and the reception side telephone 2B encrypt / decrypt the communication signal using the newly shared encryption key or the already shared encryption key. As a result, encrypted communication becomes possible, and output of an audio signal obtained by decrypting the encrypted communication is started to the receiver.

  Steps SA13 and SA14: When normal communication and encryption communication are completed, the line is disconnected. Thereafter, when encrypted communication is performed, the transmission side telephone 2A and the reception side telephone 2B return the communication mode to the normal mode.

  Since the encryption key can be shared without going through the server in this way, a security hole is created even when a firewall or the like is installed and FTP (File Transfer Protocol) communication between IP telephones is restricted. Encryption communication can be performed without any problem.

  In addition, since the identification information and the encryption key information are not output when the approval of the encrypted communication from the receiving side telephone (response to the encrypted communication request sound from the receiving side telephone) is not obtained, the receiving side without the encryption communication function. The user of the telephone does not hear a sound based on the encryption key information. That is, the sound based on the encryption key information does not become noise.

  In the above description, it is assumed that the encryption key is shared on the communication line. However, when key information is set in advance or is set by means different from the communication line, the flowchart of FIG. Follow the steps shown. In this case, steps SB1 to SB7 are the same as steps SA to SA7 in FIG.

  Step SB8: When an encryption communication function is provided, it is determined whether or not an encryption key is set. If the encryption key is set in advance or set by another different means, the process proceeds to step 9. If there is an encryption communication function but there is no encryption key, encryption communication cannot be performed, and the process proceeds to step SB7.

  Steps SB9 and SB10: When having an encryption communication function and having an encryption key, since the encryption communication is possible, a response signal to the encryption communication request is transmitted, and the mode is switched to the encryption communication mode.

  Step SB11: The telephone set 2A and the telephone set 2B encrypt / decrypt the communication signal using the set encryption key. Thereby, encryption communication becomes possible. At this time, output of the audio signal obtained by decrypting the encrypted communication is started to the receiver.

  Steps SB12 and SB13: When normal communication and encryption communication are completed, the line is disconnected. Thereafter, when encrypted communication is performed, the telephone 2A and the telephone 2B return the communication mode to the normal mode. Furthermore, since the present invention does not depend on the encryption communication method, FIG. 4 shows a flowchart in the case where the encryption key setting is neither pre-setting nor the key sharing method.

  Steps SC1 to SC4 are the same as steps SA1 to SA4 in FIG. 2 and steps SB1 to SB4 in FIG.

  Step SC5: It is determined whether a condition necessary for encryption communication including an encryption key is satisfied. It is assumed that the side that has sent the encrypted communication request sound satisfies the conditions for encrypted communication.

  Steps SC6 and SC7: When the conditions for performing encrypted communication are not satisfied, communication in normal mode communication is performed. If the normal mode communication is not performed, the process proceeds to step SC11 without performing the normal mode communication.

  Steps SC8 to SC10: When the condition for performing the encrypted communication is satisfied, a response signal for the encrypted communication request sound is transmitted, and the mode is switched to the encrypted communication mode. In the encrypted communication mode, communication can be performed by sending an audio signal obtained by decrypting the encrypted communication to the receiver.

  Steps SC11 and SC12: When normal communication and encrypted communication are completed, the line is disconnected. Thereafter, when encrypted communication is performed, the telephone 2A and the telephone 2B return the communication mode to the normal mode.

  In the description of FIGS. 2 and 3 above, the transmission side telephone switches the communication mode when the line is established. However, after it is understood that the encryption communication is performed by the normal communication, the encryption is performed. You may make it transfer to mode.

  The present invention can be applied to a system that performs cryptographic communication in an IP telephone system. Further, the present invention can also be applied to a communication device that transmits and receives information including video as well as sound.

2A Sender phone (IP phone)
2B Receiver phone (IP phone)
11 (11A, 11B) Handset 12 Digital-analog converter 13 (13A, 13B) Cryptographic processing unit 16 (16A, 16B) Audible sound sending unit 17 (17B, 17B) Audible sound detection unit 20 Network 21 (21A, 21B) Switch Unit 22 (22a, 22B) 22B Cryptographic response unit 23 (23A, 23B) Cryptographic key transmission / reception unit 24 (24A, 24B) Cryptographic processing unit

Claims (7)

An IP phone that is connected to a network and performs encrypted communication,
An audible sound sending unit that outputs a preset encryption communication request sound to the IP phone on the receiving side when performing encrypted communication;
An audible sound detector that monitors reception of the encrypted communication request sound and outputs a switching signal when the encrypted communication request sound is detected;
When receiving the encryption request indicating the sharing of the encryption key from the user and the switching signal, the circuit is arranged so that the sound of the encryption key data is not output from the receiver when the identification information or the encryption key is received as the sound data. An IP telephone comprising: an encryption processing unit that performs encryption processing by switching and sharing an encryption key, and performing encryption processing using the shared encryption key. The IP phone according to claim 1,
The cryptographic processing unit, when receiving the switching signal, a switch unit that switches to a cryptographic mode in which processing in the cryptographic processing unit is executed,
An encryption response unit for notifying that the encrypted communication request sound corresponds to the encrypted communication;
An encryption key output unit for transmitting information on the encryption key in order to share the encryption key used in the encryption communication;
An encryption processing unit that encrypts and decrypts transmission / reception data using the shared encryption key;
An IP telephone comprising: The IP phone according to claim 1 or 2,
The IP telephone set characterized in that the tone communication request sound is transmitted as a voice packet. The IP telephone set according to any one of claims 1 to 3,
The IP telephone as claimed in claim 1, wherein the tone communication request sound is a combination of one or more of a single frequency sound, voice guidance, DTMF tone, music, and melody. An IP telephone connected to the network is a method for switching between encrypted communication and normal communication,
An audible sound transmission procedure for outputting a preset encryption communication request sound to the IP phone on the receiving side when performing encrypted communication;
Audible sound detection procedure for monitoring the reception of the encrypted communication request sound and outputting a switching signal when the encrypted communication request sound is detected;
A procedure for receiving an encryption request indicating sharing of an encryption key from the user and the switching signal;
When the encryption key is received as audio data from the IP telephone on the transmission side, the reception key on the reception side is switched to share the encryption key so that the sound of the encryption key data is not output from the receiver on the reception side. Procedure and
A procedure for performing cryptographic processing using the shared cryptographic key to perform cryptographic processing;
A communication method switching method characterized by comprising: The communication method switching method according to claim 5,
The communication method switching method, wherein the sound communication request sound is transmitted as a voice packet. The communication method switching method according to claim 5 or 6,
The communication method switching method, wherein the tone communication request sound is one of a single frequency sound, voice guidance, DTMF tone, music, and melody.

Images