JP4870427B2 - Digital certificate exchange method, terminal device, and program - Google Patents

Description

  The present invention relates to a technique for easily distributing a digital certificate or the like.

  Authentication techniques based on public key cryptosystems such as digital signatures and SSL communications are currently used. In the authentication technique based on this public key cryptosystem, it is necessary to use a digital certificate to prove the owner of the public key. Generally, digital certificates are issued by a trusted third party (called a certificate authority).

  A user who wants to issue a digital certificate registers his / her public key with the certificate authority and certifies his / her identity by some method. The certificate authority distributes the information including the public key and the expiration date and the information including the digital signature of the certificate authority for the information to the user as a digital certificate.

In authentication using a digital certificate, the digital certificate is verified by verifying the digital signature of the certificate authority using the public key of the certificate authority. Incidentally, there is Patent Document 1 as a prior art document related to the present invention.
JP 2005-160005 A

  However, issuing a digital certificate using a certificate authority is complicated as described above. Also, revocation and renewal of digital certificates is complicated.

  Since the update is complicated, there are many cases where the update is not performed immediately, and there is a problem that the communication with the server using the digital certificate becomes suddenly impossible and the recovery is delayed. Further, when invalidating a digital certificate once issued, there is also a problem that the digital certificate continues to be valid unless an inquiry is made to the certificate authority.

  Further, in the case of relatively low-spec devices such as home appliances, it is difficult to incorporate an authentication technique using a digital certificate because it is difficult to revoke or renew a digital certificate. In addition, since the certificate authority needs to guarantee the reliability of the digital certificate, the digital certificate issuance fee is relatively expensive. For example, the digital certificate is used only for a short period of time. It is no longer suitable.

  Furthermore, if the secret key is leaked from the certificate authority or the user, the revocation and renewal procedures are complicated and the expiration date is long (often about one year), and there is a risk that damage during that time will increase.

  The present invention has been made in view of the above points, and provides a technique that can reduce the complexity of management such as issuance of digital certificates and can easily perform secure communication using digital certificates. The purpose is to do.

The above-described problem is a method for exchanging a digital certificate between a first terminal device and a second terminal device connected to a network using a signaling protocol, the session being connected to the network Key information for encrypted communication is exchanged between the management device and the first terminal device, the session management device and the first terminal device authenticate each other, and the session management device and the first terminal device A first encrypted communication channel establishing step for establishing a first encrypted communication channel between the session management device and the session management device and the second terminal device by exchanging key information for encrypted communication. A second encrypted communication channel establishing step in which the device and the second terminal device authenticate each other and establish a second encrypted communication channel between the session management device and the second terminal device; 1 of the terminal device, including a digital certificate of the first terminal device generated by the first terminal device to the connection request message, the connection request message to the session manager via a first encrypted communication channel A first digital certificate transmission step in which the session management device transmits the connection request message including the digital certificate of the first terminal device to the second terminal device via the second encrypted communication channel. And the second terminal device includes the digital certificate of the second terminal device generated by the second terminal device in the response message to the connection request message, and includes the response message in the second encrypted communication channel. via sending to the session management apparatus, the session management apparatus, said response message a first including a digital certificate of the second terminal device Further comprising a second digital certificate transmission step of transmitting to the first terminal device through the Goka communication channel can be solved by a method characterized.

In the second digital certificate transmission step, the second terminal device, a digital certificate of the second terminal device, and a digital certificate of the first terminal device with a digital signature of the second terminal device the The response message is included in the response message and transmitted to the session management device via the second encrypted communication channel, and the session management device transmits the digital certificate of the second terminal device and the digital signature of the second terminal device. The response message including the digital certificate of the attached first terminal device may be transmitted to the first terminal device via the first encrypted communication channel.

In the above method, the first terminal device includes the digital certificate of the second terminal device with the digital signature of the first terminal device in the confirmation message for the response message, and the confirmation message is first encrypted. The session management device transmits the confirmation message including the digital certificate of the second terminal device with the digital signature of the first terminal device to the second encrypted communication channel. It is good also as providing the step which transmits to a 2nd terminal device via this.

The present invention also provides a terminal device for exchanging a digital certificate using a signaling protocol with a second terminal device via a session management device connected to the network, wherein the session management device is connected to the network. An encrypted communication channel establishment means for exchanging key information for encrypted communication with a device, mutually authenticating with a session management device, and establishing an encrypted communication channel with the session management device, and disclosure A digital certificate generating means for generating a pair of a key and a private key and generating a digital certificate of the public key; and the connection request message including the digital certificate generated by the digital certificate generating means. transmission for transmitting the message to the second terminal device via the encrypted communication channel established by the encrypted communication channel establishment means And stage, from the second terminal device, via the session management apparatus comprises a digital certificate of the second terminal device, characterized by comprising a receiving means for receiving a response message to the connection request message It can also be configured as a terminal device. The terminal device includes the digital certificate of the second terminal device with its own digital signature in the confirmation message for the response message, and transmits the confirmation message to the second terminal device via the encrypted communication channel. Means to do this may be provided. The response message further includes its own digital certificate with a digital signature of the second terminal device , and the receiving means sends the response message from the second terminal device via the encrypted communication channel. it is also possible to receive.

  According to the present invention, since the terminal device itself issues a digital certificate and exchanges the digital certificate via an encrypted communication channel based on mutual authentication, the digital certificate can be safely used without using a certificate authority. Can be exchanged, and secure communication using a digital certificate can be easily performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Overview)
First, the outline of the embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a session management server 3 is installed between the terminal 1 and the terminal 2, and secure based on mutual authentication between the terminal 1 and the session management server 3 and between the session management server 3 and the terminal 2 respectively. Build a signaling channel. Each of the terminal 1 and the terminal 2 issues its own digital certificate by itself and exchanges the digital certificate using the secure signaling channel. Thereafter, communication using the digital certificate is performed between the terminal 1 and the terminal 2.

  When a secure signaling channel is established between the terminal 1 and the session management server 3 and between the session management server 3 and the terminal 2, between the session management server 3 and the terminal 1 and between the session management server 3 and the terminal 2. Since a trust relationship based on mutual authentication is established, a trust relationship is also established between the terminal 1 and the terminal 2. That is, a trust chain model via the session management server 3 is constructed by the mutual authentication. Therefore, the terminal 2 that has received the digital certificate of the terminal 1 via the session management server 3 may trust that the digital certificate is from the terminal 1, and the digital certificate of the terminal 2 is The terminal 1 received via the session management server 3 may trust that the digital certificate is from the terminal 2. That is, a digital certificate can be safely distributed without using a certificate authority.

(Processing sequence)
Next, a communication sequence between the terminal 1 -session management server 3 -terminal 2 will be described with reference to FIG.

  The sequence shown in FIG. 2 is based on a system configuration in which the terminal 1, the session management server 3, and the terminal 2 are connected to an IP network such as the Internet. Terminal 1 and terminal 2 generate their own public key and private key, respectively, and generate their own digital certificate. Hereinafter, the digital certificate of the terminal 1 is expressed as a digital certificate 1, and the digital certificate of the terminal 2 is expressed as a digital certificate 2.

  Each terminal performs data communication with the session management server 3 through a signaling function for performing signaling, a digital certificate management function for generating and managing a digital certificate, and a secure data channel based on the digital certificate. And an application for providing a desired service using data communication.

  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 It includes a name resolution function for acquiring an address, a database for storing IDs and passwords used for authentication, a database for storing names and IP addresses in association with each other, and the like. Further, a function equivalent to general DNS can be provided as a name resolution function.

  As shown in FIG. 2, 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.

  That is, key information (information for generating a cryptographic key) 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 authentication, a secure 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 the digital certificate 1. 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 uses the connection policy control function to connect 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). ), And transfer the connection request to the terminal 2 via the secure signaling channel (step 10). At this time, the IP address of the terminal 1 is also transmitted to the terminal 2. If the connection 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 the digital certificate 2 as a response to the connection request to the session management server 3 via the secure signaling channel (step 11), and the session management server 3 sends the response message. Is sent to the terminal 1 (step 12). At this time, the IP address of the terminal 2 is also transmitted to the terminal 1.

  With this procedure, public key-based encrypted communication using a digital certificate between the terminal 1 and the terminal 2 becomes possible.

  The fact that the secure signaling channel has been established through steps 1, 2, 4, and 5 means that the terminal-session management server has successfully authenticated each other and a trust relationship has been established. 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. Without using the certificate authority, the terminal 1 and the terminal 2 can communicate with each other by trusting that their mutual public keys are surely those of the other party.

  The sequence after step 7 in FIG. 2 may be a sequence as shown in FIGS. 3 and 4, illustration of connection policy control and name resolution is omitted.

  In the case of FIG. 3, after transmitting the digital certificate 1 from the terminal 1 to the terminal 2 (steps 7 and 10), the terminal 2 transmits the digital certificate 1 with the digital signature of the terminal 2 together with the digital certificate 2. (Step 11). The terminal 1 receives the digital certificate 2 and the digital certificate 1 with the digital signature of the terminal 2 (step 12). Here, the terminal 1 can verify the validity of the digital signature by verifying the digital signature of the terminal 2 using the digital certificate 2, but since the communication in steps 7 to 12 is performed via the secure signaling channel, this is the case. Verification is not necessarily performed.

  After step 12, public key-based secure communication can be performed between the terminal 1 and the terminal 2 as in FIG. In the case of FIG. 3, the digital data using the terminal 1 as a client and the terminal 2 as a server at an arbitrary time different from the series of sessions in steps 1 to 12 (but within a period during which the digital certificate is valid). It is possible to perform secure communication using a certificate. That is, when the terminal 1 accesses the terminal 2 that is a server, the terminal 1 transmits the digital certificate 1 with the digital signature of the terminal 2 to the terminal 2. The terminal 2 confirms that the digital certificate 1 is legitimate by confirming that it has its own digital signature (has been sent to the terminal 1 via the secure signaling channel before). Public key-based communication using the digital certificate 1 is performed. The terminal 1 may use the digital certificate 2. Thereby, the terminal 2 can prevent access from an unauthorized client.

  Further, as shown in FIG. 4, in addition to transmitting the digital certificate 1 with the digital signature of the terminal 2 from the terminal 2 to the terminal 1 (steps 11 and 12), the terminal 1 transmits the digital certificate 1 of the terminal 1 to the terminal 2. By transmitting the digital certificate 2 with a digital signature (steps 13 and 14), communication using the terminal 1 as a server and the terminal 2 as a client can be performed in the same manner as described above. That is, the digital certificate based on mutual authentication is used between the terminal 1 and the terminal 2 at an arbitrary time different from the series of sessions in the steps 1 to 14 by performing the processing as in the sequence of FIG. Public key-based communication can be performed.

  As means for realizing the above sequence, it is possible to use a protocol that is an extension of SIP (session initiation protocol). That is, the session management server 3 is caused to function as a SIP proxy server, and information exchanged in the above procedure is included in the SIP message.

  In this case, a REGISTER message can be used for establishing a secure signaling channel and registering a name, and an INVITE message can be used for exchanging digital certificates between the terminal 1 and the terminal 2.

  A sequence example in the case of using SIP is shown in FIG. The example shown in FIG. 5 corresponds to the sequence of FIG. The example shown in FIG. 5 is an example in the case of performing signaling via a plurality of session management servers connected by a secure channel. A plurality of session management servers connected by a secure channel may be referred to as a session management device. In the sequence configuration shown in FIG. 5, the IP address of the terminal 1 is 2001: 1234 :: 10, the IP address of the session management server A is 2001: 6789 :: 5060, and the IP address of the session management server B is 2001: abcd :: 5060, the IP address of the terminal 2 is 2001: cdef :: 10. Needless to say, the present invention can be applied to both IPv6 and IPv4.

  An ID and a password are distributed in advance between each terminal and the session management server, and each of the terminal and the session management server stores the other party's ID and password in its own storage device. The session management server A and the session management server B communicate via a secure channel such as TLS.

  First, the terminals 1 and 2 use the REGISTER message to establish a secure channel with the session management server and register a name (conforming to SIP) to the session management servers A and B (step 21). (Corresponding to steps 1 to 6 in FIG. 2). The procedure of this part will be described later in detail.

  Subsequently, the terminal 1 transmits an INVITE message describing the digital certificate 1 in the SIP body part as a connection request to the terminal 2 through the secure signaling channel between the terminal 1 and the session management server A (step 22). ). In addition to the digital certificate 1, information related to a communication session between the terminal 1 and the terminal 2 is described in the SIP body part. Session management server A transfers the INVITE message to session management server B via a secure channel between session management servers A and B (step 23).

  The INVITE message from the terminal 1 includes a Route-Security header. When the Route-Security header is added, the device that has received the INVITE message asks whether the route from the address indicated by the Route-Security header: [address] to the device is secure (for example, Whether the encryption is performed by IPsec) is checked, and if it is secure, the Route-Security header is left as it is and the message is transferred. When it is necessary to check whether the route is secure at the transfer destination, a message with a Route-Security header: [your address] is transferred to the transfer destination. The response message has the Route-Security header added so far, and it can be seen that the message has been transferred via a secure route. In other words, the Route-Security header provides a mechanism for ensuring the safety of the route.

  Session management server B transmits an INVITE message to terminal 2 via a secure signaling channel between terminal 2 and session management server B (step 24). The session management server A and the session management server B perform name resolution for the terminal 2.

  The terminal 2 that has received the INVITE message transmits a response message including the digital certificate 2 and the digital certificate 1 with the digital signature of the terminal 2 in the SIP body part to the terminal 1 (step 25). Then, the response message is carried in the opposite direction on the same route as the INVITE message, and is transmitted to the terminal 1 (steps 26 and 27).

  Thereafter, an acknowledgment (ACK) message including the digital certificate 2 with the digital signature of the terminal 1 is transmitted from the terminal 1 to the terminal 2 (steps 28 to 30), and the digital certificate is transmitted between the terminal 1 and the terminal 2 The used secure communication becomes possible (step 31). In addition, after the session of step 31, the digital certificate with a digital signature is executed between the terminal 1 and the terminal 2 at any time within the validity period of the digital certificate without executing a session via the session management server. By using this, secure communication can be performed.

  The sequence of the REGISTER message in step 21 in FIG. 5 is, for example, as shown in FIG.

  In this case, first, a REGISTER message including key information for encryption communication (IPsec or the like) is transmitted from the terminal to the session management server (step 211). As a response, the session management server returns a response message including the key information for encryption communication to the terminal (step 212). Subsequently, the terminal transmits a REGISTER message including authentication information for authenticating the terminal by the session management server (step 213). In response, the session management server transmits a response message including authentication information necessary for the terminal to authenticate the session management server to the terminal (step 214). After mutual authentication is obtained, encrypted communication using the secure signaling channel becomes possible.

  Thereafter, since the packet is encrypted and transmitted / received via the secure signaling channel, name registration is performed by a normal REGISTER message sequence (steps 215 and 216).

  In the above sequence, it is assumed that other information necessary for encrypted communication such as IPsec is appropriately transmitted and received. Note that the authentication information may be information including an ID, a password, or the like, or a certificate (X.509 certificate or the like). Further, authentication information (certificate) may be included in a message used for exchanging key information for encryption communication.

(Function block of the device)
Next, functional blocks of each device when SIP is used as a signaling protocol will be described with reference to FIG.

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

  Since each terminal has the same configuration, the terminal 1 will be described. The terminal 1 includes a communication function unit 11 that performs secure communication using a digital certificate, a digital certificate management unit 12, a SIP function unit 13 that performs message communication based on SIP, including transmission and reception of INVITE messages and issuance of REGISTER messages, It has an authentication module 14 that authenticates the session management server using an ID, password, certificate, or the like, and an encryption module 15 that performs encrypted communication such as IPsec.

  The digital certificate management unit 12 generates a public key / private key pair, a digital certificate, and the like. In this embodiment, the expiration date of the digital certificate is shortened to reduce the risk when the private key is leaked. In addition, the digital certificate management unit 12 manages the expiration date for each digital certificate issued by itself, and when the expiration date has arrived, for example, decrypts information encrypted with its own public key. It is possible to perform processing such as returning an error without performing it. In addition, the digital certificate is automatically reissued when the time limit is reached, and the reissued digital certificate is automatically transmitted via the secure signaling channel to the communication partner that uses the digital certificate that has reached the time limit. It is also possible to perform processing.

  The functions of the session management server and each terminal are realized by a program, and each means of the session management device and the terminal device in the present invention is realized by a program, the session management device, and the hardware of the terminal. It is what. The terminal is a computer such as a general PC including a CPU, a memory, a hard disk, and the like, a mobile device, and the like, and the functions of the terminal of the present embodiment can be realized by installing the program in the computer. The terminal may be a digital home appliance. The session management server is a computer such as a server, and the functions of the session management server according to the present embodiment can be realized by installing the program on the server.

  As described above, according to the present embodiment, a digital certificate can be issued safely without using a certificate authority, so the digital certificate issuance cost is substantially close to 0, and it can be used for various purposes. It becomes easier to use certificates. Further, since the complexity of managing digital certificates is eliminated, digital certificates can be easily introduced even in relatively low-spec devices such as home appliances. In addition, when performing communication such as HTTPS using a digital certificate, it is necessary to exchange and manage each digital certificate between terminals, and it is very difficult for a general user to perform its maintenance work, Although this was one of the factors that prevented the spread of the P2P platform on the basis of digital certificates, in this embodiment, the complexity of the maintenance work was eliminated by not using a certificate authority. It is possible to promote the spread of the P2P platform.

  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.

It is a figure for demonstrating the outline | summary of embodiment of this invention. It is a sequence diagram of communication between the terminal 1-session management server 3-terminal 2. It is a figure which shows the other example (the 1) of a sequence. It is a figure which shows the other example (the 2) of a sequence. It is a figure which shows a sequence in detail. It is a figure which shows the sequence of a REGISTER message. It is a functional block diagram of each apparatus in the case of using SIP as a signaling protocol.

Explanation of symbols

1, 2 Terminal 3, A, B Session management server 11, 21 Communication function unit 12, 22 Digital certificate management unit 13, 23 SIP function unit 14, 24 Authentication module 15, 25 Encryption module 31 SIP proxy 32 SIP registrar 33 Authentication module 34 Encryption module

Claims (7)

A method for exchanging digital certificates between a first terminal device and a second terminal device connected to a network using a signaling protocol ,
The session management apparatus connected to the network and the first terminal apparatus exchange key information for encrypted communication, and the session management apparatus and the first terminal apparatus mutually authenticate, and the session management apparatus A first encrypted communication channel establishing step for establishing a first encrypted communication channel between the first terminal device and the first terminal device;
The session management device and the second terminal device exchange key information for encrypted communication, the session management device and the second terminal device mutually authenticate, and the session management device and the second terminal device. Establishing a second encrypted communication channel with the second encrypted communication channel;
The first terminal device includes the digital certificate of the first terminal device generated by the first terminal device in the connection request message, and the session management device includes the connection request message via the first encrypted communication channel. And the session management device transmits the connection request message including the digital certificate of the first terminal device to the second terminal device via the second encrypted communication channel. Steps,
The second terminal device includes the digital certificate of the second terminal device generated by the second terminal device in a response message to the connection request message, and the response message is transmitted via the second encrypted communication channel. A second digital certificate that is transmitted to the session management device, and the session management device transmits the response message including the digital certificate of the second terminal device to the first terminal device via the first encrypted communication channel. And a document sending step. In the second digital certificate transmission step, the second terminal device, a digital certificate of the second terminal device, and a digital certificate of the first terminal device with a digital signature of the second terminal device the The response message is included in the response message and transmitted to the session management device via the second encrypted communication channel, and the session management device transmits the digital certificate of the second terminal device and the digital signature of the second terminal device. The method according to claim 1, wherein the response message including the digital certificate of the attached first terminal device is transmitted to the first terminal device via the first encrypted communication channel. The first terminal device includes the digital certificate of the second terminal device with the digital signature of the first terminal device in the confirmation message for the response message, and the confirmation message is transmitted via the first encrypted communication channel. The session management device transmits the confirmation message including the digital certificate of the second terminal device with the digital signature of the first terminal device via the second encrypted communication channel. The method according to claim 1, further comprising a step of transmitting to the terminal device. A terminal device for exchanging a digital certificate using a signaling protocol with a second terminal device via a session management device connected to a network;
Encryption that exchanges key information for encrypted communication with a session management device connected to the network, mutually authenticates with the session management device, and establishes an encrypted communication channel with the session management device A communication channel establishment means;
A digital certificate generating means for generating a public key / private key pair and generating a digital certificate of the public key;
The digital certificate generated by the digital certificate generating means is included in the connection request message, and the connection request message is transmitted to the second terminal device via the encrypted communication channel established by the encrypted communication channel establishing means. Sending means to
Receiving means for receiving a response message to the connection request message including the digital certificate of the second terminal device from the second terminal device via the session management device. Means for including a digital certificate of the second terminal device with its own digital signature in the confirmation message for the response message and transmitting the confirmation message to the second terminal device via the encrypted communication channel; The terminal device according to claim 4, wherein: The response message further includes its own digital certificate with a digital signature of the second terminal device , and the receiving means receives the response message from the second terminal device via the encrypted communication channel. The terminal device according to claim 4. A program for causing a computer to function as a terminal device that exchanges a digital certificate using a signaling protocol with a second terminal device via a session management device connected to a network, the computer comprising:
Encryption that exchanges key information for encrypted communication with a session management device connected to the network, mutually authenticates with the session management device, and establishes an encrypted communication channel with the session management device Communication channel establishment means,
A digital certificate generating means for generating a public key / private key pair and generating a digital certificate of the public key;
The digital certificate generated by the digital certificate generating means is included in the connection request message, and the connection request message is transmitted to the second terminal device via the encrypted communication channel established by the encrypted communication channel establishing means. Transmission means to
Receiving means for receiving a response message to the connection request message including the digital certificate of the second terminal device from the second terminal device via the session management device;
Program to function as.

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