JP2003338811A - Communication method, system, apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a specification or how-to-use is different for each application to be used by a user since a great number of targets to be encrypted exist at various levels in a public key encryption scheme. <P>SOLUTION: In a communication method for digital cameras 200 and 201 via an external network 100, a home gateway device 210 provides a private key to the digital camera 200 and provides a public key to the digital camera 201, a home gateway device 211 provides a common key to the digital camera 201, the digital camera 201 transmits the common key encrypted by using the public key to the digital camera 200, and the digital camera 200 decrypts the common key by using the private key and performs encrypted communications with the digital camera 201 by using the common key. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a secure communication system.

[0002]

2. Description of the Related Art With the spread of the Internet, business transactions and shopping on the Internet have become commonplace. However, there are many crimes such as "sniffing", "data tampering", "spoofing by a third party", etc., which are unique to the Internet, due to transactions that are performed without the person directly meeting each other. Along with this, how to maintain security in data transmission / reception, electronic commerce, etc., and to ensure safety has become a major issue.

As a means for solving this, PKI (Public
Key Infrastructure), there is a means to use the encryption technology called public key cryptography. It has become common to use the encryption technique to encrypt the data exchanged by both parties to address the above problems.

[0004]

However, in the above-mentioned conventional technique, there are a large number of objects to be encrypted at various levels, and the specifications and methods of encryption differ depending on the application used by the user. As a result, there is a problem in that it is complicated to keep the security for the user and ensure the safety, and it causes confusion for the user.

In addition, mobile phones, PDAs (Personal Digita
l Assistance), devices other than computers such as digital cameras can be connected to networks such as the Internet, and there is a problem that a mechanism for ensuring the above security does not exist in those devices.

The present invention has been made to solve the above problems, and does not depend on a computer or other devices or applications, that is, while maintaining versatility,
"Eavesdropping""Falsification of data""Spoofing by a third party"
It is possible to provide the user with a system that secures safety by protecting the user from such a harm.

The present invention further provides a communication method, system, and system which can relieve the user from the complexity of setting the computer and other devices without burdening the computer and other devices.
The purpose is to provide an apparatus and a program for implementing the apparatus.

The present invention is based on IPv6 (Internet Protocol Vers
ion6, hereinafter referred to as IPv6. ) Is used to establish a network connection using a link local address by stateless automatic address setting.
IPSec (IETF (Internet E
ngineering Task Force) standardized protocol) is used.

[0009]

In order to achieve the above object, the key acquisition means of the present invention is a secret for decrypting a first common key and a second common key for encryption of data communication. It has a function of acquiring a key from a first key exchange device and acquiring a public key for encrypting the first common key from a second key exchange device.

The encryption / decryption means of the present invention has a function of acquiring the first common key from the key acquisition means and encrypting / decrypting a packet, and acquiring the public key from the key acquisition means. However, it has a function of encrypting the first common key and a function of acquiring the secret key from the key acquisition means and decrypting the second common key.

The key exchange device of the present invention is characterized by comprising key generation means for generating the pair of the first common key, the secret key and the second public key.

The key generation means of the present invention generates a first common key for encryption / decryption, and a pair of a second public key for encrypting the second common key and a private key for decryption. And a function of delivering the key to a client connected to a network.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The present invention is applied to a system as shown in FIG. 1, for example.

<Overall System Configuration> FIG. 1 is a block diagram of the overall system in an embodiment of the present invention.

In the system of the present embodiment, as shown in FIG. 1, network-accessible devices (hereinafter referred to as network appliances) 110 to 11 such as PCs (personal computers), PDAs, and digital cameras.
A configuration in which a set of N and the key exchange devices 120 to 12N is connected so as to be able to communicate with each other via the network 100 is
There are two or more pairs.

The key exchange devices 120 to 12N are connected to an external network 100 such as the Internet. When the network appliances 110 to 11N are connected to the external network 100 such as the Internet, they are connected to the respective key exchange devices 120 to 110N.
It connects with the network appliances 110-11N connected to each via the key exchange apparatuses 120-12N in the external network 100 via 12N.

Here, in order to simplify the description of the present embodiment, a set of a digital camera 200 as a network appliance and a set of home gateway devices 210 in which a function of key exchange is mounted and a digital camera will be described with reference to FIG. A configuration in which a set 201 and a home gateway device 211 are connected by a network 100 such as the Internet is shown. The present invention is not limited to digital cameras,
It can be implemented in network appliances such as PCs and PDAs.

Reference numeral 200 in FIG. 2 denotes a digital camera,
In addition to the basic functions of a digital camera, the function of sending and receiving data via a network, the common key A1,
It has a function of encrypting / decrypting data using A2, and a function of encrypting the common key A1 with the public key C2 and decrypting the common key A2 with the secret key B1. 201 is also a digital camera having the same function as the digital camera 200.

Reference numeral 210 in FIG. 2 denotes a home gateway device, which is a so-called router that relays data flowing on the network to another network, and has a function of relaying or rejecting the data flowing on the network to another network, and IPv6. DHCP (Dynamim) to hosts (network appliances such as computers) that is standard in
c Host Configuration Protocol) and other functions. Further, the home gateway device 210 has a function of generating a common key A1 for encrypting / decrypting data. The home gateway device 210 also has a public key C1 for encrypting the common key A2 and a common key A2.
It has a function of generating a pair of secret keys B1 for decrypting. The common key A2 is generated by the home gateway device 211. Home gateway device 21
0 is the common key A1, the public key C1, the secret key B
1 has a function of delivering 1 to a network appliance such as the digital camera 200 or 201. Also 211
The home gateway device has the same function as the home gateway device 210.

There are a method for realizing the functions of the home gateway devices 210 and 211 in a computer system and a method for implementing the functions as a dedicated device for the computer system. In the embodiment of the present invention, both methods can be realized.

Reference numeral 100 in FIG. 2 denotes a network, which is a network appliance (digital camera 200, 2, 2) used by a user such as an intranet or the Internet.
01) is the network of the segment to which it does not belong.

Reference numeral 220 is a local link connecting the digital camera 200 and the home gateway apparatus 210, and 221 is a local link connecting the digital camera 201 and the home gateway apparatus 211. The home gateway device 210 relays data between the local link 220 and the external network 100, and the home gateway device 211 relays data between the local link 221 and the external network 100.

<Digital Camera Block Diagram> FIG. 3 is a block diagram for explaining the configuration of the digital cameras 200 and 201 shown in FIG.

In the digital camera of FIG. 3, reference numeral 300 denotes an image pickup section for picking up an optical image of a subject, and 301 denotes an image pickup section 30.
An image processing unit that converts the captured image output from 0 into image data of a predetermined format and adds watermark data to the image data, and 302 is a predetermined high-efficiency encoding for the image data output from the image processing unit 301. (For example, DCT
This is a coding / decoding unit that performs variable length coding after conversion and quantization. The encoding / decoding unit 302 also decompresses and decodes the compressed image data reproduced from the recording / reproducing unit 303,
The image data is supplied to the image processing unit 301.

Further, in the digital camera shown in FIG.
Reference numeral 3 denotes a recording / reproducing unit that records / reproduces compression-encoded image data on a recording medium (not shown), and 304 denotes the digital camera 10.
An operation unit for instructing a processing operation at 0, a control unit 305 having a microcomputer and a memory capable of storing a predetermined program code for controlling and managing the operation of each processing unit constituting the digital cameras 200 and 201. , 30
Reference numeral 6 denotes an EVF (Electr
ic View Finder), a display unit for displaying using a liquid crystal panel, and the like, and 307 is an interface for communicating image data captured by the image capturing unit 300.

Further, reference numeral 308 is a ROM in which information regarding the functions of the digital camera is stored. In the digital cameras 200 and 201 of the present embodiment, as a technique for encoding image data, for example, JPEG (Joint Photogr
aphic Experts Group) method is used for compression coding.

A network interface (NETIF) 309 controls the data transfer between the information processing devices via the network and diagnoses the connection status. The digital cameras 200 and 201 transmit data to the local links 220 and 221 and receive data from the local links 220 and 221 through the network interface 309.

Reference numeral 310 denotes a module processing unit, which is provided with a microcomputer and a memory capable of storing a predetermined program code, and undertakes a network communication stack, encryption / decryption and the like.

<Home Gateway Device Block Diagram> Here, a system block diagram as an example of the case where the device is installed as a dedicated device will be described with reference to FIG. However, this system configuration is not limited in implementing the embodiment of the present invention.

Reference numeral 401 in FIG. 4 denotes a central processing unit (hereinafter referred to as CPU) which controls the home gateway device.

Reference numeral 402 denotes a random access memory (hereinafter referred to as R
AM)), and as the main memory of the CPU 401,
And functions as an area of the execution program, an execution area of the program, and a data area.

Reference numeral 403 is a read only memory (hereinafter referred to as ROM) which stores the operation processing procedure of the CPU 401.
Is. The ROM 403 includes a program ROM in which basic software (OS) that is a system program for controlling the equipment of the information processing apparatus is recorded, and a data ROM in which information necessary for operating the system is recorded.

Reference numerals 404 to 40N denote network interfaces (NETIF), which perform control for data transfer between information processing devices via the network and diagnose connection status. Home gateway device 210, 221
Is connected to the external network 100 by the network interface 404, connected to the local links 220 and 221 by the network interface 405, and connected to the external network 100 and the local link 22.
Data is relayed between 0 and 221.

Reference numeral 400 denotes an input / output bus (address bus, data bus, and control bus) for connecting the units described above.

<Module Configuration and Function> In FIG.
The application modules in which the present invention is implemented in the digital cameras 200, 201 and the home gateway devices 210, 211 will be described.

The module processing section 310 of the digital camera 200, 201 operates as the key acquisition means 501 and the encryption / decryption means 502.

The operation of the module processing unit 310 of the digital camera 200 will be described below. The operation of the module processing unit 310 of the digital camera 201 is similar to the operation of the module processing unit 310 of the digital camera 200.

The key acquisition means 501 sends a common key A1 for encrypting / decrypting communication data and a secret key B1 for decrypting the common key C2 from the home gateway device 210.
It has a function of acquiring a public key C2 for encrypting the common key A1 from the home gateway device 211. Also, the key acquisition unit 501 has a function of storing the common key A1, the public key C2, and the secret key B1.

The encryption / decryption means 502 acquires the common key A1, the public key C2, and the secret key B1 from the key acquisition means 501, generates data to be sent to the network, and uses the common key A1 to generate an IPv6 packet. It has a function of encrypting, a function of encrypting the common key A1 with the public key C2, and a function of decrypting the encrypted common key A2 with the secret key B1.

That is, the key acquisition unit 501 acquires the common key A1 from the home gateway device 210 (key providing device) in the local link, and at the same time, the communication partner (digital camera 201) side (home gateway 211).
It functions as an acquisition unit that acquires the public key C2 from. Also, the encryption / decryption means 502 encrypts the common key A1 using the public key C2 and communicates with the communication partner (digital camera 20).
1) and also functions as an encrypted communication unit (encryption unit) that performs encrypted communication with the communication partner using the common key A1.

The module processing unit 310 includes a microcomputer and a memory capable of storing a predetermined program code. The microcomputer reads the program from the memory to obtain the public key and encrypt / Decrypt and so on. Module processing unit 31
0 stores a program that causes the microcomputer to execute the above processing.

Home gateway devices 210 and 211
Is a key providing unit 511 and a key generating unit 5 based on the program recorded in the program / data ROM 403.
12 and as described above, it operates as a routing means for relaying data flowing on the network to another network.

Here, since the routing means for performing the routing function is generally mounted, the description and illustration thereof will be omitted.

The operations of the key providing means 511 and the key generating means 512 of the home gateway device 210 will be described below.
The key providing means 51 of the home gateway device 211
1. The operation of the key generation means 512 is similar to that of the home gateway device 210.

The key providing unit 511 holds the pair of the common key A1, the public key C1 and the secret key B1 generated by the key generating unit 512. Then, the key providing means 511
It has a function of delivering the common key A1 to the digital camera 200 in the same segment in response to a request from the digital camera 200 in the same segment. The key providing unit 511 also has a function of delivering the secret key B1 to the digital camera 200 in the same segment in response to a request from the digital camera 200 in the same segment.

Further, the key providing means 511 uses the public key C
1 is stored and disclosed in an appropriate place on the network 100 such as the Internet, and the public key is released in response to a request from the digital camera 201 in a different segment from the digital camera 200 to which the common key A1 and the secret key B1 are delivered. It has a function of delivering the key C1 to a digital camera 201 in a different segment from the digital camera 200 delivering the secret key B1.

The key generation means 512 has a function of generating the common key A1 for encrypting / decrypting an IPv6 packet and a function of generating a pair of the public key C1 and the secret key B1.

<System Processing Flow> The overall processing flow of the system according to the embodiment of the present invention will be described with reference to FIG.

Before explaining the processing of this embodiment, the IP
The automatic address setting mechanism in v6 is explained.

In the case of a computer or network appliance compatible with IPv6, Ethernet (R) is usually used as the interface (309 in FIG. 3) for connection with the network, and the IEEE identifier ( Medium Access Cont
The IPv6 address is configured based on the address in the rol sublayer, abbreviated as MAC address). The IPv6 address includes a link local address,
There are three types: site-local addresses and (aggregatable) global addresses.

The address system such as details and configuration method is described in RFC 2373 `` IP Version 6 Addressing Architec
ture, '' RFC 2374 `` An IPv6 Aggregatabale Global Un
icast Address Format, '' RFC 2375 `` IPv6 Multicast
Address Assignment, '' RFC2450 `` Proposed TLA and N
LA Assignment Rule, '' RFC2461 `` Neighbor Discovery
for IP Version 6 (IPv6), '' RFC 2462 `` IPv6Statele
ss Address Autoconfiguration, '' etc.

Here, the explanation of the processing for automatically setting the link local address is given in RFC 2462 `` IPv6 Stateles.
s Address Autoconfiguration, '' will be explained with reference to the contents.

A link is a facility or medium through which a device connected to it can communicate, and contacts the lower side of the IP layer. In addition to Ethernet (R), PPP link, X.25, frame relay, ATM
There is a network.

An IPv6-compatible device connected to a link is called a node. The nodes include a router and a host (a computer or a network appliance, and in this embodiment, a digital camera, hereinafter referred to as a host). A router (in this embodiment, a home gateway device, hereinafter referred to as a router) transfers a packet not addressed to itself, but a host does not.

Ethernet (R) IEEE identifier
The (MAC address) is a 6-byte length address, and the first 3 bytes are managed and assigned by the IEEE as a manufacturer vendor code. The remaining 3 bytes are managed by each vendor and are allocated so that duplication does not occur.

As a result, each Ethernet (R) card has a unique address in the world, which is used as an address when transmitting and receiving data on the Ethernet (R). The data sent via Ethernet (R) is
It is sent out on the Ethernet (R) as a packet including a source address, a destination address and data. When a collision with the data sent by another node is detected, it is retransmitted after a random time has elapsed.

Since the sent packet can be accessed by all the nodes connected to the Ethernet (R), each node looks at the destination address of the packet and receives it if it is addressed to itself, and ignores it if it is not addressed to itself. To do. The above-mentioned mechanism enables link-layer data communication. Based on the data communication of the link layer, the IP (Internet Protocol) layer is mounted on top of it, and wide area communication without link restrictions is realized.

The IPv6 address notation will be described. IPv6 address is 128 bits, 4 hexadecimal digits (represents 16 bits)
A colon: separated list is used.

For example, FE80: 0000: 0000: 0000: 0000: 0000:
It is 0000: 0001. The 0000 in the address may be represented as 0, and if the interpretation is unique, the sequence of 0s is omitted and is written as ::. The address is the same as FE80 :: 0001 or FE80 :: 1. When indicating the upper X bits in the address, it is expressed as FE80 :: 1 / X. FE80 :: 1 /
32 is the same as FE80: 0000.

Immediately after the node is powered on or rebooted, the interface (30
No address is assigned to 9), so the following processing is first performed by the node. Ethernet (R)
Divide the MAC address (309 in Fig. 3) into 3 bytes each, insert a hexadecimal number "FFFE" in the middle, and set the 7th bit from the beginning to 1. The 128-bit data created by adding the interface ID to the FE80: 0000: 0000: 0000 prefix for the link local address is tentative link-loc.
al address.

Next, the tentative link-local address
The host performs the following processing to determine whether a is unique on the link. In FIG. 2, this link means between the digital camera 200 and the home gateway device 210,
Alternatively, it is a link between the digital camera 201 and the home gateway device 211.

First, the interface 309 is initialized. That is, all-
nodes multicast address (FF02 :: 1) and its tentative l
ink-local address solicited-node multicast addr
Allocate ess. That is, the interface is all
-nodes multicast address addressed packet or its t
solicited-node mult at entative link-local address
When it finds a packet addressed to an icast address, it receives it as a packet addressed to its interface.

By assigning the former (all-nodes multicast address), the tentative link-local
It will be possible to receive data from other nodes using address. Also, the latter (that tentative link-
(local address solicited-node multicast address)
By assigning the same tentative link-localad
It is possible to detect the presence of other nodes that are trying to use dress at the same time.

A certain tentative link-local address
RFC2461 is the solicited-node multicast address of
Tentative link-lo, as defined on page 91 of
Prefix the lower 24 bits of caladdress with FF02: 0: 0:
Data added to 0: 0: 1: FF00 :: / 104, link-local
It is a scope multicast address.

Next, a Neighbor Solicitation message is created. Target Address of Neighbor Solicitation message
(Target address) is the tentative link of the judgment target
-local address, uns as IP Source (source address)
pecified address (all 128 bits are 0), IP destinati
tentative link-local of judgment target is on (destination address)
Set solicited-node multicast address of address. Send this Neighbor Solicitation message to RetransTi
mer Sends DupAddrDetectTransmits number of Ethernet (R) at millisecond intervals.

The node that receives the Neighbor Solicitation message has its source address unspecified add
If ress, the message is DAD (Duplicate Address
It can be seen that the data is from the node that is performing detection). If multiple nodes are doing DAD for the same address at the same time, use the same address for TargetAd.
Multiple Neighbor Solicitation messages included in dress
(Neighbor Solicitation message sent by me,
Neighbor Solicitation messag sent by another node
Because e) is received, it can be seen that it is a duplicate. In that case, no node uses the address.

The received Neighbor Solicitation
If the message is what you sent (because it is looping back the multicast packet), it does not indicate that there are other nodes using or trying to use it.

On the other hand, the node that receives the Neighbor Solicitation message is the Target Address of the message.
If you have already used the address included in
Neighbor Advertisement to all-nodes multicast addr
Return to ess. Therefore, Neighbor Solicitation mess
The node that sent age is a multicast Neighbor Advertis
If the ement is received and its target address is the tentative address (judgment target), the tentat of judgment target
It turns out that the ive addresses are not unique (that is, they are duplicates).

As a result of the above DAD, the tentative to be judged
If it is confirmed that the link-local address is unique on the link, the address is assigned to the interface 309 as the link local address.

After the host has assigned the link local address, the next step is the information necessary for determining the site local address and global address (Router Advertisement).
It is attempted to acquire (referred to as t) from a router (home gateway device in this embodiment). The router sends Router Advertisements to link 206 on a regular basis. When the host wants to obtain the Router Advertisement early, the host sends data called Router Solicitation to the router. Since the host does not know the existence of the router immediately after assigning the link local address, Router Solicitation is actually sent as a multicast to all routers on the link.

The router that has received the Router Solicitation sends a Router Advertisement. Router Adverti
The host that receives the sement verifies the validity of the prefix in the message (such as it is not already in use by the device) and sends it to the interface I
The address created by adding D is assigned as the site local address or the global address to the interface 309.

As described above, the host having Ethernet (R) as an interface automatically sets the link local address, site local address, and global address.

Now, with reference to FIG. 6, the processing of the system according to the embodiment of the present invention will be described. The following is based on the premise that they know each other who wants to communicate securely.

A conceptual diagram of transmission / reception of the common key, the public key, and the secret key is as shown in FIG.

600: The user has the digital camera 200,
Turn on the power of 201 and start it.

601: The link local address is set to the digital camera 200, by the IPv6 address automatic setting mechanism.
It is given to the network interface 309 of 201.

At 602: 601, the digital cameras 200 and 201 that have received the above Router Advertisement receive the home gateway device 21 in response to the network connection made possible by the link local address being given.
The IP addresses of 0 and 211 are acquired, and the digital camera 200 connects to the home gateway apparatus 210 and the digital camera 201 connects to the home gateway apparatus 211.
After the connection is established, each of the digital cameras 200 and 201 is connected to the home gateway device 2 in the same segment.
A request for key generation is issued to 10, 211 (key generation means 512).

Upon receiving the key generation request at 603: 602, the key generation means 512 encrypts / decrypts the common key A1 (A2) and the common key A2 (A1) for encryption / decryption of the IPv6 packet. Public key C1 (C2), private key B1 (B
The pair of 2) is generated. Further, the common key A1 (A
2), the public key C1 (C2), the secret key B1 (B
2) is delivered to the key providing means 511, and the key providing means 511
Publishes the public key C1 (C2) to a segment to which it does not belong.

The common key A generated at 604: 603
1 (A2) and the secret key B1 (B2) as key acquisition means 50
1 is acquired from the key providing means 511 and held. That is, the digital cameras 200 and 201 receive the information necessary for determining the site local address and the global address from the router that provides the home gateway device (in this embodiment, the common key A1 (A2) and the secret). The key B1 (B2) is acquired.

605: Acquires the storage location of the public key from the home gateway device to which the digital camera as the communication partner belongs. Here, the other parties who want to perform secure communication are known to each other (the address of the home gateway device 211 is input to the digital camera 200, and the home gateway device 21 is input to the digital camera 201).
Since the address of 0 is input), the digital camera 200 receives the information of the storage location of the public key from the home gateway apparatus 211, and the digital camera 201 receives the information of the storage location of the public key.

Based on the information on the storage location of the public key obtained at 606: 605, the public key C is transmitted from the home gateway device to which the digital camera as the communication partner belongs.
2 (C1) is acquired. The digital camera 200 receives the public key C2 from the home gateway apparatus 211, and the digital camera 201 receives the public key C1 from the home home gateway apparatus 210.

607: Each digital camera 20
0 and 201 are the public keys C2 and C1 obtained in 606.
Then, the common keys A1 and A2 are encrypted, and the digital camera 200 and the digital camera 201 transmit and exchange the encrypted common keys A1 and A2 with each other.

608: Each of the digital cameras 20 that has received the common keys A2 and A1 transmitted at 607.
0 and 201 are the respective home gateway devices 21
The secret key B which is the pair key acquired from 0 and 211.
The common keys A2 and A1 encrypted using 1 and B2
Is decrypted by the encryption / decryption means 502.

Here, the public encryption method is used as an example, but the invention is not limited to a specific public key encryption algorithm.

With the above procedure, the digital camera 200 and the digital camera 201 take advantage of the characteristic that the network connection is established by using the link local address by the stateless automatic address setting of IPv6, and further, the IPv6 standard function IPSec. (IETF (Internet
Using the protocol standardized by the Engineering Task Force), secure communication becomes possible.

The processing at the time of communication with the above-mentioned point-to-point digital cameras 200 and 201 will be described below with reference to FIG.

800: A user who uses the digital camera 200 activates an arbitrary application for accessing an external computer through the network 100.

801: The application issues a request to send data to the network 100.

802: An IPv6 packet of data output from the application is encrypted using the common key A1 acquired from the home gateway device 210 in the same segment.

803: Send the encrypted data.

804: The digital camera 201 which is a communication partner receives the transmitted data.

805: The digital camera 201 decrypts the IPv6 packet of the received data by using the common key A1 transmitted from the digital camera 200.

806: Pass the decrypted data to the application.

When the digital camera 201 transmits data to the digital camera 200, the digital camera 201 uses the common key A2 obtained from the home gateway device 211 in the same segment to encrypt and transmit the data. Digital camera 200 that received it
Decrypts using the common key A2 transmitted from the digital camera 201.

By repeating the above, it becomes possible to send and receive the encrypted data.

Here, FIG. 9 shows a conceptual diagram of the encrypted IPv6 packet transmitted / received at 803 and 804.

As described above, in the communication method of the present embodiment performed by the digital camera 200 (first communication device) and the digital camera 201 (second communication device) via the external network 100, the digital camera 200 is used. The home gateway device 210 (first key providing device) connected to the same local link 220 as the local link 220
The private key B1 is provided to the digital camera 200 via the, and the public key C1 is provided to the digital camera 201 via the external network 100. In addition, the home gateway device 211 (second key providing device) connected to the same local link 221 as the digital camera 201 is connected to the local link 2
The common key A2 is provided to the digital camera 201 via 21. The provision of the secret key B1, public key C1, and common key A2 is performed by the provision means 511 shown in FIG.

The home gateway device 210 (router) has a secret key B1 and information (prefix) necessary for the digital camera 200 to determine an address (site local address or global address).
And the common key A1 are provided to the digital camera 200. Further, the home gateway device 210 (router) publishes the public key C1 to the external network 100. The home gateway device 211 (router) provides the common key A2 and the secret key B2 to the digital camera 201, and publishes the public key C2 to the external network 100.

The common key A for the digital camera 200
1. The device that provides the private key B1 (and the information necessary for determining the address) does not have to be the gateway device (router) as long as it is a device existing in the local link 220. One of the common key A1 and the secret key B1 may be provided to the digital camera 200 from the home gateway device 210, and the other may be provided to the digital camera 200 from another device in the local link 220. In this form, the two devices work together as a device that provides the common key A1 and the secret key B1 to the digital camera 200. The public key is sent from the home gateway device 210 to the external network 10
If it is made public to 0, it may be generated together with the secret key in a device other than the home gateway device 210.

Then, the digital camera 201 transmits the common key A2 encrypted with the public key C1 to the digital camera 200, and the digital camera 200 sends the secret key B1.
To decrypt the common key A2, and to use the common key A2 to perform encrypted communication with the digital camera 201. That is, the digital camera 200 receives the data encrypted and transmitted by the digital camera 201 using the common key A2, and decrypts the data using the common key A2. In addition, the digital camera 20
0 encrypts the data using the common key A2 and sends it,
The digital camera 201 may use the common key A2 to decrypt the received data. In addition, this encoding and decoding is
This is performed by the encryption / decryption means 502 in FIG.

As described above, the digital cameras 200 and 201
Network appliances such as receive the common key and secret key as well as the information for determining the address, and the public key is disclosed to the outside by the router of the connected network. It is possible to perform secure communication without having a function of generating and disclosing the public key.

[0103]

As described above, according to the present invention,
Independent of devices such as computers and digital cameras and applications, that is, encryption is performed while maintaining versatility, protecting users from the dangers of "eavesdropping", "tampering with data", "spoofing by a third party", and ensuring safety. It has become possible to provide the secured system to the user, and also to release the user from the complexity of such settings.

Taking advantage of the characteristic of establishing a network connection by using a link local address by stateless automatic address setting of IPv6, further, IPSec (IETF (Internet Engineeri
ng Task Force) standardized protocol).

It is also possible to protect the key for encrypting communication data from an external malicious attack and provide a system with higher security.

As a result, the user is freed from the work of setting each application used in each scene in order to ensure security, and all devices connectable to the network have the same security function as a computer. It is possible to provide users with the ability to use e-mail, web browsing, sending and receiving of digital images, business transactions and shopping that are carried out on the Internet, etc., which is very useful for users. Is brought.

Further, the first key providing device connected to the first local link provides the public key to the second communication device via the external network, and the second communication device provides this public key. Since the encrypted common key is transmitted to the first communication device, the first communication device and the second communication device can safely share the common key without depending on the device. became.

Further, the common key is acquired from the key providing device in the local link, the public key is acquired from the communication partner side, the common key is encrypted using the public key and transmitted to the communication partner. It is now possible to securely share a common key with the other party, without depending on the device.

[Brief description of drawings]

FIG. 1 is a system configuration diagram in which the present invention is used.

FIG. 2 is a system configuration diagram in which the present invention is used.

FIG. 3 is a block diagram of a digital camera in which the present invention is used.

FIG. 4 is a block diagram of a home gateway device in which the present invention is used.

FIG. 5 is a module block diagram of a system in which the present invention is used.

FIG. 6 is a process flow diagram of a system in which the present invention is used.

FIG. 7 is a conceptual diagram showing a key flow of a system in which the present invention is used.

FIG. 8 is a flowchart of a process of encrypted communication in the system in which the present invention is used.

FIG. 9 is a conceptual diagram of an IPv6 packet in which the present invention is used.

[Explanation of symbols]

110-11N Network Appliance 120-12N key exchange device 200,201 Network Appliance 210, 211 Home gateway 400 system bus 404-40N NETIF

Claims (10)

[Claims] 1. A communication method performed by a first communication device and a second communication device via an external network, comprising providing a first key connected to the same first local link as the first communication device. The device provides a secret key to the first communication device via the first local link and a public key to the second communication device via the external network, the same as the second communication device A second key providing device connected to a second local link provides a common key to the second communication device via the second local link, and the second communication device provides the public key. Is transmitted to the first communication device, the first communication device decrypts the common key using the secret key, and the second common key is transmitted using the common key. Communication characterized by performing encrypted communication with other communication devices Law. 2. A communication system comprising a network appliance and a key exchange apparatus, wherein the network appliance has a key acquisition means and an encryption / decryption means, and the key exchange apparatus is a link local. A communication system for delivering a first common key for performing encrypted communication and a secret key for decrypting a second common key to the network appliance connected by an address. 3. The key obtaining means obtains the first common key for encryption and the secret key for decrypting the second common key from the key exchange device, The communication system according to claim 2, further comprising a function of acquiring storage location information of a public key for encrypting the first common key from a second key exchange device. 4. The communication system according to claim 3, wherein the key acquisition unit has a function of acquiring the public key based on the storage location information of the public key. 5. The encryption / decryption means acquires the first common key, the public key, and the secret key from the key acquisition means, and encrypts a packet using the first common key. And a function of encrypting the first common key using the public key, and a function of decrypting the encrypted second common key using the secret key. The communication system according to claim 4. 6. The communication system according to claim 2, wherein the key exchange device includes a key providing unit and a key generating unit. 7. The key generation means has a function of generating the first common key, a second public key for encrypting the second common key, and the secret key. The communication system according to claim 6. 8. The key providing means supplies the first common key, the second public key, and the secret key to the network appliance connected by a network in accordance with an address of the network appliance. The communication system according to claim 7, which has a function of delivering. 9. An acquisition unit for acquiring a common key from a key providing device in a local link and acquiring a public key from a communication partner, and encrypting the common key using the public key and transmitting the encrypted common key to the communication partner. , A communication device comprising an encrypted communication means for performing encrypted communication with a communication partner using a common key. 10. A common key is obtained from a key providing device in a local link, a public key is obtained from a communication partner, the common key is encrypted using the public key, and the common key is transmitted to the communication partner. A communication program characterized by performing encrypted communication with a communication partner by using.