Patent Description:
The development of information and communication technology (ICT) has been remarkable in recent years, and devices connected to a network such as the Internet are not limited to conventional information processing devices, such as personal computers or smartphones, and are spreading to various things. Such a technology trend is called "IoT (Internet of Things)", and various technologies and services have been proposed and put into practical use. In the future, a world is envisioned in which billions of people on Earth and tens of billions or trillions of devices are connected at the same time. In order to realize such a networked world, it is necessary to provide a solution that is simpler, safer, and more freely connected.

Usually, on a network, data communication between devices is realized by using an IP (Internet Protocol) address statically or dynamically assigned to each device.

In order to realize data communication between devices, data transmitted from the transmission source device should be transmitted to the destination device. Such data transmission processing is referred to as "routing" or the like. In order to realize such routing, a large number of routers are arranged on the network.

As disclosed in <CIT> (Patent Document <NUM>), a router has a route information table for storing route information, and determines a route and relays a received frame according to the internetworking address in the received frame and the content of the route information table (see paragraphs [<NUM>] and [<NUM>] in <CIT>). <CIT> discloses creating IP addresses using Cryptographically Protected Prefixes("CPPs"), preventing any correlation between a CPP IP address and a host's geographic location. An IP address is subdivided into address prefixes of multiple segments. Each segment is encrypted with a cryptographic key known only to a subset of routers in the access network domain (or Privacy Domain).

According to the above Patent Document <NUM>, assuming that there is a network in which a large number of devices are present, there is a problem that a large number of routers are required and the responsibility of each router is large. For this reason, in a network in which a large number of devices are present, it is preferable that each device can independently realize data communication. The present disclosure provides a solution, such as a data transmission method in which each device independently realizes data communication in a network in which a large number of devices are present.

According to an aspect of the present disclosure, a data transmission method in a network to which a plurality of devices are connected is provided. The transmission method includes: a step in which a first device generates a first encrypted packet by encrypting a packet addressed to a second device with a first encryption key associated with the second device; a step of determining a device to be a transmission destination of the first encrypted packet, generating a second encrypted packet by encrypting the first encrypted packet with a second encryption key associated with the determined device, and transmitting the second encrypted packet to the determined device; a step in which a device that receives the second encrypted packet decrypts the second encrypted packet into the first encrypted packet and determines whether or not the decrypted first encrypted packet is addressed to the device itself; and a step of determining another device and executing the transmission step if the decrypted first encrypted packet is not addressed to the device itself in the determination regarding whether or not the decrypted first encrypted packet is addressed to the device itself and of further decrypting the first encrypted packet if the decrypted first encrypted packet is addressed to the device itself.

The data transmission method described above may further include: a step in which each of the plurality of devices transmits a public key of each device and a digital certificate associated with the public key to another device; and a step in which the device that receives the public key and the digital certificate determines an IP address of a transmission source device of the public key and the digital certificate based on a hash value calculated from the public key according to a hash function.

According to another aspect of the present disclosure, a communication processing method in a device connected to a network is provided. The communication processing method includes: as steps executed when a packet addressed to another device is given, a step of generating a first encrypted packet by encrypting the packet with a first encryption key associated with the another device; a step of determining a device to be a transmission destination of the first encrypted packet; a step of generating a second encrypted packet by encrypting the first encrypted packet with a second encryption key associated with the determined device; and a step of transmitting the second encrypted packet to the determined device. The communication processing method further includes: as steps executed when the second encrypted packet is received from another device, a step of decrypting the second encrypted packet into the first encrypted packet; a step of determining whether or not the decrypted first encrypted packet is addressed to the device itself; a step of determining still another device to be a transmission destination of the first encrypted packet, generating a second encrypted packet with a second encryption key associated with the determined device, and transmitting the generated second encrypted packet if the decrypted first encrypted packet is not addressed to the device itself; and a step of further decrypting the first encrypted packet if the decrypted first encrypted packet is addressed to the device itself.

In the aspect described above, a device to be a transmission destination may be determined based on an IP address of each device.

The communication processing method described above may further include: a step of acquiring a private key and a public key; a step of determining an IP address of the device itself based on a hash value calculated from the public key according to a hash function; a step of acquiring a digital certificate associated with the public key from a certificate authority; and a step of transmitting the public key and the digital certificate to another device.

The communication processing method described above may further include: a step in which, when the public key and a digital certificate associated with the public key are received from the another device, validity of the digital certificate is determined; and a step in which, when it is determined that the digital certificate is valid, an IP address of the another device is determined based on a hash value calculated from the public key according to a hash function.

The communication processing method described above may further include, as a step executed when a packet addressed to the another device is given, a step of searching for an IP address of the destination device.

The communication processing method described above may further include, as a step executed when a packet addressed to the another device is given, a step of establishing a session between the device itself and the another device and determining the first encryption key. In addition, the communication processing method described above may further include, as a step executed when the second encrypted packet is received from the another device, a step of establishing a session between the device itself and still another device to be a transmission destination of the first encrypted packet and determining the second encryption key.

According to still another aspect of the present disclosure, a device including a network interface for connecting to a network and a control unit connected to the network interface is provided. The control unit includes: a first encryption/decryption unit capable of executing a process for encrypting a packet into a first encrypted packet using a first encryption key associated with another device and a process for decrypting the first encrypted packet; a second encryption/decryption unit capable of executing a process for encrypting the first encrypted packet into a second encrypted packet using a second encryption key associated with a device to be a transmission destination of the first encrypted packet and a process for decrypting the second encrypted packet; and a transmission management unit that transmits the second encrypted packet, which is generated by encrypting a packet addressed to another device in the first encryption/decryption unit and the second encryption/decryption unit, to a device as a transmission destination. The transmission management unit determines whether or not a first encrypted packet generated by decrypting a second encrypted packet received from another device in the second encryption/decryption unit is addressed to the device itself, transmits a second encrypted packet generated by encrypting the first encrypted packet in the second encryption/decryption unit to still another device if the generated first encrypted packet is not addressed to the device itself, and further decrypts the first encrypted packet in the first encryption/decryption unit and outputs the decrypted first encrypted packet if the generated first encrypted packet is addressed to the device itself.

According to still another aspect of the present disclosure, a communication processing program for a computer having a network interface for connecting to a network is provided. When the communication processing program is executed by the computer, the communication processing program causes the computer to execute any of the communication processing methods described above.

According to the present disclosure, it is possible to provide a solution in which each device can independently realize data communication in a network in which a large number of devices are present.

Hereinafter, an embodiment according to the present disclosure will be described in detail with reference to the diagrams. In addition, the same or corresponding portions in the diagrams are denoted by the same reference numerals, and the description thereof will not be repeated.

First, the overall configuration of the network system <NUM> according to the present embodiment will be described.

<FIG> is a schematic diagram showing an example of the overall configuration of the network system <NUM> according to the present embodiment. Referring to <FIG>, it is assumed that a plurality of devices <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. (hereinafter, may be referred to collectively as a "device <NUM>") are connected to an arbitrary network <NUM> such as the Internet or an intranet. Some of the devices <NUM> may be connected to the network <NUM> through wireless communication established between the devices <NUM> and an access point <NUM>. Alternatively, some other devices <NUM> may be connected to the network <NUM> through wireless communication established between the devices <NUM> and a mobile base station <NUM>.

Thus, the network <NUM> may include any one of a local area network (LAN), a wide area network (WAN), a radio access network (RAN), and the Internet.

Each of the devices <NUM> connected to the network can be regarded as a "node" of the network, and in the following description, the device <NUM> may be referred to as a "node".

In the network system <NUM> according to the present embodiment, data communication is realized between the devices <NUM> according to a procedure described later. In addition, any physical connection method between the devices <NUM> may be used.

The device <NUM> includes any device having a function of performing data communication with other devices using the IP address of each device. The device <NUM> may be configured as a single communication device, may be configured as a part of any thing, or may be configured to be embedded in any thing.

More specifically, the device <NUM> may be, for example, a personal computer, a smartphone, a tablet, or a wearable device (for example, a smart watch or an AR glass) worn on the user's body (for example, an arm or a head). In addition, the device <NUM> may be a control device installed in a smart home appliance, a connected automobile, a factory, and the like or a part thereof.

The network system <NUM> according to the present embodiment further includes one or more certificate authorities <NUM>. Each of the certificate authorities <NUM> is a computer configured by one or more servers. The IP address of each device <NUM> is authenticated according to a procedure, which will be described later, by using one or more certificate authorities <NUM>. As a result, each device <NUM> has an authenticated IP address.

In this specification, the "authenticated IP address" means a state in which the validity of the IP address held by each device <NUM> is guaranteed for the communication destination or a third party. More specifically, the "authenticated IP address" means an IP address that is generated by an irreversible cryptographic hash function and is directly or indirectly authenticated by the certificate authority (details thereof will be described later). By using such an "authenticated IP address", it can be guaranteed that the IP address used by each device <NUM> for data communication is not spoofed.

As a result, any device <NUM> included in the network system <NUM> is uniquely identified based on the IP address of each device <NUM>. That is, each device can determine a device to be a destination or a transmission destination of data transmission based on the IP address of each device.

The IP address is assumed to be a global IP address that can also be used for data communication between the devices <NUM> connected to the Internet, but may be a private IP address that is used only in a specific network.

The number of bits that make up an IP address differs depending on the version. In the currently established IPv4 (Internet Protocol Version <NUM>), a <NUM>-bit address section is defined, and in the currently established IPv6 (Internet Protocol Version <NUM>), a <NUM>-bit address section is defined. In the present embodiment, an IP address according to IPv6 will be mainly described. However, the present disclosure can also be applied to a network address specified by a larger number of bits or a network address specified by a smaller number of bits.

Next, a configuration example of the hardware and software of the device <NUM> used in the network system <NUM> according to the present embodiment will be described.

<FIG> is a schematic diagram showing a hardware configuration example of the device <NUM> according to the present embodiment. Referring to <FIG>, the device <NUM> includes a control unit <NUM>, which is a processing circuitry, as a main component.

The control unit <NUM> is a calculation subject for providing functions and executing processes according to the present embodiment. The control unit <NUM> may be configured such that, by using a processor and a memory shown in <FIG>, the processor executes computer-readable instructions (an OS (Operating System) and a communication processing program shown in <FIG>) stored in the memory. Alternatively, the control unit <NUM> may be realized by using a hard-wired circuit such as an ASIC (Application Specific Integrated Circuit) in which a circuit corresponding to computer-readable instructions is provided. In addition, the control unit <NUM> may be realized by realizing a circuit corresponding to computer-readable instructions on an FPGA (field-programmable gate array). In addition, the control unit <NUM> may be realized by appropriately combining a processor, a memory, an ASIC, an FPGA, and the like.

In a configuration using the processor and the memory shown in <FIG>, the control unit <NUM> includes a processor <NUM>, a main memory <NUM>, a storage <NUM>, and a ROM (Read Only Memory) <NUM>.

The processor <NUM> is an arithmetic circuit that sequentially reads and executes computer-readable instructions. The processor <NUM> includes, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), and a GPU (Graphics Processing Unit). The control unit <NUM> may be realized by using a plurality of processors <NUM> (multiprocessor configuration), or the control unit <NUM> may be realized by using a processor having a plurality of cores (multicore configuration).

The main memory <NUM> is a volatile storage device, such as a DRAM (Dynamic Random Access Memory) or a SRAM (Static Random Access Memory). The processor <NUM> loads a designated program, among various programs stored in the storage <NUM> or the ROM <NUM>, into the main memory <NUM> and cooperates with the main memory <NUM> to realize various processes according to the present embodiment.

The storage <NUM> is, for example, a non-volatile storage device, such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash memory. The storage <NUM> stores various programs executed by the processor <NUM> or various kinds of data described later.

The ROM <NUM> fixedly stores various programs executed by the processor <NUM> or various kinds of data described later.

In the configuration shown in <FIG> in which the processor <NUM> executes computer-readable instructions stored in the memory, the memory corresponds to the storage <NUM> and the ROM <NUM>.

Here, an example of a program and data stored in the memory of the device <NUM> will be described.

<FIG> is a schematic diagram showing a configuration example of a program and data of the device <NUM> according to the present embodiment. Referring to <FIG>, in the memory (the storage <NUM> and/or the ROM <NUM>) of the device <NUM>, for example, an OS <NUM>, a communication processing program <NUM>, and various applications <NUM> are stored as programs including computer-readable instructions.

The OS <NUM> is a program that provides basic functions for realizing the processing executed by the device <NUM>. The communication processing program <NUM> is mainly a program for providing the functions and executing the processes according to the present embodiment. In addition, the communication processing program <NUM> may provide the functions and execute the processes according to the present embodiment by using a library or the like provided by the OS <NUM>.

The various applications <NUM> are programs for realizing various functions provided by the device <NUM>, and can be arbitrarily installed by the user. Typically, the various applications <NUM> provide various processes using a data communication function provided by the communication processing program <NUM>.

In addition, in the memory (the storage <NUM> and/or the ROM <NUM>) of the device <NUM>, for example, a private key <NUM>, a public key <NUM>, and a digital certificate <NUM> are stored as data necessary for providing the functions and executing the processes according to the present embodiment. The private key <NUM> and the public key <NUM> are a so-called key pair generated according to an arbitrary encryption/decryption algorithm. The private key <NUM> is used for encrypted communication with other devices. The public key <NUM> is used to determine the IP address of each device <NUM> according to a procedure described later. The digital certificate <NUM> is issued to the public key <NUM> by the certificate authority <NUM>, and is for ensuring the validity of the IP address of the device <NUM>. Usually, the digital certificate <NUM> includes a hash value (digital signature) calculated from the public key <NUM> of each device <NUM> using the private key of the certificate authority <NUM>. The device <NUM> that has received the digital certificate <NUM> checks the validity of the digital certificate <NUM> and the public key <NUM> associated with the digital certificate <NUM> by using the public key of the certificate authority <NUM>.

The generation of a key pair (the private key <NUM> and the public key <NUM>), the acquisition of the digital certificate <NUM>, the procedure for using these pieces of data, and the like will be described later.

In addition, it is not necessary to provide both the storage <NUM> and the ROM <NUM>, and only one of the storage <NUM> and the ROM <NUM> may be provided depending on the mounting type. In addition, when both the storage <NUM> and the ROM <NUM> are provided, for example, the key pair (the private key <NUM> and the public key <NUM>) may be stored in the ROM <NUM> to enhance the confidentiality.

Referring back to <FIG>, the device <NUM> further includes a network interface <NUM> for connecting the device <NUM> to the network. The network interface <NUM> performs data communication with other devices through the network.

Examples of the network interface <NUM> include wired connection terminals, such as serial ports including an Ethernet (registered trademark) port, a USB (Universal Serial Bus) port, and an IEEE1394 and a legacy parallel port. Alternatively, the network interface <NUM> may include processing circuitries and antennas for wireless communication with devices, routers, mobile base stations, and the like. The wireless communication supported by the network interface <NUM> may be any of Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), LPWA (Low Power Wide Area), GSM (registered trademark), W-CDMA, CDMA200, LTE (Long Term Evolution), and 5th generation mobile communication system (<NUM>), for example.

The device <NUM> may include a display unit <NUM>, an input unit <NUM>, and a media interface <NUM> as optional components.

The display unit <NUM> is a component for presenting the processing result of the processor <NUM> to the outside. The display unit <NUM> may be, for example, an LCD (Liquid Crystal Display) or an organic EL (ElectroLuminescence) display. In addition, the display unit <NUM> may be a head-mounted display mounted on the user's head, or may be a projector that projects an image on the screen.

The input unit <NUM> is a component for receiving an input operation of a user who operates the device <NUM>. The input unit <NUM> may be, for example, a keyboard, a mouse, a touch panel arranged on the display unit <NUM>, or an operation button arranged in the housing of the device <NUM>.

The media interface <NUM> reads various programs and/or various kinds of data from a non-transitory media <NUM> in which various programs (computer-readable instructions) and/or various kinds of data are stored.

The media <NUM> may be, for example, an optical medium, such as a DVD (Digital Versatile Disc), or a semiconductor medium, such as a USB memory. The media interface <NUM> adopts a configuration according to the type of the media <NUM>. Various programs and/or various kinds of data read by the media interface <NUM> may be stored in the storage <NUM> or the like.

In addition, instead of installing various programs and/or various kinds of data on the device <NUM> through the media <NUM>, necessary programs and data may be installed on the device <NUM> from a distribution server on the network. In this case, the necessary programs and data are acquired through the network interface <NUM>.

As described above, since the display unit <NUM>, the input unit <NUM>, and the media interface <NUM> are optional components, the display unit <NUM>, the input unit <NUM>, and the media interface <NUM> may be connected from the outside of the device <NUM> through any interface such as a USB.

Providing the functions and executing the processes according to the present embodiment are realized by the control unit <NUM>, and the technical scope of this application includes at least the hardware and/or the software for realizing the control unit <NUM>. As described above, for the hardware, not only a configuration including a processor and a memory but also a configuration using a hard-wired circuit using an ASIC or the like or a configuration using an FPGA can be included. That is, the control unit <NUM> can be realized by installing a program on a general-purpose computer, or can be realized as a dedicated chip.

In addition, the software executed by the processor may include not only software distributed through the media <NUM> but also software appropriately downloaded through a distribution server.

In addition, the configuration for providing the functions and executing the processes according to the present embodiment is not limited to the control unit <NUM> shown in <FIG>, and can be implemented by using any technology according to the time of the implementation.

Next, a process for providing an authenticated IP address to each device <NUM> and the like will be described.

In the network system <NUM> according to the present embodiment, typically, the IP address of each device <NUM> is authenticated by using an authenticated IP address. As an example, the IP address of each device <NUM> may be authenticated by using a public key infrastructure (PKI).

<FIG> is a diagram for describing an IP address authentication procedure in the network system <NUM> according to the present embodiment. In addition, reference numerals such as "S1" to "S4" in <FIG> correspond to step numbers shown in <FIG>.

Referring to <FIG>, the device <NUM> has a key pair of the private key <NUM> and the public key <NUM>. A hash value <NUM> is calculated by inputting the public key <NUM> into a predetermined hash function <NUM>, and the entirety or part of the calculated hash value <NUM> is used as an IP address <NUM> of the device <NUM>.

According to such a process of determining the IP address <NUM>, the device <NUM> transmits the public key <NUM> to the certificate authority <NUM>, and associates the digital certificate <NUM> issued by the certificate authority <NUM> with the public key <NUM>. The device <NUM> transmits the public key <NUM> and the digital certificate <NUM> of the device itself to another device. Another device checks the validity of the IP address <NUM> of the device <NUM> based on the public key <NUM> and the digital certificate <NUM> published by the device <NUM>. When the validity of the IP address <NUM> is confirmed, data communication is started using the IP address <NUM> whose validity has been confirmed. The device itself and another device can communicate directly with each other, but in addition to the direct communication processing, inquiry processing at the certificate authority <NUM> may be included.

As described above, in the network system <NUM> according to the present embodiment, the IP address <NUM> itself can be authenticated. By holding such an authenticated IP address <NUM> in the device itself, it is possible to build an independent network without using a statically or dynamically assigned IP address for each device.

Hereinafter, the details of the process for providing the authenticated IP address in the network system <NUM> according to the present embodiment will be described.

The private key <NUM> and the public key <NUM>, which are a key pair, may be generated by the device <NUM> itself, or may be provided from the outside and stored in the device <NUM> in advance. When the private key <NUM> and the public key <NUM> are provided from the outside, the device <NUM> may acquire only the private key <NUM> and generate the public key <NUM> by itself.

As an example of a method of generating the private key <NUM> and the public key <NUM> which are a key pair, a bit string of a predetermined length (for example, <NUM> bits) generated by a random number generator may be used as the private key <NUM>, and the public key <NUM> having a bit string of a predetermined length (for example, <NUM> bits) may be generated from the private key <NUM> according to a known cryptographic algorithm (for example, an elliptic curve cryptographic algorithm). In addition, when the device <NUM> itself generates the key pair, the random number generator may be realized by using the function provided by the OS <NUM>, or may be realized by using a hard-wired circuit, such as an ASIC.

As the hash function <NUM>, a known irreversible cryptographic hash function (for example, BLAKE) can be used. The hash function <NUM> calculates the hash value <NUM> having a bit string of a predetermined length (for example, <NUM> bits).

Not only the public key <NUM> but also an arbitrary keyword may be input to the hash function <NUM>. As an arbitrary keyword, a message associated with a predetermined organization may be used. As the message associated with a predetermined organization, a message including the name of the trademark owned by the predetermined organization may be used. For example, the name (for example, "connectFree") of a registered trademark owned by the predetermined organization may be used as a keyword to be input to the hash function <NUM>. By adopting such an implementation method, it is possible to prevent a third party other than the predetermined organization from implementing the network system <NUM> according to the present embodiment, a relevant method or program, and the like without the permission of the predetermined organization.

The entirety or part of the hash value <NUM> calculated by the hash function <NUM> is used as the IP address <NUM>. For example, when a <NUM>-bit (<NUM> digits in hexadecimal notation) hash value <NUM> is calculated, any <NUM> digits (for example, first <NUM> digits) of the <NUM>-digit hash value <NUM> may be used as the IP address <NUM> (<NUM> bits) corresponding to IPv6. Alternatively, the first eight digits of the <NUM>-digit hash value <NUM> may be determined as the IP address <NUM> (<NUM> bits) corresponding to IPv4.

Alternatively, a <NUM>-bit hash value <NUM> may be calculated from the hash function <NUM> in consideration of the IP address <NUM> (<NUM> bits) corresponding to IPv6. In this case, the entirety of the calculated hash value <NUM> can be determined as the IP address <NUM> (<NUM> bits) corresponding to IPv6.

According to the present embodiment, the IP address <NUM> unique to the device <NUM> can be determined based on the public key <NUM> of the device <NUM>. Thus, the device <NUM> can be connected to a network, such as the Internet, by using the IP address <NUM> determined by the device <NUM>. In addition, even if there is no service provider (server) that manages the global IP address, such as an Internet service provider (ISP), the device <NUM> can perform data communication using the IP address <NUM> determined by itself. In addition, even if there is no server that manages private IP addresses such as a DHCP (Dynamic Host Configuration Protocol) server mounted on an access point or the like, the device <NUM> can perform data communication by making a connection to a global network, such as the Internet, using the IP address <NUM> determined by itself. Therefore, it is possible to improve the user experience and user convenience for connecting to a network, such as the Internet.

It may be possible to identify that the IP address <NUM> determined by the device <NUM> has been determined according to the processing procedure according to the present embodiment. In order to perform such identification, for example, the IP address <NUM> may include a predetermined eigenvalue (unique character string) for identification. That is, the determined IP address may include a predetermined eigenvalue (unique character string) for identification.

As an example, the first two digits (first and second digits from the beginning) of the IP address <NUM> in hexadecimal notation may be fixed to a predetermined unique character string (for example, "FC"). Usually, since the hash function <NUM> is a one-way function, the public key <NUM> cannot be calculated back from the IP address <NUM>. For this reason, the private key <NUM> and the public key <NUM> may be repeatedly generated using a random number generator until the determined IP address <NUM> satisfies predetermined conditions (in this case, the first two digits become a predetermined eigenvalue). That is, the public key <NUM> may be determined so that the IP address <NUM> determined based on the hash value calculated from the public key <NUM> according to the hash function conforms to a predetermined format.

In this manner, by making a predetermined eigenvalue (for example, the first two digits are "FC") for identification be included in the IP address <NUM>, a third party can determine whether or not the IP address <NUM> of the device <NUM> has been determined by the device <NUM> itself.

The IP address <NUM> determined by the device <NUM> may include information by which the type of the device <NUM> can be identified. In order to perform such identification, for example, the IP address <NUM> may include a value corresponding to the type of the device <NUM>. That is, the determined IP address <NUM> may include a value corresponding to the type of the device <NUM> that has determined the IP address <NUM>.

As an example, a value (type identification information) corresponding to the type of the device <NUM> may be embedded in the third and fourth digits from the beginning of the IP address <NUM> in hexadecimal notation.

<FIG> is a diagram showing an example of type identification information embedded in the IP address used in the network system <NUM> according to the present embodiment. The type identification information shown in <FIG> may be stored in advance in the ROM <NUM> (see <FIG>) of the control unit <NUM> of each device <NUM>. As an example, a value corresponding to the type of device shown in <FIG> can be used.

As shown in <FIG>, for example, when the type of the device <NUM> is a personal computer, a value "<NUM>" indicating the personal computer is set in the third and fourth digits from the beginning of the IP address <NUM>.

As described above, since the hash function <NUM> is usually a one-way function, the public key <NUM> cannot be calculated back from the IP address <NUM>. For this reason, the private key <NUM> and the public key <NUM> may be repeatedly generated using a random number generator until the determined IP address <NUM> satisfies predetermined conditions (in this case, the third and fourth digits from the beginning become a value indicating the type of the device <NUM>). That is, the public key <NUM> may be determined so that the IP address <NUM> determined based on the hash value calculated from the public key <NUM> according to the hash function conforms to a predetermined format.

In this manner, by making the value indicating the type of the device <NUM> be included in the IP address <NUM>, a third party can identify the type of the device <NUM> from the IP address <NUM> determined by the device <NUM>.

Next, the registration of the public key <NUM> and the acquisition of the digital certificate <NUM> will be described.

The device <NUM> acquires the digital certificate <NUM> for proving the validity of the public key <NUM> from the certificate authority <NUM>. As a procedure for acquiring the digital certificate <NUM>, the public key <NUM> is transmitted from the device <NUM> to the certificate authority <NUM> for registration, and the digital certificate <NUM> associated with the registered public key <NUM> is acquired from the certificate authority <NUM>.

More specifically, the device <NUM> (control unit <NUM>) transmits the public key <NUM> and a digital certificate issuance request (hereinafter, also referred to as a "certificate signing request") to the certificate authority <NUM> through the network. In response to the certificate signing request received from the device <NUM>, the certificate authority <NUM> registers the public key <NUM> and issues the digital certificate <NUM> associated with the registered public key <NUM>. Then, the certificate authority <NUM> transmits the digital certificate <NUM> to the device <NUM> through the network.

Typically, the digital certificate <NUM> includes owner information of the digital certificate <NUM> (in this example, the device <NUM>), issuer information of the digital certificate <NUM> (in this example, the certificate authority <NUM>), digital signature of the issuer, expiration date of the digital certificate <NUM>, and the like.

The certificate authority <NUM> may be operated by a predetermined organization, or may be an intermediate certificate authority associated with a root certificate authority operated by a predetermined organization. In addition, in registering the public key <NUM> and issuing the digital certificate <NUM> associated with the public key <NUM>, a predetermined fee and/or a maintenance fee may be required for a predetermined organization.

According to the present embodiment, the public key <NUM> is directly authenticated by the certificate authority <NUM> through the registration of the public key <NUM> and the acquisition of the public key <NUM>, so that the IP address <NUM> determined based on the public key <NUM> is indirectly authenticated by the certificate authority <NUM>. By such authentication by the certificate authority <NUM>, the device <NUM> can realize data communication through the network by using the authenticated IP address <NUM>.

In addition, the digital certificate <NUM> associated with the public key <NUM> may include information relevant to the attributes (hereinafter, also referred to as "attribute information") of the device <NUM> in order to improve confidentiality. As the attribute information of the device <NUM>, for example, the version information of the OS <NUM> of the device <NUM> or the communication processing program <NUM> and the serial number of the hardware (for example, a processor or a storage) forming the device <NUM> can be used. In this case, the device <NUM> may transmit the attribute information of the device <NUM> to the certificate authority <NUM> when transmitting the public key <NUM> and the certificate signing request. In addition, the attribute information of the device <NUM> included in the digital certificate <NUM> may be encrypted by a known irreversible cryptographic hash function or the like.

In this manner, by making the attribute information of the device <NUM> be included in the digital certificate <NUM>, it is possible to authenticate that the digital certificate <NUM> has been issued in response to the certificate signing request from the device <NUM> itself. That is, it is possible to more reliably prevent a device other than the device <NUM> from impersonating the device <NUM> and using the public key <NUM> and the digital certificate <NUM> of the device <NUM>.

Next, a processing procedure for providing an authenticated IP address in each device <NUM> will be described.

<FIG> is a flowchart showing a processing procedure in which the device <NUM> provides an authenticated IP address in the network system <NUM> according to the present embodiment. The processing procedure shown in <FIG> is executed in each device <NUM>, and each step shown in <FIG> is executed by the control unit <NUM> of each device <NUM>.

Referring to <FIG>, the device <NUM> acquires a key pair (the private key <NUM> and the public key <NUM>) generated according to an arbitrary algorithm (step S1). This key pair may be generated by the device <NUM> itself, or may be acquired from the outside by the device <NUM>. Alternatively, the device <NUM> may acquire only the private key <NUM> from the outside and generate the public key <NUM> internally.

Then, the device <NUM> calculates the hash value <NUM> by inputting the public key <NUM> to the predetermined hash function <NUM>, and determines the IP address <NUM> of the device <NUM> from the entirety or part of the calculated hash value <NUM> (step S2). That is, the device <NUM> determines the IP address of the device itself based on the hash value <NUM> calculated from the public key <NUM> according to the hash function <NUM>.

In addition, an appropriate key pair (the private key <NUM> and the public key <NUM>) may be generated so that a unique character string (for example, the first and second digits from the beginning of the IP address <NUM>) and/or type identification information (for example, the third and fourth digits from the beginning of the IP address <NUM>) are included in the IP address <NUM>.

In addition, the device <NUM> transmits the public key <NUM> and a digital certificate issuance request (certificate signing request) to the certificate authority <NUM> (step S3). In response to the certificate signing request received from the device <NUM>, the certificate authority <NUM> registers the public key <NUM> and issues the digital certificate <NUM> associated with the registered public key <NUM>. Then, the certificate authority <NUM> transmits the digital certificate <NUM> to the device <NUM> through the network. Then, the device <NUM> receives the digital certificate <NUM> from the certificate authority <NUM> and stores the digital certificate <NUM> (step S4).

In this manner, the device <NUM> acquires the digital certificate <NUM> associated with the public key <NUM> from the certificate authority.

In addition, the execution order of the processing of step S2 and the processing of steps S3 and S4 does not matter.

Next, data communication processing between the devices <NUM> using the authenticated IP address will be described.

First, a process relevant to IP address notification between the devices <NUM> in the network system <NUM> according to the present embodiment will be described.

<FIG> and <FIG> are diagrams for describing the process relevant to the IP address notification in the network system <NUM> according to the present embodiment. <FIG> and <FIG> show examples of exchanging IP addresses between three devices <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. In addition, the same processing can be performed between the two devices <NUM>, or the same processing can be performed among a larger number of devices <NUM>.

In the state shown in <FIG> and <FIG>, it is assumed that the devices <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> have determined IP addresses <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>, respectively, according to the procedure described above and the devices <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> have completed the registration of public keys <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> in the certificate authority <NUM> and the acquisition of digital certificates <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> from the certificate authority <NUM>.

As shown in <FIG> and <FIG>, each device <NUM> transmits (broadcasts) the public key <NUM> and the digital certificate <NUM> associated with the public key <NUM> of each device regularly or every event. That is, each device <NUM> transmits the public key <NUM> and the digital certificate <NUM> to another device. In addition, if the public key <NUM> is included in the digital certificate <NUM>, only the digital certificate <NUM> may be transmitted.

<FIG> shows an example in which the device <NUM>-<NUM> transmits (broadcasts) the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> associated with the public key <NUM>-<NUM>. In the example shown in <FIG>, it is assumed that the devices <NUM>-<NUM> and <NUM>-<NUM> can receive the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>. Then, the devices <NUM>-<NUM> and <NUM>-<NUM> determine whether or not the digital certificate <NUM>-<NUM> is valid. If it is determined that the digital certificate <NUM>-<NUM> is valid, the devices <NUM>-<NUM> and <NUM>-<NUM> determine the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the associated public key <NUM>-<NUM> and register these in connection tables <NUM>-<NUM> and <NUM>-<NUM>, respectively.

Here, the connection table includes information of each device <NUM> for data communication, and each device <NUM> identifies the IP address of the destination device <NUM> or the like and establishes a necessary session with reference to the connection table. Here, the "session" means a logical communication path through which necessary data is exchanged prior to transmitting and receiving data, such as packets.

More specifically, the device <NUM>-<NUM> first determines whether or not the digital certificate <NUM>-<NUM> broadcast from the device <NUM>-<NUM> is valid. In the process of determining the validity, the integrity of the digital certificate <NUM>-<NUM> is verified.

As an example of the process for verifying integrity, first, the device <NUM>-<NUM> checks the owner information of the digital certificate <NUM>-<NUM>, the issuer information of the digital certificate <NUM>-<NUM>, and the presence of the issuer's digital signature. Then, the device <NUM>-<NUM> determines whether or not the digital certificate <NUM>-<NUM> is within the expiration date. In addition, the device <NUM>-<NUM> determines whether or not the issuer of the digital certificate <NUM>-<NUM> is reliable. In particular, when the digital certificate <NUM>-<NUM> is issued by an intermediate certificate authority, the device <NUM>-<NUM> identifies the root certificate authority associated with the intermediate certificate authority that has issued the digital certificate <NUM>-<NUM>, and determines whether or not the identified root certificate authority is reliable. For example, when the identified root certificate authority matches one root certificate authority or any of a plurality of root certificate authorities stored in the device <NUM>-<NUM>, it is determined that the issuer of the digital certificate <NUM>-<NUM> is reliable.

If the determination process described above is passed, the device <NUM>-<NUM> determines that the digital certificate <NUM>-<NUM> broadcast from the device <NUM>-<NUM> is valid. Then, the device <NUM>-<NUM> calculates a hash value <NUM>-<NUM> by inputting the public key <NUM>-<NUM> broadcast from the device <NUM>-<NUM> to the predetermined hash function <NUM>, and determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> using the entirety or part of the calculated hash value <NUM>-<NUM>. Here, it is assumed that the devices <NUM>-<NUM> and <NUM>-<NUM> have a common hash function <NUM>. In addition, it is assumed that the process of determining the IP address <NUM>-<NUM> from the hash value <NUM>-<NUM> is also common between the devices <NUM>-<NUM> and <NUM>-<NUM>.

Through the above processing, the device <NUM>-<NUM> can determine the IP address <NUM>-<NUM> of the device <NUM>-<NUM>. Then, the device <NUM>-<NUM> adds the entry of the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> to the connection table <NUM>-<NUM>. In addition, the public key <NUM>-<NUM> may be registered in association with the IP address <NUM>-<NUM>.

In addition, the same processing as in the device <NUM>-<NUM> is executed in the device <NUM>-<NUM>, and the entry of the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> is added to the connection table <NUM>-<NUM> of the device <NUM>-<NUM>. The public key <NUM>-<NUM> may be registered in association with the IP address <NUM>-<NUM>.

By the processing shown in <FIG>, the device <NUM>-<NUM> and the device <NUM>-<NUM> can acquire the IP address <NUM>-<NUM> of the device <NUM>-<NUM>.

Since a series of processes executed by the devices <NUM>-<NUM> and <NUM>-<NUM> are the same as the processes described with reference to <FIG>, the detailed description will not be repeated. By the processing shown in <FIG>, the device <NUM>-<NUM> and the device <NUM>-<NUM> can acquire the IP address <NUM>-<NUM> of the device <NUM>-<NUM>.

In addition, the device <NUM>-<NUM> may transmit (broadcast) the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> associated with the public key <NUM>-<NUM>. It is assumed that the devices <NUM>-<NUM> and <NUM>-<NUM> can receive the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>. Then, the devices <NUM>-<NUM> and <NUM>-<NUM> determine whether or not the digital certificate <NUM>-<NUM> is valid. If it is determined that the digital certificate <NUM>-<NUM> is valid, the devices <NUM>-<NUM> and <NUM>-<NUM> determine the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the associated public key <NUM>-<NUM> and register these in the connection tables <NUM>-<NUM> and <NUM>-<NUM>, respectively. By such processing, the device <NUM>-<NUM> and the device <NUM>-<NUM> can acquire the IP address <NUM>-<NUM> of the device <NUM>-<NUM>.

<FIG> is a sequence chart showing a processing procedure relevant to IP address notification in the network system <NUM> according to the present embodiment. <FIG> shows processing procedures in the three devices <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> so as to correspond to <FIG> and <FIG>.

The device <NUM>-<NUM> transmits (broadcasts) the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> associated with the public key <NUM>-<NUM> (sequence SQ10).

Upon receiving the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>, the device <NUM>-<NUM> determines the validity of the digital certificate <NUM>-<NUM> (sequence SQ11). When it is determined that the digital certificate <NUM>-<NUM> is valid, the device <NUM>-<NUM> determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the public key <NUM>-<NUM> (sequence SQ12), and registers the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> in the connection table <NUM>-<NUM> (sequence SQ13).

Similarly, upon receiving the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>, the device <NUM>-<NUM> determines the validity of the digital certificate <NUM>-<NUM> (sequence SQ14). When it is determined that the digital certificate <NUM>-<NUM> is valid, the device <NUM>-<NUM> determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the public key <NUM>-<NUM> (sequence SQ15), and registers the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> in the connection table <NUM>-<NUM> (sequence SQ16).

In addition, the device <NUM>-<NUM> transmits (broadcasts) the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> associated with the public key <NUM>-<NUM> (sequence SQ20).

Upon receiving the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>, the device <NUM>-<NUM> determines the validity of the digital certificate <NUM>-<NUM> (sequence SQ21). When it is determined that the digital certificate <NUM>-<NUM> is valid, the device <NUM>-<NUM> determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the public key <NUM>-<NUM> (sequence SQ22), and registers the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> in the connection table <NUM>-<NUM> (sequence SQ23).

Similarly, upon receiving the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>, the device <NUM>-<NUM> determines the validity of the digital certificate <NUM>-<NUM> (sequence SQ24). When it is determined that the digital certificate <NUM>-<NUM> is valid, the device <NUM>-<NUM> determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the public key <NUM>-<NUM> (sequence SQ25), and registers the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> in the connection table <NUM>-<NUM> (sequence SQ26).

In addition, the device <NUM>-<NUM> transmits (broadcasts) the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> associated with the public key <NUM>-<NUM> (sequence SQ30).

Upon receiving the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>, the device <NUM>-<NUM> determines the validity of the digital certificate <NUM>-<NUM> (sequence SQ31). When it is determined that the digital certificate <NUM>-<NUM> is valid, the device <NUM>-<NUM> determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the public key <NUM>-<NUM> (sequence SQ32), and registers the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> in the connection table <NUM>-<NUM> (sequence SQ33).

Similarly, upon receiving the public key <NUM>-<NUM> and the digital certificate <NUM>-<NUM> transmitted from the device <NUM>-<NUM>, the device <NUM>-<NUM> determines the validity of the digital certificate <NUM>-<NUM> (sequence SQ34). When it is determined that the digital certificate <NUM>-<NUM> is valid, the device <NUM>-<NUM> determines the IP address <NUM>-<NUM> of the device <NUM>-<NUM> based on the public key <NUM>-<NUM> (sequence SQ35), and registers the determined IP address <NUM>-<NUM> of the device <NUM>-<NUM> in the connection table <NUM>-<NUM> (sequence SQ36).

In addition, the processes of sequences SQ10 to SQ16, the processes of sequences SQ20 to SQ26, and the processes of sequences SQ30 to SQ36 can be executed in any order or in parallel.

Thus, when the public key <NUM> and the digital certificate <NUM> associated with the public key <NUM> are received from another device, each device <NUM> determines the validity of the digital certificate <NUM> (sequences SQ11, SQ14, SQ21, SQ24, SQ31, and SQ34). Then, when it is determined that the digital certificate <NUM> is valid, each device <NUM> determines the IP address of another device based on the hash value calculated from the public key <NUM> according to the hash function (sequences SQ12, SQ15, SQ22, SQ25, SQ32, and SQ35).

As described above, in the network system <NUM> according to the present embodiment, on the condition that the digital certificate <NUM> transmitted from another device <NUM> is determined to be valid, the IP address <NUM> of another device <NUM> is determined based on the public key <NUM> associated with the digital certificate <NUM>. Since the IP address <NUM> is determined based on the public key <NUM> on the condition that the digital certificate <NUM> associated with the public key <NUM> is valid, the validity of the public key <NUM> and the validity of the IP address <NUM> can be guaranteed. Therefore, it is possible to realize reliable data communication between the devices <NUM>.

In addition, in the network system <NUM> according to the present embodiment, since the IP address of each device <NUM> can be known based on the public key <NUM> broadcast from each device <NUM>, the devices <NUM> can be directly connected to each other even if there is no server that manages IP addresses. In particular, even if there is no virtual private network (VPN) server or the like, it is possible to realize communication in which confidentiality is ensured between the devices <NUM>, so that the cost and power consumption for maintaining the VPN server can be reduced.

Next, processing relevant to data communication between the devices <NUM> will be described. In the network system <NUM> according to the present embodiment, each device <NUM> has a routing function and a data transmission function. Due to such functions, it is possible to realize a network capable of independently performing data communication.

In addition, in the network system <NUM> according to the present embodiment, data to be data-communicated (typically, a packet or a frame) is encrypted by using an encryption key set for each session. Therefore, the confidentiality of data communication can be guaranteed.

First, an outline of data communication in the network system <NUM> according to the present embodiment will be described. In the following description, as a typical example, it is assumed that data is transmitted in the form of a "packet".

<FIG> is a diagram for describing the outline of data communication in the network system <NUM> according to the present embodiment. <FIG> describes, as an example, a data transmission method in a network including the three devices <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>.

In <FIG>, as an example, direct communication is possible between the device <NUM>-<NUM> and the device <NUM>-<NUM>, and direct communication is possible between the device <NUM>-<NUM> and the device <NUM>-<NUM>. However, it is assumed that direct communication is not possible between the device <NUM>-<NUM> and the device <NUM>-<NUM>. Here, the state in which direct communication is possible typically means a connection state in which the nodes are present within one hop. A process of transmitting a packet from the device <NUM>-<NUM> to the device <NUM>-<NUM> in such a connection state will be described.

In the network system <NUM> according to the present embodiment, a two-stage session is established. More specifically, the two-stage session includes an adjacent node session <NUM>, which is a first-stage session, an end-to-end session <NUM>, which is a second-stage session.

The adjacent node session <NUM> is a session established between the devices <NUM> between which direct communication is possible. In the example shown in <FIG>, the adjacent node session <NUM> is established between the device <NUM>-<NUM> and the device <NUM>-<NUM> and between the device <NUM>-<NUM> and the device <NUM>-<NUM>. On the other hand, the end-to-end session <NUM> is a session established between the transmission source device <NUM> and the destination device <NUM>.

In each of the adjacent node session <NUM> and the end-to-end session <NUM>, each packet is encrypted. Typically, encryption keys used between the nodes are exchanged or shared during the process of establishing each session. As a result, in the end-to-end session <NUM>, an encrypted packet <NUM> obtained by encrypting a packet to be transmitted (hereinafter, also referred to as a "transmission packet <NUM>") based on the encryption key exchanged or shared between the device <NUM>-<NUM> and the device <NUM>-<NUM> is exchanged. The transmission packet <NUM> includes a data body portion 20D and a header portion <NUM> including information, such as a destination. The encrypted packet <NUM> includes an encryption result of the entire transmission packet <NUM> as a data body portion 22D, and further includes a header portion <NUM> including information, such as a destination. By adopting such a data structure, it is possible to realize packet transmission to the destination device while maintaining the confidentiality of the transmission packet <NUM> included in the data body portion 22D.

In the adjacent node session <NUM>, an encrypted packet <NUM> obtained by further encrypting the encrypted packet <NUM> based on another encryption key exchanged or shared between the device <NUM>-<NUM> and the device <NUM>-<NUM> is exchanged. In addition, an encrypted packet <NUM> obtained by further encrypting the encrypted packet <NUM> based on still another encryption key exchanged or shared between the device <NUM>-<NUM> and the device <NUM>-<NUM> is exchanged.

The encrypted packet <NUM> includes an encryption result of the entire encrypted packet <NUM> as a data body portion 24D, and further includes a header portion <NUM> including information, such as a destination. Similarly, the encrypted packet <NUM> includes an encryption result of the entire encrypted packet <NUM> as a data body portion 26D, and further includes a header portion <NUM> including information, such as a destination.

In addition, in the device <NUM>-<NUM>, the encrypted packet <NUM> is once decrypted into the encrypted packet <NUM> and then encrypted again to generate the encrypted packet <NUM>. Even in this case, since the device <NUM>-<NUM> cannot decrypt the encrypted packet <NUM> generated in the end-to-end session <NUM>, the confidentiality of the data communication is ensured.

In the data transmission method shown in <FIG>, the device <NUM>-<NUM> generates the encrypted packet <NUM> by encrypting the transmission packet <NUM> addressed to the device <NUM>-<NUM> with an encryption key associated with the device <NUM>-<NUM>. Then, the device <NUM>-<NUM> determines a device (device <NUM>-<NUM> in the example shown in <FIG>) to be a transmission destination of the encrypted packet <NUM>, generates the encrypted packet <NUM> by encrypting the encrypted packet <NUM> with an encryption key associated with the determined device, and transmits the encrypted packet <NUM> to the determined device.

The device <NUM>-<NUM> that has received the encrypted packet <NUM> decrypts the encrypted packet <NUM> into the encrypted packet <NUM>, and determines whether or not the decrypted encrypted packet <NUM> is addressed to the device itself. Then, if the decrypted encrypted packet <NUM> is not addressed to the device itself, the device <NUM>-<NUM> executes the same processing as that of the device <NUM>-<NUM> transmitting the encrypted packet <NUM> to the device <NUM>-<NUM>. That is, the device <NUM>-<NUM> determines a device (in this case, the device <NUM>-<NUM>) to be a further transmission destination of the encrypted packet <NUM>, generates the encrypted packet <NUM> by encrypting the encrypted packet <NUM> with an encryption key associated with the determined device, and transmits the encrypted packet <NUM> to the determined device.

On the other hand, if the decrypted encrypted packet <NUM> is addressed to the device itself (in the example shown in <FIG>, when the encrypted packet <NUM> reaches the device <NUM>-<NUM>), the encrypted packet <NUM> is decrypted into the transmission packet <NUM>.

<FIG> is a schematic diagram showing a functional configuration relevant to data transmission in the device <NUM> according to the present embodiment. Referring to <FIG>, the device <NUM> includes a router engine <NUM>, a transmission engine <NUM>, and an interface <NUM> as a configuration for realizing data communication as shown in <FIG>. These components are provided by the control unit <NUM>.

The router engine <NUM> is mainly responsible for the end-to-end session <NUM>, and the transmission engine <NUM> is mainly responsible for the adjacent node session <NUM>.

When a transmission packet is given by various applications <NUM>, the router engine <NUM> encrypts the transmission packet using the encryption key exchanged or exchanged between the device itself and the destination device <NUM>, and transmits an encrypted packet including the encrypted transmission packet to the destination device <NUM>.

In addition, when the encrypted packet is given from the transmission engine <NUM>, the router engine <NUM> determines whether or not the encrypted packet is addressed to the device itself. In the case of an encrypted packet addressed to the device itself, the router engine <NUM> decrypts the transmission packet included in the encrypted packet as a received packet (hereinafter, also referred to as a "reception packet") using the encryption key exchanged or shared between the device itself and the transmission source device <NUM>, and outputs the decrypted transmission packet to the various applications <NUM>. On the other hand, in the case of an encrypted packet addressed to another device, the router engine <NUM> returns the encrypted packet to the transmission engine <NUM>.

More specifically, the router engine <NUM> includes a session management engine <NUM>, an encryption/decryption engine <NUM>, an end-to-end session management table <NUM>, and a search engine <NUM>.

The session management engine <NUM> performs session establishment, packet transmission processing, packet retransmission processing, and the like between the device itself and the destination device <NUM>. In addition, the session management engine <NUM> determines the transmission destination of the transmission packet according to the destination of the given transmission packet. The encryption/decryption engine <NUM> encrypts and decrypts the data. The end-to-end session management table <NUM> holds the IP address, encryption key, connection type, and the like of the device <NUM> for which the session management engine <NUM> can establish a session. The search engine <NUM> searches for the device <NUM> having the specified IP address on the network and its route when the IP address specified by the various applications <NUM> is not registered in the end-to-end session management table <NUM>.

When a packet is given from the interface <NUM>, the transmission engine <NUM> decrypts the packet using the encryption key exchanged or exchanged between the device itself and the device <NUM> to which the packet is directly data-communicated, and then outputs the decrypted packet to the router engine <NUM>. In addition, when a packet is given from the router engine <NUM>, the transmission engine <NUM> encrypts the packet using the encryption key exchanged or exchanged between the device itself and the device <NUM> to which the packet is directly data-communicated, and then transmits the encrypted packet to the destination device <NUM>.

More specifically, the transmission engine <NUM> includes a session management engine <NUM>, an encryption/decryption engine <NUM>, and an adjacent node session management table <NUM>.

The session management engine <NUM> performs session establishment, packet transmission processing, packet retransmission processing, and the like between the device itself and the destination device <NUM> to which the packet is directly data-communicated. The encryption/decryption engine <NUM> encrypts and decrypts the data. The adjacent node session management table <NUM> holds the IP address, encryption key, connection type, and the like of the device <NUM> for which the session management engine <NUM> can establish a session.

The interface <NUM> is a module that logically processes data physically exchanged by the network interface <NUM>. The interface <NUM> logically connects the session management engine <NUM> and a data communication path prepared for each protocol (for example, a TCP (Transmission Control Protocol) <NUM>, a UDP (User Datagram Protocol) <NUM>, and other protocols <NUM>).

<FIG> is a schematic diagram showing an operation example at the time of data transmission in the device <NUM> according to the present embodiment. <FIG> shows processing when the device <NUM> receives a packet addressed to the device itself (reception packet addressed to the device itself) and processing when the device <NUM> receives a packet addressed to another device (reception packet addressed to another device).

When a packet arrives at the device <NUM>, the packet is transmitted to the transmission engine <NUM> and decrypted using the encryption key exchanged or exchanged between the device <NUM> and the device <NUM> to which the packet is directly data-communicated. When the packet is addressed to the device itself, the decrypted packet is transmitted to the router engine <NUM> and further decrypted using the encryption key exchanged or exchanged between the device itself and the transmission source device <NUM>, and output to the various applications <NUM>. On the other hand, when the packet is addressed to another device, the decrypted packet is returned to the transmission engine <NUM> and encrypted using the encryption key exchanged or exchanged between the device itself and the next destination device, and then transmitted.

<FIG> is a flowchart showing a processing procedure when a transmission packet is generated in the device <NUM> according to the present embodiment. <FIG> is a flowchart showing a processing procedure when a packet is received from another device in the device <NUM> according to the present embodiment. <FIG> and <FIG> show a procedure of a communication processing method in the device <NUM> connected to the network. Each step shown in <FIG> and <FIG> is executed by the control unit <NUM> (see <FIG>) of the device <NUM> (typically realized by the cooperation of a processor and a memory).

Referring to <FIG>, it is determined whether or not the transmission packet <NUM> addressed to another device has been given by the various applications <NUM> or the like (step S100). If the transmission packet <NUM> addressed to another device has not been given (NO in step S100), the processing of step S100 is repeated.

On the other hand, if the transmission packet <NUM> addressed to another device has been given (YES in step S100), the processing of step S102 and steps subsequent thereto is executed. That is, the processing of step S102 and steps subsequent thereto shown in <FIG> is executed when a packet addressed to another device is given.

In step S102, the device <NUM> (session management engine <NUM> in <FIG>) determines whether or not a session corresponding to the IP address of the destination device is registered (step S102). Typically, the IP address for each session that can be established is registered in the end-to-end session management table <NUM> shown in <FIG>, so that the registered content is referred to.

If the session corresponding to the IP address of the destination device is registered (YES in step S102), the processing of step S114 described later is executed.

If the session corresponding to the IP address of the destination device is not registered (NO in step S102), the device <NUM> (search engine <NUM> in <FIG>) first stores the transmission packet <NUM> in a queue (step S104), and starts searching for a destination device and a route to the destination device for each data communication path (step S106). Then, the device <NUM> determines whether or not the search is successful (step S108). If the search is successful (YES in step S108), the processing of step S114 described later is executed. In this manner, when a packet addressed to another device is given, the device <NUM> searches for the IP address of the destination device.

On the other hand, if the search is not successful (NO in step S108), the device <NUM> determines whether or not a predetermined time limit (timeout time) has passed from the storage of the transmission packet <NUM> in the queue (step S110). If the predetermined time limit has not passed from the storage of the transmission packet <NUM> in the queue (NO in step S110), the processing of step S108 and steps subsequent thereto is repeated.

On the other hand, if the predetermined time limit has passed from the storage of the transmission packet <NUM> in the queue (YES in step S110), the device <NUM> discards the transmission packet <NUM> stored in the queue (step S112). Then, the process ends.

In step S114, the device <NUM> (session management engine <NUM> in <FIG>) determines whether or not the end-to-end session <NUM> has been established between the device itself and the destination device (step S114).

If no end-to-end session <NUM> has been established between the device itself and the destination device (NO in step S114), the device <NUM> establishes the end-to-end session <NUM> between the device itself and the destination device (step S116). When establishing the end-to-end session <NUM>, the device <NUM> exchanges or shares the encryption key associated with the end-to-end session <NUM> with the destination device. In this manner, the device <NUM> establishes the end-to-end session <NUM> between the device itself and another device and determines the encryption key associated with the end-to-end session <NUM> (that is, another device).

On the other hand, if the end-to-end session <NUM> has already been established between the device itself and the destination device (YES in step S114), the processing of step S116 is skipped.

Then, the device <NUM> (encryption/decryption engine <NUM>) generates the encrypted packet <NUM> by encrypting the transmission packet <NUM> with the encryption key associated with the end-to-end session <NUM> established between the device itself and the destination device (step S118). That is, the device <NUM> generates the encrypted packet <NUM> by performing encryption with the encryption key associated with another destination device.

Then, the device <NUM> (session management engine <NUM>) determines a device to be a transmission destination of the encrypted packet <NUM> (step S120). Typically, the IP address for each session that can be established is registered in the adjacent node session management table <NUM> shown in <FIG>, so that the registered content is referred to. In addition, the device <NUM> (encryption/decryption engine <NUM>) determines whether or not the adjacent node session <NUM> has been established between the device itself and the determined transmission destination device (step S122).

If no adjacent node session <NUM> has been established between the device itself and the determined transmission destination device (NO in step S122), the device <NUM> establishes the adjacent node session <NUM> between the device itself and the determined transmission destination device (step S124). When establishing the adjacent node session <NUM>, the device <NUM> exchanges or shares the encryption key associated with the adjacent node session <NUM> with the target device. In this manner, the device <NUM> establishes the adjacent node session <NUM> between the device itself and still another device to be a transmission destination of the encrypted packet <NUM>, and determines the encryption key associated with the adjacent node session <NUM> (that is, the device to be a transmission destination).

On the other hand, if the adjacent node session <NUM> has already been established between the device itself and the determined transmission destination device (YES in step S122), the processing of step S124 is skipped.

Then, the device <NUM> (encryption/decryption engine <NUM>) generates the encrypted packet <NUM> by encrypting the encrypted packet <NUM> with the encryption key associated with the adjacent node session <NUM> established between the device itself and the determined transmission destination device (step S126). That is, the device <NUM> generates the encrypted packet <NUM> by encrypting the encrypted packet <NUM> with the encryption key associated with the determined transmission destination device.

Finally, the device <NUM> (session management engine <NUM>) transmits the generated encrypted packet <NUM> to the determined transmission destination device (step S128). As described above, the process when the transmission packet <NUM> is given ends.

Referring to <FIG>, it is determined whether or not the encrypted packet <NUM> has been received from another device (step S200). If the encrypted packet <NUM> has not been received from another device (NO in step S200), the processing of step S200 is repeated.

On the other hand, if the encrypted packet <NUM> has been received from another device (YES in step S200), the processing of step S202 and steps subsequent thereto is executed. That is, the processing of step S202 and steps subsequent thereto shown in <FIG> is executed when the encrypted packet <NUM> is received from another device.

The device <NUM> (encryption/decryption engine <NUM>) decrypts the encrypted packet <NUM> into the encrypted packet <NUM> with the encryption key associated with the adjacent node session <NUM> between the device itself and another device (step S202). Then, the device <NUM> (session management engine <NUM>) determines whether or not the decrypted encrypted packet <NUM> is addressed to the device itself (step S204).

If the decrypted encrypted packet <NUM> is not addressed to the device itself (NO in step S204), the device <NUM> (session management engine <NUM>) determines a device to be a further transmission destination of the encrypted packet <NUM> (step S210). Typically, the adjacent node session management table <NUM> shown in <FIG> is referred to. In addition, the device <NUM> (encryption/decryption engine <NUM>) determines whether or not the adjacent node session <NUM> has been established between the device itself and the determined transmission destination device (step S212). If no adjacent node session <NUM> has been established between the device itself and the determined transmission destination device (NO in step S212), the device <NUM> establishes the adjacent node session <NUM> between the device itself and the determined transmission destination device (step S214). In addition, if the adjacent node session <NUM> has already been established between the device itself and the determined transmission destination device (YES in step S212), the processing of step S214 is skipped.

Then, the device <NUM> (encryption/decryption engine <NUM>) generates the encrypted packet <NUM> by encrypting the encrypted packet <NUM> with the encryption key associated with the adjacent node session <NUM> established between the device itself and the determined transmission destination device (step S216). Finally, the device <NUM> (session management engine <NUM>) transmits the generated encrypted packet <NUM> to the determined transmission destination device (step S218).

Thus, if the decrypted encrypted packet <NUM> is not addressed to the device itself (NO in step S204), the device <NUM> determines still another device to be a transmission destination of the encrypted packet <NUM>, generates the encrypted packet <NUM> with the encryption key associated with the determined device, and transmits the generated encrypted packet <NUM>. As described above, the process when the encrypted packet <NUM> is received from another device ends.

On the other hand, if the decrypted encrypted packet <NUM> is addressed to the device itself (YES in step S204), the device <NUM> (encryption/decryption engine <NUM>) decrypts the encrypted packet <NUM> into the transmission packet <NUM> with the encryption key associated with the end-to-end session <NUM> established between the device itself and the transmission source device (step S206). Then, the device <NUM> outputs the decrypted transmission packet <NUM> to the various applications <NUM> as a reception packet (step S208). As described above, the process when the encrypted packet <NUM> is received from another device ends.

As described above, in the network system <NUM> according to the present embodiment, when transmitting a packet from the transmission source device to the destination device, the encrypted packet <NUM> is generated by using the encryption key associated with the end-to-end session <NUM> between the transmission source device and the destination device. The encrypted packet <NUM> may be sequentially transmitted by one or more devices. However, even in such a process, since the encrypted packet <NUM> is sequentially transmitted in the encrypted state, the confidentiality of the packet can be maintained until the packet reaches the destination device.

In addition, in the network system <NUM> according to the present embodiment, even between devices between which the encrypted packet <NUM> is sequentially transmitted, the encrypted packet <NUM> is further encrypted by using the encryption key associated with the adjacent node session <NUM> between the devices. Therefore, even in the data communication process in which the encrypted packet <NUM> is sequentially transmitted, the confidentiality can be further improved.

According to the network system <NUM> according to the present embodiment, it is possible to provide a solution through which each device <NUM> can independently realize data communication in a network in which a large number of devices are present.

Claim 1:
A data transmission method in a network (<NUM>) to which a plurality of devices (<NUM>) are connected, the method comprising:
a step in which a first device (<NUM>-<NUM>) generates (S118) a first encrypted packet (<NUM>) by encrypting an entire packet (<NUM>) addressed to a second device (<NUM>-<NUM>) with a first encryption key associated with the second device;
a step of determining (S120) a device to be a transmission destination of the first encrypted packet, generating (S126) a second encrypted packet (<NUM>) by encrypting the entire first encrypted packet with a second encryption key associated with the determined device, and transmitting (S128) the second encrypted packet to the determined device;
a step in which a device that receives (S200) the second encrypted packet decrypts (S202) the second encrypted packet into the first encrypted packet and determines (S204) whether or not the decrypted first encrypted packet is addressed to the device itself;
a step of determining (S210) another device and executing (S212-S218) the transmission step if the decrypted first encrypted packet is not addressed to the device itself in the determination regarding whether or not the decrypted first encrypted packet is addressed to the device itself; and
a step of further decrypting (S206) the first encrypted packet into the entire packet if the decrypted first encrypted packet is addressed to the device itself in the determination regarding whether or not the decrypted first encrypted packet is addressed to the device itself, wherein the entire packet is output to an application (<NUM>) on the second device.