WO2021107389A1

WO2021107389A1 - Network system and message security method thereof

Info

Publication number: WO2021107389A1
Application number: PCT/KR2020/013707
Authority: WO
Inventors: 권태경; 곽명철; 이현우; 이현민; 임정환; 신유정
Original assignee: 서울대학교 산학협력단
Priority date: 2019-11-29
Filing date: 2020-10-08
Publication date: 2021-06-03
Also published as: KR20210067208A; KR102265611B1

Abstract

A network system according to an embodiment of the present invention comprises: a producer terminal for generating a topic; a subscriber terminal for subscribing to the topic; and a broker terminal which communicates with the subscriber terminal and the producer terminal, decrypts an encrypted topic by using a second topic encryption key shared with the producer terminal so as to identify a subscriber terminal which is subscribing to the decrypted topic when a message including the encrypted topic and an encrypted payload is received from the producer terminal, and encrypts the topic by using a first topic encryption key shared with the subscriber terminal so as to transmit the encrypted topic together with the encrypted payload to the subscriber terminal.

Description

Network system and its message security method

Embodiments disclosed herein relate to a network system and its message security method. More particularly, it relates to a network system capable of increasing message security so as to prevent leakage or manipulation of a message by a broker relaying between a producer and a subscriber, and a message security method thereof.

This study was carried out as a result of the research results of the broadcasting and communication industry technology development project of the Ministry of Science and ICT and the Information and Communication Planning and Evaluation Institute (IITP-2016-0-00160-005).

The Message Queuing Telemetry Transport (MQTT) protocol is used as a lightweight subscription/production (Pub(Publish)/Sub(Subsribe)) message protocol. The MQTT protocol was created for use in Machine to Machine (M2M) and Internet of Things (IoT) environments. The MQTT protocol is a protocol designed to be used in a low-power, low-bandwidth environment.

This MQTT protocol operates as a basic principle of publishing messages and subscribing to topics of interest. To this end, in a network using the MQTT protocol, when a subscriber terminal subscribes to a topic of interest, the producer terminal may generate a message related to the topic and deliver it to the subscriber terminal.

In relation to this, in Korea Patent Application Laid-Open No. 10-2018-0105917, a prior art document, a wearable information service including a wearable device that generates wearable data, a wearable broker that receives and distributes wearable data over a network, and a user terminal that receives wearable data Describe the system.

In a system using MQTT as in the prior art literature, situations such as data leakage or manipulation by a broker located in the middle of data transmission are not considered. For this reason, when exchanging sensitive information such as health care information between the producer terminal and the subscriber terminal, the producer terminal or the subscriber terminal has a problem that has to take the risk of data leakage or manipulation by a broker or the like.

Therefore, in recent years, there is a need for an apparatus and method for solving these problems.

On the other hand, the above-mentioned background art is technical information that the inventor possessed for the derivation of the present invention or acquired in the process of derivation of the present invention, and it cannot be said that it is necessarily known technology disclosed to the general public before the filing of the present invention. .

Embodiments disclosed herein have an object to provide a network system capable of preventing message leakage or manipulation by a broker relaying between producers and subscribers and a message security method thereof.

In order to solve the above technical problem, the embodiments disclosed in the present specification, when receiving an encrypted topic and a payload from a producer terminal that generates a topic, decrypts the topic using an encryption key shared with the producer terminal. Checks the subscriber terminal subscribing to , encrypts the topic using an encryption key shared with the subscriber terminal, and then transmits it to the subscriber terminal together with the encrypted payload.

According to the above-described technical solution, it is possible to provide a network system capable of preventing message leakage or manipulation by a broker that relays between producers and subscribers, and a message security method thereof.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art from the following description. will be.

1 is a diagram illustrating a network system according to an embodiment.

2 is a flowchart illustrating an operation of a network system according to an embodiment.

3 is a flowchart illustrating an operation of a subscriber terminal according to an embodiment.

4 is a flowchart illustrating an operation of a broker terminal according to an embodiment.

5 to 6 are flowcharts illustrating an operation of a producer terminal according to an embodiment.

As a technical means for achieving the above technical problem, according to an embodiment, the network system communicates with a producer terminal generating a topic, a subscriber terminal subscribing to the topic, and the subscriber terminal and the producer terminal, When a message including an encrypted topic and an encrypted payload is received from the producer terminal, the encrypted topic is decrypted using a second topic encryption key shared with the producer terminal to check the subscriber terminal subscribing to the decrypted topic and a broker terminal for encrypting the topic using a first topic encryption key shared with the subscriber terminal and transmitting the encrypted payload to the subscriber terminal.

According to another embodiment, a message security method performed in a network system includes, by a broker terminal, establishing a session with a subscriber terminal subscribing to a topic, the broker terminal establishing a session with a producer terminal generating the topic Step, when the broker terminal receives a message including an encrypted topic and an encrypted payload from the producer terminal, decrypting the encrypted topic using a second topic encryption key shared with the producer terminal; and the broker terminal identifies a subscriber terminal subscribing to the decrypted topic, encrypts the topic using a first topic encryption key shared with the subscriber terminal, and transmits it to the subscriber terminal together with the encrypted payload including the steps of

Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. The embodiments described below may be modified and implemented in various different forms. In order to more clearly describe the characteristics of the embodiments, detailed descriptions of matters widely known to those of ordinary skill in the art to which the following embodiments belong are omitted. In addition, in the drawings, parts irrelevant to the description of the embodiments are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a component is said to be "connected" with another component, it includes not only a case of 'directly connected' but also a case of 'connected with another component interposed therebetween'. In addition, when a component "includes" a component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

The network system refers to a system that communicates using a producer terminal and a subscriber terminal, that is, a producer and subscriber model. Such a network system can operate based on a publish subscription-based message protocol, for example, a lightweight subscription/production (Pub(Publish)/Sub(Subsribe)) message protocol with message queuing telemetry transport (MQTT). : Message Queuing Telemetry Transport) protocol can be applied. Such a network system may include all systems capable of utilizing a proxy, such as a smart factory or a smart home.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a network system according to an embodiment.

As shown in FIG. 1 , the network system 100 may include a subscriber terminal 110 , a broker terminal 120 , a producer terminal 130 , and a master terminal 140 .

The subscriber terminal 110 may be connected to the broker terminal in order to subscribe to the topic generated by the producer terminal 130, and the message generated by the producer terminal 130 may be received through the broker terminal 120 relaying the message. have. Here, the message may include a topic and a payload corresponding to the topic, and each is encrypted.

Meanwhile, the broker terminal 120 may communicate with the subscriber terminal 110 and the producer terminal 130 . The broker terminal 120 may establish a session with each of the subscriber terminal 110 and the producer terminal 130 for communication. Through this, when the broker terminal 120 receives the payload related to the topic subscribed to by the subscriber terminal 110 from the producer terminal 130, the broker terminal 120 may provide the payload related to the topic to the subscriber terminal.

The broker terminal 120 may generate a first topic encryption key 20 when establishing a session with the subscriber terminal 110, and may generate a second topic encryption key 30 when establishing a session with the producer terminal 130 have. At this time, the subscriber terminal 110 may also generate the first topic encryption key 20 when the session is established, and the producer terminal 130 may also generate the second topic encryption key 30 when the session is established.

The producer terminal 130 may generate a payload encryption key 40 for encrypting the payload. In this case, when the producer terminal 130 manages and uses one group key in the same layer, it may receive the group key from the master terminal 140 . The producer terminal 130 may set the group key as the payload encryption key 40 or generate the payload encryption key 40 using the group key. The producer terminal 130 may encrypt the payload using the payload encryption key, and may encrypt the topic using the second topic encryption key 30 . Through this, the producer terminal 130 may generate a message including an encrypted topic and an encrypted payload. The producer terminal 130 may transmit a message to the broker terminal.

On the other hand, the master terminal 140 may manage the group key when the group key of the same layer is unified and managed. The master terminal 140 may not be included in the network system 10 when the group key is not unified and managed, and individual payload encryption keys are generated in each of the producer terminals. The master terminal 140 may provide the group key to the producer terminal 130 by establishing a session with the broker terminal 120, and if direct communication with the producer terminal 130 is possible, do not go through the broker terminal 120 It is also possible to directly provide the group key to the producer terminal 130 without the need to.

The broker terminal 120 may receive a message from the producer terminal 130 . The broker terminal 120 may classify the encrypted topic and the encrypted payload in the message, and may decrypt the encrypted topic with the second topic encryption key 30 . The broker terminal 120 may check the decrypted topic and the subscriber terminal subscribing to the corresponding topic. The broker terminal 120 may encrypt the decrypted topic with the first topic encryption key 20 and deliver the topic together with the encrypted payload to the subscriber terminal 110 subscribing to the topic.

The subscriber terminal 110 may decrypt the received message using the encryption key, decrypt the encrypted topic using the first topic encryption key 20, and use the encrypted payload as the payload encryption key ( 40) can be used for decryption. The subscriber terminal 110 receives the payload encryption key 40 encrypted with the one-time encryption key generated by exchanging the public key with the producer terminal 130, and decrypts it with the one-time encryption key to obtain it.

As such, when the broker terminal 120 checks the encrypted topic among the encrypted topic and the encrypted payload in the message transmitted between the subscriber terminal 110 and the producer terminal 130, the message is transmitted without checking the message content. Because it can be delivered, the message transmitted between the subscriber terminal 110 and the producer terminal 130 can be encrypted and delivered so that the broker cannot see the message content.

Through this, the subscriber terminal 110 and the broker terminal 120 or the broker terminal 120 and the producer terminal 130 to share the topic encryption key (20, 30) with each other, the subscriber terminal 110 and the producer terminal ( 130) can be used by sharing the payload encryption key 40 for encrypting the actual data, that is, the payload.

Through this, the topic can be confirmed and transmitted in the broker terminal 120 in which the session is established, so that message security is possible. Moreover, since the payload transmitted between the subscriber terminal 110 and the producer terminal 130 cannot be checked by the broker terminal 120, the payload cannot be leaked or manipulated by the broker terminal 120, so message security can increase

As shown in FIG. 2 , the network system includes a subscriber terminal 110 , a broker terminal 120 , and a producer terminal 130 .

The subscriber terminal 110 may request session establishment from the broker terminal 120 (S211). In this case, the subscriber terminal may generate a public key, for example, a Diffe-Hellman (DH) public key. The subscriber terminal 110 may transmit a public key (DH public key), a signature, and a certificate together when requesting session establishment.

The broker terminal 120 may respond to the request for session establishment to the subscriber terminal 110 (S213). The broker terminal 120 may store the public key (DH public key), signature, and certificate of the subscriber terminal 110 received according to the session establishment request. When the broker terminal responds to session establishment, the broker terminal 120 may provide its own certificate to the subscriber terminal.

In this way, the subscriber terminal 110 may perform a handshake with the broker terminal 120 to subscribe to a specific topic.

Through this, the subscriber terminal 110 and the broker terminal 120 may establish a session (S215). The subscriber terminal 110 and the broker terminal 120 may establish, for example, a Transport Layer Security (TLS) session. The subscriber terminal 110 and the broker terminal 120 may generate a session key when establishing a session. In this case, the generated session key may be used as the first topic encryption key 20 for encrypting or decrypting a topic in each of the broker terminal 120 and the subscriber terminal 110 .

The subscriber terminal 110 may make a connection request for subscription to a specific topic to the broker terminal 120 (S217). In addition, the broker terminal 120 may make a connection response to the connection request of the subscriber terminal 110 (S219).

The subscriber terminal 110 may request a subscription to a specific topic desired to be subscribed to to the broker terminal 120 (S221). The broker terminal 120 may make a subscription response to the subscription request to the subscriber terminal 110 (S223). In this way, the subscriber terminal 110 makes a subscription request for a specific topic between the broker terminals 120 , and when receiving a subscription response corresponding to the subscription request, the subscriber terminal 110 sends a message message for the specific topic desired by the subscriber terminal 110 . Ready to receive.

On the other hand, if there is a message to be transmitted on the topic that the producer terminal 130 generates, it may request the broker terminal 120 to establish a session (S225). The producer terminal 130 may generate the payload encryption key 40 while generating the topic, and may initialize the payload sequence number to 0. Here, the payload sequence number is information counted when a message is transmitted, and may be used to verify the payload in the subscriber terminal 110 and to check whether the message is manipulated or the order is changed.

The broker terminal 120 may respond to the request for session establishment to the producer terminal 130 (S227). In this case, the broker terminal 120 may transmit the public key (DH public key), the signature, and the certificate received from the subscriber terminal to the producer terminal 130 .

In this way, the producer terminal 130 may perform a handshake with the broker terminal 120 in order to transmit a message related to the topic.

Through this, the producer terminal 130 and the broker terminal 120 may establish a session (S229). The producer terminal 130 and the broker terminal 120 may establish, for example, a Transport Layer Security (TLS) session. The producer terminal 130 and the broker terminal 120 may generate a session key when establishing a session. In this case, the generated session key may be used as the second topic encryption key 30 for encrypting or decrypting the topic in each of the producer terminal 130 and the broker terminal 120 .

When the producer terminal 130 receives the certificate of the subscriber terminal 110 , the producer terminal 130 may verify the signature and determine whether to participate in the topic generated by the producer terminal 130 .

When the producer terminal 130 determines that the subscriber terminal 110 is a subscriber terminal capable of participating in the topic, the producer terminal 130 may transmit a subscriber authentication message to the broker terminal 120 to complete the subscriber authentication (S231). The broker terminal 120 may transmit the received subscriber authentication message to the subscriber terminal 110 to complete subscriber authentication (S233).

In addition, the producer terminal 130 may generate the one-time encryption key 50 with the public key (DH public key) transmitted from the subscriber terminal 110 based on the key exchange algorithm with the subscriber terminal 110 . The one-time encryption key 50 is used as an encryption key for encrypting the payload encryption key 40 and delivering it to the subscriber terminal 110, and may also be used for encryption of the payload sequence number. This, one-time encryption key 50 may be used only once for delivery of the payload encryption key 40 .

The producer terminal 130 may generate a message and transmit the generated message to the broker terminal 120 (S235). In this case, the producer terminal 130 may generate a message by encrypting the topic with the second encryption key 30 and encrypting the payload related to the topic with the payload encryption key 40 . The producer terminal 130 may transmit the payload encryption key and the payload sequence number encrypted with the one-time encryption key together using the message. Also, the producer terminal 130 may transmit the DH public key, signature, and certificate of the producer terminal 130 to the broker terminal 120 together with the message.

Thereafter, the producer terminal 130 may give a current payload sequence number to the payload when transmitting the message, encrypt the payload and the payload sequence number with the payload encryption key, and transmit it to the broker terminal 120 .

The broker terminal 120 may transmit the message of the producer terminal 130 to the subscriber terminal 110 (S237). In this case, the broker terminal 120 may classify the encrypted topic and the encrypted payload in the message of the producer terminal 130 , and decrypt it with the second topic encryption key 30 . Through this, the broker terminal 120 may use the decrypted topic to check the subscriber terminal 110 subscribing to the corresponding topic. The broker terminal 120 may encrypt the topic with the first topic encryption key 20 and transmit it to the confirmed subscriber terminal 110 together with the encrypted payload.

When the subscriber terminal 110 receives a message including the payload encryption key from the broker terminal 120, it generates a one-time encryption key 50 with the public key transmitted from the producer terminal 130 based on the key exchange algorithm, and generates The one-time encryption key 50 can decrypt the encrypted payload encryption key 40 and the encrypted payload sequence number.

The subscriber terminal 110 may decrypt the encrypted payload included in the message with the decrypted payload encryption key 40 . In addition, the subscriber terminal 110 may decrypt the topic included in the message using the first topic encryption key 20 generated when the session with the broker terminal 120 is established.

Also, the subscriber terminal 110 may decrypt the payload sequence number with the payload encryption key 40 . Such a payload sequence number may be used for data verification for confirming manipulation or order change of messages in the subscriber terminal 110 . When the verification of the message is completed, the subscriber terminal 110 may receive a message corresponding to the subscription-requested topic.

Meanwhile, the producer terminal 130 may update, ie, change, the payload encryption key 40 at predetermined intervals to enhance message security. The producer terminal 130 may generate a new payload encryption key 60 for changing the payload encryption key 40 . The producer terminal 130 activates the key update flag information in the message in order to deliver the new payload encryption key 60 to the subscriber terminal 110 (eg, change the bit value 0 -> 1, etc.), The new payload encryption key 60 may be encrypted with the existing payload encryption key 40 . At this time, if there is a payload to be transmitted, the producer terminal 130 may encrypt the payload with the new payload encryption key 60 and transmit it to the broker terminal 120 (S239).

The broker terminal 120 may transmit the message of the producer terminal 130 to the subscriber terminal 110 (S241). At this time, the broker terminal 120 may extract the encrypted topic from the message of the producer terminal 130 and decrypt it with the second topic encryption key 30, and encrypt the topic with the first topic encryption key 20 It can be transmitted to the subscriber terminal 110 together with the payload.

The subscriber terminal 110 may check that the key is updated by checking the key update flag in the message. The subscriber terminal 110 may decrypt the new payload encryption key 60 using the existing payload encryption key 40 , and decrypt the encrypted payload included in the message with the new payload encryption key 60 . can do. Also, the subscriber terminal 110 may decrypt the encrypted topic included in the encrypted message using the first topic encryption key 20 .

In this way, the producer terminal 130 and the subscriber terminal 120 may encrypt and decrypt the payload by changing the payload encryption key at predetermined intervals.

As shown in FIG. 3 , the subscriber terminal 110 may establish a session by performing a handshake with the broker terminal 120 ( S310 ). The subscriber terminal 110 may use the session key generated during session establishment as the first topic encryption key for decrypting the topic of the received message.

The subscriber terminal 110 may transmit a subscription request for a topic for which message reception is desired to the broker terminal 120 (S320).

The subscriber terminal 110 may determine whether a message has been received from the broker terminal 120 (S330).

As a result of the determination in step S330, if the message is not received, the subscriber terminal 110 may proceed to step S340 and wait for a predetermined time to receive the message.

As a result of the determination in step S330, upon receiving the message, the subscriber terminal 110 may proceed to step S340.

The subscriber terminal 110 may check the message by decrypting the message. In this case, the subscriber terminal may decrypt the encrypted topic in the message with the first topic encryption key. Also, the subscriber terminal 110 may decrypt the encrypted payload in the message with the payload encryption key.

At this time, when the subscriber terminal 110 receives the payload encryption key, it generates a one-time encryption key using the public key (DH public key) transmitted from the producer terminal 130 using a key exchange algorithm, and the encrypted pay It can be obtained by decrypting the load encryption key with a one-time encryption key.

In addition, when the subscriber terminal 110 confirms the change of the payload encryption key through the key update flag, the new payload encryption key encrypted with the existing payload encryption key may be decrypted to obtain a new payload encryption key.

As such, when the subscriber terminal 110 obtains the payload encryption key or the new payload encryption key, it may decrypt the encrypted payload.

The subscriber terminal 110 may determine whether to end the operation (S350).

As a result of the check in step S350, if the operation is not terminated, the subscriber terminal 110 may proceed to step S330 and wait for reception of the next message. However, the subscriber terminal 110 may proceed to another step as needed.

As a result of checking in step S350, when the operation ends, the subscriber terminal 110 may end the operation.

As shown in FIG. 4 , the broker terminal 120 may establish a session with the subscriber terminal 110 ( S410 ). The broker terminal 120 may use the session key generated during session establishment as a second topic encryption key for encrypting the topic of a message to be transmitted to the subscriber terminal 110 .

The broker terminal 120 may set up a subscription with the subscriber terminal 110 for a specific topic to be subscribed to in the subscriber terminal 110 (S420).

The broker terminal 120 may check whether a session establishment request exists from the producer terminal 130 (S430).

As a result of checking in step S430 , if there is no session establishment request from the producer terminal 130 , the broker terminal 120 waits for a predetermined time and then proceeds to step S430 to check whether the session establishment request exists.

As a result of checking in step S430 , if there is a session establishment request from the producer terminal 130 , the broker terminal 120 may proceed to step S440 .

The broker terminal 120 may establish a session with the producer terminal 130 (S440). The broker terminal 120 may use the session key generated during session establishment as the second topic encryption key for decrypting the topic of the message received from the producer terminal 130 .

The broker terminal 120 may determine whether a message has been received from the producer terminal 130 (S450).

As a result of the determination in step S450 , if a message is not received from the producer terminal 130 , the broker terminal 120 waits for a predetermined time and then proceeds to step S450 to determine reception of the message from the producer terminal 130 .

As a result of the determination in step S450, when a message is received from the producer terminal 130, the broker terminal 120 may proceed to step S460.

The broker terminal 120 may decrypt the encrypted topic in the message with the second topic encryption key, and encrypt the decrypted topic with the first topic encryption key (S460).

The broker terminal 120 may transmit a message including the topic encrypted with the first topic encryption key and the encrypted payload in the message to the subscriber terminal 110 (S470).

The broker terminal 120 may determine whether to end the operation (S480).

As a result of checking in step S480, if the operation is not terminated, the broker terminal 120 may proceed to step S450 and wait for reception of the next message. However, the broker terminal 120 may proceed to another step as needed.

As a result of checking in step S480, when the operation is terminated, the broker terminal 120 may end the operation.

As shown in FIG. 5 , the producer terminal 130 may establish a session ( S511 ). The producer terminal 130 may establish a session when there is a message to be transmitted for the topic.

The producer terminal 130 may check whether to use the group key (S513). These group keys may be unified and managed as one in the same layer for payload transmission. At this time, the producer terminal 130 must receive the group key from the master terminal that manages the group key, that is, the master node. For this reason, when the producer terminal 130 newly enters the network system, it can determine whether to use the group key or its own payload encryption key while generating the topic.

As a result of checking in step S513, if the group key is not used, the producer terminal 130 may proceed to step S525.

As a result of checking in step S513, if the group key is used, the producer terminal 130 proceeds to step S515. For example, the producer terminal 130 to register the topic of '/building/5thfloor/temperature' may use the /building/5thfloor key.

When using the group key, the producer terminal 130 may search for the group key to receive the group key from the master terminal (S515).

The producer terminal 130 may determine whether the group key has been received within a preset time according to the group key search (S517).

As a result of the determination in step S517, if the group key is received within a preset time, the producer terminal 130 may proceed to step S519.

The producer terminal 130 may generate a payload encryption key using the group key and proceed to step S525. For example, the producer terminal 130 may directly use the group key as the payload encryption key, but may also generate the payload encryption key using the group key.

As a result of the determination in step S517, if the group key is not received within a preset time, the producer terminal 130 may proceed to step S521. The producer terminal 130 must receive the group key from the master terminal. However, in the case of the MQTT protocol, since it is impossible for the producer terminal 130 to communicate with the master terminal in real time, a temporary payload key may be generated and used in a situation in which it is difficult to receive the group key.

The producer terminal 130 may generate a temporary payload key (S521).

The producer terminal 130 may generate a payload encryption key using the temporary payload key, and proceed to step S521 (S523). After receiving the group key, the producer terminal 130 performs the payload encryption key update operation described in steps S239 to S241 of FIG. 2 to generate the payload encryption key generated as a temporary payload key using the group key. It can be used by converting the payload encryption key.

The producer terminal 130 may check whether a subscriber authentication request has been received from the broker terminal 120 (S525).

As a result of the determination in step S525, if the subscriber is not authenticated, the producer terminal 130 may proceed to step S535.

As a result of the determination in step S525, if the subscriber is authenticated, the producer terminal 130 may proceed to step S527.

The producer terminal 130 may generate a message by encrypting the topic and the payload. The producer terminal 130 may generate a payload encryption key while generating a topic when not using the group key. In this case, the producer terminal 130 may also initialize the payload sequence number to 0. The producer terminal 130 may encrypt the topic with the topic encryption key generated when establishing a session with the broker terminal, and the payload may be encrypted with the payload encryption key.

In addition, the producer terminal 130 may generate a one-time encryption key using the public key received from the subscriber terminal 110 . The producer terminal 130 may encrypt the payload encryption key with a one-time encryption key.

The producer terminal 130 may transmit a message to the broker terminal (S529). When the producer terminal 130 transmits the payload encryption key to the producer terminal, there is no need to transmit the payload encryption key when transmitting the next message.

However, the producer terminal 130 may check whether to update the payload encryption key when a predetermined period or the like arrives (S531).

As a result of the determination in step S531, if the payload encryption key is not updated, the producer terminal 130 may generate a message by proceeding to step S527.

As a result of the determination in step S531, when updating the payload encryption key, the producer terminal 130 may proceed to step S533.

The producer terminal 130 may generate a new payload encryption key and encrypt the new payload encryption key with the existing payload encryption key (S533). When the new payload encryption key is generated, the producer terminal 130 may encrypt the payload to be transmitted with the new payload encryption key if there is a payload to be transmitted.

The producer terminal 130 may transmit a message in which the payload encryption key is updated including the new encrypted payload encryption key to the subscriber terminal 110 through the broker terminal 120 .

The producer terminal 130 may determine whether to end the operation (S537).

As a result of the check in step S537, if the operation is not terminated, the producer terminal 130 may proceed to step S527 to generate a message. However, the producer terminal 130 may proceed to another step as needed.

As a result of checking in step S527, when the operation is terminated, the broker terminal 120 may end the operation.

The term '~ unit' used in this embodiment means software or hardware components such as field programmable gate array (FPGA) or ASIC, and '~ unit' performs certain roles. However, '~part' is not limited to software or hardware. The '~ unit' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Thus, as an example, '~' refers to components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program patent code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

Functions provided in components and '~ units' may be combined into a smaller number of components and '~ units' or separated from additional components and '~ units'.

In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card.

Also, the message security method according to an embodiment of the present invention may be implemented as a computer program (or computer program product) including instructions executable by a computer. The computer program includes programmable machine instructions processed by a processor, and may be implemented in a high-level programming language, an object-oriented programming language, an assembly language, or a machine language. . In addition, the computer program may be recorded in a tangible computer-readable recording medium (eg, a memory, a hard disk, a magnetic/optical medium, or a solid-state drive (SSD), etc.).

Accordingly, the message security method according to an embodiment of the present invention may be implemented by executing the computer program as described above by a computing device. The computing device may include at least a portion of a processor, a memory, a storage device, a high-speed interface connected to the memory and the high-speed expansion port, and a low-speed interface connected to the low-speed bus and the storage device. Each of these components is connected to each other using various buses, and may be mounted on a common motherboard or in any other suitable manner.

Here, the processor may process a command within the computing device, such as for displaying graphic information for providing a Graphical User Interface (GUI) on an external input or output device, such as a display connected to a high-speed interface. Examples are instructions stored in memory or a storage device. In other embodiments, multiple processors and/or multiple buses may be used with multiple memories and types of memory as appropriate. In addition, the processor may be implemented as a chipset formed by chips including a plurality of independent analog and/or digital processors.

Memory also stores information within the computing device. In one example, the memory may be configured as a volatile memory unit or a set thereof. As another example, the memory may be configured as a non-volatile memory unit or a set thereof. The memory may also be another form of computer readable medium such as, for example, a magnetic or optical disk.

In addition, the storage device may provide a large-capacity storage space to the computing device. A storage device may be a computer-readable medium or a component comprising such a medium, and may include, for example, devices or other components within a storage area network (SAN), a floppy disk device, a hard disk device, an optical disk device, or a tape device, a flash memory, or other semiconductor memory device or device array similar thereto.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims

a producer terminal that creates a topic;

a subscriber terminal subscribing to the topic; and

When communicating with the subscriber terminal and the producer terminal, and receiving a message including an encrypted topic and an encrypted payload from the producer terminal, using a second topic encryption key that shares the encrypted topic with the producer terminal Checking the subscriber terminal subscribing to the decrypted topic by decryption, encrypting the topic using the first topic encryption key shared with the subscriber terminal, and transmitting the encrypted payload to the subscriber terminal together with the broker terminal included network system
The method of claim 1,

The producer terminal,

generating a payload encryption key for decrypting the encrypted payload, generating a one-time encryption key by exchanging a public key with the subscriber terminal, encrypting the payload encryption key with the one-time encryption key, and delivering to the subscriber terminal network system.
3. The method of claim 2,

The subscriber terminal,

A network system for generating a one-time encryption key by exchanging a public key with the producer terminal, and decrypting the payload encryption key using the one-time encryption key when receiving an encrypted payload encryption key from the producer terminal.
3. The method of claim 2,

The producer terminal,

The payload encryption key generates a new payload encryption key at a predetermined interval, and when the new payload encryption key is generated, the new payload encryption key is encrypted with the existing payload encryption key and delivered to the subscriber terminal network system.
5. The method of claim 4,

The subscriber terminal,

When receiving the encrypted new payload encryption key, the network system decrypts the new payload encryption key with the existing payload encryption key and uses it to decrypt the encrypted payload.
The method of claim 1,

The broker terminal,

A network system for establishing a session with the subscriber terminal and generating the first topic encryption key when the session is established.
The method of claim 1,

The broker terminal,

A network system for establishing a session with the producer terminal and generating the second topic encryption key when the session is established.
The method of claim 1,

The network system is

Further comprising a master terminal that manages the group key,

The producer terminal,

Upon new access to the network system, when a group key is retrieved and received from the master terminal within a predetermined time, a payload encryption key for decrypting the encrypted payload is generated using the group key,

If the group key is not received from the master terminal within a predetermined time, a temporary group key is generated, and the payload encryption key is generated using the temporary group key.
A message security method performed in a network system, comprising:

establishing, by the broker terminal, a session with the subscriber terminal subscribing to the topic;

establishing, by the broker terminal, a session with a producer terminal generating the topic;

When the broker terminal receives a message including an encrypted topic and an encrypted payload from the producer terminal, decrypting the encrypted topic using a second topic encryption key shared with the producer terminal; and

The broker terminal identifies a subscriber terminal subscribing to the decrypted topic, encrypts the topic using a first topic encryption key shared with the subscriber terminal, and transmits it to the subscriber terminal together with the encrypted payload A message security method comprising steps.
10. The method of claim 9,

generating, by the producer terminal, a payload encryption key for decrypting the encrypted payload, and generating a one-time encryption key by exchanging a public key with the subscriber terminal;

generating, by the subscriber terminal, a one-time encryption key by exchanging a public key with the producer terminal;

encrypting, by the producer terminal, the payload encryption key with the one-time encryption key and transmitting the encryption key to the subscriber terminal; and

When the subscriber terminal receives the encrypted payload encryption key from the producer terminal, the method further comprising the step of decrypting the payload encryption key using the one-time encryption key.
11. The method of claim 10,

The producer terminal generates a new payload encryption key using the payload encryption key at a predetermined interval, and when the new payload encryption key is generated, the new payload encryption key is encrypted with the existing payload encryption key to Message security method further comprising the step of delivering to the subscriber terminal.
12. The method of claim 11,

After the step of delivering to the subscriber terminal,

and, when the subscriber terminal receives the encrypted new payload encryption key, decrypting the new payload encryption key with the existing payload encryption key and using it to decrypt the encrypted payload.
10. The method of claim 9,

The step of establishing a session with the subscriber terminal comprises:

and generating, by the broker terminal, the first topic encryption key when establishing the session with the subscriber terminal.
10. The method of claim 9,

The step of establishing a session with the producer terminal,

Message security method comprising the step of generating, by the broker terminal, the second topic encryption key when establishing the session with the producer terminal.
10. The method of claim 9,

When the producer terminal newly accesses the network system, searches for the group key and receives the group key within a predetermined time from the master terminal, the payload encryption key for decrypting the encrypted payload using the group key create,

If the group key is not received from the master terminal within a predetermined time, generating a temporary group key, and generating the payload encryption key using the temporary group key.