JP2013039276A - Game terminal, game system, control method of game terminal, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a game terminal and the like suitable to make analysis of communication difficult, in a game system advancing a game by communicating a game state.SOLUTION: In each of the game terminals 200a, 200b of this game system, a storage part 201 stores the game state, a genuineness generation part 202 generates a genuine message, and a dummy generation part 203 generates dummy message. A transmission part 204 transmits the generated genuine message and dummy message to the other game terminal, an acceptance part 205 accepts an instruction from a player, and a reception part 206 receives the messages transmitted from the other game terminal. An update part 207 updates the game state stored in the storage part 201 from the game state of the other game terminal designated in the genuine message of the received messages and the accepted instruction. Furthermore, the dummy generation part 203 changes frequency of generating the dummy message according to communication quality with the other game terminal.

Description

  The present invention relates to a game terminal, a game system, a game terminal control method, and a program suitable for making analysis of communication difficult in a game system that progresses a game by communicating game states.

  In recent years, network games (online games) using networks such as the Internet have become widespread. The online game is a type of game in which a plurality of player terminals are connected via a network so that each player plays in cooperation or in a battle.

  In online games, fraudulent acts performed by some malicious players are a problem. Such a fraudulent act is also referred to as a cheat act, and is an act of altering data used in a game to something that is not intended by the creator, mainly by crafting a memory area. For example, an act of improving a character's ability beyond the limit or making an unusable item available can be used. The data is altered to a state advantageous to

  Such a cheat action not only simply breaks the game balance but also involves many players, especially in an online game, where the opponent is in a disadvantageous situation, and thus has a high degree of adverse effect. For this reason, various techniques for preventing cheat acts in online games have been developed. For example, Patent Literature 1 discloses a technique for detecting a cheat action such as trying to invalidate a result of a communication battle by changing a setting of a router device in an online game using the router device.

JP 2009-189622 A

  However, a player who wants to execute a cheat action can achieve the cheat action by using various data used in the online game in order to bypass the producer's prevention means. For example, there is a method of creating illegal data by analyzing communication data exchanged between a plurality of game terminals. Therefore, there has been a demand for a technique that makes it difficult to analyze such communication data and prevents creation of illegal data.

  The present invention solves the above-described problems, and in a game system that progresses a game by communicating a game state, a game terminal, a game system, and a game terminal that are suitable for making communication analysis difficult. It is an object to provide a control method and a program.

  In order to achieve the above object, a game terminal according to a first aspect of the present invention is a game terminal in a game system in which a game terminal advances a game by communicating the game state of each other, and a storage unit and an authenticity A generation unit, a dummy generation unit, a transmission unit, a reception unit, a reception unit, and an update unit are provided.

  A typical game provided by the game system of the present invention is, for example, a battle game in which two players battle each other. Such a game system includes two game terminals, and various parameters constituting a game including a current game state in each of one game terminal and its opponent game terminal, that is, an operation instruction input by each player. The game is progressed while communicating via the network and sharing the game state.

  In addition, the present invention is not limited to the one having only two game terminals, but a game that progresses using three or more game terminals such as an online game in which a large number of players advance the game while cooperating and fighting. It can also be applied. That is, the present invention can be applied to a game system in which a game progresses by communicating a game state between one of the three or more game terminals and another game terminal. For example, game terminal A, game terminal B, and game terminal C are provided as three game terminals, of which game terminal A and game terminal B, game terminal B and game terminal C, game terminal C and game terminal A, respectively. In the case of a game that progresses by communicating the game state of each other, the game terminal A and the game terminal B, the game terminal B and the game terminal C, the game terminal C and the game terminal A, respectively, Will be realized.

  The storage unit stores the game state of the game terminal. That is, the storage unit is a memory area installed in the game terminal and stores various parameters constituting the game.

  The authenticity generation unit generates a message (hereinafter referred to as “authentic message”) that specifies the game state stored in the storage unit. Here, the message corresponds to a transmission unit (packet or the like) of communication data when communicating with another game terminal connected via a network such as the Internet. Among such messages, the authenticity generation unit generates a message (authentication message) including the game state stored in the storage unit.

  The dummy generation unit generates a message (hereinafter referred to as “dummy message”) that specifies discrimination information for discrimination from the generated genuine message. Here, the dummy message means a message that is not the genuine message while the authentic message specifies the game state. The dummy generation unit generates such a dummy message by adding discrimination information for the received game terminal to discriminate from the genuine message.

  The transmission unit transmits the generated genuine message and the generated dummy message to another game terminal. That is, the transmission unit transmits the generated message to other game terminals connected via a network such as the Internet. At that time, by sending a genuine message, it informs the game state information of its game terminal, and also by sending a dummy message, the third party recognizes which message contains the correct game state. I can't do it.

  The reception unit receives an instruction from the player. That is, the accepting unit accepts various operation instructions for the player to play the game, using a controller, a keyboard, or the like connected to the game terminal.

  The receiving unit receives a message transmitted from another game terminal. That is, the receiving unit receives the genuine message and the dummy message generated and transmitted by another game terminal.

  The update unit updates the game state stored in the storage unit from the game state of the other game terminal designated as the genuine message among the received messages and the received instruction. That is, the updating unit reflects the operation instruction from the player in its own game state and shares the game state with other game terminals, so that the game state of the other game terminal included in the received authentic message is To reflect the game state.

  Further, the dummy generation unit changes the frequency of generating the dummy message according to the communication quality with other game terminals. That is, the dummy generation unit increases or decreases the frequency of generating the dummy message according to the communication quality such as the communication speed and delay, the data loss rate and discontinuity during communication with other game terminals.

  With such a configuration, the game terminal of the present invention mixes a dummy message with a message when communicating the game state with another game terminal. As a result, since a third party who cannot distinguish between a genuine message and a dummy message cannot recognize which message contains the correct game state, it must analyze the message during communication before reaching another game terminal. It becomes difficult to use the game state for cheating such as rewriting the game state illegally and making the game progress so as to be advantageous to the player. At this time, the game terminal of the present invention can make communication analysis by a third party difficult without greatly degrading the communication quality by changing the ratio of mixing the dummy messages according to the communication quality. .

In the game terminal of the present invention,
The authentic message is attached with order information indicating the order number in which the authentic message is generated,
The communication quality with other game terminals can be measured by the degree to which the sequence numbers represented by the sequence information attached to the authentic messages are consecutive among the received messages.

  Here, the “order information indicating the order number in which the genuine message is generated” is information that can be managed in association with the number by determining the temporal order in which the genuine message is generated. For example, typically, numerical values such as “1”, “2”, “3”... Are used so that the smaller the numerical value, the earlier the order. On the other hand, using alphabets such as “A”, “B”, “C”..., “A” is first, “B” is second, “C” is third, etc. Numbers may be associated with each other, and any other can be used as long as the order can be associated with numbers and managed.

  For example, when generating the authentic messages one by one, the authenticity generation unit attaches consecutive numbers indicating the generated order to individual authenticity messages such as “1”, “2”, “3”. To do. Messages with such sequence numbers are communicated between the two game terminals. The communication quality is acquired based on whether the authentic message is received in the order of the numbers assigned by other game terminals. For example, when data is lost during transmission or the reception order is changed due to transmission delay, it is determined that the communication quality has deteriorated.

  With such a configuration, the game terminal of the present invention measures whether or not the communication quality is deteriorated due to the sequence number of the received authentic message, and the dummy generation unit responds to the measurement result. Change the frequency of generating dummy messages. As a result, when the communication quality is degraded, it is possible to prevent the communication quality from further deteriorating by suppressing the number of messages to be transmitted by reducing the frequency of dummy message generation.

In the game terminal of the present invention,
The dummy generation unit includes a sequence number represented by the sequence information attached to the last genuine message among the received messages, and an order represented by the sequence information attached to the last genuine message among the transmitted messages. It is also possible to change the frequency of generating the dummy message so that the change in the difference between the number and the number becomes smaller.

  A small change in the difference between the order number of the received message and the order number of the transmitted message corresponds to the fact that the number of messages received and the number of transmitted messages per unit time are substantially equal. That is, here, the number of genuine messages to be transmitted and received is made substantially equal so that the game can be advanced while maintaining balanced communication.

  Specifically, when the number of genuine messages received per unit time decreases due to deterioration in communication quality, the change in the difference increases. At this time, the dummy generation unit reduces the frequency of generating the dummy message. This is expected to reduce the number of messages transmitted per unit time and improve communication quality. When the communication quality is improved, a decrease in the number of genuine messages received per unit time is suppressed, and the change in the difference becomes small. As described above, the dummy generation unit adjusts the frequency of generating the dummy message so that the change in the difference between the sequence number of the received message and the sequence number of the transmission message becomes small.

In the game terminal of the present invention,
The dummy generation unit includes a sequence number represented by the sequence information attached to the last genuine message among the received messages, and an order represented by the sequence information attached to the last genuine message among the transmitted messages. It is also possible to change the frequency of generating a dummy message so that an evaluation value obtained by applying a predetermined evaluation function to a difference between the number and a change in the difference becomes small.

  Here, the dummy generation unit does not adjust the dummy message generation frequency based only on the amount of change in the difference between the received message sequence number and the transmission message sequence number, but based on a predetermined evaluation function. Adjust the frequency of message generation. That is, a predetermined evaluation function is prepared in advance, which takes the difference and the change in the difference as input values and returns an evaluation value. Then, the dummy generator determines whether to increase or decrease the frequency of generating the dummy message based on the evaluation value.

  As described above, the game terminal of the present invention uses not only the change in the difference in the sequence number but also the difference between the sequence number of the received message and the sequence number of the transmitted message, using the predetermined evaluation function, Change the frequency of generation. Thereby, the game terminal of this invention can adjust the production | generation frequency of a dummy message more flexibly, and can advance a game, maintaining communication balance. In particular, the difference between the sequence number of the received message and the sequence number of the transmitted message is equivalent to the difference between the total number of received messages and the total number of transmitted messages. Compared to the above, the game terminal of the present invention can keep the communication balance by paying attention to the total number of messages to be transmitted and received.

In the game terminal of the present invention,
The storage unit stores a history of game states,
Any one of the game states included in the stored history can be specified in the dummy message.

  In other words, not only the current game state but also the past game state is accumulated and stored in the storage unit as a history. And a dummy production | generation part produces | generates a dummy message based on the game state in any one of log | history like the genuine production | generation part produced | generated the genuine message containing the present game state.

  With such a configuration, in the game terminal of the present invention, the dummy generation unit does not generate the dummy message at all independently, but generates it based on the past game state accumulated in the storage unit. As a result, a dummy message imitating a genuine message can be generated without taking the trouble of generating a dummy message.

In the game terminal of the present invention,
The game state includes checksum information, the generated genuine message specifies the correct checksum information of the game state, and the generated dummy message specifies the incorrect checksum information of the game state. Is also possible.

  Here, the checksum is obtained by taking the data in the message as a numerical value and taking the sum, and the game terminal uses the checksum information attached to the message to determine whether the received message is a genuine message or not. To distinguish.

  That is, the authenticity generation unit acquires a checksum for the designated game state, generates a genuine message with the acquired checksum information, and the dummy generation unit includes the checksum acquired for the specified game state. A different message is added as checksum information to generate a dummy message. When the game terminal receives such a message, it obtains a new checksum for the game state specified by the message, and when the obtained checksum matches the checksum information attached to the message, the received message is authentic. Judged as a message.

  In order to achieve the above object, a game system according to a second aspect of the present invention is a game system in which a game terminal and a server device advance a game by communicating with each other the game state. That is, the game system connects a game terminal (client device) operated by the player to the server device, and advances the game while communicating the game state between the game terminal and the server device. Specifically, the game terminal and the server device in the game system have the following configuration.

(A) The game terminal includes a terminal-side storage unit, a terminal-side authenticity generation unit, a terminal-side dummy generation unit, a terminal-side transmission unit, a reception unit, a terminal-side reception unit, and a terminal-side update unit.
The terminal-side storage unit stores a game state of the game terminal (hereinafter referred to as “terminal-side game state”).
The terminal-side authenticity generation unit generates a message (hereinafter referred to as “terminal-side authentic message”) that specifies the terminal-side game state stored in the terminal-side storage unit.
The terminal-side dummy generation unit generates a message (hereinafter referred to as “terminal-side dummy message”) that specifies discrimination information for discrimination from the generated terminal-side authentic message.
The terminal-side transmitting unit transmits the generated terminal-side authentic message and the generated terminal-side dummy message to the server device.
The reception unit receives an instruction from the player.
The terminal side receiving unit receives a message transmitted from the server device.
Further, the terminal side dummy generation unit changes the frequency of generating the terminal side dummy message according to the communication quality with the server device.

(B) The server device includes a server-side storage unit, a server-side authenticity generation unit, a server-side dummy generation unit, a server-side transmission unit, a server-side reception unit, and a server-side update unit.
The server-side storage unit stores a game state of the server device (hereinafter referred to as “server-side game state”).
The server-side authenticity generation unit generates a message (hereinafter referred to as “server-side authenticity message”) that specifies the server-side game state stored in the server-side storage unit.
The server-side dummy generation unit generates a message (hereinafter referred to as “server-side dummy message”) that specifies discrimination information for discrimination from the generated server-side authentic message.
The server-side transmission unit transmits the generated server-side authentic message and the generated server-side dummy message to the game terminal.
The server side receiving unit receives a message transmitted from the game terminal.
Furthermore, the server-side dummy generation unit changes the frequency of generating the server-side dummy message according to the communication quality with the game terminal.

(C) The terminal-side update unit of the game terminal is stored in the terminal-side storage unit from the server-side game state specified in the server-side authentic message among the received messages and the received instruction. Update the terminal game state.
(D) The server-side update unit of the server device updates the server-side game state stored in the server-side storage unit from the terminal-side game state specified in the terminal-side authentic message among the received messages.

  With such a configuration, the invention according to the second aspect provides a dummy game state while maintaining a balance of communication quality in a game system in which a game progresses while communicating the game state between the game terminal and the server device. It is difficult to cheat such as allowing a third party to illegally rewrite the game state during communication and to advance the game so that it is advantageous to itself by mixing messages that indicate it can.

  The invention according to the second aspect is typically provided with one game terminal and one server device. However, the invention is not limited to this, and two or more game terminals and one server device are used. It can also be applied to a game that is progressing. For example, the game terminal A and the game terminal B are provided with two game terminals and one server device, and the game terminal A and the server device, and the game terminal B and the server device communicate with each other the game state. In the case of a game proceeding by the above, the present invention is realized in each of the game terminal A and the server device, and the game terminal B and the server device.

  In order to achieve the above object, a game terminal control method according to a third aspect of the present invention provides a game in a game system in which a game terminal advances a game by communicating the game state of each other, a storage unit, A control method executed by a game terminal including a genuine generation unit, a dummy generation unit, a transmission unit, a reception unit, a reception unit, and an update unit, a genuine generation step, a dummy generation step, a transmission step, a reception step, a reception step, and an update A process is provided.

The storage unit stores the game state of the game terminal.
In the authenticity generation step, the authenticity generation unit generates a message (hereinafter referred to as “authentic message”) that specifies the game state stored in the storage unit.
In the dummy generation step, the dummy generation unit generates a message (hereinafter referred to as “dummy message”) that specifies discrimination information for discrimination from the generated genuine message.
In the transmission step, the transmission unit transmits the generated genuine message and the generated dummy message to another game terminal.
In the reception process, the reception unit receives an instruction from the player.
In the reception process, the reception unit receives a message transmitted from another game terminal.
In the update step, the update unit updates the game state stored in the storage unit from the game state of the other game terminal designated as the genuine message among the received messages and the received instruction.
Further, in the dummy generation step, the dummy generation unit changes the frequency of generating the dummy message according to the communication quality with other game terminals.

  In order to achieve the above object, a program according to a fourth aspect of the present invention is configured to cause a computer to function as the game terminal and to cause the computer to execute each step of the game terminal control method. .

  The program of the present invention can be recorded on a computer-readable information storage medium such as a compact disk, flexible disk, hard disk, magneto-optical disk, digital video disk, magnetic tape, and semiconductor memory.

  The program can be distributed and sold via a computer communication network independently of the computer on which the program is executed. The information storage medium can be distributed and sold independently from the computer.

  According to the present invention, there are provided a game terminal, a game system, a game terminal control method, and a program suitable for making communication analysis difficult in a game system that progresses a game by communicating game states. be able to.

It is a mimetic diagram showing the outline composition of the typical information processor with which the game terminal concerning the embodiment of the present invention is realized. 1 is a schematic diagram illustrating a schematic configuration according to a game system of Embodiment 1. FIG. (A) is a figure which shows the structure of a genuine message, (b) is a figure which each shows the structure of a dummy message simply. It is a figure which shows a mode that two game terminals are communicating. (A), (b) is a figure which shows a mode that the transmission frequency of a dummy message falls in Embodiment 1, when the order number of the received genuine message is not continuous. It is a flowchart which shows the flow of the process which concerns on the game terminal of this invention. 6 is a flowchart illustrating a flow of processing for adjusting the frequency of generating a dummy message in the first embodiment. It is a figure which shows the time change of the sequence number of the genuine message which the game terminal transmitted last, and the sequence number of the genuine message received last. 10 is a flowchart illustrating a flow of processing for adjusting the frequency of generating a dummy message in the second embodiment. 12 is a flowchart illustrating a flow of processing for adjusting the frequency of generating a dummy message in the third embodiment. It is a schematic diagram which shows the schematic structure which concerns on the game system of Embodiment 4. 10 is a flowchart illustrating a process flow of a game terminal according to the game system of the fourth embodiment. 14 is a flowchart illustrating a processing flow of a server device according to the game system of the fourth embodiment. In the game system of Embodiment 5, it is a figure which shows a mode that two game terminals are communicating via one server apparatus.

  Embodiments of the present invention will be described below. In the following, for ease of understanding, an embodiment in which the present invention is realized using a game information processing device will be described. However, the embodiment described below is for explanation, and the present invention It does not limit the range. Therefore, those skilled in the art can employ embodiments in which these elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a schematic configuration of a typical information processing apparatus in which a game terminal according to an embodiment of the present invention is realized. Hereinafter, a description will be given with reference to FIG.

  The information processing apparatus 100 includes a central processing unit (CPU) 101, a read only memory (ROM) 102, a random access memory (RAM) 103, an interface 104, a controller 105, an external memory 106, and an image processing unit 107. A DVD-ROM (Digital Versatile Disc ROM) drive 108, a NIC (Network Interface Card) 109, and an audio processing unit 110.

  When a DVD-ROM storing a game program and data is loaded into the DVD-ROM drive 108 and the information processing apparatus 100 is turned on, the program is executed, and the game terminal of the present embodiment is realized. Is done.

  The CPU 101 controls the overall operation of the information processing apparatus 100 and is connected to each component to exchange control signals and data. Further, the CPU 101 uses arithmetic operations such as addition / subtraction / multiplication / division, logical sum, logical product, etc. using an ALU (Arithmetic Logic Unit) (not shown) for a storage area called a register (not shown) that can be accessed at high speed. , Logic operations such as logical negation, bit operations such as bit sum, bit product, bit inversion, bit shift, and bit rotation can be performed. In addition, the CPU 101 itself is configured so that saturation operations such as addition / subtraction / multiplication / division for multimedia processing, vector operations such as trigonometric functions, etc. can be performed at a high speed, and those provided with a coprocessor. There is.

  The ROM 102 records an IPL (Initial Program Loader) that is executed immediately after the power is turned on, and when this is executed, the program recorded on the DVD-ROM is read out to the RAM 103 and execution by the CPU 101 is started. The The ROM 102 stores an operating system program and various data necessary for operation control of the entire information processing apparatus 100.

  The RAM 103 is for temporarily storing data and programs, and holds programs and data read from the DVD-ROM and other data necessary for game progress and chat communication. In addition, the CPU 101 provides a variable area in the RAM 103, performs an operation by directly operating the ALU on the value stored in the variable, and temporarily stores the value stored in the RAM 103 in a register. Performs an operation on the register and writes the result back to the memory.

  The controller 105 connected via the interface 104 receives an operation input performed when the player executes the game. For example, the controller 105 has a direction button used to input an operation indicating up, down, left, and right, and a button for inputting an instruction such as a determination operation, a cancel operation, and a menu display at a predetermined position on the surface. Is done. Each of these buttons is provided with a pressure sensor, and it is possible to detect which button is pressed. The player inputs an operation instruction to the information processing apparatus 100 by pressing such buttons arranged on the controller 105.

  The external memory 106 detachably connected via the interface 104 stores data indicating game play status (past results, etc.), data indicating the progress of the game, and log of chat communication in a network battle ( Data) is stored in a rewritable manner. The player can appropriately record these data in the external memory 106 by inputting an instruction via the controller 105.

  A DVD-ROM mounted on the DVD-ROM drive 108 stores a program for realizing the game and image data and audio data associated with the game. Under the control of the CPU 101, the DVD-ROM drive 108 performs a reading process on the DVD-ROM loaded therein, reads out necessary programs and data, and these are temporarily stored in the RAM 103 or the like.

  The image processing unit 107 processes the data read from the DVD-ROM by an image arithmetic processor (not shown) included in the CPU 101 or the image processing unit 107, and then processes the processed data on a frame memory ( (Not shown). The image information recorded in the frame memory is converted into a video signal at a predetermined synchronization timing and output to a monitor (not shown) connected to the image processing unit 107. Thereby, various image displays are possible.

  The image calculation processor can execute a two-dimensional image overlay calculation, a transmission calculation such as α blending, and various saturation calculations at high speed.

  Also, polygon information arranged in the virtual three-dimensional space and added with various texture information is rendered by the Z buffer method, and the polygon arranged in the virtual three-dimensional space from the predetermined viewpoint position is determined in the direction of the predetermined line of sight It is also possible to perform high-speed execution of operations for obtaining rendered images.

  Further, the CPU 101 and the image arithmetic processor cooperate to draw a character string as a two-dimensional image in the frame memory or draw it on the surface of each polygon according to the font information that defines the character shape. Is possible. The font information is recorded in the ROM 102, but it is also possible to use dedicated font information recorded in the DVD-ROM.

  The NIC 109 is used to connect the information processing apparatus 100 to a computer communication network (not shown) such as the Internet, and is based on the 10BASE-T / 100BASE-T standard used when configuring a LAN (Local Area Network). To connect to the Internet using an analog modem, ISDN (Integrated Services Digital Network) modem, ADSL (Asymmetric Digital Subscriber Line) modem, cable television line A cable modem or the like and an interface (not shown) that mediates between these and the CPU 101 are configured.

  The audio processing unit 110 converts audio data read from the DVD-ROM into an analog audio signal and outputs the analog audio signal from a speaker (not shown) connected thereto. Further, under the control of the CPU 101, sound effects and music data to be generated during the progress of the game are generated, and sound corresponding to this is output from the speaker.

  When the audio data recorded on the DVD-ROM is MIDI data, the audio processing unit 110 refers to the sound source data included in the audio data and converts the MIDI data into PCM data. If the compressed audio data is in ADPCM format or Ogg Vorbis format, it is expanded and converted to PCM data. The PCM data can be output by performing D / A (Digital / Analog) conversion at a timing corresponding to the sampling frequency and outputting it to a speaker.

  Further, the information processing apparatus 100 can measure time using a predetermined synchronization timing when the image processing unit 107 displays an image on a monitor. That is, since the output of the image information to the monitor is performed every predetermined cycle t seconds (for example, 1/60 seconds), by counting the number of times of output with the counter variable prepared in the RAM 103, Time can be measured. In addition, the information processing apparatus 100 may include an RTC (Real Time Clock) therein and may be used for processing for time measurement.

  In addition, the information processing apparatus 100 uses a large-capacity external storage device such as a hard disk so as to perform the same function as the ROM 102, the RAM 103, the external memory 106, the DVD-ROM mounted on the DVD-ROM drive 108, and the like. You may comprise.

  Further, it is possible to adopt a form in which a keyboard for accepting a character string editing input from a player, a mouse for accepting various position designations and selection inputs, and the like are connected. In addition, a general-purpose personal computer can be used instead of the information processing apparatus 100 of the present embodiment.

  The information processing apparatus 100 described above corresponds to a so-called “consumer video game terminal”, but the present invention can be realized as long as it communicates with other devices via a computer communication network. it can. Therefore, the present invention can be realized on various computers such as a mobile phone, a portable game device, a karaoke apparatus, and a general business computer.

  For example, a general computer includes an CPU, a RAM, a ROM, a DVD-ROM drive, and an NIC as in the information processing apparatus 100, and an image processing unit having a simpler function than the information processing apparatus 100. In addition to having a hard disk as an external storage device, a flexible disk, a magneto-optical disk, a magnetic tape, and the like can be used. Further, not the controller 105 but a keyboard or a mouse is used as an input device.

  FIG. 2 is a schematic diagram showing a schematic configuration according to the game system of the present embodiment. Here, the game terminals 200a and 200b are typically realized by the information processing apparatus 100 described above. Hereinafter, a schematic configuration will be described with reference to FIG.

  The game system shown in FIG. 2 is a game system in which two game terminals 200a and 200b advance a game by communicating with each other's game state. The game terminal 200a includes a storage unit 201a and an authentic generation. Unit 202a, dummy generation unit 203a, transmission unit 204a, reception unit 205a, reception unit 206a, and update unit 207a. Game terminal 200b includes storage unit 201b, authenticity generation unit 202b, and dummy generation unit. 203b, a transmission unit 204b, a reception unit 205b, a reception unit 206b, and an update unit 207b. Note that the game terminals 200a and 200b appropriately include a time measuring unit realized by a synchronization function of the image processing unit 107, an RTC, or the like in order to measure time.

  The storage units 201a and 201b store game states of the game terminals 200a and 200b. In other words, the storage units 201a and 201b are storage areas for storing various data necessary for the progress of the game being executed on the game terminals 200a and 200b, and are realized by functions such as the RAM 103, for example. The

  The authenticity generation units 202a and 202b generate messages (hereinafter referred to as “authentic messages”) that specify the game state stored in the storage units 201a and 201b. That is, the authenticity generation units 202a and 202b access the storage units 201a and 201b, acquire the stored game state, and generate an authentic message including the acquired game state. Then, the generated genuine message is supplied to transmitting units 204a and 204b described later. Such authenticity generation units 202a and 202b are realized, for example, when the CPU 101 cooperates with the ROM 102, the RAM 103, and the like.

  The dummy generation units 203a and 203b generate a message (hereinafter referred to as “dummy message”) that specifies discrimination information for discrimination from the generated genuine message. That is, the dummy generation units 203a and 203b acquire the game state stored in the storage units 201a and 201b in the same manner as the authentic generation units 202a and 202b, and generate a message. Here, the dummy message imitating the authentic message is used. Is generated. Then, the generated dummy message is supplied to transmitters 204a and 204b described later. Furthermore, the dummy generation units 203a and 203b change the frequency of generating dummy messages according to the communication quality with other game terminals, that is, opponent game terminals. That is, the current communication quality is acquired based on a message received by receiving units 206a and 206b described later, and the frequency of generating a dummy message is adjusted. Such dummy generation units 203a and 203b are realized, for example, when the CPU 101 cooperates with the ROM 102, the RAM 103, and the like.

  The transmission units 204a and 204b transmit the generated genuine message and the generated dummy message to another game terminal, that is, the opponent game terminal. That is, the transmission units 204a and 204b transmit the authentic message supplied from the authenticity generation units 202a and 202b and the dummy message supplied from the dummy generation units 203a and 203b to the opponent game terminal via the network. Such transmission units 204a and 204b are realized, for example, when the CPU 101 cooperates with the ROM 102, the RAM 103, and the NIC 109 connected to the computer communication network.

  The receiving units 205a and 205b receive instructions from the player. Here, there are two players, a player A who is operating the game terminal 200a and a player B who is operating the game terminal 200b. The receiving unit 205a is from the player A, and the receiving unit 205b is the receiving unit 205b. The player B receives various instructions for playing the game. Then, the receiving units 205a and 205b supply the received instructions to update units 207a and 207b described later. Such accepting units 205 a and 205 b are realized by the function of the controller 105 connected via the interface 104, for example.

  The receiving units 206a and 206b receive messages transmitted from other game terminals, that is, opponent game terminals. That is, the receiving units 206a and 206b receive the genuine message and the dummy message generated and transmitted by another game terminal, that is, the opponent game terminal. Then, it is determined whether the received message is a genuine message or a dummy message. For example, the authentic message and the dummy message are discriminated based on the checksum information of the transmission data. Further, the receiving units 206a and 206b supply the received messages that are determined to be authentic messages to the updating units 207a and 207b described later. Such receiving units 206a and 206b are realized by, for example, the CPU 101 cooperating with the ROM 102, the RAM 103, and the NIC 109 connected to the computer communication network.

  The update units 207a and 207b store in the storage units 201a and 201b from the game state of the other game terminal designated as the authentic message among the received messages, that is, the game state of the opponent game terminal and the instruction received from the player. Update the game state being played. In other words, the updating units 207a and 207b receive their instructions from the players supplied from the receiving units 205a and 205b and the game state included in the authentic message from the opponent game terminal supplied from the receiving units 206a and 206b. In order to reflect in the game state, the storage units 201a and 201b are accessed to update the stored game state. Such update units 207a and 207b are realized, for example, when the CPU 101 cooperates with the ROM 102, the RAM 103, and the like.

  FIG. 3 is a diagram simply showing the configuration of the authentic message (FIG. 3A) and the dummy message (FIG. 3B) according to the present embodiment. In the present embodiment, a genuine message 300 and a dummy message 350 as shown in FIG. 3 are generated and transmitted / received between the two game terminals 200a and 200b.

  As shown in FIG. 3A, the genuine message 300 includes transmission order information 301T, reception order information 302T, checksum information 303T, and data information 304T as its constituent elements.

  The transmission order information 301T represents the order number in which the genuine message 300 is generated. That is, when generating the authentic message 300 one by one, the authenticity generation unit 202 transmits a continuous sequence number indicating the generated order such as “1”, “2”, “3”. It is attached to the genuine message 300 generated as the order information 301T. Then, the genuine message 300 is transmitted to the opponent game terminal according to the attached order. The transmission order information 301T is not necessarily limited to numerical values such as “1”, “2”, “3”..., And can represent the order number in which the genuine message 300 is generated, such as an alphabet. I just need it.

  The reception order information 302T represents transmission order information 301T attached to the last genuine message 300 that has been correctly received among the messages received by the reception unit 206. In other words, this is for informing the opponent game terminal of information on which genuine messages 300 have been successfully received. The opponent game terminal determines whether or not the authentic message 300 needs to be transmitted again based on the reception order information 302T.

  The checksum information 303T is used to distinguish whether the message is the genuine message 300 or the dummy message 350, and the data included in the data information 304T below is regarded as a numerical value and summed. . The opponent game terminal that has received the message again regards the data included in the data information 304T as a numerical value and takes the sum, and based on whether or not it matches the checksum information 303T, the received message is the authentic message 300. Or a dummy message 350.

  The data information 304T specifies the latest game state stored in the storage unit 201, and normally occupies the largest proportion in the authentic message 300. The information shown here corresponds to various data necessary for proceeding with the online game, for example, the position and state of the character, the operation information of the player, etc. The authentic message 300 including this information is 2 By communicating with each other between the two game terminals 200, the latest game state on each game terminal 200 is shared with the opponent game terminal.

  The constituent elements of the authentic message 300 are not limited to these, and may include, as appropriate, constituent elements such as message generation time information, version information, destination and source address information, and various flag information.

  On the other hand, the dummy message 350 has a configuration imitating the authentic message 300 as shown in FIG. 3B, but the content of each component is different from that of the authentic message 300 as described below. .

  The transmission order information 301D of the dummy message 350 imitates the transmission order information 301T of the genuine message 300. For example, in order to make it resemble the genuine message 300, for example, the transmission order of the genuine message 300 transmitted immediately before is transmitted. Information 301T is added as it is. Alternatively, for example, a continuous sequence number different from the transmission sequence information 301T of the genuine message 300 may be used, or a random number may be used.

  The reception order information 302D of the dummy message 350 imitates the reception order information 302T of the genuine message 300, and represents the transmission order information 301T attached to the last genuine message 300 received in the same manner as the genuine message 300. It may be random or random.

  The checksum information 303D of the dummy message 350 corresponds to the checksum information 303T in the authentic message 300, but here intentionally incorrect checksum information is described. That is, here, a value different from that obtained by regarding the data included in the following data information 304D as a numerical value and taking the sum thereof is described. The opponent game terminal that has received the message can distinguish whether the received message is the genuine message 300 or the dummy message 350 based on whether the checksum information 303 is correct or incorrect.

  The data information 304D of the dummy message 350 imitates the data information 304T of the genuine message 300, and the information shown here is dummy data that is not used in the progress of the online game. In order to easily generate such dummy data information 304D, in the present embodiment, what designates one of the game states included in the history stored in the storage unit 201 is the data information 304D of the dummy message 350. To do. That is, the history including the past game state is stored in the storage unit 201, and the latest game state in which the data information 304T of the authentic message 300 is stored is specified. The data information 304D designates one of the stored past game states.

  Note that the data information 304D of the dummy message 350 may be associated with any of the game states included in the history stored in the storage unit 201, such as partly modified using random numbers. Good. By modifying a part of the game state, it becomes more difficult for a third party to analyze the message.

  In the game system according to the present embodiment, the game progresses when the two game terminals 200 mutually transmit and receive the authentic message 300 and the dummy message 350 having such a configuration.

  FIG. 4 is a diagram illustrating a state where two game terminals 200a and 200b are communicating. FIG. 4 shows a state in which two game terminals 200a and 200b are connected via a computer communication network and send and receive an authentic message 300 and a dummy message 350 to each other. In FIG. 4, the dummy message 350 is represented by being shaded for convenience to distinguish it from the genuine message 300.

  Here, the two game terminals 200a and 200b attach the transmission order information 301 to the respective messages and transmit the messages. Specifically, in FIG. 4, the number indicated in the message corresponds to the transmission order information 301, and the genuine message 300 includes “1”, “2”, “3”, “4” in the order of transmission. .., And the number of the previous genuine message 300 is added to the dummy message 350.

  Then, the two game terminals 200a and 200b transmit such a genuine message 300 and a dummy message 350 mixedly. Specifically, in FIG. 4, the game terminal 200a transmits the message to the opponent game terminal 200b in the order of authentic message 300a, dummy message 350a, authentic message 300b, authentic message 300c, authentic message 300d, dummy message 350b,. doing. The ratio of mixing the dummy messages 350 at this time changes according to the communication quality as will be described later. However, in the initial state, for example, 30% of the entire message is set in advance so as to become the dummy messages 350. May be.

  The transmitted dummy messages 350a and 350b are transmitted in the communication path without being distinguished from the genuine messages 300a to 300d, that is, without being discarded as illegal by the firewall or the router. And it is delivered to the receiving part 206b of the other party game terminal 200b with the transmitted genuine messages 300a-300d.

  The opponent game terminal 200b that has received such a message determines whether the received message is the genuine message 300 or the dummy message 350. Specifically, using the checksum information 303 attached to the message, it is distinguished whether the received message is the genuine message 300 or the dummy message 350. That is, the data about the data information 304 in the message is regarded as a numerical value, a sum is obtained, and it is checked whether or not it matches the checksum information 303 attached to the message. As a result, if they match, it is determined that the received message is a genuine message 300, and if they do not match, it is determined that the received message is a dummy message 350.

  The received message determined to be the genuine message 300 is then used by the update unit 207b to update the game state stored in the storage unit 201b with the game state specified by the message. On the other hand, the received message determined to be the dummy message 350 is discarded without being used to update the stored game state.

  And the other party game terminal 200b which received such a message produces | generates a message similarly to the game terminal 200a, and transmits toward the game terminal 200a. That is, as shown in FIG. 4, the opponent game terminal 200b is also connected to the authentic message 300 in the order of an authentic message 300e, a dummy message 350c, an authentic message 300f, a dummy message 350d, an authentic message 300g, an authentic message 300h,. The dummy message 350 is mixed and transmitted. The game terminal 200a that has received such a message discriminates whether the message received using the checksum information 303 is the genuine message 300 or the dummy message 350, similarly to the game terminal 200b. The authentic message 300 is used to update the game state stored in the storage unit 201 according to the designated game state, and the dummy message 350 is discarded.

  In this way, the two game terminals 200a and 200b can advance the online game while sharing the current game state by transmitting and receiving messages to and from each other via the computer communication network. In that case, by mixing the message with the dummy message 350, the message being communicated is analyzed, the game state is illegally rewritten before reaching the opponent game terminal, and the game proceeds to be advantageous to the player It is difficult for a third party who wants to cheat such as to make a message which is worthy of analysis.

  In this embodiment, the frequency at which the dummy message 350 is generated / transmitted is further changed from this state in accordance with the communication quality between the two game terminals 200a and 200b. Hereinafter, a description will be given with reference to FIG.

  FIG. 5 is a diagram illustrating how the transmission frequency of the dummy message 350 is reduced when the sequence numbers of the received genuine messages 300 are not consecutive. First, FIG. 5A shows a state in which the game terminal 200b transmits the genuine messages 300e to 300h and the dummy messages 350c and 350d in a mixed manner toward the game terminal 200a. At this time, as in FIG. 4, the authentic messages 300e to 300h are transmitted as “1”, “2”, “3”, “4” in order as transmission order information 301T, and are transmitted as dummy messages 350c, 350d. Is transmitted with the same number as the authentic message 300 immediately before as the transmission order information 301D.

  Thereafter, the game terminal 200a receives the authentic messages 300e to 300h and the dummy messages 350c and 350d transmitted by the game terminal 200b. At this time, a case is considered in which a part of the transmitted message does not reach the game terminal 200a for some reason such as data loss or transmission delay in the transmission path.

  Specifically, as shown in FIG. 5 (b), the game terminal 200a has received authentic messages 300e, 300f, and 300h with “1”, “2”, and “4” as the transmission order information 301T. However, consider a state in which the genuine message 300g labeled “3” has not been received. That is, in FIG. 5B, the authentic message 300g does not reach the game terminal 200a for some reason, such as data loss or transmission delay in the transmission path, and the authentic message 300h that should have been transmitted later is the game terminal. It has reached 200a first.

  In the present embodiment, the generation / transmission frequency of the dummy message 350 is adjusted according to the reception status of such a message. That is, the game terminal 200a measures whether or not the transmission order information 301T of the received genuine message 300 is continuous. Then, since the genuine message 300g cannot be received as shown in FIG. 5B, when the transmission order information 301T is not continuous, the frequency of the dummy message 350 transmitted by itself is lowered.

  Here, the fact that the transmission order information 301T is not continuous means that, for some reason, the message is lost during transmission, or the order of messages is changed due to a transmission delay or the like, so the communication quality deteriorates. It can be judged that Under such deteriorated communication quality, if a large number of dummy messages 350 are mixed in the genuine message 300, the total number of messages to be transmitted increases accordingly, causing further transmission delay and data loss. End up. For this reason, the game terminal 200a in the present embodiment reduces the frequency of generation of the dummy message 350, for example, from 30% of the total message up to 10% before sending the message to be transmitted. Decrease the total number.

  Thus, the act of adjusting the generation / transmission frequency of the dummy message 350 while considering not to deteriorate the communication quality is also effective in preventing third-party message analysis. That is, a third party who analyzes a transmitted / received message is usually in an environment where the communication quality is good, and on the contrary, there are few third parties who analyze a message in an environment where the communication quality is poor. Under the present embodiment, since the transmission frequency of the dummy message 350 is not lowered in an environment where the communication quality is good, the dummy message 350 included in the message in an environment where it is assumed that a third party often analyzes the message. The ratio can be relatively high, and as a result, analysis of a third party message can be made difficult.

  When the authentic message 300 is received discontinuously as shown in FIG. 5, the game terminal 200a buffers the authentic message 300h received earlier after the unreceived authentic message 300g, and then receives the unreceived authentic message. Wait for 300g to arrive. Then, after receiving the genuine message 300g which has not been received, the buffered genuine message 300h may be used for updating the game state.

  At this time, the transmitting game terminal 200b transmits the unreached authentic message 300g again as necessary. That is, the game terminal 200b on the transmission side refers to the reception order information 302T included in the message transmitted from the game terminal 200a, determines that the genuine message 300g that should have been transmitted has not yet been reached, and retransmits it. May be. As a result, it is possible to prevent a message that has not been reached, such as being lost during transmission, from remaining unreached.

  FIG. 6 is a flowchart showing a flow of processing related to the game terminal 200 (200a, 200b) according to the first embodiment of the present invention. A summary of the flow of processing realized in the game terminal 200 in the present embodiment that has been described so far will be described below.

  First, the CPU 101 of the game terminal 200 performs various initialization processes (step S601). Here, various information such as images and sounds necessary for starting the game is read from a DVD-ROM or the like using the DVD-ROM drive 108, or communication with the opponent game terminal is started.

  When the game is started, the reception unit 205 of the game terminal 200 investigates an instruction from the player (step S602). That is, the player performs various operations such as pressing a button on the controller 105 in order to play the game. Here, the accepting unit 205 checks whether or not such an instruction from the player has been accepted by the controller 105 or the like, and if so, holds the contents of the instruction in the RAM 103.

  Next, the receiving unit 206 of the game terminal 200 determines whether or not a message has been received (step S603). That is, the receiving unit 206 determines whether or not a message from the opponent game terminal has arrived.

  When the message has not been received (step S603; NO), the update unit 207 of the game terminal 200 updates the game state stored in the storage unit 201 (step S604). That is, the updating unit 207 updates the state of various elements constituting the game, such as moving a game character, advancing the stage, or advancing music playback, and advances the game.

  At this time, if an instruction from the player is accepted in step S602, the update unit 207 further reflects the instruction and updates the game state. That is, the update unit 207 refers to the instruction from the player received by the receiving unit 205 and held in the RAM 103, and updates the game state according to the instruction. For example, in an action game in which a game is advanced by moving a character or attacking an enemy, an instruction from the player to move the character or attack the enemy is reflected in the game state. To advance the game.

  On the other hand, when it is determined in step S603 that a message has been received (step S603; YES), the process of the game terminal 200 does not immediately shift to the update process of step S604. In this case, first, the receiving unit 206 determines whether or not the genuine message 300 is received (step S605).

  For example, the receiving unit 206 regards the data about the data information 304 in the message as a numerical value, obtains the sum, and checks whether or not it matches the attached checksum information 303. If they match, it is determined that the received message is a genuine message 300, and if they do not match, it is determined that the received message is a dummy message 350.

  If it is determined that the dummy message 350 has been received (step S605; NO), the reception unit 206 discards the received dummy message 350 (step S606), and then the update unit 207 updates the game state (step S606). S604). That is, when the received message is not the genuine message 300 but the dummy message 350, the dummy message 350 is discarded without being used for updating the game state. In the update process in step S604, as in the process described above, when the instruction from the player is accepted, the update unit 207 updates the game state stored in the storage unit 201 while reflecting the instruction. To do.

  On the other hand, if it is determined in step S605 that the genuine message 300 has been received (step S605; YES), the dummy generation unit 203 of the game terminal 200 adjusts the generation frequency of the dummy message 350 based on the communication quality. (Step S607). Details of the processing here will be described below with reference to the flowchart of FIG.

  FIG. 7 is a flowchart showing a flow of processing for adjusting the frequency of generating the dummy message 350 in the present embodiment. When this flowchart is started, the receiving unit 206 of the game terminal 200 first determines whether or not the sequence numbers of the received genuine messages 300 are consecutive (step S701). That is, in this embodiment, the continuity of the sequence numbers of the received genuine messages 300 is used as an index of communication quality.

  Specifically, the receiving unit 206 acquires a sequence number from the transmission sequence information 301T included in the received genuine message 300. Then, it is determined that the acquired sequence number is continuous when the sequence number of the genuine message 300 received so far is added with 1, and otherwise, it is determined that it is not continuous. To do. When the authentic message 300 is received for the first time at the start of the game, the continuity of the sequence numbers cannot be determined because there is no authentic message 300 that has been received so far. It is determined that there is sex.

  When it is determined that they are continuous (step S701; YES), the dummy generation unit 203 increases the generation frequency of the dummy message 350 (step S702). That is, here, the current communication quality is good, and it is determined that there is no problem even if the total number of messages to be transmitted is increased, and the frequency with which the dummy generation unit 203 generates the dummy message 350 is increased. As a result, the ratio of the dummy message 350 in the message transmitted by the transmitting unit 204 described later is increased, and it is possible to make the analysis of the message by a third party difficult.

  On the other hand, if it is determined that they are not continuous (step S701; NO), the dummy generation unit 203 decreases the generation frequency of the dummy message 350 (step S703). That is, since the current communication quality is deteriorated, it is determined that the total number of messages to be transmitted should be reduced, and the frequency with which the dummy generation unit 203 generates the dummy message 350 is reduced. As a result, the communication quality is recovered.

  As described above, when the generation frequency of the dummy message 350 is adjusted based on the continuity of the sequence numbers of the received genuine messages 300, the processing in this flowchart is ended, and the processing of the game terminal 200 is performed again in FIG. Return to the flowchart. And a process transfers to the process (step S604) in which the update part 207 updates a game state.

  In the updating process here after receiving the authentic message 300, the updating unit 207 updates the game state to reflect the instruction from the player accepted in step S602, and receives the received authentic message. The game state stored in the storage unit 201 is updated by reflecting the game state of the opponent game terminal designated by 300. That is, the update unit 207 acquires the game state of the opponent game terminal included in the data information 304T in the authentic message 300 and reflects it in its own game state, thereby sharing the latest game state with the opponent game terminal.

  Here, the received genuine message 300 is determined to have a discontinuous sequence number in step S701, and the authentic message 300 with the sequence number before the sequence number is not received. In some cases, the received authentic message 300 is once buffered in the RAM 103. Then, after receiving the unreceived genuine message 300, the game stored in the storage unit 201 is reflected again in the update process in step S 607, that is, the game state of the opponent game terminal designated by the buffered authentic message 300. Used for state update processing.

  When the update process in step S604 is performed, the game terminal 200 determines whether or not the present time is the timing for generating the authentic message 300 (step S608). That is, the game terminal 200 in the present embodiment generates and transmits the authentic message 300 for each preset period in order to regularly share the game state with the opponent game terminal. Therefore, here, the time is measured by the function of the time measuring unit, and it is determined whether or not the present time is a predetermined timing at which the genuine message 300 should be generated and transmitted.

  When the present time is the timing for generating the authentic message 300 (step S608; YES), the authentic generation unit 202 generates the authentic message 300 (step S609), and the transmission unit 204 transmits the generated authentic message 300 (step S609). Step S610). That is, the authenticity generation unit 202 acquires the game state stored in its own storage unit 201, updated in step S604, and generates the authentic message 300 as shown in FIG. To do. Then, the authenticating message 300 generated by the transmission unit 204 is transmitted to the opponent game terminal. Thereafter, the process proceeds to step S611.

  On the other hand, if it is not the time to generate the authentic message 300 (step S608; NO), the process proceeds to step S611 without passing through the generation / transmission process of the authentic message 300.

  Next, in step S611, the game terminal 200 determines whether it is time to generate the dummy message 350 (step S611). That is, based on the generation frequency of the dummy message 350 adjusted in the above step S607, it is determined whether the current timing for generating the dummy message 350 is determined.

  If the current timing is to generate the dummy message 350 (step S611; YES), the dummy generation unit 203 generates the dummy message 350 (step S612), and the transmission unit 204 transmits the generated dummy message 350 (step S612). Step S613). That is, here, the dummy generation unit 203 selects any one of the game state histories stored in the storage unit 201, modifies the selected game state, and then deliberately uses the checksum information 303. The dummy message 350 as shown in FIG. 3B is generated by performing a predetermined process such as adding the error message to the above. Then, the transmission unit 204 transmits the generated dummy message 350 to the opponent game terminal. Thereafter, the process returns to step S602.

  On the other hand, if the current timing is not the timing for generating the dummy message 350 (step S611; NO), the process returns to step S602 without passing through the generation / transmission processing of the dummy message 350.

  Thereafter, the process of the game terminal 200 that has returned to step S602 repeats the processes after step S602. That is, the game terminal 200 updates the game state based on the instruction from the player and the received authentic message 300, generates and transmits the authentic message 300 including the updated game state at a predetermined timing, and at a predetermined frequency. A dummy message 350 is also generated and transmitted. The game terminal 200 advances the game while repeating such processing.

  With such a configuration, the game terminal 200 of the present embodiment measures whether or not the communication quality is deteriorated due to the sequence number of the received genuine message 300 being continuous, and according to the measurement result, The frequency with which the dummy generation unit 203 generates the dummy message 350 is changed. As a result, the game terminal 200 of the present embodiment prevents the communication quality from further deteriorating by reducing the number of messages to be transmitted by reducing the generation frequency of the dummy message 350 when the communication quality is deteriorating. On the other hand, when the communication quality is good, it is possible to make third party analysis difficult by increasing the generation frequency of the dummy message 350.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described. In the first embodiment, the frequency at which the dummy generation unit 203 generates the dummy message 350 is changed according to the degree to which the sequence numbers of the received genuine messages 300 are consecutive. On the other hand, in the present embodiment, the dummy generation unit 203 generates the dummy message 350 so that the change in the difference between the sequence number of the received genuine message 300 and the sequence number of the transmitted genuine message 300 becomes small. Change the frequency. Specifically, this will be described with reference to FIG.

  FIG. 8 is a diagram illustrating a time change of the sequence number of the genuine message 300 transmitted last by the game terminal 200 and the sequence number of the genuine message 300 received last. FIG. 8 shows how the order number of the transmitted and received genuine message 300 changes with time, with the order number on the vertical axis and the elapsed time on the horizontal axis.

  First, the graph 800a shows a time change with respect to the sequence number represented by the transmission sequence information 301T attached to the authentic message 300 transmitted last among the messages transmitted from the game terminal 200 to the opponent game terminal. ing. That is, since the genuine message 300 is generated and transmitted with a sequential sequence number indicating the generated sequence, the sequence number increases as the sequence is transmitted one after another. Go up. Here, in order to keep the game state shared between the two game terminals 200 up to date, the authentic message 300 is constantly generated and transmitted at a constant frequency. Therefore, as shown in the graph 800a of FIG. 8, the sequence number increases in proportion to the elapsed time.

  On the other hand, the graph 800b shows a time change with respect to the sequence number represented by the transmission sequence information 301T attached to the last received genuine message 300 among the messages received by the game terminal 200 from the opponent game terminal. Yes. In other words, since the received genuine message 300 is also generated and transmitted by the opponent game terminal with a sequential sequence number, the value of the sequence number increases as the messages are received one after another. Goes up in the figure.

  Here, since the opponent game terminal also generates and transmits the genuine message 300 with the same frequency as the game terminal 200 of itself, if the communication quality is good, the authentic message with the same frequency as that of the own game terminal 200 is transmitted. 300 should be received. Specifically, in a state where the communication quality is good, a graph 800a for the transmitted genuine message 300 and a graph 800b for the received genuine message 300 are as shown in a section 801a in FIG. It increases with the same slope as time passes. Therefore, when attention is paid to the difference between the two graphs 800a and 800b, the difference 802a and the difference 802b between the sequence numbers at two different times are substantially equal. That is, in the section 801a, the change in the difference regarding the sequence number is almost zero.

  In the present embodiment, it is determined that the communication quality is good in the section 801a where the change in the difference between the sequence numbers is zero, and there is a grace period to increase the total number of messages transmitted per unit time. The generation frequency of 350 is increased. As a result, it becomes difficult for a third party to distinguish which message is the genuine message 300 worthy of analysis.

  On the other hand, if the communication quality deteriorates due to a large amount of communication or a communication failure, the game terminal 200 can receive the authentic message 300 at the frequency generated and transmitted by the opponent game terminal. Disappear. That is, at this time, as in a section 801b in FIG. 8, the graph 800b for the received genuine message 300 has a gentler slope than that in the section 801a. On the other hand, since the transmission frequency of the genuine message 300 is not changed, the difference between the graph 800a and the graph 800b is widened. Specifically, paying attention to the difference 802c and the difference 802d between the sequence numbers at two different times, the difference 802d at the later time is larger than the difference 802c at the previous time. That is, in the section 801b, the change in the difference in the sequence number has a value greater than zero.

  In this embodiment, when the value of the change in the sequence number difference increases in this way, it is determined that the communication quality deteriorates and it is necessary to suppress the total number of messages transmitted per unit time. Generation frequency is suppressed. Specifically, the game terminal 200 of the present embodiment prepares a predetermined threshold in advance, and the frequency with which the dummy message 350 is generated / transmitted when the change in the sequence number difference exceeds the predetermined threshold Is reduced.

  If the communication quality is restored as a result of the transmission frequency of the dummy message 350 being reduced, the reception frequency of the authentic message 300 again becomes almost the same as the transmission frequency. Specifically, as in a section 801c in FIG. 8, the graph 800a for the transmitted genuine message 300 and the graph 800b for the received genuine message 300 increase with the same slope as time passes. Return to state. At this time, the magnitudes of the difference between the sequence numbers 802e and 802f at two different times return to substantially the same. When the change in the difference regarding the sequence number returns to almost zero, it is determined that the grace period for increasing the total number of messages transmitted per unit time has been born again due to the recovery of the communication quality, and the dummy message 350 is generated and transmitted. The frequency is increased again.

  As described above, in this embodiment, paying attention to the change in the difference between the sequence number of the transmitted genuine message 300 and the sequence number of the received authentic message 300, while applying feedback so that the change in the difference becomes small, The generation frequency of the dummy message 350 is adjusted.

  Here, the sequence number of the authentic message 300 received “lastly” representing the graph 800b is received “the last among the consecutive authenticity messages 300 among the received authentic messages 300”. The order number for the item. In other words, the authentic message 300 received in a state where the order of generation / transmission by the opponent game terminal is changed or a message in the middle is missing is not immediately used for the update process and is not received yet. Are typically not included in the concept of the last received authentic message 300.

  FIG. 9 is a flowchart showing a flow of processing for adjusting the frequency of generating the dummy message 350 in the present embodiment. The processing flow of the game terminal 200 in the present embodiment as described above will be described with reference to FIG. The flowchart in FIG. 9 corresponds to the flowchart in FIG. 7 in the first embodiment, and corresponds to the process in step S607 in the flowchart of the entire process (FIG. 6). That is, the overall processing flow of the game terminal 200 in the present embodiment follows the flowchart in FIG. 6 (FIG. 6), but the processing in step S607 is unique.

  Specifically, the game terminal 200 in the present embodiment receives the message (step S603; YES), and if the received message is the authentic message 300 (step S605; YES), the dummy message is based on the communication quality. The generation frequency of 350 is adjusted (step S607), but in this embodiment, this adjustment process is different from that in the first embodiment. Therefore, in the present embodiment, the process of step S607 will be described with reference to FIG. 9 again.

  When this flowchart is started, first, the game terminal 200 acquires a difference in sequence number (step S901). That is, the difference between the sequence number of the genuine message 300 received last and the sequence number of the genuine message 300 transmitted last is acquired.

  Next, the game terminal 200 determines whether or not the change in the difference exceeds a threshold value (step S902). That is, for the difference between the acquired sequence numbers, the amount of change from the difference acquired so far is obtained, and it is determined whether or not it exceeds a threshold value prepared in advance in the RAM 103. Note that there may be a case where there is no difference between the sequence numbers that have been acquired so far, such as when the game is started, and a change in the difference cannot be acquired. In this case, it is determined that the threshold is not exceeded for convenience.

  If the threshold is not exceeded (step S902; NO), the dummy generation unit 203 increases the generation frequency of the dummy message 350 (step S903). That is, here, the current communication quality is good, and it is determined that there is no problem even if the total number of messages to be transmitted is increased, and the frequency with which the dummy generation unit 203 generates the dummy message 350 is increased.

  On the other hand, when the threshold value is exceeded (step S902; YES), the dummy generation unit 203 decreases the generation frequency of the dummy message 350 (step S904). That is, since the current communication quality is deteriorated, it is determined that the total number of messages to be transmitted should be reduced, and the frequency with which the dummy generation unit 203 generates the dummy message 350 is reduced.

  At this time, the dummy generation unit 203 also reduces the generation frequency of the dummy message 350 not only when the change in the sequence number difference exceeds the threshold value but also when the difference itself exceeds a certain threshold value. You may decide. In other words, when it is based only on the change in the difference, the communication quality is improved in a state where the deterioration in the communication quality is relatively mild and the change in the difference in the sequence number does not exceed the threshold. It wo n’t come off. However, when the difference in sequence numbers simply exceeds a certain threshold, the frequency of generation of the dummy message 350 is reduced, so that even when the communication quality deteriorates relatively mildly, Improvements can be made.

  As described above, when the generation frequency of the dummy message 350 is adjusted based on the difference of the sequence numbers between the transmitted and received genuine messages 300, the processing in this flowchart ends, and the processing of the game terminal 200 is the same as that in FIG. Return to the flowchart. That is, after that, the update unit 207 updates the game state (step S604), and generates and transmits the authentic message 300 at the timing when the authentic message 300 is generated (steps S608 to S610), and further transmits the dummy message 350. If it is time to generate, dummy message 350 is generated and transmitted (steps S611 to S613). Thereafter, the processing of the game terminal 200 returns to step S602, and the processing after step S602 is repeated.

  With this configuration, in the present embodiment, the dummy message unit 350 causes the dummy message generator 203 to reduce the change in the difference between the sequence number of the received genuine message 300 and the sequence number of the transmitted genuine message 300. The frequency of generating is changed. As a result, the game terminal 200 of the present embodiment transmits the message by mixing the dummy messages 350 while maintaining the communication balance by making the number of messages transmitted / received per unit time substantially the same. It is difficult for the person to analyze the message, and the game can proceed.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. In the second embodiment, the dummy generation unit 203 changes the generation frequency of the dummy message 350 so that the change in the difference between the sequence number of the received genuine message 300 and the sequence number of the transmitted genuine message 300 becomes small. I let you. On the other hand, the dummy generation unit 203 in the present embodiment changes the generation frequency of the dummy message 350 based not only on such a difference change value but also on a more general evaluation value.

  Specifically, the game terminal 200 of the present embodiment determines the difference z between the sequence number of the genuine message 300 received last and the sequence number of the genuine message 300 transmitted last, and the change v (= An evaluation function E (z, v) as shown in the following [Expression 1] having two values of dz / dt, that is, a change dz) of the difference per unit time dt is prepared.

  E (z, v) = a * z * z + b * v * v ... [Equation 1]

  Here, a and b are zero or more constants. That is, the evaluation function always returns a value of zero or more regardless of the difference between the sequence number difference z and the change in the difference v, and when both the sequence number difference z and the change in the difference v are close to zero. Returns a value close to zero.

  In the present embodiment, the frequency with which the dummy generation unit 203 generates the dummy message 350 is changed so that the evaluation value of the evaluation function E (z, v) is as small as possible. The smaller evaluation value means that both the sequence number difference z and the change v of the difference are small, that is, the total number of messages to be transmitted and received is substantially the same, and the number of messages to be transmitted and received per unit time is also substantially the same. It means that. Therefore, in this embodiment, while maintaining the balance of transmission / reception between the two game terminals 200, that is, for example, the ratio of the dummy message 350 in the transmission message is not increased so that the number of messages transmitted / received does not vary. In addition, the generation frequency of the dummy message 350 is adjusted. Specifically, this will be described with reference to the flowchart of FIG.

  FIG. 10 is a flowchart showing a flow of processing for adjusting the frequency of generating the dummy message 350 in the present embodiment. The flowchart in FIG. 10 corresponds to the flowchart in FIG. 7 in the first embodiment or the flowchart in FIG. 9 in the second embodiment, and corresponds to the process in step S607 in the flowchart of the entire process (FIG. 6). Is. That is, the overall process flow of the game terminal 200 in the present embodiment follows the flowchart (FIG. 6) in the first embodiment, but the process in step S607 is unique as in the second embodiment. Become.

  Specifically, the game terminal 200 in the present embodiment receives the message (step S603; YES), and if the received message is the authentic message 300 (step S605; YES), the dummy message is based on the communication quality. The generation frequency of 350 is adjusted (step S607), but in this embodiment, this adjustment process is different from that in the first embodiment. Therefore, in the present embodiment, the process of step S607 will be described with reference to FIG.

  When this flowchart is started, first, the game terminal 200 acquires a difference in sequence number (step S1001). That is, the difference between the sequence number of the genuine message 300 received last and the sequence number of the genuine message 300 transmitted last is acquired.

  Next, the game terminal 200 applies a predetermined evaluation function to the difference between the acquired sequence numbers and the change in the difference (step S1002). That is, the evaluation value is obtained by applying the evaluation function E (z, v) as shown in the above [Equation 1] to the difference z between the sequence numbers and the change v of the difference.

  And the game terminal 200 determines whether the acquired evaluation value became small (step S1003). That is, here, it is determined whether or not the acquired evaluation value is smaller than the evaluation value acquired so far. Note that there may be a case where there is no evaluation value acquired so far, such as at the start of a game. In this case, it is determined that the evaluation value has decreased for convenience.

  When the evaluation value becomes small (step S1003; YES), the dummy generation unit 203 changes the generation frequency of the dummy message 350 in the forward direction (step S1004). That is, if the generation frequency of the dummy message 350 has been increased until then, the frequency is further increased. On the other hand, if the generation frequency of the dummy message 350 has been decreased until then, the frequency is further decreased.

  On the other hand, when the evaluation value becomes large (step S1003; NO), the dummy generation unit 203 changes the generation frequency of the dummy message 350 in the reverse direction (step S1005). That is, if the generation frequency of the dummy message 350 has been increased until then, the switching is made to decrease, while if the generation frequency of the dummy message 350 has been reduced until then, the generation is switched to increase. .

  That is, in Steps S1003 to S1005, if the evaluation value becomes smaller as a result of increasing or decreasing the generation frequency of the dummy message 350, the change is continued as it is, and it is investigated whether a smaller evaluation value can be obtained. On the other hand, if the evaluation value becomes larger than before, the opposite change is made to prevent the evaluation value from further increasing. In this way, feedback is performed according to the variation in the magnitude of the evaluation value, and the generation frequency of the dummy message 350 is changed.

  When the generation frequency of the dummy message 350 is adjusted so that the evaluation value becomes small in steps S1003 to S1005, the processing in this flowchart is terminated, and the processing of the game terminal 200 returns to the flowchart in FIG. That is, after that, the update unit 207 updates the game state (step S604), and generates and transmits the authentic message 300 at the timing when the authentic message 300 is generated (steps S608 to S610), and further transmits the dummy message 350. If it is time to generate, dummy message 350 is generated and transmitted (steps S611 to S613). Thereafter, the processing of the game terminal 200 returns to step S602, and the processing after step S602 is repeated.

  With this configuration, in the present embodiment, the dummy generation unit 203 applies a predetermined evaluation function to the difference between the sequence number of the received genuine message 300 and the sequence number of the transmitted genuine message 300 and the change in the difference. The frequency of generating the dummy message 350 is changed so that the applied evaluation value becomes small. As a result, the game terminal 200 of the present embodiment transmits as much as possible while maintaining the communication balance by making the total number of messages to be transmitted and received substantially the same, and further making the number of messages to be transmitted and received per unit time substantially the same. The frequency of the dummy message 350 can be increased to make it difficult for a third party to analyze the message.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. In the above embodiment, the game is advanced by the two game terminals 200a and 200b communicating with each other about the game state. On the other hand, in this embodiment, one game terminal 200 and one server device advance a game by communicating with each other's game state.

  That is, this embodiment corresponds to the case where any one of the two game terminals 200a and 200b plays the role of a server device in the first to third embodiments. Here, one game terminal is used. The game progresses while the game state of the game played at 200 is communicated to and updated by server devices at different locations. In the present embodiment, in a game system in which the game state is communicated between such a game terminal 200 and the server device, the game progresses illegally because the game state being communicated is illegally rewritten by a third party. This is to prevent this from happening.

  FIG. 11 is a schematic diagram showing a schematic configuration according to the game system of the present embodiment. As shown in FIG. 11, the game system of this embodiment includes one game terminal 200 and one server device 1150. Such a game terminal 200 and the server device 1150 are typically realized by the information processing device 100 shown in FIG.

  11, the game terminal 200 includes a terminal-side storage unit 1101, a terminal-side authenticity generation unit 1102, a terminal-side dummy generation unit 1103, a terminal-side transmission unit 1104, a reception unit 1105, and a terminal-side reception unit 1106. The terminal side update unit 1107 is provided. Here, the game terminal 200 is equivalent to the game terminal 200 (200a, 200b) in the above-described embodiment, and its constituent elements are also equivalent to those shown in FIG. In order to distinguish from the components on the “server side”, here, for the sake of convenience, a prefix “terminal side” will be described.

  The terminal-side storage unit 1101 stores the game state of the game terminal 200 (hereinafter referred to as “terminal-side game state”). That is, the terminal-side storage unit 1101 is a storage area for storing various data necessary for the progress of the game being executed in the game system, and is realized by a function of the RAM 103, for example.

  The terminal-side authenticity generation unit 1102 generates a message (hereinafter referred to as “terminal-side authentic message”) that specifies the terminal-side game state stored in the terminal-side storage unit 1101. In other words, the terminal-side authenticity generation unit 1102 accesses the terminal-side storage unit 1101, acquires the stored game state, and generates a terminal-side authentic message including the acquired game state. Then, the generated terminal-side authentic message is supplied to a terminal-side transmitting unit 1104 described later.

  The terminal-side dummy generation unit 1103 generates a message (hereinafter referred to as “terminal-side dummy message”) that specifies discrimination information for discrimination from the generated terminal-side authentic message. That is, the terminal-side dummy generation unit 1103 acquires the game state stored in the terminal-side storage unit 1101 in the same manner as the terminal-side authenticity generation unit 1102, and generates a message. Here, the terminal-side authenticity message is imitated. Generate a dummy message on the terminal side. Then, the generated terminal-side dummy message is supplied to a terminal-side transmitting unit 1104 described later. Further, the terminal-side dummy generation unit 1103 changes the frequency of generating the terminal-side dummy message according to the communication quality with the server device 1150. That is, the current communication quality is acquired based on a message received by a terminal-side receiving unit 1106, which will be described later, and the frequency of generating a terminal-side dummy message is adjusted.

  The terminal-side transmitting unit 1104 transmits the generated terminal-side authentic message and the generated terminal-side dummy message to the server device 1150. That is, the terminal-side transmission unit 1104 sends the terminal-side authentic message supplied from the terminal-side authenticity generation unit 1102 and the terminal-side dummy message supplied from the terminal-side dummy generation unit 1103 to the server device 1150 via the network. Send.

  The accepting unit 1105 accepts an instruction from the player. That is, the reception unit 1105 receives various instructions for playing a game from a player. Then, the accepting unit 1105 supplies the accepted instruction to the terminal side updating unit 1107 described later.

  The terminal side receiving unit 1106 receives the message transmitted from the server device 1150. That is, the terminal-side receiving unit 1106 receives the server-side authentic message and the server-side dummy message generated and transmitted by the server device 1150. Then, it is determined whether the received message is a server-side genuine message or a server-side dummy message. For example, the server side genuine message and the server side dummy message are discriminated based on the checksum information of the transmission data. Further, the terminal-side receiving unit 1106 supplies the received message that has been determined as the server-side authentic message to the terminal-side updating unit 1107 described later.

  The terminal-side update unit 1107 is configured to store the terminal-side game stored in the terminal-side storage unit 1101 based on the server-side game state specified in the server-side authentic message among the received messages and the instruction received from the player. Update state. That is, the terminal-side update unit 1107 receives the instruction from the player supplied from the reception unit 1105 and the game state included in the server-side authentic message from the server device 1150 supplied from the terminal-side reception unit 1106. In order to reflect in the game state, the terminal-side storage unit 1101 is accessed to update the stored game state.

  On the other hand, the server device 1150 also includes the same components as the game terminal 200 in principle. However, unlike the game terminal 200, the server device 1150 does not receive an instruction from the player, and therefore does not include anything corresponding to the reception unit 1105. That is, the server device 1150 includes a server-side storage unit 1151, a server-side authenticity generation unit 1152, a server-side dummy generation unit 1153, a server-side transmission unit 1154, a server-side reception unit 1156, and a server-side update unit 1157. Each component has the following functions.

  The server-side storage unit 1151 stores a game state of the server device 1150 (hereinafter referred to as “server-side game state”). That is, the server-side storage unit 1151 is a storage area for storing various data necessary for the progress of the game being executed in the game system, and is realized by a function of the RAM 103, for example.

  The server-side authenticity generation unit 1152 generates a message (hereinafter referred to as “server-side authentic message”) that specifies the server-side game state stored in the server-side storage unit 1151. That is, the server-side authenticity generation unit 1152 accesses the server-side storage unit 1151, acquires the stored game state, and generates a server-side authentic message including the acquired game state. Then, the generated server-side authentic message is supplied to a server-side transmitting unit 1154 described later.

  The server-side dummy generation unit 1153 generates a message (hereinafter referred to as “server-side dummy message”) that specifies discrimination information for discrimination from the generated server-side authentic message. That is, the server-side dummy generation unit 1153 generates a message by acquiring the game state stored in the server-side storage unit 1151 in the same manner as the server-side authenticity generation unit 1152, but here the server-side authentic message is imitated. Generate a dummy message on the server side. Then, the generated server-side dummy message is supplied to a server-side transmission unit 1154 described later. Furthermore, the server-side dummy generation unit 1153 changes the frequency of generating the server-side dummy message according to the communication quality with the game terminal 200. That is, the current communication quality is acquired based on a message received by a server-side receiving unit 1156 described later, and the frequency of generating a server-side dummy message is adjusted.

  The server-side transmission unit 1154 transmits the generated server-side authentic message and the generated server-side dummy message to the game terminal 200. That is, the server-side transmitting unit 1154 sends the server-side authentic message supplied from the server-side authenticity generating unit 1152 and the server-side dummy message supplied from the server-side dummy generating unit 1153 to the game terminal 200 via the network. Send.

  Server-side receiving unit 1156 receives a message transmitted from game terminal 200. That is, the server side receiving unit 1156 receives the terminal side authentic message and the terminal side dummy message generated and transmitted by the game terminal 200. Then, it is determined whether the received message is a terminal side genuine message or a terminal side dummy message. For example, the terminal side genuine message and the terminal side dummy message are discriminated based on the checksum information of the transmission data. Further, the server-side receiving unit 1156 supplies the received message that has been determined as the terminal-side authentic message to the server-side updating unit 1157 described later.

  The server-side update unit 1157 updates the server-side game state stored in the server-side storage unit 1151 from the terminal-side game state specified in the terminal-side authentic message among the received messages. That is, the server-side update unit 1157 accesses the server-side storage unit 1151 in order to reflect the game state included in the terminal-side authentic message from the game terminal 200 supplied from the server-side receiving unit 1156 in its own game state. To update the stored game state.

  Here, both the terminal-side authentic message generated by the terminal-side authenticity generating unit 1102 of the game terminal 200 and the server-side authenticity message generated by the server-side authenticity generating unit 1152 of the server device 1150 are both shown in FIG. The configuration is the same as that of the genuine message 300 shown in FIG. That is, the terminal-side authentic message and the server-side authentic message include transmission order information 301T indicating the order number in which these messages are generated, reception order information 302T indicating the order number of the last message received, and an authentic message or dummy. Checksum information 303T for distinguishing between messages and data information 304T for designating the latest game state stored in the storage unit (terminal-side storage unit 1101 or server-side storage unit 1151).

  Furthermore, both the terminal-side dummy message generated by the terminal-side dummy generation unit 1103 of the game terminal 200 and the server-side dummy message generated by the server-side dummy generation unit 1153 of the server device 1150 are both shown in FIG. The same configuration as that of the dummy message 350 shown in FIG. That is, the terminal-side dummy message and the server-side dummy message are used to distinguish between transmission order information 301D imitating transmission order information 301T, reception order information 302D imitating reception order information 302T, and a genuine message or a dummy message. Checksum information 303D and data information 304D imitating data information 304T.

  Here, in the checksum information 303T of the terminal-side authentic message and the server-side authentic message, the data included in the data information 304T is regarded as a numerical value and the sum is obtained, as in the authentic message 300 of FIG. Things are included. On the other hand, in the checksum information 303D of the terminal side dummy message and the server side dummy message, intentionally erroneous checksum information is described as in the dummy message 350 of FIG. In other words, the game terminal 200 or the server device 1150 that has received the message again considers the data included in the data information as a numerical value and takes the sum, and if it matches the checksum information, the received message is the authentic message. If it is determined that the message is a terminal-side authentic message or a server-side authentic message, and if they do not match, it can be determined that the received message is a dummy message (terminal-side dummy message or server-side dummy message).

  As described above, in the game system of the present embodiment, the game terminal 200 and the server device 1150 advance the game by communicating the game state of each other while mixing the dummy message in the message to be transmitted and received. Thereby, the player who is playing the game with the game terminal 200 can play the game realized jointly with the remote server apparatus 1150 in an environment in which communication is difficult to be analyzed by a third party. .

  At that time, the game terminal 200 and the server device 1150 in the present embodiment measure the current communication quality and change the frequency of generating a dummy message accordingly. The communication quality at this time is typically measured by the degree to which the sequence numbers of received messages are continuous as in the first embodiment. The present invention is not limited to this, and the frequency of generating the dummy message is set so that the change in the difference between the received message sequence number and the transmitted message sequence number becomes small as in the second embodiment. It may be changed. Alternatively, as in the third embodiment, the dummy is set so that the evaluation value obtained by applying a predetermined evaluation function to the difference between the sequence number of the received message and the sequence number of the transmitted message and the change in the difference is small. You may change the frequency which produces | generates a message. This makes it difficult to analyze communications by a third party while adjusting the ratio of dummy messages so as to maintain the balance of communication quality.

  In the present embodiment, the components in the game terminal 200 described so far and the components in the server device 1150 are similar in principle, but they need to perform the same functions. They may have different functions.

  For example, the terminal-side updating unit 1107 and the server-side updating unit 1157 may distinguish the contents to be updated, and the contents of the game state specified and transmitted in the message may be different. Specifically, for example, the server-side update unit 1157 is responsible for updating the game state based on a predetermined scenario such as advancing a stage or advancing music playback, and from a player who moves a character, etc. The game update content is divided between the game terminal 200 and the server device 1150, for example, the terminal-side update unit 1107 is in charge of updating the game state based on the received instruction.

  In this case, for example, if the terminal side update unit 1107 is an action game in which a game is advanced by moving a character or attacking an enemy, the terminal-side updating unit 1107 is for moving the character or attacking an enemy. The game is progressed by reflecting the instruction from the player in the terminal-side game state. The terminal-side game state in which the instruction from the player is reflected is specified in the message and transmitted to the server device 1150 by the terminal-side transmission unit 1104.

  When the server side receiving unit 1156 receives the terminal side game state reflecting the instruction from the player, the server side updating unit 1157 updates the server side game state so that the instruction is reflected. In addition to updating the server-side game state based only on the received terminal-side game state information, for example, a predetermined progressing game such as advancing the stage or advancing music playback. The server-side game state is updated based on the scenario. The updated server-side game state is specified in the message and transmitted to the game terminal 200.

  Then, when the terminal-side receiving unit 1106 receives the server-side game state in which the predetermined scenario is reflected, the terminal-side updating unit 1107 updates the terminal-side game state so that the scenario is reflected again. At this time, if there is an instruction from the player, the terminal-side update unit 1107 further updates the terminal-side game state to reflect the instruction. As a result, the server apparatus 1150 is in charge of updating with a large load, and in the game terminal 200 on the player side that is often in an environment where resources that can be generally used are limited, it is possible to reduce the large update. be able to.

  FIG. 12 is a flowchart showing a process flow of the game terminal 200 according to the game system of the present embodiment. The flowchart shown in FIG. 12 is basically the same as the flowchart shown in FIG. 6 above, but in FIG. 6 the target for sending and receiving messages is the opponent game terminal. Here, the server device 1150 is the target for sending and receiving messages. Specifically, this will be briefly described below.

  First, when the game is started, the game terminal 200 of this embodiment performs various initialization processes (step S1201), and the reception unit 1105 of the game terminal 200 investigates an instruction from the player (step S1202). ). That is, it is investigated whether or not an instruction from the player is received by the controller 105 or the like.

  Next, it is determined whether the terminal side receiving unit 1106 of the game terminal 200 has received a message from the server device 1150 (step S1203).

  When the message is not received from the server apparatus 1150 (step S1203; NO), the terminal side update part 1107 updates the game state memorize | stored in the terminal side memory | storage part 1101 (step S1204). At this time, if an instruction from the player is accepted in step S1202, the terminal side update unit 1107 updates the game state by reflecting the instruction and advances the game.

  On the other hand, when a message is received from the server apparatus 1150 (step S1203; YES), the terminal side receiving unit 1106 determines whether or not the received message is a genuine message (step S1205). For example, the terminal-side receiving unit 1106 regards the data about the data information 304 in the message as a numerical value, obtains the sum, and checks whether or not it matches the attached checksum information 303. If they match, it is determined that the received message is a genuine message, and if they do not match, it is determined that the received message is a dummy message.

  When it is determined that the dummy message has been received (step S1205; NO), the terminal side receiving unit 1106 discards the dummy message received from the server device 1150, that is, the server side dummy message (step S1206), and then the terminal The side update unit 1107 updates the game state (step S1204).

  On the other hand, if it is determined that a genuine message has been received (step S1205; YES), the terminal-side dummy generation unit 1103 adjusts the generation frequency of the terminal-side dummy message generated by itself based on the communication quality ( In step S1207, based on the received server-side authentic message and the received instruction, the terminal-side update unit 1107 updates the game state (step S1204).

  Details of the process of adjusting the frequency of generating the terminal side dummy message in step S1207 are the same as the process shown in the flowchart of FIG. That is, the generation frequency of the terminal-side dummy message is adjusted based on the degree to which the sequence numbers of the received server-side genuine messages are consecutive. In the present invention, the processing here is not limited to this, and the change in the difference between the order number of the received message and the order number of the transmitted message is small as in the flowchart of FIG. 9 in the second embodiment. As described above, the frequency of generating the dummy message may be changed. Alternatively, as shown in the flowchart of FIG. 10 in the third embodiment, the evaluation value obtained by applying a predetermined evaluation function to the difference between the order number of the received message and the order number of the transmitted message and the change in the difference is small. As described above, the frequency of generating the dummy message may be changed.

  Thereafter, the game terminal 200 determines whether or not the present time is the timing for generating a genuine message (step S1208). If the current time is the timing for generating a genuine message (step S1208; YES), the terminal-side authenticity generating unit 1102 generates a terminal-side authentic message (step S1209), and the terminal-side transmitting unit 1104 sends to the server device 1150. The generated terminal-side authentic message is transmitted (step S1210). On the other hand, if it is not the time to generate an authentic message (step S1208; NO), the process proceeds to step S1211 without passing through such a terminal-side authentic message generation / transmission process.

  Furthermore, the game terminal 200 determines whether or not the present time is a timing for generating a dummy message (step S1211). If the current time is the timing for generating a dummy message (step S1211; YES), the terminal-side dummy generation unit 1103 generates a terminal-side dummy message (step S1212), and the terminal-side transmission unit 1104 sends to the server device 1150. The generated terminal side dummy message is transmitted (step S1213). On the other hand, if the current timing is not the timing for generating a dummy message (step S1211; NO), the process returns to step S1202 without passing through such a terminal-side dummy message generation / transmission process.

  Thereafter, the processing of the game terminal 200 that has returned to step S1202 repeats the processing after step S1202. That is, the game terminal 200 updates the game state based on the instruction from the player and the received server-side authentic message, generates and transmits a terminal-side authentic message including the updated game state at a predetermined timing, and further, Generate and send terminal-side dummy messages at a frequency. The game terminal 200 advances the game while repeating such processing.

  Further, FIG. 13 is a flowchart showing a processing flow of the server device 1150 according to the game system of the present embodiment. In principle, the flowchart shown in FIG. 13 is obtained by replacing the relationship between the game terminal 200 and the server device 1150 with respect to the flowchart of the game terminal 200 of FIG. Specifically, this will be briefly described below.

  First, the server device 1150 of this embodiment performs various initialization processes when a game is started (step S1301). Thereafter, in the process of the game terminal 200 in FIG. 12, a process for investigating an instruction from the player is performed. However, since the server apparatus 1150 does not have a reception unit, there is no corresponding process in this flowchart.

  Next, the server-side receiving unit 1156 of the server device 1150 determines whether a message has been received from the game terminal 200 (step S1303).

  When the message is not received from the game terminal 200 (step S1303; NO), the server side update unit 1157 updates the game state stored in the server side storage unit 1151 (step S1304). At this time, since the server device 1150 does not accept an input from the outside, the server-side update unit 1157 updates the game state stored in the server storage unit 1151 in accordance with a game scenario prepared in advance, and plays the game. Will proceed.

  On the other hand, when a message is received from the game terminal 200 (step S1303; YES), the server side receiving unit 1156 determines whether or not the received message is a genuine message (step S1305). For example, the server-side receiving unit 1156 obtains the sum by regarding the data about the data information 304 in the message as a numerical value, and checks whether or not it matches the attached checksum information 303. If they match, it is determined that the received message is a genuine message, and if they do not match, it is determined that the received message is a dummy message.

  If it is determined that a dummy message has been received (step S1305; NO), the server-side receiving unit 1156 discards the dummy message received from the game terminal 200, that is, the terminal-side dummy message (step S1306), and then the server The side update unit 1157 updates the game state (step S1304).

  On the other hand, if it is determined that a genuine message has been received (step S1305; YES), the server-side dummy generator 1153 adjusts the generation frequency of the server-side dummy message generated by itself based on the communication quality ( In step S1307), based on the received terminal-side authentic message, the server-side update unit 1157 updates the game state (step S1304).

  The details of the processing for adjusting the generation frequency of the server side dummy message in step S1307 are the same as the processing shown in the flowchart of FIG. That is, the generation frequency of the server side dummy message is adjusted based on the degree to which the sequence numbers of the received terminal side genuine messages are consecutive. In the present invention, the processing here is not limited to this, and the change in the difference between the order number of the received message and the order number of the transmitted message is small as in the flowchart of FIG. 9 in the second embodiment. As described above, the frequency of generating the dummy message may be changed. Alternatively, as shown in the flowchart of FIG. 10 in the third embodiment, the evaluation value obtained by applying a predetermined evaluation function to the difference between the order number of the received message and the order number of the transmitted message and the change in the difference is small. As described above, the frequency of generating the dummy message may be changed.

  Thereafter, the server apparatus 1150 determines whether or not the present time is the timing for generating a genuine message (step S1308). When the current time is the timing for generating the authentic message (step S1308; YES), the server-side authenticity generating unit 1152 generates a server-side authentic message (step S1309), and the server-side transmitting unit 1154 sends the game terminal 200 to the game terminal 200. The generated server-side authentic message is transmitted (step S1310). On the other hand, if it is not the time to generate a genuine message (step S1308; NO), the process moves to step S1311 without passing through such server-side genuine message generation / transmission processing.

  Further, the server apparatus 1150 determines whether or not the present time is a timing for generating a dummy message (step S1311). If the current timing is to generate a dummy message (step S1311; YES), the server-side dummy generation unit 1153 generates a server-side dummy message (step S1312), and the server-side transmission unit 1154 sends to the game terminal 200, The generated server side dummy message is transmitted (step S1313). On the other hand, if the current timing is not the timing for generating a dummy message (step S1311; NO), the process returns to step S1303 without passing through such a server-side dummy message generation / transmission process.

  Thereafter, the processing of the server device 1150 that has returned to step S1303 repeats the processing after step S1303. That is, the server device 1150 updates the game state based on the instruction from the player and the received terminal-side authentic message, generates and transmits a server-side authentic message including the updated game state at a predetermined timing, Server-side dummy messages are also generated and transmitted at a frequency. The server device 1150 advances the game while repeating such processing.

  With such a configuration, in the game system of this embodiment, the game terminal 200 and the server device 1150 advance the game by communicating each other's game state while mixing a dummy message in a message to be transmitted and received. At that time, the game terminal 200 and the server device 1150 acquire the current communication quality and change the frequency of generating a dummy message accordingly. As a result, the game system of the present embodiment provides a game that is realized in an environment in which communication is difficult to be analyzed by a third party while maintaining a balance of communication quality between the game terminal 200 and the server device 1150. can do.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described. In the game system according to the fourth embodiment, one game terminal 200 and one server device 1150 advance the game by communicating the game state of each other. On the other hand, the game system according to the present embodiment further develops the fourth embodiment, and the two game terminals 200a and 200b communicate with each other via the one server device 1150 to play a game. To advance. Such a game system can be used, for example, in a game in which two players battle each other. Specifically, this will be described below with reference to FIG.

  FIG. 14 is a diagram illustrating a state in which two game terminals 200a and 200b communicate via one server device 1150 in the game system of the present embodiment. In FIG. 14, two game terminals 200a and 200b are operated by different players A and B, respectively, and instructions are input. The game terminal 200a exchanges messages with the server device 1150 via the network, and the game terminal 200b exchanges messages with the server device 1150 via the network. In other words, in the present embodiment, the game system according to the fourth embodiment, which includes one game terminal 200 and one server device 1150 in each of the game terminal 200a and the server device 1150, and the game terminal 200b and the server device 1150, respectively. Can be seen as being realized.

  Specifically, each of the game terminals 200a and 200b updates the stored game state from the instruction received from the player A and the player B and the server-side authentic message received from the server device 1150. Then, a terminal-side authentic message designating the updated game state is generated and transmitted to the server device 1150.

  At this time, each of the game terminals 200a and 200b generates a terminal-side dummy message at a frequency corresponding to the communication quality with the server device 1150 in order to make it difficult to analyze communication from a third party, and authenticate the terminal-side authenticity. The message is transmitted to the server apparatus 1150 together with the message.

  On the other hand, the server apparatus 1150 updates the stored game state based on the terminal-side authentic message received from each of the two game terminals 200a and 200b, and generates a server-side authentic message that designates the updated game state. And it transmits to each game terminal 200a, 200b.

  At this time, the server device 1150 also generates a server-side dummy message at a frequency according to the communication quality with each game terminal 200a, 200b in order to make it difficult to analyze communication from a third party, It transmits to each game terminal 200a, 200b with a side authentic message. At that time, since the communication quality with the game terminal 200a and the communication quality with the game terminal 200b are not necessarily the same, the server device 1150 measures the communication quality corresponding to each, and the frequency corresponding to each. Thus, a server-side dummy message is generated and transmitted to the game terminals 200a and 200b.

  With such a configuration, in the game system according to the present embodiment, the two game terminals 200a and 200b communicate with each other the game state via a single server device 1150 while mixing dummy messages into messages to be transmitted and received. Then, let the game progress. At that time, the game terminals 200a and 200b and the server device 1150 acquire the current communication quality and change the frequency of generating the dummy message accordingly. As a result, the game system of the present embodiment is a game that is realized in an environment in which communication is difficult to be analyzed by a third party while maintaining the balance of communication quality between the game terminals 200a and 200b and the server device 1150. Can be provided.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation and application are possible. Moreover, it is also possible to freely combine the constituent elements of the above-described embodiments.

  For example, in the above embodiment, the game terminal 200 distinguishes whether the received message is the genuine message 300 or the dummy message 350 using the checksum information 303. On the other hand, in addition to this, it may be distinguished whether the received message is the genuine message 300, the dummy message 350, or neither.

  More specifically, for example, for the authentic message 300, the remainder obtained by dividing the sum of the data in the data information 304T by 8 is the checksum information 303T, and for the dummy message 350, the sum of the data in the data information 304D is 8. The check sum information 303D is obtained by adding 1 to the remainder. The game terminal 200 that has received the message with the checksum information 303 takes the sum of the data information 304 again, obtains the remainder divided by the sum 8, and then adds the checksum information 303 attached. Compare with As a result, if the attached checksum information 303 is equal to the acquired remainder, it is determined that the received message is the genuine message 300, and the attached checksum information 303 is obtained by adding 1 to the acquired remainder. If so, it is determined that the received message is a dummy message 350.

  On the other hand, in other cases, that is, when the attached checksum information 303 is obtained by adding any value from 2 to 7, the received message is the authentic message 300 and It is determined that none of the dummy messages 350 are present. That is, this corresponds to a case where a message is broken during communication due to an attack by a third party or a failure in a transmission path. By adopting such a configuration, the game terminal 200 can check not only whether the received message is genuine or dummy, but also whether the message has been received correctly without being broken during communication.

  Further, the game terminal 200 may distinguish the message from the authentic message 300 by adding a unique symbol or the like to the dummy message 350 without using the checksum information 303. Alternatively, as in the checksum information 303, the game terminal 200 is not limited to taking the sum of the data included in the data information 304, and the game terminal 200 takes the product or average of the data included in the data information 304 and The message 300 and the dummy message 350 may be distinguished.

  In the above embodiment, the dummy generation unit 203 changes the generation frequency of the dummy message 350 based on the transmission order information 301T attached to the transmitted and received genuine message 300. On the other hand, in addition to this, the reception order information 302T attached to the authentic message 300 may be referred to.

  That is, since the reception order information 302T represents the transmission order information 301T attached to the last authentic message 300 correctly received by the receiving unit 206 of the opponent game terminal, by referring to the reception order information 302T, It is possible to obtain an index of how correctly the genuine message 300 transmitted by the game terminal 200 of the player reaches the opponent game terminal. Therefore, for example, the difference between the order number of the reception order information 302T attached to the received genuine message 300 and the order number of the transmission order information 301T attached to the transmitted genuine message 300 is a good communication quality. As long as you can communicate correctly with, it should be within a certain difference. Here, the difference may be incorporated into the evaluation function as an index of communication quality, and the dummy generation unit 203 may change the generation frequency of the dummy message 350 based on the evaluation value.

  Moreover, in the said Embodiment 1-3, the two game terminals 200a and 200b advanced the game by communicating each other's game state. On the other hand, the number of game terminals 200 is not limited to two and may be three or more. That is, the present invention can be applied to a game system in which a game progresses by communicating a game state between one of the three or more game terminals 200 and the other game terminal 200. It is.

  For example, three game terminals 200, that is, a game terminal A, a game terminal B, and a game terminal C are provided, of which a game terminal A and a game terminal B, a game terminal B and a game terminal C, a game terminal C and a game terminal A, respectively. In the case of a game that progresses by communicating the game state of each other, the game terminal A and game terminal B, the game terminal B and game terminal C, and the game terminal C and game terminal A, respectively. Thus, the configurations in the first to third embodiments are realized. Further, when the number of game terminals 200 is further increased to four or more, only the combinations that can realize the configurations in the first to third embodiments are increased, and the same can be considered.

  Moreover, in the said Embodiments 4-5, the game was advanced by one or two game terminals 200 and one server apparatus 1150 communicating each other's game state. On the other hand, the number of game terminals 200 is not limited to these, and may be three or more. That is, the present invention can be applied to a game system in which three or more game terminals 200 advance a game by communicating with each other via the one server device 1150.

  For example, in the case of a game in which three game terminals 200, game terminal A, game terminal B, and game terminal C, advance by communicating with each other one game apparatus 1150, game terminal A and server In each of the device 1150, the game terminal B and the server device 1150, and the game terminal C and the server device 1150, the configuration in the fourth embodiment is realized. Further, when the number of game terminals 200 is further increased to four or more, only the combinations that can realize the configuration in the fourth embodiment are increased, and the same can be considered.

  In such an embodiment using three or more game terminals 200, different players correspond to each of the three or more game terminals 200, and each player advances the game while inputting an instruction. This is effective in realizing a game, that is, an online game in which, for example, a team is formed with a large number of people and a scenario is advanced.

  As described above, according to the present invention, in a game system that progresses a game by communicating a game state, a game terminal, a game system, and a game terminal control method suitable for making communication analysis difficult, In addition, a program can be provided.

100 Information processing apparatus 101 CPU
102 ROM
103 RAM
104 Interface 105 Controller 106 External Memory 107 Image Processing Unit 108 DVD-ROM Drive 109 NIC
110 voice processing unit 200 (200a, 200b) game terminal 201 (201a, 201b) storage unit 202 (202a, 202b) authenticity generation unit 203 (203a, 203b) dummy generation unit 204 (204a, 204b) transmission unit 205 (205a, 205b) Reception unit 206 (206a, 206b) Reception unit 207 (207a, 207b) Update unit 300 Authentic message 301 (301T, 301D) Transmission order information 302 (302T, 302D) Reception order information 303 (303T, 303D) Checksum information 304 (304T, 304D) Data information 350 Dummy message 800 (800a, 800b) Graph 801 (801a to 801c) Section 802 (802a to 802f) Difference 1101 Terminal side storage unit 1102 Terminal side authenticity Generation unit 1103 Terminal side dummy generation unit 1104 Terminal side transmission unit 1105 Reception unit 1106 Terminal side reception unit 1107 Terminal side update unit 1150 Server device 1151 Server side storage unit 1152 Server side genuine generation unit 1153 Server side dummy generation unit 1154 Server side transmission Part 1156 server side receiving part 1157 server side updating part

Claims (9)

A game terminal in a game system in which a game progresses by communicating game states of each other,
A storage unit for storing a game state of the game terminal;
An authenticity generating unit for generating a message (hereinafter referred to as “authentic message”) for designating a game state stored in the storage unit;
A dummy generation unit that generates a message (hereinafter referred to as “dummy message”) that specifies discrimination information for discrimination from the generated genuine message;
A transmission unit for transmitting the generated genuine message and the generated dummy message to another game terminal;
A reception unit that receives instructions from the player,
A receiving unit for receiving a message transmitted from the other game terminal;
An update unit for updating the game state stored in the storage unit from the game state of the other game terminal designated as a genuine message among the received messages and the received instruction;
The said dummy production | generation part changes the frequency which produces | generates the said dummy message according to communication quality with said other game terminal. The game terminal characterized by the above-mentioned. The game terminal according to claim 1,
The authentic message is attached with order information indicating the order number in which the authentic message is generated,
The communication quality with the other game terminal is measured by the degree to which the sequence numbers represented by the sequence information attached to the genuine message among the received messages are continuous. The game terminal according to claim 2,
The dummy generation unit is represented by a sequence number represented by the sequence information attached to the last genuine message of the received messages and the sequence information attached to the last authentic message of the transmitted messages. The game terminal is characterized in that the frequency of generating the dummy message is changed so that the change in the difference between the generated order number and the order number is reduced. The game terminal according to claim 2,
The dummy generation unit is represented by a sequence number represented by the sequence information attached to the last genuine message of the received messages and the sequence information attached to the last authentic message of the transmitted messages. A game terminal, wherein the frequency of generating the dummy message is changed so that an evaluation value obtained by applying a predetermined evaluation function to a difference between the sequence number and a change in the difference is reduced. The game terminal according to any one of claims 1 to 4,
The storage unit stores a history of the game state,
Any one of game states included in the stored history is specified in the dummy message. The game terminal according to claim 5,
The game state includes checksum information, the generated genuine message specifies correct game state checksum information, and the generated dummy message specifies incorrect game state checksum information. A game terminal characterized by being played. A game system in which a game terminal and a server device advance a game by communicating each other's game state,
(A) The game terminal
A terminal-side storage unit in which a game state of the game terminal (hereinafter referred to as “terminal-side game state”) is stored;
A terminal-side authenticity generating unit that generates a message (hereinafter referred to as “terminal-side authentic message”) that specifies the terminal-side game state stored in the terminal-side storage unit;
A terminal-side dummy generation unit that generates a message (hereinafter referred to as “terminal-side dummy message”) that specifies discrimination information for discrimination from the generated terminal-side authentic message;
A terminal-side transmitter that transmits the generated terminal-side authentic message and the generated terminal-side dummy message to the server device;
A reception unit that receives instructions from the player,
A terminal-side receiving unit that receives a message transmitted from the server device;
The terminal-side dummy generation unit changes the frequency of generating the terminal-side dummy message according to the communication quality with the server device,
(B) The server device
A server-side storage unit that stores a game state of the server device (hereinafter referred to as a “server-side game state”);
A server-side authenticity generation unit that generates a message (hereinafter referred to as “server-side authenticity message”) that specifies the server-side game state stored in the server-side storage unit;
A server-side dummy generating unit that generates a message (hereinafter referred to as “server-side dummy message”) that specifies discrimination information for discrimination from the generated server-side authentic message;
A server-side transmitter that transmits the generated server-side authentic message and the generated server-side dummy message to the game terminal;
A server-side receiving unit for receiving a message transmitted from the game terminal;
The server-side dummy generation unit changes the frequency of generating the server-side dummy message according to the communication quality with the game terminal,
(C) The game terminal
The terminal side that updates the terminal-side game state stored in the terminal-side storage unit from the server-side game state specified in the server-side authentic message among the received messages and the received instruction. An update unit,
(D) The server device
A server-side update unit that updates the server-side game state stored in the server-side storage unit from the terminal-side game state specified in the terminal-side authentic message among the received messages. Game system to play. A game terminal that provides a game in a game system in which game terminals advance a game by communicating game states with each other, and includes a storage unit, a genuine generation unit, a dummy generation unit, a transmission unit, a reception unit, a reception unit, and an update unit Is a control method executed by
The storage unit stores a game state of the game terminal,
A authenticity generating step in which the authenticity generating unit generates a message (hereinafter referred to as “authentic message”) that specifies a game state stored in the storage unit;
A dummy generation step in which the dummy generation unit generates a message (hereinafter referred to as “dummy message”) for specifying discrimination information for discrimination from the generated genuine message;
A transmitting step in which the transmitting unit transmits the generated genuine message and the generated dummy message to another game terminal;
A receiving step in which the receiving unit receives an instruction from a player;
A receiving step in which the receiving unit receives a message transmitted from the other game terminal;
The update unit updates the game state stored in the storage unit from the game state of the other game terminal designated as a genuine message among the received messages and the received instruction. With an update process,
In the dummy generation step, the dummy generation unit changes the frequency of generating the dummy message according to the communication quality with the other game terminal. A program for causing a computer to function as a game terminal in a game system in which a game terminal advances a game by communicating the game state of each other,
The program causes the computer to
A storage unit for storing a game state of the game terminal;
An authenticity generating unit for generating a message (hereinafter referred to as “authentic message”) for designating a game state stored in the storage unit;
A dummy generation unit that generates a message (hereinafter referred to as “dummy message”) that specifies discrimination information for discrimination from the generated genuine message;
A transmission unit for transmitting the generated genuine message and the generated dummy message to another game terminal;
A reception unit that receives instructions from the player,
A receiving unit for receiving a message transmitted from the other game terminal;
Based on the game state of the other game terminal designated as a genuine message in the received message and the received instruction, the update unit updates the game state stored in the storage unit. ,
The dummy generation unit functions to change the frequency of generating the dummy message according to communication quality with the other game terminal.

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