Media file anti-hotlinking method, system, server and storage medium

Abstract

The application provides a media file anti-linking method, system, server and storage medium. Whether the received request for obtaining a media file is a legal request of a user is judged through an authentication token. After determining that the request is a legal request, a new authentication token is generated, and an old authentication token is invalidated. Then, a uniform resource locator capable of obtaining the media file with the new authentication token is sent to the user, so that the user obtains the media file and the new authentication token. Furthermore, in order to prevent a link thief from obtaining the new authentication token by intercepting the uniform resource locator, the new authentication token is encrypted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Internet security, and particularly relates to a media file anti-linking method and system, a server and a storage medium. BACKGROUND

[0002] In the related art, when performing anti-linking processing on a media file, an additional field (such as a timestamp) is added to a uniform resource locator (URL) corresponding to the media file to prevent link theft. However, in this encryption method, the additional field is displayed in plaintext, and the security is still low. With the development of Internet technology, the means of link theft has also developed, and the above anti-linking measures of the related art are easily cracked by link thieves. SUMMARY

[0003] Therefore, the present application aims to provide a media file anti-linking method, system, server and storage medium.

[0004] To achieve the above purpose, the present application provides a media file anti-linking method, comprising:

[0005] receiving a request for obtaining a media file sent by a user, wherein the request comprises a username, a password and a first authentication token previously sent to the user;

[0006] comparing the username, the password and the first authentication token with reference data previously stored in a database;

[0007] in response to determining that the username, the password and the first authentication token respectively match the corresponding reference data, generating a second authentication token of the user according to a pre-set authentication token generation rule;

[0008] replacing the first authentication token in the database with the second authentication token;

[0009] encrypting the second authentication token according to a pre-set encryption rule to obtain an encrypted second authentication token;

[0010] sending a uniform resource locator corresponding to the media file to the user to enable the user to obtain the media file, wherein the uniform resource locator comprises the encrypted second authentication token.

[0011] The present application also provides a media file anti-linking system, comprising:

[0012] a request receiving module configured to receive a request for obtaining a media file sent by a user, wherein the request comprises a username, a password and a first authentication token previously sent to the user;

[0013] a database module configured to store reference data of the username, the password and the first authentication token;

[0014] a data comparison module configured to compare the username, the password, and the first authentication token with reference data;

[0015] an authentication token generation module configured to generate a second authentication token corresponding to the user according to a preset authentication token generation rule;

[0016] a data rewriting module configured to replace the first authentication token in the database with the second authentication token;

[0017] a data encryption module configured to encrypt the second authentication token according to a preset encryption rule to obtain an encrypted second authentication token;

[0018] a uniform resource locator sending module configured to send a uniform resource locator corresponding to the media file to the user, so that the user obtains the media file, wherein the uniform resource locator comprises the encrypted second authentication token.

[0019] The application further provides a server, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the above method when executing the program.

[0020] The application further provides a non-transitory computer readable storage medium, which stores computer instructions for causing a computer to execute the above method.

[0021] As can be seen from the above, the media file anti-linking method, system, server, and storage medium provided by the application determine whether the received request for obtaining the media file is a legal request of the user through the authentication token, generate a second authentication token (new authentication token) and invalidate the first authentication token (old authentication token) after determining that the request is a legal request, then send a uniform resource locator capable of obtaining the media file with the second authentication token to the user, so that the user obtains the media file and the second authentication token. Moreover, in order to prevent the linkers from obtaining the second authentication token by intercepting the uniform resource locator, the second authentication token is encrypted. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The flowchart of the media file anti-linking method of the embodiment of the application.

[0024] Figure 2A structural schematic diagram of a media file anti-linking system according to an embodiment of the present application.

[0025] Figure 3 A hardware structural schematic diagram of a server according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] To make the objects, technical solutions, and advantages of the present application clearer, the present application will be described in further detail below with reference to the embodiments and accompanying drawings.

[0027] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be understood as their common meanings to those having ordinary skills in the art to which the present application pertains. The terms such as "comprise" or "include" mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms such as "connect" or "connected" do not mean physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0028] With the development of multimedia technology and Internet technology, people can conveniently play media files (such as videos and audios) through the network. However, in the process of searching for media files, people will find that some media files are paid resources in the regular playing way. At this time, some people will search for free and irregular playing ways, i.e. pirate websites, in order to avoid paying while playing media files.

[0029] These pirate websites usually set a large number of advertisements in the pages, attract users to visit through free playing of media files stolen by the link, and make a profit by earning advertising fees. Therefore, these pirate websites affect the interests of the regular playing way, occupy the bandwidth and network speed of the regular playing way, and affect the operation of the regular playing way.

[0030] In order to prevent pirate websites from linking, the related technology performs anti-linking processing on media files, and adds an additional field (such as a timestamp) in the uniform resource locator corresponding to the media file to prevent linking. However, in this encryption method, the additional field is displayed in plaintext, and the security is still low. Moreover, with the development of Internet technology, the linking means has also been developed, and the above anti-linking measures of the related technology are extremely easy to be cracked by linkers.

[0031] Based on the low security and the ease of cracking of the above anti-linking method of the related technology, the embodiments of the present application provide a media file anti-linking method, system, server, and storage medium.

[0032] The media file anti-hotlinking method, system, server, and storage medium provided in this application determine whether a received request to obtain media files is a legitimate request from a user through an authentication token.

[0033] After a request is deemed legitimate, a second authentication token (the new authentication token) is generated, and the first authentication token (the old authentication token) is invalidated. Then, a Uniform Resource Locator (URL) containing the second authentication token, enabling the user to access the media file, is sent to them, allowing the user to obtain the media file and the second authentication token. Furthermore, to prevent hotlinkers from obtaining the second authentication token by intercepting the URL, the second authentication token is encrypted.

[0034] Figure 1 This diagram illustrates a flowchart of the method for creating a production report template provided in an embodiment of this application. Figure 1 As shown, this application provides a method for preventing hotlinking of media files, including:

[0035] Receive a request from a user to retrieve media files, wherein the request may include the user's username, password, and a first authentication token pre-sent to the user.

[0036] The username, password, and first authentication token are compared with reference data pre-stored in the database.

[0037] 5. In this embodiment, the media file can be an encrypted file, for example, one encrypted using FFmpeg.

[0038] The file is segmented and encrypted using the AES algorithm (Advanced Encryption Standard).

[0039] In this way, the user's identity can be determined by their username and password, and the first authentication token can be used to verify whether the request is a legitimate request from the user, preventing hot-chain thieves from stealing the username and password of legitimate users and then impersonating them to make requests.

[0040] A response of 0 indicates that any one of the username, password, or first authentication token differs from the reference data.

[0041] Request denied.

[0042] In this way, by comparing the username, password, and first authentication token to reference data stored in the database (e.g., identical, or with a fixed difference), it can be determined whether the request belongs to a legitimate user.

[0043] A legitimate request is considered valid. If any one of the three is different from the reference data, the request is deemed invalid, the request is rejected, and the media file is not provided to the user.

[0044] In response to determining that the username, the password and the first authentication token match the reference data, a second authentication token of the corresponding user is generated according to a preset authentication token generation rule.

[0045] In the embodiment, whether the username, the password and the first authentication token match the reference data in the database is compared to determine whether the request is a legal request of a legal user.

[0046] When the three match the reference data respectively, it is determined that the request is a legal request, and the request is received. After determining to receive the request, a new authentication token, i.e., a second authentication token, used for a next legal request of the user is generated.

[0047]

[0048] In a specific implementation, the second authentication token can be generated by a hash algorithm (for example, an MD5 algorithm (Message Digest Algorithm) or an SHA algorithm (Secure Hash Algorithm)). For example, the username, the password and the first authentication token of the user are spliced in sequence to obtain a string, and the hash algorithm is calculated on the string to obtain the second authentication token.

[0049] The first authentication token in the database is replaced by the second authentication token.

[0050] In this way, the old authentication token is invalidated immediately after the old authentication token takes effect, and the authentication token obtained by the link thief after intercepting the legal request is prevented from being used to pretend legal access.

[0051] The second authentication token is encrypted according to a preset encryption rule to obtain an encrypted second authentication token.

[0052] In this way, the second authentication token is encrypted to prevent the link thief from directly obtaining the second authentication token and using the second authentication token to pretend legal access when the second authentication token is intercepted in the process of sending the second authentication token.

[0053] The uniform resource locator corresponding to the media file is sent to the user to enable the user to obtain the media file, wherein the uniform resource locator includes the encrypted second authentication token.

[0054] In this way, the second authentication token and the media file are sent to the user through the uniform resource locator, so that the user can play the media file and use the second authentication token for authentication comparison when making a media file obtaining request next time.

[0055] As an optional embodiment, in the anti-link theft method of the embodiment 1, the encrypted second authentication token is obtained by encrypting the second authentication token according to a preset encryption rule, and the encryption rule includes:

[0056] ​In the at least one encryption rule arranged in the preset order, one encryption rule is randomly selected as a target encryption rule, and a serial number of the target encryption rule in the arrangement is obtained.

[0057] In the embodiment, the serial number of the encryption rule and the encryption key corresponding to each encryption rule are stored in the database, and the serial number of the encryption rule and the decryption key corresponding to each encryption rule are stored in the device of the user.

[0058] In this way, different encryption rules can be used for encryption, improving the complexity of encryption and the difficulty of encryption cracking by a pirate.

[0059] The second authentication token is encrypted according to the target encryption rule.

[0060] In the embodiment, the encryption rule can include a symmetric encryption algorithm and an asymmetric encryption algorithm, such as a DES algorithm (Data Encryption Standard algorithm), a 3DES algorithm (Triple Data Encryption Standard algorithm), an RSA algorithm, and an ECC algorithm (Elliptic Curve Cryptography algorithm). The encryption rule is not limited in the embodiment.

[0061] The serial number is spliced into the encrypted second authentication token to obtain an encrypted second authentication token.

[0062] In the embodiment, by splicing the serial number into the second authentication token, the user obtains the serial number of the encryption rule when receiving the encrypted second authentication token, so as to use the corresponding decryption key for decryption to obtain the actual second authentication token.

[0063] In the implementation, the serial number can be spliced into the head of the encrypted second authentication token, or spliced into the tail of the encrypted second authentication token, or spliced into a fixed position in the middle of the encrypted second authentication token (for example, the 5th position from the head), and the splicing position is not limited in the embodiment.

[0064] In this way, after the user's device parses the encrypted second authentication token from the received uniform resource locator, the serial number of the encryption rule can be extracted from the encrypted second authentication token, and the corresponding decryption key is selected according to the serial number to decrypt the remaining part (i.e., the encrypted second authentication token) in the encrypted second authentication token, to obtain the actual second authentication token.

[0065] As an optional embodiment, in the anti-piracy method of the embodiment 2, after the second authentication token is encrypted according to the pre-set encryption rule, the anti-piracy method further includes generating a random number and splicing it into the encrypted second authentication token.

[0066] In a specific implementation, a random number of a fixed number of bits can be generated, such as a 2-bit, 3-bit, or 4-bit hexadecimal random number. Then, the random number can be spliced into a fixed position of the encrypted second authentication token, such as the head, tail, or middle of the encrypted second authentication token. The number of bits of the random number and the splicing position are not limited in the embodiments of the present application.

[0067] In this way, the encrypted second authentication token is complicated by splicing the random number into the encrypted second authentication token, thereby increasing the difficulty of the pirate to parse the actual second authentication token from the encrypted second authentication token.

[0068] As an optional embodiment, in the anti-piracy method of Embodiment 3 of the present application, after the second authentication token is encrypted according to the pre-set encryption rule, the anti-piracy method further includes:

[0069] determining the length of the encrypted second authentication token.

[0070] In response to determining that the length of the encrypted second authentication token is less than the pre-set threshold, a random number is generated and spliced into the encrypted second authentication token, so that the length of the spliced string meets the pre-set threshold.

[0071] In this embodiment, the shortest number of bits of the encrypted second authentication token is limited by setting the pre-set threshold.

[0072] In a specific implementation, the pre-set threshold can be a 20-bit hexadecimal number, a 25-bit hexadecimal number, or a 30-bit hexadecimal number. The size of the pre-set threshold is not limited in the embodiments of the present application.

[0073] In this way, the shortest number of bits of the encrypted second authentication token can be ensured, and the number of bits of the encrypted second authentication token is prevented from being too small, so that the encrypted second authentication token is extremely easy to be cracked by the pirate.

[0074] The length value of the encrypted second authentication token is spliced into the spliced string.

[0075] In a specific implementation, the length value can be spliced into a fixed position of the encrypted second authentication token, such as the head, tail, or middle of the encrypted second authentication token. The splicing position of the length value is not limited in the embodiments of the present application.

[0076] In this way, the length of the encrypted second authentication token is recorded by the length value, so that the user's device can correctly obtain the actual second authentication token.

[0077] As an optional embodiment, in the anti-piracy method of Embodiment 4 of the present application, the methods in Embodiments 1 and 2 are used at the same time. Therefore, Embodiment 4 has the technical means and technical effects obtained by combining Embodiments 1 and 2, which will not be described here.

[0078] As an optional embodiment, in the anti-hotlinking method of Embodiment 5 of the present application, the method in Embodiment 1 and the method in Embodiment 3 are simultaneously used. Therefore, Embodiment 5 has the technical means and technical effects obtained by combining Embodiment 1 and Embodiment 3, which will not be repeated here.

[0079] As an optional embodiment, in the anti-hotlinking method of Embodiment 6 of the present application, the method in Embodiment 1, the method in Embodiment 2 and the method in Embodiment 3 are simultaneously used. Therefore, Embodiment 6 has the technical means and technical effects obtained by combining Embodiment 1, Embodiment 2 and Embodiment 3, which will not be repeated here.

[0080] As an optional embodiment, before the uniform resource locator corresponding to the media file is sent to the user, the anti-hotlinking method further comprises encrypting the parameter value in the uniform resource locator according to an encryption rule.

[0081] In this way, the parameter value in the uniform resource locator can be protected, and the rest of the parameters can be obtained by the hotlinker.

[0082] As an optional embodiment, before the uniform resource locator corresponding to the media file is sent to the user, the anti-hotlinking method further comprises rewriting the uniform resource locator.

[0083] In this way, the parameter item in the uniform resource locator can be hidden, and the parameter item information can be obtained by the hotlinker.

[0084] As an optional embodiment, the anti-hotlinking method further comprises obtaining the reference data of the username and the password by the following method:

[0085] According to a pre-set hash algorithm, the correct username and the correct password are calculated respectively to obtain the reference data of the username and the password.

[0086] The comparison of the username, the password and the first authentication token with the reference data pre-stored in the database in the anti-hotlinking method comprises:

[0087] According to a hash algorithm, the hash values of the username and the password are calculated respectively.

[0088] The hash values of the username, the password and the first authentication token are compared with the reference data.

[0089] In specific implementation, the hash algorithm can be MD5 algorithm or SHA algorithm, and the present application does not limit the hash algorithm.

[0090] In the present embodiment, the reference data of the username and the password pre-stored in the database is the hash value. In this way, the number of bits of the data in the database is consistent, which is convenient for storage and subsequent comparison, and at the same time, the correct username and password can be obtained by the hotlinker from the database.

[0091] Based on the same inventive concept, the disclosure also provides a media file anti-linking system corresponding to the method of any of the above embodiments.

[0092] Reference Figure 2 The media file anti-linking system comprises:

[0093] A request receiving module is configured to receive a request for obtaining a media file sent by a user, wherein the request comprises a username, a password and a first authentication token sent to the user in advance.

[0094] A database module is configured to store reference data of the username, the password and the first authentication token.

[0095] A data comparison module is configured to compare whether the username, the password and the first authentication token match the reference data.

[0096] An authentication token generation module is configured to generate a second authentication token corresponding to the user according to a pre-set authentication token generation rule.

[0097] A data rewriting module is configured to replace the first authentication token in the database with the second authentication token.

[0098] A data encryption module is configured to encrypt the second authentication token according to a pre-set encryption rule to obtain an encrypted second authentication token.

[0099] A uniform resource locator sending module is configured to send a uniform resource locator corresponding to the media file to the user to enable the user to obtain the media file, wherein the uniform resource locator comprises the encrypted second authentication token.

[0100] For the convenience of description, the above system is described in various modules according to functions. Of course, the functions of the modules can be implemented in one or more software and / or hardware when the disclosure is implemented.

[0101] The device of the above embodiment is used to implement the corresponding media file anti-linking method of any of the above embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be described here.

[0102] Based on the same inventive concept, the disclosure also provides a server comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the media file anti-linking method of any of the above embodiments when executing the program.

[0103] Figure 3A more specific server hardware structure diagram provided by the embodiment is shown, which can include: a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040 and a bus 1050. The processor 1010, the memory 1020, the input / output interface 1030 and the communication interface 1040 are connected to each other through the bus 1050 for internal communication.

[0104] The processor 1010 can be implemented by a general CPU (Central Processing Unit), a microprocessor, an ASIC (Application Specific Integrated Circuit) or one or more integrated circuits, etc., for executing related programs to implement the technical solutions provided by the embodiments of the present specification.

[0105] The memory 1020 can be implemented by a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, etc. The memory 1020 can store an operating system and other application programs, and when the technical solutions provided by the embodiments of the present specification are implemented by software or firmware, the related program codes are stored in the memory 1020 and called and executed by the processor 1010.

[0106] The input / output interface 1030 is used to connect input / output modules to realize information input and output. The input / output modules can be configured as components in the server (not shown in the figure) or externally connected to the server to provide corresponding functions. The input device can include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device can include a display, a speaker, a vibrator, an indicator light, etc.

[0107] The communication interface 1040 is used to connect a communication module (not shown in the figure) to realize the communication interaction between the server and other devices. The communication module can realize communication through a wired manner (such as USB, network cable, etc.) or a wireless manner (such as mobile network, WIFI, Bluetooth, etc.).

[0108] The bus 1050 includes a channel for transmitting information between various components (such as the processor 1010, the memory 1020, the input / output interface 1030 and the communication interface 1040) of the server.

[0109] It should be noted that although the above server only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040 and the bus 1050, but in the specific implementation process, the server can also include other components necessary for normal operation. In addition, those skilled in the art can understand that the above server can also only contain the components necessary to implement the embodiments of the present application, and does not have to contain all the components shown in the figure.

[0110] The server of the above embodiment is used to implement the corresponding media file anti-linking method in any of the preceding embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described here.

[0111] Based on the same inventive concept, the present disclosure also provides a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the media file anti-linking method according to any of the preceding embodiments.

[0112] The computer-readable medium of the present embodiment includes permanent and non-permanent, removable and non-removable media, which can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device.

[0113] The computer instructions stored in the storage medium of the above embodiment are used to cause the computer to execute the media file anti-linking method according to any of the preceding embodiments, and have the beneficial effects of the corresponding method embodiments, which are not described here.

[0114] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary and is not intended to imply that the scope of the present application (including claims) is limited to these examples; under the idea of the present application, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in detail.

[0115] While the present application has been described in connection with specific embodiments thereof, it will be understood that many modifications, substitutions, and changes will be apparent to those of ordinary skill in the art from the foregoing description.

[0116] It is intended that the present embodiments encompass all such substitutions, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any one or more features of any embodiment are intended to be combinable with any one or more features of any other embodiment unless otherwise explicitly stated (e.g., by a direct contradiction).

Claims

1. A method for preventing hotlinking of media files, comprising: Receive a request from a user to obtain media files, wherein the request includes the user's username, password, and a first authentication token pre-sent to the user; The username, the password, and the first authentication token are compared with reference data pre-stored in the database; In response to determining that the username, the password, and the first authentication token match the corresponding reference data, a second authentication token corresponding to the user is generated according to a pre-set authentication token generation rule; Replace the first authentication token in the database with the second authentication token; The second authentication token is encrypted according to the pre-set encryption rules to obtain an encrypted second authentication token; The Uniform Resource Locator (URL) corresponding to the media file is sent to the user so that the user can obtain the media file, wherein the URL includes the encrypted second authentication token.

2. The method according to claim 1, wherein, The step of encrypting the second authentication token according to a pre-set encryption rule to obtain the encrypted second authentication token includes: In at least one of the encryption rules arranged in a predetermined order, one of the encryption rules is randomly selected as the target encryption rule, and the sequence number of the target encryption rule in the arrangement is obtained; The second authentication token is encrypted according to the target encryption rule; The serial number is concatenated to the encrypted second authentication token to obtain the encrypted second authentication token.

3. The method according to claim 1, wherein, After encrypting the second authentication token according to the preset encryption rules, the method further includes: A random number is generated and concatenated to the encrypted second authentication token.

4. The method according to claim 1, wherein, After encrypting the second authentication token according to the preset encryption rules, the method further includes: Determine the length of the encrypted second authentication token; In response to determining that the length of the encrypted second authentication token is less than a preset threshold, a random number is generated and concatenated to the encrypted second authentication token so that the length of the concatenated string meets the preset threshold; The length value of the encrypted second authentication token is appended to the concatenated string.

5. The method according to claim 1, wherein, Before sending the Uniform Resource Locator (URL) corresponding to the media file to the user, the method further includes: The parameter values ​​in the Uniform Resource Locator are encrypted according to the encryption rules.

6. The method according to claim 1, wherein, Before sending the Uniform Resource Locator (URL) corresponding to the media file to the user, the method further includes: The Uniform Resource Locator is rewritten.

7. The method according to claim 1, wherein, The method also includes obtaining reference data for the username and password through the following methods: Based on a pre-set hash algorithm, the correct username and the correct password are calculated to obtain reference data for the username and the password. The method of comparing the username, the password, and the first authentication token with reference data pre-stored in the database includes: Calculate the hash values ​​of the username and the password respectively according to the hash algorithm. The hash value of the username, the hash value of the password, and the first authentication token are compared with the reference data.

8. A media file anti-hotlinking system, comprising: A request receiving module is used to receive a request from a user to obtain a media file, wherein the request includes the user's username, password, and a first authentication token pre-sent to the user; A database module is used to store reference data for the username, the password, and the first authentication token; The data comparison module is used to compare whether the username, the password, and the first authentication token match the reference data. The authentication token generation module is used to generate a second authentication token corresponding to the user according to a pre-set authentication token generation rule; The data rewriting module is used to replace the first authentication token in the database with the second authentication token; The data encryption module is used to encrypt the second authentication token according to a pre-set encryption rule to obtain an encrypted second authentication token; A Uniform Resource Locator (URL) sending module is used to send the URL corresponding to the media file to the user so that the user can obtain the media file, wherein the URL includes the encrypted second authentication token.

9. A server comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as claimed in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the method as described in any one of claims 1 to 7.

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