KR20230124271A - Document sharing service server for processing saving and sharing of document files with unauthorized fonts, in the cloud-based document sharing service, and the operating method thereof - Google Patents

Abstract

A cloud-based document sharing service, a document sharing service server for storing and sharing document files with unauthorized fonts applied thereto, and an operating method thereof are disclosed. In the cloud-based document sharing service of the present invention, document files with unauthorized fonts applied are encrypted and stored in document file storage. By presenting technology to ensure that only authorized members can view the document files, the possibility of legal disputes due to the use of unauthorized fonts can be minimized.

Description

Document sharing service server for storing and sharing document files with unauthorized fonts applied in a cloud-based document sharing service and its operating method , IN THE CLOUD-BASED DOCUMENT SHARING SERVICE, AND THE OPERATING METHOD THEREOF}

The present invention relates to a document sharing service server for storing and sharing a document file to which unauthorized fonts are applied in a cloud-based document sharing service and an operation method thereof.

BACKGROUND ART [0002] Recently, as a high-speed Internet environment has been widely spread and the demand for telecommuting has increased, the introduction of cloud-based document sharing services has increased in various fields such as companies and schools.

The cloud-based document sharing service stores document files in a separate document file storage rather than the electronic terminals of members who have subscribed to the document sharing service, so that members can share document files stored in the document file storage. services that are supported.

Members subscribed to the document sharing service can store new document files in the document file storage or view document files stored in the document file storage by accessing the document file storage without physical limitations.

On the other hand, fonts representing the shapes of characters are applied to characters included in electronic documents. These fonts may be open fonts for users to freely use, but only users with a certain license can use them. It can also be a distributed font.

In recent years, as users download unauthorized font files without permission and apply them to electronic documents they create, copyright infringement on font files has emerged as a social problem.

In particular, since document files stored in the document file storage can be easily shared with other members through document sharing services, if unauthorized fonts are applied to document files stored in the document file storage, they will not be permitted later. There is a possibility of legal disputes due to unauthorized use of fonts that have not been used.

In this regard, before storing a document file in the document file storage, it is checked whether a character to which an unauthorized font is applied exists in an electronic document according to the document file, and a character to which an unauthorized font is applied is checked. If it is confirmed to exist, if the document file is encrypted and stored in the document file storage, and only authorized members can view the document file, there is a possibility of legal disputes due to unauthorized use of unauthorized fonts. will be able to minimize

Therefore, in a cloud-based document sharing service, research on a technology for encrypting and storing a document file with unauthorized fonts applied thereto in a document file storage and allowing only authorized members to view the document file is required.

In a cloud-based document sharing service, the present invention encrypts a document file to which unauthorized fonts are applied and stores it in a document file storage, and provides a technology for supporting only authorized members to view the document file, Minimize the possibility of legal disputes due to the use of unregistered fonts.

In the cloud-based document sharing service according to an embodiment of the present invention, the document sharing service server for storing and sharing a document file to which an unlicensed font is applied is pre-specified n ( n is a natural number of 2 or more) a permitted font identifier storage unit in which font identifiers for each of the permitted fonts are stored, member identification information of each of a plurality of members subscribed to the document sharing service, and each of the plurality of members From the member information storage unit in which the terminal identification information of the electronic terminals possessed is stored in correspondence with each other, and the first electronic terminal possessed by the first member, which is one of the plurality of members, information about the first electronic document is stored. When a first document file is received and an upload request for the first document file is received, the first document file is read and a font for a font applied to a plurality of characters included in the first electronic document is received. After checking the identifier, font identifiers for each of the n permitted fonts stored in the permitted font identifier storage unit are referred to, and among the plurality of characters, fonts that are not included in the n permitted fonts are applied. A font checking unit that checks whether there is a character that has been designated, and confirms that at least one first character is a character to which a font that is not included in the n permitted fonts is applied among the plurality of characters. If so, to the first electronic terminal, an upload query message including content querying whether to upload the first document file despite the presence of characters with unauthorized fonts applied to the first electronic document is transmitted When an upload command indicating to upload the first document file is received from the first electronic terminal in response to the upload query message, the upload query message transmission unit refers to the member information storage unit, so that the first member A document file storage processing unit configured to identify first member identification information of the first member, encrypt the first document file, and store the encrypted first document file and the first member identification information in a document file storage by matching them with each other; and After the first document file and the first member identification information correspond to each other and are stored in the document file storage, from a second electronic terminal owned by a second member, which is another one of the plurality of members, When a request for sharing a document file is received, the first member identification information stored in correspondence to the encrypted first document file is checked from the document file storage, and based on the first member identification information, the After checking the first terminal identification information stored in correspondence with the first member identification information from the member information storage unit, based on the first terminal identification information, the first electronic terminal sends the information to the second member. An approval command for sharing the first document file from the first electronic terminal to the second member by transmitting a sharing approval query message including content querying whether to approve sharing the first document file. and a document file transmission unit for extracting the encrypted first document file from the document file storage and then decrypting the encrypted first document file and transmitting the encrypted first document file to the second electronic terminal.

In addition, in the cloud-based document sharing service according to an embodiment of the present invention, a method of operating a document sharing service server for storing and sharing a document file to which an unauthorized font is applied is a font that is licensed. Maintaining a permitted font identifier storage unit in which font identifiers for each of n (n is a natural number equal to or greater than 2) pre-designated as , and member identification information of each of a plurality of members subscribed to the document sharing service are stored. and maintaining a member information storage unit in which terminal identification information of an electronic terminal possessed by each of the plurality of members is stored in correspondence with each other, and a first member possessed by one of the plurality of members When a first document file for a first electronic document is received from an electronic terminal and an upload request for the first document file is received, the first document file is read, and a plurality of documents included in the first electronic document are received. After confirming font identifiers for fonts applied to the characters of , font identifiers for each of the n permitted fonts stored in the permitted font identifier storage unit are referred to, and among the plurality of characters, the n Checking whether a character to which a font not included in the n permitted fonts is applied exists, among the plurality of characters, a character to which a font not included in the n permitted fonts is applied, at least one If it is confirmed that the first character of exists, the contents of querying whether to upload the first document file to the first electronic terminal despite the presence of characters to which unauthorized fonts are applied to the first electronic document. Transmitting an upload query message including the upload query message, when an upload command instructing to upload the first document file is received from the first electronic terminal in response to the upload query message, referring to the member information storage unit , Confirming first member identification information of the first member, encrypting the first document file, and then matching the encrypted first document file with the first member identification information and storing the first member identification information in a document file storage. and after the encrypted first document file and the first member identification information are stored in the document file storage in correspondence with each other, from a second electronic terminal possessed by a second member, which is another one of the plurality of members, When a request for sharing a first document file is received, the first member identification information stored in correspondence to the encrypted first document file is checked from the document file storage, and based on the first member identification information, , After checking the first terminal identification information stored in correspondence with the first member identification information from the member information storage unit, based on the first terminal identification information, to the first electronic terminal, the second member for sharing the first document file from the first electronic terminal to the second member by sending a sharing approval inquiry message including content querying whether to approve sharing of the first document file. When an approval command is received, extracting the encrypted first document file from the document file storage, decrypting the encrypted first document file, and transmitting the encrypted first document file to the second electronic terminal.

In a cloud-based document sharing service, the present invention encrypts a document file to which unauthorized fonts are applied and stores it in a document file storage, and provides a technology for supporting only authorized members to view the document file, The possibility of legal disputes due to the use of unregistered fonts can be minimized.

1 is a diagram showing the structure of a document sharing service server for storing and sharing a document file to which unauthorized fonts are applied in a cloud-based document sharing service according to an embodiment of the present invention.
2 is a flowchart illustrating an operating method of a document sharing service server for storing and sharing a document file to which unauthorized fonts are applied in a cloud-based document sharing service according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. This description is not intended to limit the present invention to specific embodiments, but should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. While describing each drawing, similar reference numerals have been used for similar components, and unless otherwise defined, all terms used in this specification, including technical or scientific terms, are common knowledge in the art to which the present invention belongs. has the same meaning as commonly understood by the person who has it.

In this document, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated. In addition, in various embodiments of the present invention, each component, functional block, or means may be composed of one or more sub-components, and the electrical, electronic, and mechanical functions performed by each component are electronic It may be implemented with various known elements or mechanical elements such as circuits, integrated circuits, ASICs (Application Specific Integrated Circuits), and may be implemented separately or two or more may be integrated into one.

On the other hand, the blocks of the accompanying block diagram or the steps of the flowchart are computer program instructions that perform designated functions by being loaded into a processor or memory of a device capable of data processing, such as a general-purpose computer, a special purpose computer, a portable notebook computer, and a network computer. can be interpreted as meaning Since these computer program instructions may be stored in a memory included in a computer device or in a computer readable memory, the functions described in blocks of a block diagram or steps of a flowchart are produced as a product containing instruction means for performing them. It could be. Further, each block or each step may represent a module, segment or portion of code that includes one or more executable instructions for executing specified logical function(s). Also, it should be noted that in some alternative embodiments, functions mentioned in blocks or steps may be executed out of a predetermined order. For example, two blocks or steps shown in succession may be performed substantially simultaneously or in reverse order, and in some cases, some blocks or steps may be omitted.

1 is a diagram showing the structure of a document sharing service server for storing and sharing a document file to which unauthorized fonts are applied in a cloud-based document sharing service according to an embodiment of the present invention.

Referring to FIG. 1, a document sharing service server 110 according to an embodiment of the present invention includes a font identifier storage unit 111, a member information storage unit 112, a font check unit 113, and an upload query message transmission unit. 114, a document file storage processing unit 115 and a document file transmission unit 116.

The font identifier storage unit 111 stores font identifiers for each of n (n is a natural number equal to or greater than 2) permitted fonts pre-specified as permitted fonts.

For example, when n is '5', the font identifier storage unit 111 may store font identifiers for each of '5' permitted fonts as shown in Table 1 below.

'5' licensed fonts font identifier font 1 identifier 1 font 2 identifier 2 font 3 identifier 3 font 4 identifier 4 font 5 identifier 5

The member information storage unit 112 stores member identification information of each of a plurality of members subscribed to the document sharing service and terminal identification information of an electronic terminal possessed by each of the plurality of members in correspondence with each other.

Here, the member identification information means information such as ID and resident registration number for distinguishing each member, and the terminal identification information means identification information pre-assigned to each electronic terminal to identify each electronic terminal. As such, a MAC address or International Mobile Equipment Identity (IMEI) may be utilized.

For example, the member information storage unit 112 includes member identification information of each of a plurality of members subscribed to the document sharing service as shown in Table 2 below, and terminal identification information of an electronic terminal possessed by each of the plurality of members. may be stored in correspondence with each other.

multiple members Member identification information electronic terminal Terminal identification information member 1 Member identification information 1 electronic terminal 1 Terminal identification information 1 member 2 Member identification information 2 electronic terminal 2 Terminal identification information 2 member 3 Member identification information 3 electronic terminal 3 Terminal identification information 3 member 4 Member identification information 4 electronic terminal 4 Terminal identification information 4 ... ... ... ..

The font checking unit 113 receives the first document file for the first electronic document from the first electronic terminal 151 possessed by the first member 141, which is one of the plurality of members, When an upload request for a first document file is received, the first document file is read, a font identifier for a font applied to a plurality of characters included in the first electronic document is checked, and then the permitted font identifier is stored. With reference to the font identifier for each of the n permitted fonts stored in the unit 111, whether there is a character to which a font not included in the n permitted fonts is applied among the plurality of characters. Check the

The upload query message transmission unit 114 determines that there is at least one first character among the plurality of characters, to which a font that is not included in the n allowed fonts is applied, the first electronic To the terminal 151, an upload query message including content inquiring about whether to upload the first document file is transmitted despite the presence of characters with unauthorized fonts applied to the first electronic document.

When receiving an upload command instructing to upload the first document file from the first electronic terminal 151 in response to the upload query message, the document file storage processing unit 115 stores the member information storage unit 112. Referring to, after checking the first member identification information of the first member 141, encrypting the first document file, and then matching the encrypted first document file with the first member identification information, the document file storage Save to (137).

Hereinafter, operations of the font checking unit 113, the upload query message transmission unit 114, and the document file storage processing unit 115 will be described in detail by way of example.

First, while the document sharing service server 110 receives 'document file 1' for 'electronic document 1' from 'electronic terminal 1 151' owned by 'member 1 141', 'document file 1' is received. Assume that an upload request for file 1' is received.

Then, the font checking unit 113 reads 'document file 1', checks font identifiers for fonts applied to a plurality of characters included in 'electronic document 1', and then allows fonts as shown in Table 1 above. With reference to the font identifier for each of the '5' permitted fonts stored in the identifier storage unit 111, a character to which a font not included in the '5' permitted fonts is applied among the plurality of characters. You can check whether it exists or not.

As a result, it is assumed that among the plurality of characters, it is confirmed that at least one first character is a character to which a font that is not included in the '5' allowed fonts is applied.

Then, the upload query message transmission unit 114 determines whether to upload the 'document file 1' to the 'electronic terminal 1 151' despite the presence of characters with unauthorized fonts applied to the 'electronic document 1'. An upload query message containing the content to be queried can be transmitted.

Correspondingly, when an upload command instructing to upload 'document file 1' is received from 'electronic terminal 1 151', the document file storage processing unit 115 refers to the member information storage unit 112, After confirming 'member identification information 1', which is member identification information of 'member 1 (141)', encrypting 'document file 1', and then matching the encrypted 'document file 1' with 'member identification information 1' It can be stored in the document file storage 137.

At this time, according to one embodiment of the present invention, the document file storage processing unit 114 includes a table maintenance unit 119, an encryption event generating unit 120, a password setting request unit 121, a serial number extraction unit 122, It may include an operation code generator 123, an encryption key generator 124, and an encryption storage processing unit 125.

The table maintenance unit 119 is a series of different t (t is a natural number of 2 or more) digits corresponding to each of a plurality of preset document formats that are pre-shared with electronic terminals possessed by each of the plurality of members. The serial number table in which the number is recorded is stored and maintained. Here, the document format means a file format for each document having an extension such as '.hwp', '.docx', or '.pdf'.

For example, when t is set to '4', the table maintenance unit 119 records serial numbers of different '4' digits corresponding to each of a plurality of preset document formats, as shown in Table 3 below. You can save and maintain the table.

multiple document formats Serial Number format 1 6401 format 2 3286 format 3 5429 format 4 1752 format 5 9367 ... ...

In this case, the serial number table as shown in Table 3 may be pre-stored in an electronic terminal possessed by each of the plurality of members.

When the upload command is received from the first electronic terminal 151 in response to the upload query message, the encryption event generating unit 120 refers to the member information storage unit 112, so that the first member 141 First member identification information is checked, and an encryption event for encrypting the first document file is generated.

When the encryption event is generated by the encryption event generating unit 120, the password setting request unit 121 requests the first electronic terminal 151 to set a t-digit password for encryption of the first document file Sends a password setting request message that includes the

When the serial number extractor 122 receives the first password from the first electronic terminal 151 as the first password is set by the first member 141 in response to the password setting request message, the After confirming the first document format of the first document file, a first serial number corresponding to the first document format is extracted from the serial number table.

The operation code generation unit 123 configures the resultant value when a modulo-2 operation is performed on each of the t numbers constituting the first password as a bit string to obtain a t-bit first operation code And a t-bit second operation code is generated by configuring a resultant value obtained when a modulo-2 operation is performed on each of the t numbers constituting the first serial number as a bit string.

Here, the modulo-2 operation means an operation of dividing a dividend by 2 and calculating a remainder thereto.

The encryption key generator 124 generates a t-bit seed code by performing an exclusive OR (XOR) operation between the first operation code and the second operation code, and then encrypts the seed code in advance It is applied as an input to a key generation function to generate a first encryption key. Here, the encryption key generating function may be a predetermined hash function.

The encryption storage processing unit 125 encrypts the first document file with the first encryption key, and stores the encrypted first document file and the first member identification information in the document file storage 137 in correspondence with each other.

Hereinafter, the encryption event generation unit 120, password setting request unit 121, serial number extraction unit 122, operation code generation unit 123, encryption key generation unit 124 and encryption storage processing unit 125 The operation will be described in detail by taking an example.

First, as in the above example, 'document file 1' is sent to 'electronic terminal 1 151' by the upload query message transmission unit 114 despite the presence of characters with unauthorized fonts applied to 'electronic document 1'. Suppose that an upload query message including a content querying whether to upload ' is sent. At this time, it is assumed that 'member 1 (141)' who confirmed the upload query message applied an upload command instructing to upload 'document file 1' on 'electronic terminal 1 (151)', and accordingly, the document sharing service Assume that the server 110 receives the upload command from the 'electronic terminal 1 (151)'.

Then, the encryption event generation unit 120 refers to the member information storage unit 112 as shown in Table 2 above, and converts 'member identification information 1', which is identification information of 'member 1 (141)', to the first member identification information. , and an encryption event for encrypting 'document file 1' can be generated.

Then, the password setting request unit 121 transmits, to the 'electronic terminal 1 151', a password setting request message including a request to set a '4' digit password for encryption of 'document file 1'. can

At this time, it is said that 'Member 1 (141)' who confirmed the password setting request message set the first password '1230' as a '4' digit password for encryption of 'document file 1', and accordingly, the document Assume that the sharing service server 110 receives the first password '1230' from the 'electronic terminal 1 (151)'.

Then, the serial number extraction unit 122 may check the first document format of 'document file 1'.

As a result, when it is confirmed that the first document format of 'document file 1' is 'format 3', the serial number extraction unit 122, from the serial number table as shown in Table 3, corresponds to 'format 3'. The serial number '5429' may be extracted as the first serial number.

Then, the operation code generation unit 123 configures the result value when performing the modulo-2 operation on each of the '4' numbers constituting the first password '1230' as a bit string to ' When a 4'-bit first operation code can be generated as '1010' and a modulo-2 operation is performed on each of the '4' numbers constituting the first serial number '5429' A second operation code of '4' bits, such as '1001', can be generated by configuring the resulting value as a bit string.

Then, the encryption key generation unit 124 performs an exclusive OR operation between the first operation code '1010' and the second operation code '1001', thereby converting the '4' bit seed code to '0011'. can create

Then, the encryption key generation unit 124 may generate 'encryption key 1' by applying the seed code '0011' as an input to a preset encryption key generation function.

Then, the encryption storage processing unit 125 encrypts the 'document file 1' with 'encryption key 1', and then maps the encrypted 'document file 1' and 'member identification information 1' to each other to store the document file storage 137. can be saved

In this way, after the first document file encrypted by the document file storage processing unit 115 and the first member identification information are stored in the document file storage 137 in correspondence with each other, the second member who is another one of the plurality of members. When a request for sharing the first document file is received from the second electronic terminal 152 possessed by the member 142, the document file transmission unit 116 transmits the encrypted first document file from the document file storage 137. 1 Check the first member identification information stored in correspondence with the document file, and based on the first member identification information, from the member information storage unit 112, the stored corresponding to the first member identification information After confirming the first terminal identification information, the first electronic terminal 151 queries the second member 142 for permission to share the first document file based on the first terminal identification information. When an approval command for sharing the first document file is received from the first electronic terminal 151 to the second member 142 by transmitting a sharing approval query message including content, the document file storage 137 After extracting the encrypted first document file, the encrypted first document file is decrypted and transmitted to the second electronic terminal 152 .

At this time, according to an embodiment of the present invention, the document file transmission unit 116 includes an identification information confirmation unit 126, a sharing approval query message transmission unit 127, a decryption event generation unit 128, and a reply request unit 129. ), an operation code regenerating unit 130, an encryption key regenerating unit 131, and a decryption transmission processing unit 132.

After the identification information confirmation unit 126 corresponds to the first document file encrypted by the document file storage processing unit 115 and the first member identification information and stores them in the document file storage 137, the second electronic terminal ( 152), when a request for sharing the first document file is received, the first member identification information stored in correspondence with the encrypted first document file is checked from the document file storage 137.

When the first member identification information is confirmed by the identification information verification unit 126, the sharing approval query message transmission unit 127 transmits information from the member information storage unit 112 based on the first member identification information. 1 After confirming the first terminal identification information stored in correspondence with member identification information, the sharing approval query message is transmitted to the first electronic terminal 151 based on the first terminal identification information.

The decryption event generation unit 128 extracts the encrypted first document file from the document file storage 137 when the approval command is received from the first electronic terminal 151 in response to the sharing approval query message. , generates a decryption event for decrypting the encrypted first document file.

When the decryption event is generated by the decryption event generating unit 128, the reply request unit 129 requests the first electronic terminal 151 to input a password set for encryption of the first document file. At the same time as transmitting the password input request message including the content, extract and reply the serial number corresponding to the document format of the first document file from the serial number table stored on the first electronic terminal 151. Sends the requested serial number return command.

Operation code regenerating unit 130 responds to the password input request message, as the first member inputs the first password on the first electronic terminal 151, from the first electronic terminal 151 The first password is received, and in response to the serial number reply command, by the first electronic terminal 151, from the serial number table stored on the first electronic terminal 151 to the first document format As the corresponding first serial number is extracted, when the first serial number is returned from the first electronic terminal 151, a modulo-2 operation is performed on each of t numbers constituting the first password Result value when the first operation code of t bits is generated by configuring the result value as a bit string, and the modulo-2 operation is performed on each of the t numbers constituting the first serial number The second operation code of t bits is generated by constructing a bit string.

The encryption key regeneration unit 131 generates the seed code of t bits by performing an exclusive OR operation between the first operation code and the second operation code, and then inputs the seed code to the encryption key generation function. and generates the first encryption key.

The decryption transmission processing unit 132 decrypts the encrypted first document file with the first encryption key, restores the first document file, and transmits the restored first document file to the second electronic terminal 152. do.

Hereinafter, an identification information confirmation unit 126, a sharing approval query message transmission unit 127, a decryption event generation unit 128, a reply request unit 129, an operation code generation unit 130, an encryption key generation unit 131 ) and the operation of the decryption transmission processing unit 132 will be described in detail, for example.

First, as in the above example, it is assumed that the encrypted 'document file 1' and 'member identification information 1' are stored in the document file storage 137 in correspondence with each other by the document file storage processing unit 115, and thereafter, Assume that the document sharing service server 110 receives a sharing request for 'document file 1' from 'electronic terminal 2 152' possessed by 'member 2 142'. And, suppose that the 'electronic terminal 1 (151)' stores and maintains a serial number table as shown in Table 3, which is previously shared with the document sharing service server 110.

Then, the identification information checking unit 126 can check the stored 'member identification information 1' corresponding to the encrypted 'document file 1' from the document file storage 137.

After that, the sharing approval query message transmission unit 127, based on 'member identification information 1', from the member information storage unit 112 as shown in Table 2 above, 'member identification information 1' is stored in correspondence with 'member identification information 1'. Terminal identification information 1' can be checked.

Then, the sharing approval query message transmission unit 127 decides to share the 'document file 1' to the 'electronic terminal 1 151' and to the 'member 2 142' based on the 'terminal identification information 1'. The sharing approval query message including the content for querying whether to approve the sharing may be transmitted.

At this time, 'Member 1 (141)', who has confirmed the sharing approval query message, applies an approval command for sharing 'Document File 1' to 'Member 2 (142)' on 'Electronic Terminal 1 (151)'. Assume that the document sharing service server 110 receives the approval command from the 'electronic terminal 1 (151)'.

Then, the decryption event generating unit 128 may generate a decryption event for decrypting the encrypted 'document file 1' after extracting the encrypted 'document file 1' from the document file storage 137.

Then, the reply request unit 129 transmits, to the 'electronic terminal 1 151', a password input request message including a request to input the password set for the encryption of the 'document file 1', and At the same time, a serial number reply command requesting to extract and return a serial number corresponding to the document format of 'document file 1' from the serial number table such as Table 3 stored on 'electronic terminal 1 (151)' can transmit

At this time, it is assumed that 'member 1 (141)' who confirmed the password input request message entered the first password '1230' on 'electronic terminal 1 (151)', and accordingly, the document sharing service server 110 Assume that '1230', which is the first password, is received from 'electronic terminal 1 (151)'.

At the same time, in response to the serial number reply command, 'electronic terminal 1 (151)' is stored on 'electronic terminal 1 (151)' from the serial number table such as Table 3, 'document file 1'. As a serial number corresponding to 'Format 3', which is a document format, it is assumed that '5429', which is the first serial number, is extracted and returned to the document sharing service server 110. Accordingly, the document sharing service server 110 ' Assume that the first serial number '5429' is received from the electronic terminal 1 (151)'.

Then, the operation code regenerating unit 130 configures the result value when performing the modulo-2 operation on each of the '4' numbers constituting '1230', which is the first password, into a bit string, thereby forming '4'. When the first operation code of 'bit' can be generated as '1010' and a modulo-2 operation is performed on each of the '4' numbers constituting the first serial number '5429' The second operation code of '4' bits, such as '1001', can be generated by configuring the resulting value as a bit string.

Then, the encryption key regeneration unit 131 converts the seed code of '4' bits to '0011' by performing an exclusive OR operation between '1010', which is the first operation code, and '1001', which is the second operation code. After generating as described above, 'encryption key 1' may be generated by applying the seed code '0011' as an input to the encryption key generation function.

At this time, according to the above example, since the encrypted 'document file 1' is a file generated by encrypting the 'document file 1' with the 'encryption key 1', the decryption transmission processing unit 132 sends the encrypted 'document file 1'. By decrypting with 'encryption key 1', 'document file 1' can be restored normally. Then, the decryption transmission processing unit 132 may transmit the restored 'document file 1' to the 'electronic terminal 2 152'. Through this, 'member 2 (142)' can browse 'document file 1'.

According to one embodiment of the present invention, the document sharing service server 110 may further include a storage history information generator 117 and a registration request unit 118.

The storage history information generation unit 117 stores the encrypted first document file in the document file storage 137 by the document file storage processing unit 115, and the encrypted first document file is stored in the document file storage ( 137), after generating time information for a time point stored in the first electronic terminal 151 and receiving current location information of the first electronic terminal 151, the first member identification information, the first document file, Storage history information composed of the time information and the current location information is created.

When the storage history information is generated by the storage history information generator 117, the registration request unit 118 generates a transaction including the storage history information, and then generates a transaction including the storage history information, A block chain network of the transaction ( 100) transmits a registration request.

Hereinafter, operations of the storage history information generator 117 and the registration request unit 118 will be described in detail, for example.

First, as in the above example, it is assumed that 'document file 1' encrypted by the document file storage processing unit 115 and 'member identification information 1' are stored in the document file storage 137 in correspondence with each other.

At this time, the storage history information generator 117 may generate 'time information 1', which is time information about the time when the encrypted 'document file 1' and 'member identification information 1' are stored in the document file storage 137, , 'Location information 1', which is the current location information of the 'electronic terminal 1 151', may be received from the 'electronic terminal 1 151'.

Then, the storage history information generation unit 117 may generate storage history information composed of 'member identification information 1', 'document file 1', 'time information 1', and 'location information 1'.

Then, after the registration request unit 118 generates a transaction including the storage history information, the plurality of node devices 101, 102, 103, 104, 105, and 106 constituting the blockchain network 100 Any one of the first node devices may be randomly selected.

At this time, when the first node device is referred to as the node device 101, the registration request unit 118 transmits the transaction to the node device 101 and sends a registration request to the blockchain network 100 of the transaction. can transmit

At this time, when the first node device receives the transaction and the registration request from the document sharing service server 110, based on the previous block chained to the block chain data stored on the memory of the first node device , After completing the storage of the first block by generating a first block including the transaction and linking the first block to the blockchain data in a chain, the first block is stored through the blockchain network 100. 1 block may be propagated to other node devices other than the first node device among the plurality of node devices.

For example, as in the above example, as the registration request unit 118 transmits the registration request to the blockchain network 100 of the transaction while transmitting the transaction to the node device 101, the node device 101 Suppose that the transaction and the registration request are received.

Then, the node device 101 generates a first block including the transaction based on the previous block chained to the blockchain data stored on the memory of the node device 101, and the first block After completing the storage of the first block by connecting the chain to the blockchain data, the first block is transferred through the blockchain network 100 to a plurality of node devices 101, 102, 103, 104, It can propagate to the remaining node devices 102, 103, 104, 105, and 106 except for the node device 101 among nodes 105 and 106.

Specifically, when the transaction and the registration request are received from the document sharing service server 110, the node device 101 refers to the block header of the previous block chained to the blockchain data to include the transaction. The first block, which is a new block, may be created. Then, the node device 101 connects the first block to the blockchain data in a chain, thereby completing the storage of the first block and then transferring the first block to the remaining nodes through the blockchain network 100. It can propagate to devices 102, 103, 104, 105, 106.

In this way, the document sharing service server 110 according to the present invention, when the encrypted first document file is stored in the document file storage 137, generates the storage history information and registers it in the blockchain network 100 As a result, when a legal dispute occurs due to an unauthorized font applied to the first document file, it is possible to check the storage history information to support checking who uploaded the first document file, when, and where. there is.

In addition, the document sharing service server 110 according to an embodiment of the present invention includes a permitted font data storage unit 133, a font replacement query message transmission unit 134, a calculation value calculation unit 135, and a font data transmission unit ( 136) may be further included.

Font data for each of the n permitted fonts is stored in the permitted font data storage unit 133 .

Here, the font data refers to data used to apply a font format to characters included in the document file when the document file is loaded, and the font data for each of the n allowed fonts includes , different unique identification numbers consisting of integers greater than or equal to 0 and less than n are pre-assigned.

For example, as in the above example, when n is '5', font data for each of '5' permitted fonts as shown in Table 4 below may be stored in the permitted font data storage unit 133. .

'5' licensed fonts font data unique identification number font 1 font data 1 0 font 2 font data 2 One font 3 font data 3 2 font 4 font data 4 3 font 5 font data 5 4

When the transmission of the first document file to the second electronic terminal 152 is completed by the document file transmission unit 116, the font substitution query message transmission unit 134 sends the first document file to the second electronic terminal 152. It informs that there are characters applied with unauthorized fonts in the electronic document and at the same time inquires whether or not to replace the font of characters applied with unauthorized fonts existing in the first electronic document with a substitute font. font substitution query message.

In response to the font replacement query message, the calculation value calculation unit 135 replaces, from the second electronic terminal 152, the font of characters to which an unauthorized font existing in the first electronic document is applied is applied with a substitute font. When a font replacement command indicating a font replacement command is received, a date value for the point in time at which the font replacement command is received from the second electronic terminal 152 is generated, and then a modulo operation is performed on the date value with n as a divisor. By doing so, the calculation value is calculated.

When the calculation value is calculated by the calculation value calculation unit 135, the font data transmission unit 136 selects the font data for each of the n permitted fonts stored in the permitted font data storage unit 133. The first font data having the calculation value as a unique identification number is extracted and transmitted to the second electronic terminal 152 .

At this time, when the first font data is received from the document sharing service server 110, the second electronic terminal 152, based on the first font data, the at least one first font included in the first electronic document The first electronic document may be corrected by substituting and applying a font style of a character to a font style according to the first font data.

Hereinafter, operations of the font replacement query message transmission unit 134, calculation value calculation unit 135, and font data transmission unit 136 will be described in detail, for example.

First, as in the above example, it is assumed that the transmission of 'document file 1' to 'electronic terminal 2 (152)' is completed by the document file transmission unit 116.

Then, the font substitution query message transmission unit 134 informs the 'electronic terminal 2 152' that there are characters applied with an unauthorized font in the 'electronic document 1' and at the same time informs the 'electronic terminal 1' A font substitution query message including contents querying whether to replace the font of characters applied with an existing unauthorized font with a substitute font may be transmitted.

At this time, 'Member 2 (142)', who has confirmed the font replacement query message, converts the font of the text to which the unauthorized font existing in 'Electronic Document 1' is applied on the 'Electronic Terminal 2 (152)' as a substitute font. Assume that a font replacement command indicating replacement is applied, and accordingly, the document sharing service server 110 receives the font replacement command from the 'electronic terminal 2 152'.

In this regard, when the document sharing service server 110 receives the font replacement command from the 'electronic terminal 2 152' as 'January 26, 2022', the calculation value calculation unit 135 A date value for the point in time at which the font replacement command is received from the 'electronic terminal 2 152' may be generated as '20220126'.

Then, the calculation value calculation unit 135 may calculate the calculation value as '1' by performing a modulo operation with '5' as a divisor for '20220126'.

After that, the font data transmission unit 136 sets '1' as a unique identification number among the font data for each of the '5' permitted fonts stored in the permitted font data storage unit 133 as shown in Table 4 above. 'Font data 2', which is the font data having, may be extracted and transmitted to the 'electronic terminal 2 (152)'.

Then, the 'electronic terminal 2 152' converts the font format of the at least one first character included in the 'electronic document 1' into a font format according to 'font data 2' based on 'font data 2'. By replacing and applying, 'Electronic Document 1' can be modified.

Through this, 'Member 2 (142)' can acquire 'Electronic Document 1' to which the font format of the at least one first character is replaced with the font format according to 'Font Data 2'.

2 is a flowchart illustrating an operating method of a document sharing service server for storing and sharing a document file to which unauthorized fonts are applied in a cloud-based document sharing service according to an embodiment of the present invention.

In step S210, a permitted font identifier storage unit in which font identifiers for each of n (n is a natural number equal to or greater than 2) previously designated as permitted fonts is stored is maintained.

In step S220, a member information storage unit in which member identification information of each of a plurality of members subscribed to the document sharing service and terminal identification information of an electronic terminal possessed by each of the plurality of members are stored in correspondence with each other. keep

In step S230, a first document file for a first electronic document is received from a first electronic terminal possessed by a first member, which is one of the plurality of members, and an upload request for the first document file is received. is received, the first document file is read, font identifiers for fonts applied to a plurality of characters included in the first electronic document are checked, and then the n stored in the allowed font identifier storage unit is checked. With reference to font identifiers for each of the allowed fonts, it is checked whether there is a character to which a font not included in the n permitted fonts is applied among the plurality of characters.

In step S240, if it is confirmed that at least one first character exists as a character to which a font that is not included in the n allowed fonts is applied among the plurality of characters, to the first electronic terminal, An upload query message including content inquiring about whether to upload the first document file is transmitted despite the existence of texts applied with an unauthorized font to the first electronic document.

In step S250, when an upload command instructing to upload the first document file is received from the first electronic terminal in response to the upload query message, the member information storage unit is referred to the first member information storage unit. After confirming the first member identification information and encrypting the first document file, the encrypted first document file and the first member identification information are matched and stored in a document file storage.

In step S260, after the encrypted first document file and the first member identification information are mapped to each other and stored in the document file storage, a second electronic document possessed by a second member, which is another one of the plurality of members, is stored. When a request for sharing the first document file is received from the terminal, the first member identification information stored in correspondence to the encrypted first document file is checked from the document file storage, and the first member identification information is stored. Based on the information, after checking the first terminal identification information stored in correspondence with the first member identification information from the member information storage unit, based on the first terminal identification information, to the first electronic terminal, A sharing approval query message including content querying whether to approve sharing of the first document file is transmitted to the second member, and the first electronic terminal transmits the first document file to the second member. When an approval command for sharing is received, the encrypted first document file is extracted from the document file storage, and the encrypted first document file is decrypted and transmitted to the second electronic terminal.

At this time, according to one embodiment of the present invention, in the operating method of the document sharing service server, when the encrypted first document file is stored in the document file storage, the encrypted first document file is stored in the document file storage. After generating time information for a stored time point and receiving current location information of the first electronic terminal from the first electronic terminal, the first member identification information, the first document file, the time information and the current location Generating storage history information composed of information, and when the storage history information is generated, after generating a transaction including the storage history information, a first one of a plurality of node devices constituting a blockchain network The method may further include randomly selecting a node device and transmitting a request for registration of the transaction to the blockchain network while transmitting the transaction to the first node device, wherein the first node device When the transaction and the registration request are received from the document sharing service server, based on the previous block chained to the blockchain data stored on the memory of the first node device, the first node including the transaction After completing the storage of the first block by generating a block and connecting the first block to the blockchain data in a chain, the first block is transmitted through the blockchain network to the plurality of node devices. Among them, it is possible to propagate to the remaining node devices except for the first node device.

In addition, according to one embodiment of the present invention, in step S250, different t (t is a natural number of 2 or more) storing and maintaining a serial number table in which serial numbers of digits are recorded, in response to the upload query message, when the upload command is received from the first electronic terminal, refer to the member information storage unit checking the first member identification information of the first member, and generating an encryption event for encrypting the first document file; when the encryption event occurs, to the first electronic terminal, Transmitting a password setting request message including content requesting setting a password of t digits for encryption of a document file, in response to the password setting request message, as a first password is set by the first member , When the first password is received from the first electronic terminal, checking the first document format of the first document file, and then extracting a first serial number corresponding to the first document format from the serial number table. , A first operation code of t bits is generated by configuring the resultant value when a modulo-2 operation is performed on each of the t numbers constituting the first password as a bit string, and the first serial number Generating a second operation code of t bits by configuring a value obtained when a modulo-2 operation is performed on each of the t numbers constituted as a bit string, the first operation code and the second operation code After generating a t-bit seed code by performing an exclusive OR operation between the two, generating a first encryption key by applying the seed code as an input to a preset encryption key generation function, and converting the first document file to the first After encrypting with 1 encryption key, the encrypted first document file and the first member identification information may be mapped to each other and stored in the document file storage.

At this time, according to one embodiment of the present invention, in step S260, after the encrypted first document file and the first member identification information are stored in the document file storage in correspondence with each other, from the second electronic terminal, When a request for sharing a first document file is received, checking the first member identification information stored in correspondence with the encrypted first document file from the document file storage, the first member identification information being checked , based on the first member identification information, after checking the first terminal identification information stored in correspondence with the first member identification information from the member information storage unit, based on the first terminal identification information , Transmitting the sharing approval query message to the first electronic terminal, in response to the sharing approval query message, when the approval command is received from the first electronic terminal, from the document file storage, the encrypted first After extracting the document file, generating a decryption event for decrypting the encrypted first document file, when the decryption event occurs, to the first electronic terminal, the password set for encryption of the first document file At the same time as transmitting a password input request message including content requesting input, a serial number corresponding to the document format of the first document file is extracted from the serial number table stored on the first electronic terminal. Sending a serial number reply command requesting a reply, in response to the password input request message, as the first member inputs the first password on the first electronic terminal, the first The first password is received from the electronic terminal, and in response to the serial number return command, the first document format is corresponding to the serial number table stored on the first electronic terminal by the first electronic terminal. As the first serial number is extracted, when the first serial number is returned from the first electronic terminal, when a modulo-2 operation is performed on each of the t numbers constituting the first password The first operation code of t bits is generated by configuring the result value as a bit string, and the result value when the modulo-2 operation is performed on each of the t numbers constituting the first serial number is a bit string Generating the second operation code of t bits by configuring, generating the seed code of t bits by performing an exclusive OR operation between the first operation code and the second operation code, and then generating the seed code After restoring the first document file by decrypting the encrypted first document file with the first encryption key, an encryption key regeneration unit generating the first encryption key by applying the input to the encryption key generation function as an input, and then restoring the first document file. and transmitting the first document file to the second electronic terminal.

In addition, according to an embodiment of the present invention, the operating method of the document sharing service server includes font data for each of the n permitted fonts (the font data is included in the document file when the document file is loaded). It refers to data used to apply font formatting to characters, and different unique identification numbers composed of integers between 0 and less than n are pre-assigned to the font data for each of the n permitted fonts.) Maintaining a permitted font data storage unit in which is stored, when the transmission of the first document file to the second electronic terminal is completed, to the second electronic terminal, a character to which a font that is not permitted to the first electronic document is applied is displayed. At the same time as notifying existence, transmitting a font replacement query message including content for querying whether to replace the font of a character to which an unauthorized font is applied existing in the first electronic document with a replacement font; In response to the font substitution query message, if a font substitution command instructing to replace the font of a character to which an unauthorized font existing in the first electronic document is applied with a substitute font is received from the second electronic terminal, the After generating a date value for the time point at which the font replacement command is received from a second electronic terminal, calculating a calculation value by performing a modulo operation with n as a divisor on the date value, and the calculation value is When calculated, among the font data for each of the n permitted fonts stored in the permitted font data storage unit, first font data having the operation value as a unique identification number is extracted and transmitted to the second electronic terminal The method may further include, wherein, when the second electronic terminal receives the first font data from the document sharing service server, the at least one included in the first electronic document is configured based on the first font data. The first electronic document may be corrected by replacing the font style of one first character with a font format according to the first font data.

In the above, with reference to FIG. 2 , a method of operating a document sharing service server for storing and sharing a document file to which an unauthorized font is applied has been described according to an embodiment of the present invention. Here, since the operating method of the document sharing service server according to an embodiment of the present invention may correspond to the configuration of the operation of the document sharing service server 110 described with reference to FIG. 1, a detailed description thereof is omitted. do it with

A method of operating a document sharing service server according to an embodiment of the present invention may be implemented as a computer program stored in a storage medium for execution through a combination with a computer.

In addition, the operating method of the document sharing service server according to an embodiment of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the medium may be those specially designed and configured for the present invention or those known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. - includes hardware devices specially configured to store and execute program instructions, such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler.

As described above, the present invention has been described by specific details such as specific components and limited embodiments and drawings, but these are provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , Those skilled in the art in the field to which the present invention belongs can make various modifications and variations from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and it will be said that not only the claims to be described later, but also all modifications equivalent or equivalent to these claims belong to the scope of the present invention. .

110: Document sharing service server for storing and sharing document files with unlicensed fonts applied thereto
111: permission font identifier storage unit 112: member information storage unit
113: font check unit 114: upload query message transmission unit
115: document file storage processing unit 116: document file transmission unit
117: storage history information generation unit 118: registration request unit
119: table maintenance unit 120: encryption event generating unit
121: password setting request unit 122: serial number extraction unit
123: operation code generation unit 124: encryption key generation unit
125: encryption storage processing unit 126: identification information confirmation unit
127: Share approval query message transmission unit 128: Decryption event generation unit
129: reply request unit 130: operation code regeneration unit
131: encryption key regeneration unit 132: decryption transmission processing unit
133: permission font data storage unit 134: font replacement query message transmission unit
135: operation value calculation unit 136: font data transmission unit
137: Document file storage
100: blockchain network
101, 102, 103, 104, 105, 106: multiple node devices
141: first member 142: second member
151: first electronic terminal 152: second electronic terminal

Claims (12)

In a document sharing service server for storing and sharing processing for document files to which unauthorized fonts are applied in a cloud-based document sharing service,
a permitted font identifier storage unit in which font identifiers for each of n (n is a natural number equal to or greater than 2) previously designated as permitted fonts are stored;
a member information storage unit for storing member identification information of each of the plurality of members subscribed to the document sharing service and terminal identification information of an electronic terminal possessed by each of the plurality of members in correspondence with each other;
When a first document file for a first electronic document is received from a first electronic terminal possessed by a first member, which is one of the plurality of members, and an upload request for the first document file is received, the After reading a first document file and checking font identifiers for fonts applied to a plurality of characters included in the first electronic document, each of the n permitted fonts stored in the permitted font identifier storage unit a font checking unit for checking whether there exists a character to which a font not included in the n allowed fonts is applied, among the plurality of characters, by referring to a font identifier for ;
Among the plurality of characters, if it is determined that at least one first character exists as a character to which a font that is not included in the n permitted fonts is applied, the first electronic document is sent to the first electronic terminal. an upload query message transmission unit which transmits an upload query message including content inquiring about whether to upload the first document file despite the existence of texts with unauthorized fonts applied thereto;
When an upload command instructing to upload the first document file is received from the first electronic terminal in response to the upload query message, the first member identification information of the first member is referred to by the member information storage unit. a document file storage processing unit that checks the first document file, encrypts the first document file, and then stores the encrypted first document file and the first member identification information in a document file storage in correspondence with each other; and
After the encrypted first document file and the first member identification information are stored in the document file storage in correspondence with each other, from a second electronic terminal owned by a second member, which is another one of the plurality of members, When a request for sharing 1 document file is received, the first member identification information stored in correspondence to the encrypted first document file is checked from the document file storage, and based on the first member identification information, After confirming the stored first terminal identification information corresponding to the first member identification information from the member information storage unit, based on the first terminal identification information, the first electronic terminal is sent to the second member. Approval of sharing the first document file from the first electronic terminal to the second member by sending a sharing approval query message including contents querying whether to approve sharing of the first document file If a command is received, a document file transmitter extracting the encrypted first document file from the document file storage, decrypting the encrypted first document file, and transmitting the encrypted first document file to the second electronic terminal.
A document sharing service server including a. According to claim 1,
When the encrypted first document file is stored in the document file storage by the document file storage processing unit, time information about a time when the encrypted first document file is stored in the document file storage is generated, and the first document file is stored in the document file storage. 1 Storage history information for generating storage history information composed of the first member identification information, the first document file, the time information, and the current location information after receiving current location information of the first electronic terminal from an electronic terminal. generating unit; and
When the storage history information is generated, after generating a transaction including the storage history information, a first node device that is any one of a plurality of node devices constituting a blockchain network is randomly selected, and the first node device is selected. A registration request unit for transmitting a registration request to the blockchain network of the transaction while transmitting the transaction to a node device.
Including more,
The first node device is
When the transaction and the registration request are received from the document sharing service server, the first block including the transaction is based on the previous block chained to the blockchain data stored on the memory of the first node device. After completing the storage of the first block by generating and linking the first block to the blockchain data in a chain, the first block is selected from among the plurality of node devices through the blockchain network. Document sharing service server, characterized in that for propagating to the remaining node devices other than the first node device. According to claim 1,
The document file storage processing unit
A serial number table in which serial numbers of different t (t is a natural number of 2 or more) digits corresponding to each of a plurality of preset document formats pre-shared with electronic terminals possessed by each of the plurality of members are recorded a table holding unit that stores and maintains;
In response to the upload query message, when the upload command is received from the first electronic terminal, the first member identification information of the first member is checked with reference to the member information storage unit, and the first document file is stored. an encryption event generator generating an encryption event for encryption;
When the encryption event occurs, a password setting request unit for transmitting, to the first electronic terminal, a password setting request message including content requesting setting a password of t digits for encryption of the first document file;
In response to the password setting request message, as the first password is set by the first member, when the first password is received from the first electronic terminal, after confirming the first document format of the first document file , a serial number extraction unit extracting a first serial number corresponding to the first document format from the serial number table;
A first operation code of t bits is generated by configuring a resultant value when a modulo-2 operation is performed on each of the t numbers constituting the first password as a bit string, and the first series an operation code generation unit configured to generate a t-bit second operation code by configuring a resultant value obtained by performing a modulo-2 operation on each of t numbers constituting the number as a bit string;
After generating a t-bit seed code by performing an exclusive OR (XOR) operation between the first operation code and the second operation code, applying the seed code as an input to a preset encryption key generation function to an encryption key generating unit that generates a first encryption key; and
After encrypting the first document file with the first encryption key, an encryption storage processor configured to store the encrypted first document file and the first member identification information in the document file storage in correspondence with each other.
A document sharing service server including a. According to claim 3,
The document file transfer unit
After the encrypted first document file and the first member identification information are stored in the document file storage in correspondence with each other, when a request for sharing the first document file is received from the second electronic terminal, the document file storage an identification information checking unit configured to check the first member identification information stored in correspondence with the encrypted first document file;
When the first member identification information is confirmed, based on the first member identification information, after checking the first terminal identification information stored in correspondence with the first member identification information from the member information storage unit, the a sharing permission query message transmission unit transmitting the sharing permission query message to the first electronic terminal based on the first terminal identification information;
In response to the sharing approval query message, when the approval command is received from the first electronic terminal, extracting the encrypted first document file from the document file storage and then decrypting the encrypted first document file. a decryption event generating unit generating a decryption event;
When the decryption event occurs, a password input request message including contents requesting input of a password set for encryption of the first document file is transmitted to the first electronic terminal, and at the same time, the first electronic terminal a reply requesting unit for transmitting a serial number reply command requesting to extract and reply to a serial number corresponding to the document format of the first document file from the serial number table stored on the terminal;
In response to the password input request message, as the first password is input by the first member on the first electronic terminal, the first password is received from the first electronic terminal, and the serial number is returned. In response to a command, as the first serial number corresponding to the first document format is extracted from the serial number table stored on the first electronic terminal by the first electronic terminal, the first electronic terminal When the first serial number is returned from the terminal, the first operation of t bits by configuring the result value when a modulo-2 operation is performed on each of the t numbers constituting the first password as a bit string An operation to generate the second operation code of t bits by generating a code and configuring a result value when a modulo-2 operation is performed on each of the t numbers constituting the first serial number as a bit string code regeneration unit;
After generating the t-bit seed code by performing an exclusive OR operation between the first operation code and the second operation code, applying the seed code as an input to the encryption key generation function to obtain the first encryption key an encryption key regeneration unit to generate; and
A decryption transmission processing unit for restoring the first document file by decrypting the encrypted first document file with the first encryption key and then transmitting the restored first document file to the second electronic terminal.
A document sharing service server including a. According to claim 1,
Font data for each of the n permitted fonts - The font data refers to data used to apply a font style to characters included in the document file when the document file is loaded, wherein the n a permitted font data storage unit in which font data for each of the permitted fonts is pre-allocated with different unique identification numbers composed of integers greater than or equal to 0 and less than n;
When the transmission of the first document file to the second electronic terminal is completed by the document file transmission unit, the second electronic terminal is notified that there is a character to which an unauthorized font is applied to the first electronic document. and at the same time, a font replacement query message transmission unit that transmits a font replacement query message including content for querying whether to replace the font of characters to which an unauthorized font existing in the first electronic document is applied with a replacement font;
In response to the font replacement query message, when a font replacement command instructing to replace the font of a character to which an unauthorized font existing in the first electronic document is applied is received from the second electronic terminal, a calculation value calculation unit generating a date value corresponding to a point in time at which the font replacement command is received from the second electronic terminal, and then calculating a calculation value by performing a modulo operation with n as a divisor on the date value; and
When the calculation value is calculated, first font data having the calculation value as a unique identification number is extracted from font data for each of the n allowed fonts stored in the permitted font data storage unit, and the second electronic font data is extracted. Font data transmission unit that transmits to the terminal
Including more,
The second electronic terminal
When the first font data is received from the document sharing service server, the font format of the at least one first character included in the first electronic document is converted to the first font data based on the first font data. The document sharing service server, characterized in that for modifying the first electronic document by replacing and applying a font format according to the font format. In a cloud-based document sharing service, a method of operating a document sharing service server for storing and sharing a document file to which an unauthorized font is applied,
maintaining a permitted font identifier storage unit in which a font identifier for each of n (n is a natural number equal to or greater than 2) previously designated as a permitted font is stored;
maintaining a member information storage unit in which member identification information of each of the plurality of members subscribed to the document sharing service and terminal identification information of an electronic terminal possessed by each of the plurality of members are stored in correspondence with each other;
When a first document file for a first electronic document is received from a first electronic terminal possessed by a first member, which is one of the plurality of members, and an upload request for the first document file is received, the After reading a first document file and checking font identifiers for fonts applied to a plurality of characters included in the first electronic document, each of the n permitted fonts stored in the permitted font identifier storage unit checking whether there is a character to which a font that is not included in the n allowed fonts is applied, among the plurality of characters, by referring to a font identifier for ?;
Among the plurality of characters, if it is determined that at least one first character exists as a character to which a font that is not included in the n permitted fonts is applied, the first electronic document is sent to the first electronic terminal. transmitting an upload query message including content inquiring about whether to upload the first document file despite the existence of texts with unauthorized fonts applied thereto;
When an upload command instructing to upload the first document file is received from the first electronic terminal in response to the upload query message, the first member identification information of the first member is referred to by the member information storage unit. confirming, encrypting the first document file, and then storing the encrypted first document file and the first member identification information in a document file storage in correspondence with each other; and
After the encrypted first document file and the first member identification information are stored in the document file storage in correspondence with each other, from a second electronic terminal owned by a second member, which is another one of the plurality of members, When a request for sharing 1 document file is received, the first member identification information stored in correspondence to the encrypted first document file is checked from the document file storage, and based on the first member identification information, After confirming the stored first terminal identification information corresponding to the first member identification information from the member information storage unit, based on the first terminal identification information, the first electronic terminal is sent to the second member. Approval of sharing the first document file from the first electronic terminal to the second member by sending a sharing approval query message including contents querying whether to approve sharing of the first document file If a command is received, extracting the encrypted first document file from the document file storage, decrypting the encrypted first document file, and transmitting the encrypted first document file to the second electronic terminal.
A method of operating a document sharing service server comprising a. According to claim 6,
When the encrypted first document file is stored in the document file storage, time information about the point in time at which the encrypted first document file is stored in the document file storage is generated, and the first electronic terminal receives the first electronic device. After receiving the current location information of the terminal, generating storage history information composed of the first member identification information, the first document file, the time information, and the current location information; and
When the storage history information is generated, after generating a transaction including the storage history information, a first node device that is any one of a plurality of node devices constituting a blockchain network is randomly selected, and the first node device is selected. Transmitting, with a node device, a request for registration of the transaction to the blockchain network while transmitting the transaction.
Including more,
The first node device is
When the transaction and the registration request are received from the document sharing service server, the first block including the transaction is based on the previous block chained to the blockchain data stored on the memory of the first node device. After completing the storage of the first block by generating and linking the first block to the blockchain data in a chain, the first block is selected from among the plurality of node devices through the blockchain network. Method of operating a document sharing service server, characterized in that for propagating to the remaining node devices other than the first node device. According to claim 6,
Correspondingly storing the encrypted first document file and the first member identification information in a document file storage
A serial number table in which serial numbers of different t (t is a natural number of 2 or more) digits corresponding to each of a plurality of preset document formats pre-shared with electronic terminals possessed by each of the plurality of members are recorded Storing and maintaining;
In response to the upload query message, when the upload command is received from the first electronic terminal, the first member identification information of the first member is checked with reference to the member information storage unit, and the first document file is stored. generating an encryption event for encryption;
When the encryption event occurs, transmitting, to the first electronic terminal, a password setting request message including content requesting to set a password of t digits for encryption of the first document file;
In response to the password setting request message, as the first password is set by the first member, when the first password is received from the first electronic terminal, after confirming the first document format of the first document file , extracting a first serial number corresponding to the first document format from the serial number table;
A first operation code of t bits is generated by configuring a resultant value when a modulo-2 operation is performed on each of the t numbers constituting the first password as a bit string, and the first series generating a t-bit second operation code by configuring a resultant value obtained by performing a modulo-2 operation on each of t numbers constituting the number as a bit string;
After generating a t-bit seed code by performing an exclusive OR (XOR) operation between the first operation code and the second operation code, applying the seed code as an input to a preset encryption key generation function to generating a first encryption key; and
After encrypting the first document file with the first encryption key, storing the encrypted first document file and the first member identification information in the document file storage in correspondence with each other.
A method of operating a document sharing service server comprising a. According to claim 8,
The step of decrypting the encrypted first document file and transmitting it to the second electronic terminal
After the encrypted first document file and the first member identification information are stored in the document file storage in correspondence with each other, when a request for sharing the first document file is received from the second electronic terminal, the document file storage checking the first member identification information stored in correspondence with the encrypted first document file from;
When the first member identification information is confirmed, based on the first member identification information, after checking the first terminal identification information stored in correspondence with the first member identification information from the member information storage unit, the transmitting the sharing permission query message to the first electronic terminal based on the first terminal identification information;
In response to the sharing approval query message, when the approval command is received from the first electronic terminal, extracting the encrypted first document file from the document file storage and then decrypting the encrypted first document file. generating a decryption event;
When the decryption event occurs, a password input request message including contents requesting input of a password set for encryption of the first document file is transmitted to the first electronic terminal, and at the same time, the first electronic terminal transmitting a serial number reply command requesting a serial number corresponding to a document format of the first document file to be extracted and returned from the serial number table stored on a terminal;
In response to the password input request message, as the first password is input by the first member on the first electronic terminal, the first password is received from the first electronic terminal, and the serial number is returned. In response to a command, as the first serial number corresponding to the first document format is extracted from the serial number table stored on the first electronic terminal by the first electronic terminal, the first electronic terminal When the first serial number is returned from the terminal, the first operation of t bits by configuring the result value when a modulo-2 operation is performed on each of the t numbers constituting the first password as a bit string Generating the second operation code of t bits by generating a code and configuring a result value when a modulo-2 operation is performed on each of the t numbers constituting the first serial number as a bit string ;
After generating the t-bit seed code by performing an exclusive OR operation between the first operation code and the second operation code, applying the seed code as an input to the encryption key generation function to obtain the first encryption key an encryption key regeneration unit to generate; and
restoring the first document file by decrypting the encrypted first document file with the first encryption key, and then transmitting the restored first document file to the second electronic terminal;
A method of operating a document sharing service server comprising a. According to claim 6,
Font data for each of the n permitted fonts - The font data refers to data used to apply a font style to characters included in the document file when the document file is loaded, wherein the n maintaining a permitted font data storage unit in which font data for each of the permitted fonts is pre-allocated with different unique identification numbers composed of integers greater than or equal to 0 and less than n;
When the transmission of the first document file to the second electronic terminal is completed, the second electronic terminal is notified of the existence of texts to which unauthorized fonts are applied to the first electronic document, and at the same time, the first electronic document Transmitting a font replacement query message including content for querying whether to replace a font of characters to which an unauthorized font is applied, existing in the font, with a replacement font;
In response to the font replacement query message, when a font replacement command instructing to replace the font of a character to which an unauthorized font existing in the first electronic document is applied is received from the second electronic terminal, generating a date value for a point in time at which the font replacement command is received from the second electronic terminal, and then calculating a calculation value by performing a modulo operation with n as a divisor on the date value; and
When the calculation value is calculated, first font data having the calculation value as a unique identification number is extracted from font data for each of the n allowed fonts stored in the permitted font data storage unit, and the second electronic font data is extracted. Step to transmit to terminal
Including more,
The second electronic terminal
When the first font data is received from the document sharing service server, the font format of the at least one first character included in the first electronic document is converted to the first font data based on the first font data. A method of operating a document sharing service server, characterized in that by modifying the first electronic document by replacing and applying a font format according to the method. A computer-readable recording medium recording a computer program for executing the method of any one of claims 6 to 10 through a combination with a computer. A computer program stored in a storage medium for executing the method of any one of claims 6 to 10 through a combination with a computer.

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