KR100826250B1 - Electronic document management device and method - Google Patents

Abstract

An electronic document management apparatus and method capable of long-term preservation while preventing forgery of electronic documents are presented.

An electronic document management apparatus of the present invention includes a hash processing unit for calculating a hash value for each node constituting a hash tree and storing the hash value in a database, an electronic signature processing unit for performing an electronic signature on the hash value stored in the root node of the hash tree; Stores and manages the hash tree serial number, the depth of the hash tree, the number of all leaf nodes, and the number of leaf nodes where data is stored in the database, and according to the request of the hash tree manager and the operator to store the generated hash tree in the database. A document storage unit for storing at least one document with a document serial number in memory, adding the document serial number and hash value to the hash tree, and updating the hash value from the parent node to the root node of the hash tree, You can safely store and manage large volumes of electronic documents at low cost.

Electronic document, hash tree

Description

Apparatus and Method for Management of Electronic Filing Document

1 is a block diagram of an electronic document management apparatus according to an embodiment of the present invention;

2 is a view for explaining an electronic document storage structure according to the present invention;

3 is a flowchart for explaining an electronic document storage method according to an embodiment of the present invention;

4A to 4E are views for explaining an electronic document storage method according to an embodiment of the present invention;

5 is a flowchart for explaining an electronic document storage method according to another embodiment of the present invention;

6a to 6f are views for explaining an electronic document storage method according to another embodiment of the present invention;

7 is a flowchart for explaining an electronic document retrieval method according to an embodiment of the present invention;

8A and 8B are views for explaining an electronic document withdrawal method according to an embodiment of the present invention;

9 is a flowchart illustrating a method of deleting an electronic document according to an embodiment of the present invention;

10A and 10B are views for explaining an electronic document deleting method according to an embodiment of the present invention;

11 is a flowchart illustrating a hash tree merging method according to an embodiment of the present invention;

12A and 12B illustrate a hash tree merging method according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: electronic document management device 102: control unit

104: interface 106: memory

108: Database 110: Metadata Database

112: hash tree database 114: hash processing unit

116: digital signature processing unit 118: hash tree management unit

120: document storage unit 122: document extraction unit

124 Delete Document

The present invention relates to an electronic document management apparatus and method, and more particularly to an electronic document management apparatus and method that can be preserved for a long time while preventing forgery of the electronic document.

In recent years, public institutions, financial institutions, etc. have electronically stored documents generated as a result of business processing. Electronic documents should be stored securely to prevent forgery, tampering, illegal viewing or deletion, and for this purpose, electronic documents are stored in WORM (Write Only, Read Many) storage.

WORM storage refers to a disk having a property that a user can write data once, but cannot erase or update the data once written. WORM is a large-capacity storage medium having a capacity of hundreds of MB to several GB, and is mainly used for storing data which has a duty of preservation or data which is difficult to be deleted or changed accidentally because data once recorded cannot be deleted or changed.

However, since WORM storage is expensive, it is only used by some companies and it is difficult to commercialize.

In addition, at the present time, when the electronic document is stored, forgery is prevented by performing an electronic signature on each electronic document. When the electronic document expires, the electronic signature on all the electronic documents must be updated. This complexity is disadvantageous.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and disadvantages, and replaces expensive WORM storage and provides an electronic document management apparatus and method capable of safely storing and managing electronic documents at low cost. There is.

Another technical problem of the present invention is to store an electronic document using a hash tree, thereby safely storing and managing the electronic document only by the electronic signature on the root node, and simplifying the process of updating the electronic signature.

Electronic document storage device according to an embodiment of the present invention for achieving the above technical problem is a control unit for controlling the overall operation; interface; A memory in which the hashed electronic document is stored; A database storing a hash tree and hash tree related information; A hash processing unit for calculating a hash value for each node constituting a hash tree and storing the hash value in the database; An electronic signature processor for performing an electronic signature on a hash value stored in a root node of the hash tree; A hash tree manager which stores and manages the serial number of the hash tree, the depth of the hash tree, the number of all leaf nodes, the number of leaf nodes in which data is stored in the database, and stores the generated hash tree in the database; And storing at least one document along with the document serial number in the memory according to an operator's request, adding the document serial number and the hash value to the hash tree, and then hashing from the upper node of the hash tree to the root node. And a document storage unit for updating the value.

In addition, the electronic document storage method according to an embodiment of the present invention includes a first step of calculating a hash value for the document to be stored, as the operator intends to store the electronic document; A second step of selecting a hash tree having the largest serial number when the hash tree is generated and checking whether an empty leaf node exists in the selected hash tree; A third step of determining whether an index (final index) of a leaf note in which data is finally stored is a power of 2 when an empty leaf node exists in the selected hash tree; A fourth step of generating as many empty leaf nodes as the number of final indexes when the final index is a power of two; A fifth step of storing a document serial number and a hash value calculated in the first step in a leaf node corresponding to a next index of a final index, and storing the document in a memory; A sixth step of updating a hash value from an upper node of the leaf node to a root node; And a seventh step of performing an electronic signature on the hash value of the root node.

In addition, the electronic document storage method according to another embodiment of the present invention includes a first step of calculating a hash value for each document to be stored, as the operator wants to collectively store a plurality of electronic documents; A second step of selecting a hash tree having the largest serial number when the hash tree is generated and checking whether an empty leaf node exists in the selected hash tree; A third step of determining whether an index (final index) of a leaf note in which data is finally stored is an odd number when an empty leaf node exists in the selected hash tree; A fourth step of storing the document serial number for the first electronic document to be added and the hash value calculated in the first step for the electronic document and updating the final index when the final index is odd. ; A fifth step of generating a hash tree having a depth of 2 using the remaining hash value and the serial number of the document except the hash value stored in the fourth step; A sixth step of checking whether the final index is an odd multiple of two; A seventh step of adding one of the hash trees having a depth of 2 generated in the fifth step to a previously generated hash tree and updating the final index by two when the final index is an odd multiple of two; An eighth step of generating a hash tree having a depth of three using the hash tree other than the hash tree used in the seventh step among the hash trees having the depth two generated in the fifth step; A ninth step of adding the hash tree generated in the eighth step to the hash tree updated in the seventh step; A tenth step of updating a hash value from an upper node of the leaf node to a root node; And an eleventh step of performing an electronic signature on the hash value of the root node.

In the electronic document retrieval method according to an embodiment of the present invention, as a document serial number (index of a leaf node) to be withdrawn from an operator is input, a hash tree storing a hash value of a document according to the document serial number is retrieved. A first step of making; With respect to the retrieved hash tree, a hash value on all paths including a leaf node storing the document serial number and a root node connected to the leaf node is retrieved, and a hash value of neighboring nodes of the retrieved hash value is obtained. Withdrawing the second step; A third step of verifying an electronic signature value with respect to the root node hash value; A fourth step of calculating a hash value for each node sequentially from the root node to the leaf node; And a fifth step of fetching the document using the calculated hash value for the leaf node.

On the other hand, in the electronic document deletion method according to an embodiment of the present invention, as the document serial number (index of the leaf node) to be deleted from the operator is input, the hash tree storing the hash value of the document according to the document serial number A first step of searching; A second step of checking whether an index to be deleted exists in a leaf node of the searched hash tree; Updating the leaf node with an empty leaf node if there is an index to be deleted and deleting the corresponding electronic document stored in the memory; And a fourth step of updating a hash value from an upper node of the leaf node to a root node and performing an electronic signature on the root node hash value.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description, document serial numbers are integers monotonically increasing according to document storage order, for example, 1, 2, 3,... The document serial number is defined as having the same value as the index of the hash tree leaf node. In addition, the maximum allowable depth of the hash tree will be named n (an integer greater than 2), and the depth of the hash tree will be named k, and the hash tree serial number t is given an integer increasing monotonically in the order of generation.

1 is a block diagram of an electronic document management apparatus according to an embodiment of the present invention.

As shown in the drawing, the electronic document management apparatus 10 of the present invention allows the control unit 102 to control the overall operation, the operator to operate the electronic document management apparatus 10, and the processing result of the electronic document management apparatus 10. Interface 104 for providing the operator to the memory, a memory 106 in which the hashed electronic document and the like are stored, a database 108 in which the hash tree and related information are stored, a hash processing unit 114, and an electronic signature processing unit 116. , A hash tree managing unit 118, a document storing unit 120, a document extracting unit 122, and a document deleting unit 124.

The hash tree applied to the present invention is calculated from 2 ^n-1 leaf nodes, which store the document serial number and the hash value for each document, when the depth is n, for example. Hash stored in the root node, including one root node that stores hash values calculated from the first to n-second order parent nodes storing the hash value and two adjacent n-first order parent nodes. The value is stored in the digitally signed state.

Hereinafter, the components illustrated in FIG. 1 will be described in detail.

First, the hash processor 114 calculates a hash value for each node (leaf node, upper node, root node) of the hash tree, and stores the hash value in the hash tree database 112.

The digital signature processing unit 116 performs the digital signature on the hash value stored in the root node of the hash tree, and updates the digital signature on the hash value stored in the root node when the validity period of the electronic signature expires.

The digital signature may use a time stamp protocol (TSP), for example. TSP is a protocol for time stamping services that send and receive tokens for time stamping between the Time Stamp Authority (TSA) and the requestor. It is a protocol used to support that data existed before a certain time.

The hash tree manager 118 stores the serial number of the hash tree, the depth of the hash tree, the number of all leaf nodes, the number of leaf nodes where data is stored, and the like in the metadata DB 110, and stores the hash tree in the hash tree DB ( 112). In addition, the hash tree management unit 118 merges two hash trees when the sum of the number of leaf nodes in which data is stored is less than or equal to the total allowable leaf nodes in one hash tree for two adjacent hash trees. It can also be done.

The document storage unit 120 stores at least one document along with the document serial number in the memory 106 according to an operator's request, adds the document serial number and hash value to the hash tree, and then adds the document to the root node. Update the hash value up to.

The document retrieval unit 122 retrieves a hash value from the hash tree by referring to the document serial number requested by the operator, and extracts and provides a document stored in the memory 106 by using the same.

In addition, the document deleting unit 124 retrieves a hash tree storing the hash value for the document requested by the operator, deletes the leaf node storing the hash value for the document from the retrieved hash tree, the hash of the leaf node is deleted Update the hash value from the top node of the tree to the root node. Detailed procedures for storing, retrieving and deleting documents will be described later with reference to FIGS. 3 to 12.

2 is a view for explaining an electronic document storage structure according to the present invention.

In FIG. 2, the depth k of the hash tree 20 is 3, and the number of leaf nodes is 2 ^k−1 , that is, 4. Each leaf node 22a, 22b, 22c, 22d stores a document serial number and a hash value for the document, and the primary parent nodes 24a, 24b store two adjacent leaf nodes 22a-22b, 22c-. The hash value calculated from the hash value of 22d) is stored.

In addition, the root node 26 stores the hash value calculated from the hash values of two adjacent upper parent nodes 24a and 24b in a digitally signed state.

In the present invention, since the digital signature is performed only on the hash value of the root node, the digital signature is updated only on the root node instead of updating the digital signature on all the electronic documents when the digital signature is expired. The procedure can be simplified.

3 is a flowchart illustrating an electronic document storage method according to an embodiment of the present invention, Figures 4a to 4e is a view for explaining an electronic document storage method according to an embodiment of the present invention.

As the operator intends to store the electronic document, the hash processing unit 114 calculates a hash value for the document to be stored (S101).

Subsequently, the document storage unit 118 refers to the metadata DB 110, selects a hash tree having the largest serial number, and checks whether an empty leaf node exists in the selected hash tree (S103). That is, it is to check whether the index (document serial number) of the leaf node in which the data is finally stored is smaller than the total number of leaf nodes (2 ^n-1 ) for the selected hash tree.

4A illustrates a hash tree having a depth of 2, and finally, an index of a leaf node in which data is stored is 2, and an index (index = 2) of a leaf node in which data is finally stored is smaller than 2 ^n-1 . . That is, there is an extra leaf node to add data to the hash tree.

In this way, after confirming that there is an extra leaf node, it is finally confirmed whether the index of the leaf note where the data is stored is a power of 2 (S105). do. That is, after the first parent node is generated by creating a new leaf node, the second parent parent using the hash value stored in the existing first parent node 34 and the hash value stored in the newly created primary parent node. It allows you to store hash values in nodes.

Referring to FIG. 4B, since the final index is 2, it can be seen that two empty leaf nodes 32c and 32d are generated.

Next, the hash value and the document serial number calculated in step S101 are stored in the next leaf node (32c in FIG. 4B) of the final index (S109), and the document to be added to the memory 106 is stored (S111). .

Thereafter, the hash value of the upper node of the leaf node is updated, and as shown in FIG. 4C, the hash value of the primary upper node 34a using the hash values of two adjacent leaf nodes 32c and 32d. Is updated, and the hash value for the secondary upper node 36 is updated by using the hash values for the existing upper parent node 34 and the newly generated primary upper node 34a. This hash value update process is repeatedly performed until the hash value of the root node is updated (S113 and S115).

After the hash value for the root node is updated, the digital signature is performed on the root node hash value (S117).

On the other hand, if the extra empty leaf node does not exist as a result of checking in step S103, a new hash tree having a depth k of 2 is created (S119), and the first leaf node of the generated hash tree, that is, the leaf having an index of 1 The hash value and the document serial number calculated in step S101 are stored in the node (S121).

In addition, if the final index is not a power of 2, as a result of confirming in step S105, the process proceeds to step S109 and the process after that. Referring to FIG. 4D, since the index of the leaf node 32a in which the data is finally stored is 1, the index is increased by 1 in step S109, and step S101 is applied to the index 2, that is, the leaf node 32b, as shown in FIG. 4E. After storing the hash value and the document serial number calculated by, the hash value of the upper node 34 is updated.

In FIGS. 3 and 4, a case of adding individual documents has been described. However, when a plurality of documents are added, the above process is performed. The processing time for adding documents is continuously updated due to a problem such as updating a hash value. This will be delayed. Accordingly, there is a need for a batch process of adding a plurality of documents, which will be described below with reference to FIGS. 5 and 6.

5 is a flowchart illustrating an electronic document storage method according to another embodiment of the present invention, Figures 6a to 6f is a view for explaining an electronic document storage method according to another embodiment of the present invention.

First, as the operator intends to store a plurality of electronic documents, the hash processing unit 114 calculates a hash value for each document to be stored (S201).

Subsequently, the document storage unit 118 refers to the meta data DB 110, selects the hash tree having the largest serial number, and checks whether an empty leaf node exists in the selected hash tree (S203). That is, it is to check whether the index of the leaf node in which data is finally stored is smaller than the total number of leaf nodes (2 ^n-1 ) for the selected hash tree.

If there is an extra leaf node to add data to the selected hash tree, the final index is odd (S205). If the final index is odd, the first hash of the hash values calculated in step S201 is next to the next index of the final index. The values and document serial numbers are stored, and the final indexes are updated (S207 and S209).

Referring to FIG. 6A, it can be seen that the final index is odd as 1, in this case, as shown in FIG. 6B, the hash value and the document serial number are stored in the leaf node 42b having the index 2, and then the final index. Is updated to 2.

Next, a hash tree having a depth k of 2 is generated using the remaining hash value and the serial number of the document except the hash value stored in step S207 (S211) (see FIG. 6C).

Then, it is checked whether the final index is an odd multiple of two (S213). In FIG. 6B, the final index is updated to 2, and it can be seen that 2 = 2 * 1, that is, an odd multiple of two. The process of checking whether the final index is an odd multiple of 2 is that the hash value of the secondary parent node 46 calculated from the hash value of the leaf node that stores the hash value of the stored document before adding the document is a new leaf. As you add nodes, the process checks to see if they need to be updated.

If the final index is an odd multiple of 2, one of the trees of depth 2 generated in step S211 is added to the hash tree (S215). Referring to FIG. 6D, it can be seen that one of the hash trees 52, 54, and 56 having a depth of 2 generated in FIG. 6C is added to the hash tree illustrated in FIG. 6A.

After adding a hash tree with a depth of 2, update the index with a value of 2. In this embodiment, the index is updated to four.

Thereafter, a hash tree having a depth of 3 is generated using the hash tree having a depth of 2 generated in step S211 (S219). Referring to FIG. 6E, it can be seen that a hash tree 64 having a depth of 3 is generated using the hash trees 54 and 56 except for the hash tree used in FIG. 6D among the hash trees generated in FIG. 6C.

The hash tree 64 generated in step S219 is added to the hash tree 62 generated in step S215 to generate a hash tree as shown in FIG. 6F (S221), and then each document to be added is stored in the memory 106. Store in (S223).

Next, the hash value of the upper node is updated from the hash values of two adjacent leaf nodes, and this process is repeated until the root node (S225, S227). After updating the hash value of the root node 34, an electronic signature is performed on the hash value of the root node (S229).

On the other hand, if there is no spare leaf node as a result of checking in step S203, a new hash tree is generated (S231). If the number of documents to be added is larger than the maximum allowable depth n of the hash tree, the documents are added in units of 2 ^n-1 .

When the final index is not an odd multiple of 2, that is, the final index is an even multiple of 2, the process proceeds to step S219 to perform the subsequent process. When the final index is not an odd number as a result of checking in step S205, the process proceeds to step S211 to perform the subsequent process.

7 is a flowchart illustrating a method for extracting an electronic document according to an embodiment of the present invention, and FIGS. 8A and 8B illustrate a method for extracting an electronic document according to an embodiment of the present invention.

As the document serial number (index of the leaf node) to be retrieved is input, the hash tree in which the hash value of the document having the serial number is stored is searched (S301).

Here, to search for a hash tree including the hash value to be retrieved, an integer t that satisfies [Equation 1] is calculated.

[Equation 1]

(t-1) 2 ^n-1 <Document Serial Number <t2 ^n-1

t is the serial number of the hash tree, and n is the maximum depth of the hash tree.

Referring to FIG. 8A, since the document serial number is 6 and the maximum depth of the hash tree is 3, the integer t greater than 1.5 and smaller than 2.5 becomes 2, corresponding to the document serial number 6 in the leaf node index 6 of hash tree 2. You can see that the hash value is stored.

Next, hash values on all paths connected to the corresponding leaf node are extracted (S303), and hash values of neighboring nodes of the extracted hash value are also extracted (S305) (see FIG. 8B).

Then, after verifying the digital signature value of the root node (S307), if it is determined that it is legal, the hash value for each node is calculated inversely descending from the root node to the leaf node (S309).

When the hash value for the leaf node is calculated, the document is retrieved from the memory 106 using the same (S311), and the retrieved document and the electronic signature value are returned (S313).

9 is a flowchart illustrating a method for deleting an electronic document according to an embodiment of the present invention, and FIGS. 10A and 10B are diagrams for describing a method for deleting an electronic document according to an embodiment of the present invention.

As the operator designates the document serial number to be deleted, that is, the leaf node index of the hash tree, the hash tree including the index is searched by the method of Equation 1 above (S401).

Then, it is checked whether an index to be deleted exists in the leaf node of the retrieved hash tree (S403). If there is, the corresponding leaf node is updated to an empty leaf node and the corresponding document is deleted from the memory 106 (S405).

Since the leaf node value has been changed, the hash value is updated from the upper node to the root node (S407 and S409). After updating the hash value for the root node, the digital signature is performed on the root node hash value (S411).

Referring to FIG. 10A, when a document for index 2 is to be deleted, the index is changed to an empty leaf node as shown in FIG. 10B, and the hash value from the parent node to the root node is updated.

As the document is deleted in this way, the leaf node of the hash tree is updated to an empty leaf node, and it is more efficient in terms of data management to use such empty leaf nodes when adding documents. However, in the case of adding a plurality of electronic documents, it may be inefficient to add the documents for each empty leaf node. Therefore, it is preferable to merge the mergeable hash tree.

11 is a flowchart illustrating a hash tree merging method according to an embodiment of the present invention, and FIGS. 12A and 12B are diagrams for describing a hash tree merging method according to an embodiment of the present invention.

First, the sizes of two adjacent hash trees are checked (S501). That is, the number of leaf nodes in which data is stored for each hash tree of serial number t-1 and a hash tree of serial number t is checked.

Then, it is checked whether the sum of the two hash tree sizes is equal to or less than the total number of leaf nodes (2 ^n-1 ) (S503).

Referring to FIG. 12A, the size of the hash tree t-1 having a depth of 3 is 2, and the size of the hash tree t having a depth of 3 is 1, and the sum of the two hash tree sizes (3) is the total number of leaf nodes (4). You can see that it is smaller.

As such, when the sum of the two hash tree sizes is equal to or less than the total number of leaf nodes, the leaf nodes in which data is stored are rearranged while maintaining the pre-stored order (see FIG. 12B) (S505), and the total number of leaf nodes (2). ^n-1 ) adds empty leaf nodes by subtracting two hash tree sizes (add one empty leaf node in FIG. 12B) (S507).

Next, the serial number of the hash tree is updated to t-1, and the hash values from the upper node to the root node are updated (S511 and S513), and the digital signature on the root node hash value is performed (S515). .

Then, the hash tree t is merged into another hash tree and all leaf nodes become empty leaf nodes (S517).

By doing in this way, an unnecessary increase in the number of hash trees can be prevented and an electronic document can be managed systematically according to a serial number.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

According to the present invention, a large amount of electronic documents can be safely stored and managed at low cost.

In addition, since the digital signature is performed only for the root node of the hash tree structure, forgery or tampering with all the electronic documents can be prevented only by updating the digital signature for the root node when the digital signature validity period expires.

Claims (19)

A control unit for controlling the overall operation; interface; A memory in which the hashed electronic document is stored; A database storing a hash tree and hash tree related information; A hash processing unit for calculating a hash value for each node constituting a hash tree and storing the hash value in the database; An electronic signature processor for performing an electronic signature on a hash value stored in a root node of the hash tree; A hash tree manager which stores and manages the serial number of the hash tree, the depth of the hash tree, the number of all leaf nodes, the number of leaf nodes in which data is stored in the database, and stores the generated hash tree in the database; And At least one document is stored in the memory according to an operator's request, and the hash value from the upper node of the hash tree to the root node after adding the document serial number and hash value to the hash tree. Document storage unit for updating; Electronic document management apparatus comprising a. The method of claim 1, The electronic document management apparatus searches for a hash value for a document requested to be retrieved from the hash tree by referring to a document serial number requested by an operator and extracts a document stored in the memory using the retrieved hash value. Electronic document management device further comprises a drawing unit. The method according to claim 1 or 2, The electronic document management apparatus searches for a hash tree in which a hash value for a document requested to be deleted by an operator is deleted, deletes a leaf node in which a hash value for a document requested to be deleted is stored from the found hash tree, and the leaf node is deleted. And a document deleting unit which updates a hash value from an upper node of the tree to a root node, and deletes the requested document from the memory by using a hash value of the deleted requested document. Management device. The method according to claim 1 or 2, The hash tree management unit merges two neighboring hash trees when the sum of the number of leaf nodes in which data is stored is less than or equal to the total allowable leaf nodes in one hash tree, for two neighboring hash trees. Electronic document management device. The method of claim 1, And the electronic signature is performed using a time stamp protocol (TSP). The hash value and the document serial number of the stored document are stored in the leaf node, and the hash value from the parent node to the root node is stored according to the hash values stored in two adjacent child nodes, and the hash value stored in the root node is stored. An electronic document management method having a hash tree structure stored electronically, A first step of calculating a hash value for the document to be stored as an operator wants to store the electronic document; A second step of selecting a hash tree having the largest serial number when the hash tree is generated and checking whether an empty leaf node exists in the selected hash tree; A third step of determining whether an index (final index) of a leaf note in which data is finally stored is a power of 2 when an empty leaf node exists in the selected hash tree; A fourth step of generating as many empty leaf nodes as the number of final indexes when the final index is a power of two; A fifth step of storing a document serial number and a hash value calculated in the first step in a leaf node corresponding to a next index of a final index, and storing the document in a memory; A sixth step of updating a hash value from an upper node of the leaf node to a root node; A seventh step of performing an electronic signature on the hash value of the root node; Electronic document management method comprising a. The method of claim 6, An eighth step of generating a hash tree having a depth of two when there is no empty leaf node as a result of the checking of the second step; And A ninth step of storing a document serial number and a hash value calculated in the first step in a first leaf node of the hash tree generated in the eighth step; Electronic document management method comprising a further. The method of claim 6, And if the final index is not a power of 2 as a result of the checking in the third step, branching to the fifth step. The hash value and the document serial number of the stored document are stored in the leaf node, and the hash value from the parent node to the root node is stored according to the hash values stored in two adjacent child nodes, and the hash value stored in the root node is stored. An electronic document management method having a hash tree structure stored electronically, A first step of calculating a hash value for each of the documents to be stored as an operator wants to collectively store a plurality of electronic documents; A second step of selecting a hash tree having the largest serial number when the hash tree is generated and checking whether an empty leaf node exists in the selected hash tree; A third step of determining whether an index (final index) of a leaf note in which data is finally stored is an odd number when an empty leaf node exists in the selected hash tree; A fourth step of storing the document serial number for the first electronic document to be added and the hash value calculated in the first step for the electronic document and updating the final index when the final index is odd. ; A fifth step of generating a hash tree having a depth of 2 using the remaining hash value and the serial number of the document except the hash value stored in the fourth step; A sixth step of checking whether the final index is an odd multiple of two; A seventh step of adding one of the hash trees having a depth of 2 generated in the fifth step to a previously generated hash tree and updating the final index by two when the final index is an odd multiple of two; An eighth step of generating a hash tree having a depth of three using the hash tree other than the hash tree used in the seventh step among the hash trees having the depth two generated in the fifth step; A ninth step of adding the hash tree generated in the eighth step to the hash tree updated in the seventh step; A tenth step of updating a hash value from an upper node of the leaf node to a root node; And An eleventh step of performing an electronic signature on a hash value of the root node; Electronic document management method comprising a. The method of claim 9, If the final index is not an odd number as a result of the checking in the third step, branching to the fifth step. The method of claim 9, And as a result of the sixth step, if the final index is not an odd multiple of two, branching to the eighth step. The method of claim 9, And a twelfth step of adding a document by creating a new hash tree when the empty leaf node does not exist as a result of the checking in the second step. The hash value and the document serial number of the stored document are stored in the leaf node, and the hash value from the parent node to the root node is stored according to the hash values stored in two adjacent child nodes, and the hash value stored in the root node is stored. An electronic document management method having a hash tree structure stored electronically, A first step of retrieving a hash tree in which a hash value of a document according to the document serial number is stored, as a document serial number (index of a leaf node) to be retrieved from an operator is input; With respect to the retrieved hash tree, a hash value on all paths including a leaf node storing the document serial number and a root node connected to the leaf node is retrieved, and a hash value of neighboring nodes of the retrieved hash value is obtained. Withdrawing the second step; A third step of verifying an electronic signature value with respect to the root node hash value; A fourth step of calculating a hash value for each node sequentially from the root node to the leaf node; And A fifth step of extracting a corresponding document using the calculated hash value for the leaf node; Electronic document management method comprising a. The method of claim 13, The first step is to search for an integer t that satisfies (t-1) 2 ^n-1 <document serial number <t2 ^n-1 when the hash number of the tree is t and the maximum depth of the hash tree is n. Electronic document management method characterized in that. The method of claim 13, And after the fifth step, a sixth step of providing the document and the electronic signature value withdrawn in the fifth step. The hash value and the document serial number of the stored document are stored in the leaf node, and the hash value from the parent node to the root node is stored according to the hash values stored in two adjacent child nodes, and the hash value stored in the root node is stored. An electronic document management method having a hash tree structure stored electronically, A first step of searching for a hash tree in which a hash value of a document according to the document serial number is stored, as a document serial number (index of a leaf node) to be deleted from an operator is input; A second step of checking whether an index to be deleted exists in a leaf node of the searched hash tree; Updating the leaf node with an empty leaf node if there is an index to be deleted and deleting the corresponding electronic document stored in the memory; And A fourth step of updating a hash value from an upper node of the leaf node to a root node and performing an electronic signature on the root node hash value; Electronic document management method comprising a. The method of claim 16, The first step is to search for an integer t that satisfies (t-1) 2 ^n-1 <document serial number <t2 ^n-1 when the hash number of the tree is t and the maximum depth of the hash tree is n. Electronic document management method characterized in that. The method of claim 16, After the fourth step, A fifth step of checking the sizes of the hash tree from which the leaf node is deleted and the adjacent one hash tree; A sixth step of checking whether the sum of the two hash tree sizes is equal to or less than the total number of leaf nodes; If the sum of the two hash tree sizes is equal to or less than the total number of leaf nodes, a seventh step of rearranging leaf nodes in which data is stored while maintaining a pre-stored order; An eighth step of adding an empty leaf node by subtracting the sum of two hash tree sizes from the total number of leaf nodes; Ninth step of updating a serial number of a hash tree; And A tenth step of updating a hash value from an upper node of the hash tree whose serial number is updated to a root node, and performing an electronic signature on the root node hash value; Electronic document management method comprising a further. The method of claim 18, And after the tenth step, an eleventh step of deleting a hash tree in which all leaf nodes are empty leaf nodes.

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