KR20020096689A - Method of protecting digital information and system thereof - Google Patents

Abstract

PURPOSE: A method for securing digital information and a system thereof are provided to prevent an internal illegal usage for a digital information security such as an important document, data, a program of a company or an institution. CONSTITUTION: A company information server(10) is connected to an operator computer(12) and includes various detailed contents of a digital information security operation. A server manager manages the company information server(10) and controls an operation through the operator computer(12). A user in a remote place being connected to a PSDN(Public Switched Data Network)(20) connects to the company information server(10). The user computer(22) receives code company information from the company information server(10). An application tool for a digital information security is installed in a terminal(14) or the user computer(22). A managing tool and various kinds of databases are mounted in the company information server(10) for managing a user who uses the terminal(14) or the user computer(22), and securing/managing supplied(or received) company information.

Description

METHOD OF PROTECTING DIGITAL INFORMATION AND SYSTEM THEREOF

The present invention relates to a method and system for securing a digital information stored in a public computer of a corporation and an institution through wired or wireless communication or a storage medium such as a diskette and leaking it to the outside. The present invention relates to a method and a system for preventing an internal user (or an external user) from illegally using digital information, such as a digital document or a program, which is shared in the Internet.

Recently, various information such as documents and data are digitized by computers, and as the Internet, e-mail and digital storage media are developed, there is an opportunity to obtain desired data more quickly and easily. ought.

However, due to the nature of digital information, not only can you easily make copies or variations of the originals, but also distribute them easily. Problems that can lead to weakening are emerging.

In particular, as the construction of LAN (Local Area Network) or KMS (Knowledge Management System) is rapidly progressing in recent years, the information and data within the company are simply coming and going. Therefore, due to the ease of access to digital information, The possibility of information disclosure by institutions is increasing. Indeed, as employees move or retire from one company to another, they are also leaking their secrets illegally.

Therefore, the demand for the protection technology of digital information is increasing rapidly, and various technologies in the field of technology and service are being developed to prevent illegal distribution and use. These technologies include firewall installation technology, digital rights management (DRM) technology that protects, secures, and manages digital documents. E-mail user restriction technology;

Firewall installation technology for system security, network security, facility security, etc. is mainly to prevent illegal intrusion from the outside, and mainly aims at preventing intrusion from outside rather than managing users of companies or institutions. Therefore, there is a problem in that it does not play a role in the illegal intrusion or behavior in the enterprise or organization.

DRM technology is a technology that prevents illegal distribution and duplication of multimedia information, manages users so that only legitimate users can use the information, and manages copyright of multimedia information through billing services such as payment. Such DRM technology is currently accepted as a realistic solution to protect and manage copyrights of digital information in the market, but the current DRM system is very complicated and bloated because of its structure and system. There is a problem that is not easy.

In particular, the management of authentication keys used by general users to actually purchase and reproduce information is often operated entirely by the DRM server provider, and the actual information is also transmitted to the server registrant to register and encrypt it. After receiving it again, it is often operated. As a result, when using it in a general company or institution, there is an inconvenience of double operation in which information is sent to the server registrant and received again in terms of system construction and actual information management. The complexity of the transmission path increases the likelihood of information leakage in the middle.

Moreover, in the case of such DRM technology, there is a concern that source contents may be easily distributed when encryption surrounding information is released. In addition, in the information protection using the existing DRM, the route of the information provider and the information user constitute a one-way route, and thus, the communication of the distribution system through mutual exchange of opinions in the information distribution system is difficult. In case of applying such DRM technology for document security such as enterprise or government, it is difficult to apply it except for commercial purpose information because it is inconvenient to send all the target documents for security to server registrant and encrypt and receive them again. It also has its drawbacks.

On the other hand, in the case of document security through the management of e-mail, the list is created by limiting the size of e-mail attachments, controlling traffic through TIP / IP (Transmission Control Protocol / Internet Protocol), or controlling through monitoring. It is a technology that reports or calls attention through an alarm or monitors a user. However, document security through the management of e-mail has a problem that violates individual freedom in that it monitors personal information of companies or institutions. Recently, in addition to e-mail, files can be transferred via the World Wide Web (WWW) or FTP (File Transfer Protocol). Also, floppy disks, "Zip" disks, "Jazz" disks, compact disks and The development of the same mass storage media has a problem that can not block the path through which information leaks. Recently, since data, data, and programs can be transmitted over the air, such as a PDA (Personal Digital Assistant), document security through the control of e-mail is showing its limitations.

Accordingly, an object of the present invention is to provide a digital information security method and a system which can prevent illegal use of internal information for the security of digital information such as important documents, data, programs, etc. of a company or organization.

Another object of the present invention is to provide a digital information security method and system that can prevent illegal use even if digital information such as important documents, data, programs, etc. of an enterprise or organization is illegally leaked.

In order to achieve the above object, an aspect of the present invention is a digital information security system, which is installed in a user terminal, a user application tool for generating a unique key of the user using system-specific information of the user terminal, and user information And a data storage unit for storing digital information and a server, which are installed in a server, receive a user's unique key generated by a user application tool, and store the data as a part of the user information in the data storage unit. And a user management tool for comparing a key with a unique key provided by a user application tool of a user currently authenticating.

According to another aspect of the present invention, in the digital information security method, a process of reading a user's unique key generated using system-specific information of a corresponding user terminal when a user accesses a server, and the user's unique key read in advance and stored in advance Compare the user's unique key included in the user information about the currently connected user and verify the suitability of the connected user, and encrypt the file using the preset encryption key when uploading the authenticated user's file. And storing it as digital information, and encrypting and downloading the digital information using a user's unique key included in the user information when requesting to download the digital information of the authenticated user. .

1 is a schematic overall block diagram of a digital information security system according to an embodiment of the present invention.

2 is a block diagram of a corporate information server and a terminal of FIG.

3 is an operation flowchart of a user registration process in an enterprise information server according to an embodiment of the present invention.

4 is a flowchart illustrating an operation of uploading a corporate document from a user in a corporate information server according to an exemplary embodiment of the present invention.

5 is a flowchart illustrating a process of downloading a corporate document to a user in a corporate information server according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and it is understood that these specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

According to the present invention, since digital information (hereinafter referred to as corporate document) to be secured is produced and has value as information in the enterprise, it can be used by various users through a network or any path via offline. It presents security methods and devices throughout the entire process of creation, distribution, and disposal, up to the moment the document is discarded. The present invention proposes all management systems such as protecting corporate documents and allowing users to use their rights in a legitimate manner so that information cannot be stolen, tampered with, or tampered with.

1 is a schematic overall block diagram of a digital information security system according to an embodiment of the present invention. Referring to FIG. 1, the enterprise information server 10 is connected to a plurality of terminals 14 such as a personal computer through an internal network, and is also used by remote users through a packet switched data network (PSDN) 20, which is a data communication network. It is a system that can be connected to, and provides corporate information or data provided by a predetermined company in accordance with the present invention.

The enterprise information server 10 is connected to the operator computer 12, and various details of the digital information security operation according to the present invention may be set by the instructions received from the operator computer 12. The server administrator manages the enterprise information server 10 through the operator computer 12 and controls the operation.

A remote user connected through the PSDN 20 may access the corporate information server 10 using the personal computer 22. The user computer 22 may be connected to the corporate information server 10 through the PSDN 20 to receive corporate information encrypted according to the present invention. Alternatively, the user computer 22 may be connected to the enterprise information server 10 by using a local area network (LAN) or a local area network (WAN), which will be described as being included in the PSDN 10. .

As described above, the terminal 14 or user computer 22 which receives encrypted corporate information or provides corporate information by accessing the corporate information server 10 of the present invention through the internal network or the PSDN 20 is provided with the present invention. Application tool for digital information security is installed, the enterprise information server 10 manages the user using the terminal 14 or the user computer 22, provided (or received) corporate information Management tools and various data storage databases are established for security and management. This will be described in more detail with reference to FIG. 2.

FIG. 2 is a block diagram of the enterprise information server 10 and the terminal 14 connected thereto in FIG. 1. The enterprise information server 10 includes a network interface 110, a data distribution path 120, a server controller 130, a data storage 140, a history manager 150, and an operator computer interface 160. It is composed of

The network interface 110 is connected to the PSDN 20 and the internal network to transfer data received from the internal terminal 14 and the user computer 22 to the data distribution path 120 and input from the data distribution path 120. The transmitted data to each corresponding terminal through the PSDN 20 or the internal network.

The data distribution path 120 may be configured differently according to the system configuration of the present invention. For example, in the case of one system, it can be configured as a bus for transferring data between each functional unit. As another example, when each functional unit is configured as an independent system, it may be connected by using a local area network (LAN) or the like. In addition, when the several functional units form an independent system and are connected to each other, the independent systems may be connected to a local area network, and the devices connected therein may be configured as a bus. As such, the data distribution path 120 may be configured using various methods for transferring data.

The server controller 130 which collectively controls the enterprise information server 10 performs various processes of displaying screen information and data available for disclosure at the time of initial access to the server. In addition, it provides information for processing data that does not require the security of various information, such as providing bulletin board and general operator mail information. In addition, according to a feature of the present invention, when the encryption of the document and the user access to the corporate document is required, various operations for user authentication, corporate document download / upload, and the like are controlled. The server controller 130 includes a user management tool 132 for managing an encryption key and a user unique key.

Data storage unit 140 is an interface unit 141, rule setting unit 142, encryption unit 143, combining unit 144, encryption document DB 145, user information DB 146, corporate document information DB 146, corporate document DB 148, and rule DB 149.

The interface unit 141 may provide each internal function unit or databases according to a destination of data input through the data distribution path 120 from the outside, or read data of various databases and transfer it to other external function units. Output to the data distribution path 120. The rule setting unit 142 sets various items or rules for the user and the document according to various rule setting items recorded and stored in the rule DB 149. The corporate document DB 148 stores corporate documents, the corporate document information DB 147 stores corporate document information, and the user information DB 146 stores user information including a user unique key. The encryption unit 143 encrypts various types of information stored in the corporate document DB 148, the corporate document information DB 147, and the user information DB 146 through an encryption key. The combiner 144 combines the enterprise document with the user's unique key, encryption key, rule, and the like and encrypts the encrypted document DB in the cipher document DB 145. The cipher document DB 145, the user information DB 146, the corporate document information DB 146, the corporate document DB 148, and the rule DB 149 are logically separated, but physically one. Can be built into a database.

The history manager 150 may be classified into a history manager 151 and a usage history memory 152. When the history management device 151 receives information according to the browsing history of the information provided from the network interface 110, the history management device 151 divides the information into pieces of information and stores the information in the usage history memory 152. This history information becomes more necessary for the higher security level information.

Meanwhile, a user application tool 214 is installed in a user unit (terminal 14 in the embodiment of FIG. 1) that creates and uses an enterprise document, and the user application tool 214 has an ID of a system of a user installed therein. By using the user to generate a unique key and transmit it to the enterprise information server (10).

That is, a user downloads and installs a user application tool 214 from the enterprise information server 10 through user registration, and the user application tool 214 generates a user unique key using a unique system ID installed therein. Then, it is transmitted to the enterprise information server 10 to perform user registration.

In connection with authentication of the use of digital information generated in the above process, the user application tool 214 provides the user management tool 132 with various available conditions and user unique keys, and provides data or signals for these conditions. send. Accordingly, the user management tool 132 receives the unique key information of the user from the user application tool 214 and receives various rules for controlling the corporate document file through the rule setting unit 142 from the rule DB 149. Set. Information about the unique key of the user is stored in the user information DB unit 146.

The corporate document uploaded by the user 10 is stored in the corporate document DB 148, and this document is stored in the corporate document DB 148. Combined with the corporate document encryption key. The encrypted corporate document is provided to the user application tool 214 through a user password input and user authentication procedure on the Web through a LAN, an offline path, or the Internet, and the user can receive or view corporate information through the user. It becomes possible.

The user application tool 214 and the user management tool 132 described above are the contents control key (CCR) contents turn key system (CTS) of the patent application No. 2001-23562 filed to the applicant. Protection and management systems).

Meanwhile, when the user application tool 214 describes a user's unique key generation operation in more detail, the components constituting the computer system include a CPU, a RAM, a hard disk, and various devices. There is. User-specific key generation by the system-specific information proposed in the present invention generates a user-specific key using the unique information of the system components of each user, thereby controlling the user authentication and whether to use the information playback.

In more detail, in the case of the CPU, the Pentium III or higher chip has a unique ID. Hard disks can also find manufacturer information (IDE) by examining the physical sectors of their master area. Manufacturer information includes the manufacturer name, serial number, model information. In the case of the serial number, the numbers used by the manufacturer A, manufacturer B, etc. may overlap. In the present invention, information indicating the characteristics of the system is extracted as described above, and a user unique key is generated based on the extracted system specific information.

The user application tool 214 having a function of blocking the extracted unique information from being externally confirmed is stored in a known black box, and then a user unique key is generated using the unique information. An algorithm for generating a user unique key may be implemented by various methods. The generated user's unique key does not remain in the registry for security maintenance, and retrieves the user's unique key every time the user plays the information in the user application tool 214 provided in the present invention to release the encrypted information. . Of course, this plug-in has a built-in black box. The information authenticated by a specific user by the above series of processes is controlled to be redistributed to the second and third users by the rules set by the rule setting unit 142 and not reused without the authorized permission.

The generated user unique key is transferred to the user information DB unit 146 and managed as information on users who use the system according to the present invention. Accordingly, the user management tool 132 manages information about an encryption key generated for encryption of digital information provided to users along with the user's unique key.

As described above, if the user management tool 132 authenticates the user through the user management tool 132, including authentication for the use of digital information, the user is encrypted. Information can be received through a procedure such as downloading.

The basic function of the user management tool 132 is to protect the information through encryption process and to prevent the illegal distribution or illegal use of the information throughout the entire process from creation, distribution, use, and disposal of digital information. It manages and protects copyrights and confidentiality. Only a legitimate user with an encryption key can decrypt and use the encrypted information, and protects the information by disabling the key if it is illegally distributed.

Particularly, in the present invention, the key to decrypt the encrypted information is transmitted to the user through the user application tool 214 to increase the security thereof, thereby preventing the key from being leaked. As the encryption key, an encryption key having a byte length of a predetermined size (128 bits in one embodiment of the present invention) may be used. Various encryption algorithms that are commercially available may be used for such encryption, and for example, twofish encryption algorithm or blowfish encryption algorithm may be applied.

The user uses the key only when using the information, and the information is always present in an encrypted and locked state, and is provided in a form that can be used through authentication of the user's unique key and the enterprise document encryption key only through the user application tool 214. In this information dissemination and authentication scheme, rules for using information are set in the rule setting unit 142, which indicates the rules and rights of each individual when distributing and using the information, and is not directly related to copyright protection of digital information. . By setting such rules, it is possible to provide efficient information through free rule management such as adding or modifying rules according to redistribution of digital information. It is of course possible for the user to use the information only in accordance with the authorized rules.

Hereinafter, the above-described user registration and upload / download of corporate information will be described in detail with reference to the accompanying drawings.

3 is an operation flowchart of a user registration process in the enterprise information server 10 according to an embodiment of the present invention. First, when the user accesses the enterprise information server 10 in step 302, the enterprise information server 10 checks whether the user application tool of the user is installed in step 304 to determine whether the corresponding connected user is a registered user. If the user is confirmed and registered, the process proceeds to step 306 to perform the corresponding function. If the user is not a registered user, the process proceeds to step 308 to perform a series of procedures for authenticating the user as an appropriate user. If the user is not a suitable user, the process proceeds to step 310, and the subsequent processing operation is performed as an inappropriate user. If the user is a suitable user, the process proceeds to step 312.

In step 312, the user application tool program is downloaded to the user's system and automatically executed. When the user application tool is installed in the user system, the user application tool reads the unique information from the user's system, generates a user unique key using the same, and transmits it to the user management tool. Accordingly, if the user's unique key is transmitted from the user in step 314, the enterprise information server 10 performs the corresponding user registration in step 316, and then stores the information of the registered user in the user information DB in step 318.

3 is a series of processes in which the user installs the user application tool 214 and transmits the user unique key to the server 10 to register the user's unique key. As shown in FIG. 3, when a user is an unregistered user of a service provided by a system according to an embodiment of the present invention, a user is first registered. At the time of registration, it receives the user application tool from the user management tool 132 and installs it in the user's computer. The data is transmitted to the user management tool 132 to encrypt the user's information, and then stored in a separate database, that is, the user information DB 146.

4 is a flowchart illustrating a process of uploading a corporate document from a user in the corporate information server 10 according to an exemplary embodiment of the present invention. Referring to FIG. 4, when the user accesses the server in step 402, the user management tool first checks whether the user application tool is installed in the user's system in step 404, and confirms whether the user is registered or not. In step 406, the user registration process as disclosed in FIG. 3 is performed. If the user application tool is installed, the process proceeds to step 408, in which the user's unique key is read and compared with the previously stored user information of the user information DB, thereby authenticating whether the user is suitable for system use. If the user is not suitable for system use, the process proceeds to step 410 and the user cannot perform authentication. If the user is authenticated, the user proceeds to step 412 to allow the user to upload a file.

Accordingly, the uploaded document is divided into user information, corporate document information, and corporate document, respectively, and is encrypted in steps 414, 424, and 434, respectively, and then, in steps 416, 426, and 436, user information DB, company document information DB, And it is stored in the corporate document DB again. After that, the content of setting the rules of the corporate document is added in step 440, and then, in step 442, they are merged in the combining unit, and in step 444, they are stored as encrypted corporate documents in the cipher document DB.

Referring to the process illustrated in FIG. 4, when a user uploads an enterprise document to be uploaded to the server 10 after undergoing a process such as user authentication on a LAN or a web service through the user management tool 132, The digital corporate document information is input through a DB gateway (interface unit 141 of FIG. 2), encrypted by the encryption unit 143, and then stored in the corporate document information DB 147, and the corporate document file is encrypted by the encryption unit 143. After encrypted with the encryption key through the corporate document is stored in the DB (148). The unique key information of the user is read from the user information DB 146 and transmitted by the rule setting unit 142 to the combining unit 144 with the rules set in the settings of the rule DB 149. The combiner 144 combines user unique keys, rules, corporate document information, and corporate document stored in each database, and the combined information is stored in the cipher document DB 145.

5 is a flowchart illustrating an operation of downloading a corporate document to a user in an enterprise information server according to an exemplary embodiment of the present invention. Referring to FIG. 5, when the user accesses the server in step 502, the user management tool first checks whether the user application tool is installed in the user's system in step 504, and confirms whether or not the user is registered. In step 506, the user registration process as disclosed in FIG. 3 is performed. If the user application tool is installed, the process proceeds to step 508 to read the user's unique key and compare the information with the corresponding user information stored in the user information DB to verify whether the user is suitable for system use. If the user is not suitable for system use, the process proceeds to step 510 to perform a user authentication impossible processing. If the user is authenticated, the user proceeds to step 512 to accept the user's request for downloading a corporate document. Thereafter, the corporate document is transmitted to the user application tool in step 514.

In operation 520, the user application tool checks whether the user unique key included in the document downloaded from the server and the user's unique key generated by the user match. If there is a mismatch, the process proceeds to step 522, where a unique key mismatch processing operation is performed. If there is a match, the process proceeds to step 524. In step 524, the decryption key included in the downloaded enterprise document is converted into a key that can be decrypted to check whether decryption is possible. If the decryption is possible, the process proceeds to step 526 and the decryption processing operation is performed. If the decryption is possible, the process proceeds to step 530. The decryption of the corporate document is performed using the encryption key included in the corresponding corporate document. Thereafter, in step 532, the decrypted corporate document is output so that it can be viewed, modified, or stored.

Looking at the process as shown in FIG. 5 in more detail, if there is a request for a specific digital information from the user, the user management tool 132 is an encrypted company stored in the cipher document DB 145 after the user authentication process The document is sent to the user application tool 214 of the user. Encrypted corporate documents are transmitted via LAN or Internet at the request of the user.

The user must go through a decryption process to play this encrypted corporate document file. At this time, an information decryption key is required to reproduce this information, and a key necessary for decryption is provided encrypted by a unique key of the user of the information mentioned above. That is, the decryption key of the corporate document file encrypted with the user's unique key is provided.

Therefore, in order to transmit the digital information to the user to reproduce the information, it is important whether the information can be decrypted using the decryption key transmitted together with the encrypted information. That is, in order to reproduce the information, a key for decrypting the information is required. Since the decryption key is also encrypted and transmitted to the user, the process of decrypting the key must be performed first.

The key capable of decrypting the encrypted information may be said to be extracted through the user application tool 214 from the system specific information of the user. In other words, the user using the information first creates a user unique key with the unique information extracted from the system information and encrypts the information decryption key. Therefore, in order to decrypt it again, the user unique key and the information decryption key generated from the system information of another user are encrypted. It must match by checking whether one key matches. If the key for encrypting the encrypted corporate document file decryption key and the user's unique key are not the same at the check, the user ends the operation with a message indicating that the user is not a valid licensee.

However, when the key for encrypting the decryption key of the encrypted corporate document file and the user unique key extracted and generated by the user's system match, the information decryption key is used by using the decryption key of the corporate document encrypted with the user's system unique key. You can extract it. The company document file is decrypted using the extracted information decryption key and the company information is reproduced using the user application tool 214.

Meanwhile, the path through which digital information is distributed may use an online path through wired or wireless communication, but may also use an offline direct transmission path as needed. In the description of the embodiment of the present invention, the digital information is provided, purchased, and the like, and a series of programs and information are also downloaded online. However, according to circumstances, the digital information may be a floppy disk. It may be stored on a storage medium such as a compact disc (CD), a DVD ROM, a "zip" disk, a laser disk, or a video tape or a cassette tape to be distributed offline.

As such, even when digital information is distributed offline, when a user first opens or plays information on a terminal such as a computer, a user's unique key is generated through execution of a user application tool, and then the user's unique key is generated. Determine and control information playback.

Through this process, even if a user wants to leak a corporate document by downloading a file using a storage medium, the user can only view, modify, save, or print the corporate document using a user application tool installed on the user terminal. It is impossible to leak corporate document information.

According to the above configuration, the digital information security method and system according to the features of the present invention can be made. In the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Can be. Therefore, the scope of the present invention should not be defined by the described embodiments, but by the claims and equivalents of the claims.

As described above, the present invention not only prevents the illegal distribution of information such as documents and data in the enterprise, but also operates the system in conjunction with the conventional KMS construction that the enterprise establishes for user restriction and data sharing. By doing so, information and data in the company can freely travel and prevent leakage to the outside. In addition, even if a company does not have a KMS, it can be used in a LAN or WAN to prevent document leakage in the enterprise. Even if a user wants to leak an enterprise document through a storage medium, the user's unique key is different from computer to computer.

In addition, even if the database of the corporate document is hacked by an illegal hacker from the outside, it cannot be used because it is an encrypted corporate document. Therefore, it is possible to operate a security system for corporate documents that is safe from outside intrusion.

Claims (8)

In the digital information security system, A user application tool installed in a user terminal and generating a unique key of a corresponding user using system-specific information of the user terminal; A data storage unit for storing user information and digital information; It is installed in the server, and receives the user unique key generated by the user application tool to store it as part of the user information in the data storage unit, and during the user authentication of the stored user unique key and the user currently authenticated And a user management tool for comparing whether or not a user unique key provided by the user application tool is matched. The method of claim 1, wherein the user management tool transmits the user's unique key included in the user information of the user at the time of downloading to the user of the digital information, And the user application tool determines whether to output the downloaded digital information by comparing the transmitted user unique key with the user unique key generated by the user application tool when the digital information is downloaded. The system of claim 1 or 2, wherein the security system is Further having a rule setting unit for setting a rule in accordance with a user rule preset for each of the stored digital information, The user management tool includes the rule information set by the rule setting unit for the user at the time of downloading to the user of the digital information, and transmits it. And the user application tool determines whether to output the downloaded digital information according to the received rule information when the digital information is downloaded. The security system of claim 1, wherein the system specific information includes at least one of unique information of a central processing unit of the user terminal, unique information of a hard disk, and serial information of the terminal. . In the digital information security method, Reading the user's unique key generated using the system's unique information of the user's terminal when the user's access from the server; Comparing the read user's unique key with a user's unique key stored in user information about the currently connected user, and authenticating the suitability of the connected user; Encrypting the file using an encryption method using a predetermined encryption key and storing the file as the digital information when uploading the file of the authenticated user; And encrypting the decryption key of the digital information by using the user's unique key included in the user information when downloading the digital information of the authenticated user. Security method. The method of claim 5, And decrypting the digital information by decrypting the encrypted decryption key of the downloaded digital information by using a user unique key generated by using the system specific information. The program according to claim 5, wherein the server generates a program for generating and transmitting a unique key of the user by using the system-specific information of the user terminal when the user is not registered when the user accesses the server. To send and install, And registering the user by using the unique key of the user generated and transmitted by the installed program. In the digital information security method, Generating a user unique key using system-specific information of the corresponding user terminal when playing encrypted digital information in the user terminal; Decrypting, at the user terminal, an encrypted decryption key included in the digital information by using the generated user unique key; Decrypting the digital information using the decrypted decryption key; and decrypting the encrypted decryption key when the key used to encrypt the encrypted decryption key and the generated user unique key do not match. Security method characterized by the impossible.