KR100741144B1 - Apparatus and method for preventing of reprinting digital contents - Google Patents

Abstract

The present invention relates to a digital content copy protection device and method for effectively preventing illegal copying of digital content provided to a client. The authentication server of the present invention generates a service registration key by an authentication server based on user information of a client connected through a network and information of a digital content providing server, and decrypts a digital content file encrypted by system information of a client terminal. Create a user authorization key for The digital content providing server encrypts the digital content file by providing a file encryption key by encrypting the service registration key in multiple stages and provides the encrypted content file to the client. The client decrypts the encrypted digital content file by generating a file decryption key by multi-level encryption and decryption of the user authorization key. In addition, in the present invention, a two-pass algorithm is used to generate a service registration key, a file encryption key, and a file decryption key.

Digital Content, Authentication Server, Replication, System Information, File Encryption Key, File Decryption Key, Two Fish Algorithm

Description

Apparatus and method for preventing copying digital content {APPARATUS AND METHOD FOR PREVENTING OF REPRINTING DIGITAL CONTENTS}             

1 is a block diagram of a digital content piracy prevention device according to the present invention.

2 is a schematic flow diagram for registering a service of a client.

3 is a schematic block diagram of a two-pass block encryptor.

4 is a schematic flow diagram for canceling service registration of a client;

5 is a schematic flow diagram for receiving a digital content file of a client.

6 is a diagram illustrating a header configuration of an encrypted digital content file.

7 is a flow chart for performing digital content copy protection according to the present invention.

8 is a flowchart for performing file encryption key generation for digital content file encryption.

9 is a flow chart for performing user authority information generation by the authentication server.

10 is a flow chart for decoding a digital content file according to the present invention.

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

100: authentication server

102: digital content providing server

104: client

106: Client Information Database

108: digital content information database

110: authentication information database

The present invention relates to a digital content copy protection device and method, and more particularly, to a digital content copy protection device and method for effectively preventing illegal copying of digital content provided to a client.

Modern people live in the flood of information provided through various media such as broadcasting and publishing. There is an information provider who wants to supply the information provided through various media at one time, and a user who wants to selectively receive only the desired content among the digital content provided by the information provider has been created.                         

This will lead to the emergence of digital content delivery systems consisting of information providers that convert various information into digital content and store the digital content for each user, and users who receive digital content from the information provider over the network. It became.

Such a digital content delivery system has provided a user with an application that can easily download digital content.

In addition, the user connected to the digital content delivery system by the network can obtain all the desired information through the downloaded application program.

The digital content supplied by the digital content transmission system is supplied to the user for free or for a fee.

For digital content that is supplied for a fee, each service fee is determined by the digital content transmission system.

When the user receives the digital content with the predetermined service fee, the service server accumulates the service fee according to the user's information usage and charges the user.

However, when a user accesses a system that provides digital content commercially using a network and receives paid digital content, most users have a problem of distributing paid digital content to others in a duplicate form without permission. .

In addition, there is a serious damage to the supplier for use by the copied digital content, but there is also a problem that can not be fundamentally prevented.

Accordingly, an object of the present invention is to provide an apparatus and method for preventing digital content copying for encrypting a digital content file by using a file encryption key generated through multi-level encryption. have.

Another object of the present invention is to provide a digital content duplication apparatus and method for generating a user authorization key for decrypting an encrypted digital content file by system information of a client terminal.

In order to achieve the above objects, the authentication server of the present invention generates a service registration key by an authentication server based on user information of a client connected through a network and information of a digital content providing server, and encrypts the information by a system information of a client terminal. A user authorization key for decrypting the digital content file is generated.

The digital content providing server encrypts the digital content file by providing a file encryption key by encrypting the service registration key in multiple stages and provides the encrypted content file to the client.

In addition, the client may generate a file decryption key by multi-level encryption and decryption of the user authorization key to decrypt the encrypted digital content file.                     

In addition, in the present invention, a two-pass algorithm is used to generate a service registration key, a file encryption key, and a file decryption key.

Hereinafter, an apparatus and method for preventing illegal copying of digital content according to the present invention will be described in detail with reference to a preferred embodiment.

FIG. 1 is a block diagram illustrating an apparatus for preventing illegal copying of digital content according to the present invention, FIG. 2 is a schematic flow diagram for registering a service of a client, and FIG. 3 is a schematic block diagram of a two peer block encryptor.

4 is a schematic flow diagram for canceling service registration of a client, FIG. 5 is a schematic flow diagram for receiving a digital content file of a client, and FIG. 6 is a diagram illustrating a header structure of an encrypted digital content file.

As shown in FIG. 1, the present invention provides an authentication server 100, a digital content providing server 102, a client 104, a client information database 106, a digital content information database 108, and an authentication information database 110. It is configured to include).

Here, the authentication server 100 generates a seed key (Cap ID) for encrypting the digital content file provided through the digital content providing server 102 and generating file permission information of the client 104. It is composed.

Here, the seed key Cap ID is a service registration key for receiving digital content information or providing a service for decrypting encrypted digital content.

In addition, the authentication server 100 encrypts the seed key (Cap ID) and the system information of the client 104 by a predetermined encryption algorithm to decrypt the encrypted digital content file, using the authority key of the digital content file (hereinafter, A token, and sends the generated token to the client 104.

In this case, the system information of the client 104 for token generation includes information on the size, number of CPUs, and page size information of the hard disk. Also, the encryption algorithm for token generation is twofish.

Digital content providing server 102 is configured to generate a file encryption key (FKey1) through a four-step encryption of the seed key (Cap ID) transmitted from the authentication server 100 using a two-fiche algorithm.

The client 104 stores the token transmitted from the authentication server 100 in a registry that is a storage area inside the terminal, encrypts the token according to the encrypted digital content file header information downloaded from the digital content providing server 102, and By decrypting, a file decryption key FKey2 corresponding to the file encryption key FKey1 is generated to decrypt the encrypted digital content file.

Here, the present invention uses a two-fish algorithm for encrypting and decrypting a key when generating a file encryption key (FKey1).

The client information database 106 stores user information of the client 104 and a corresponding seed key Cap ID, and the digital content information database 108 is configured to store corresponding digital content information classified according to the file ID.

In addition, the authentication information database 110 is configured to store a corresponding service registration key, that is, a seed key (Cap ID) of the client 104.

Referring to the accompanying drawings, the operation of the digital content copy protection device according to the present invention configured as described above is as follows.

First, a service registration process of the client 104 for receiving a digital content file from the digital content providing server 102 will be described with reference to FIG. 2.

The client 104 downloads a digital content execution program for executing the digital content file transmitted from the digital content providing server 102, and installs the digital content execution program as the downloaded execution program is executed.

At this time, it is apparent that the downloading of the digital content execution program may be included in the service registration process and executed, as well as being downloaded and installed in advance before the service registration.

Here, the digital content execution program may be an MP3 player, a media player or a real player.

Subsequently, the client 104 accesses the digital content providing server 102 through a network, for example, an internet connection, inputs user information (step 200), and requests service registration (step 202).

Here, the user information includes at least the name, ID, password and social security number of the client 104.

The digital content providing server 102 stores the user information input from the client 104 in the client information database 106, among which the social security number, client name (or ID) and password, and the digital content providing server number (SP_NO) are stored. An authentication user registration is requested as it is transmitted to the authentication server 100 (step 204).

Here, the digital content providing server number SP_NO is information for distinguishing a plurality of digital content providing servers network-connected to the authentication server 100.

The authentication server 100 generates a seed key (Cap ID) for authentication user registration requested from the digital content providing server 102.

That is, as shown in Equation 1, the authentication server 100 sets the service providing server number SP_NO, the social security number, and the name of the client, which are transmitted from the digital content providing server 102, according to the first setting key (auLKey). Encrypt to generate a seed key (Cap ID) (step 206).

Here, the first setting key aulKey may be set to a key value preset by a program.

In this case, numbers in parentheses indicate a byte unit, and a preset key value (auLKey) is a value predefined by a programmer or the like for encryption, and E stands for encryption.                     

Here, the two-fiche algorithm is an algorithm adopted by the Advanced Encryption Standard (ASE) issued by the US Department of Commerce's Technical Standards Bureau (NIST) to replace the Data Encryption Standards.

The two-fiche algorithm is a 128-bit symmetric block encryptor, has various key lengths such as 128-bit, 192-bit and 256-bit, and is efficient for various software and hardware platforms.

In addition, the structure of the two-fiche block cipher has a 16-cycle Fiestel network structure with the F function of the shear yarn function, as shown in Figure 3, and the additional whitening portion (whitening) to the input and output unit Have

In this case, the facetel network includes a plurality of S-boxes, an MDS matrix, and PHT.

The ciphertext generation process according to the two-fiche block encryptor having such a configuration will be described schematically.

The original document is divided into 32 bit words of 4r, and these four are exclusive ORs with the key words in the input whitening step. Thereafter, 16 cycles are performed sequentially. In each round, the two words on the left are used as inputs to the function g, the most important part of the tuffy.

The g function consists of four byte wide key independent S-boxes, and then one linear mixing step based on the MS matrix is performed. The results of the two g functions are combined using PA, and two keywords are added.                     

These two results are the exclusive OR, which is the right word (first of which rotates one bit to the left and then the other to the right) and the exclusive OR.

The left and right halves are then swapped for the next processing step, and the last processing step after all processing steps is reversed.

Then, the four words are exclusive OR with four or more key words to generate the cipher text.

The authentication server 100 generates a seed key (Cap ID) generated by the two-pass algorithm which performs the above-described operation and a user authentication registration completion message (step 208), and transmits it to the digital content providing server 102. (Step 210).

The digital content providing server 102 stores the seed key (Cap ID) from the authentication server 100 in the client information database 106 (step 212), and generates a service registration completion message (step 214). 104) (step 216).

Next, an operation according to the service registration cancellation request of the client 104 will be described with reference to FIG. 4.

First, the client 104 inputs user information, that is, a social security number and a password (step 400), and transmits a service registration request signal to the digital content providing server 102 (step 402).

The digital content providing server 102 compares the social security number and password from the client 104 with the client information stored in the client information database 106 to determine whether the client 104 is a service registrant (step 404).

If the client 104 is a service registrant, the digital content providing server 102 retrieves the corresponding seed key (Cap ID) of the client 104, and the digital content providing server number (SP_NO), social security number and seed key (Cap ID). In step 406, the user authentication request is canceled (step 408).

The authentication server 100 searches the authentication information database 110 according to the user authentication cancellation request signal from the digital content providing server 102 to determine whether the client 104 is an authentication user (step 410).

If the client 104 is an authenticated user, the authentication server 100 performs user authentication cancellation according to deleting the user authentication information of the client 104 (step 412), and generates a user authentication cancellation completion message to provide digital content. Send to server 102 (step 414).

The digital content providing server 102 generates a service registration cancellation completion message according to the user authentication cancellation completion message from the authentication server 100 (step 418), and transmits the generated service registration cancellation completion message to the client 104. Accordingly, service registration cancellation of the client 104 is completed (step 420).

Next, an operation of receiving and executing a digital content file from the digital content providing server 102 by the client 104 having completed service registration will be described with reference to FIG. 5.

First, the client 104 accesses the digital content providing server 102 through a network, logs in according to ID and password input, and then inputs a file request signal for selecting any one of various digital content files provided. (Step 500).

The digital content providing server 102 determines whether to register a service by comparing the ID and password input from the client 104 with the corresponding information stored in the client information database 106 (step 502).

If the client 104 is a service registrant, the digital content providing server 102 generates a file key FKey1 for encrypting the corresponding digital content file requested by the client 104 (step 504).

That is, the digital content providing server 102 performs multi-level encryption on the seed key Cap ID and the user information of the client to generate a file encryption key FKey1 by a two-pass algorithm, which will be described in detail as follows. .

First, the digital content providing server 102 encrypts the first file by encrypting the corresponding seed key Cap ID of the client 104 stored in the client information database 106 using the second setting key asUkey. Create a key (DasUKey1).

In this case, the second setting key asUkey may be configured to be the same as the first setting key aulKey when generating the seed key Cap ID, or may be configured differently.

Subsequently, the digital content providing server 102 generates a stream of the digital content providing server number SP_NO, the social security number, and the seed key Cap ID by using the generated first file encryption key DasUKey1 as shown in Equation 2. By encrypting, a second file encryption key UKey1, which is an initial encryption key for generating a file encryption key FKey1, is generated.                     

UKey1 = E _DasUKey1 [SP_NO (4) ∥resident registration number (13) ∥Cap ID (16)]

Here, E stands for encryption, the algorithm for encryption is a two-fiche algorithm, the number in parentheses represents the byte number.

In addition, the digital content providing server 102 generates a third file encryption key DaufKey1 by encrypting a random value of the digital content providing server 102 according to a preset key value aupPKey.

Here, the random value of the digital content service server is a value randomly formed by a predetermined program and is composed of 16 bytes.

Subsequently, the digital content providing server 102 uses the third file encryption key DaFF1 as a second file encryption key UKey1, the selected digital content file ID, and the digital content providing server random value as shown in Equation 3 below. By encrypting, a file encryption key FKey1 is generated.

FKey1 = E _DauFKey1 [UKey1 (16) ∥File_ID (8) ∥ Digital Content Provision Server Random (8)]

Here, the number in parentheses is a byte unit, the digital content providing server random value is a value formed randomly by a certain program, E represents the abbreviation of encryption.

The digital content providing server 102 encrypts the digital content file requested from the client 104 by the file encryption key FKey1 generated through the multi-level encryption, and transmits the digital content file to the client 104.

At this time, the digital content file encrypted and transmitted to the client 104 has a header having the configuration as shown in FIG.

Referring to FIG. 6, header information of a digital content file includes a digital content providing server number field 600, a file description field 602, a file type field 604, a file ID field 606, and a client 104 name field. 608, a first flag field 610, a total size field 612 of a file to be encrypted, a total size field 614 of a digital content file including a header, body, and extended area, an encrypted file The total size field 616 of the file, the checksum field 618 of the file to be encrypted for error detection, the second spare area field 620, the service server random field 622, and the file encryption key confirmation value (KVC). Field 624, a third spare area field 626, and a checksum field 628 for error detection of the file header.

Here, the confirmation value KVC of the file encryption key confirmation value field 624 is generated by encrypting a null of 16 bytes with a previous file encryption key, and the digital content providing server 102 is configured for file encryption. By comparing the generated file encryption key FKey1 with the confirmation value KVC, it is checked whether the generated file encryption key FKey1 is normal.

The client 104 downloads the digital content file including the header having the configuration as described above, and performs decoding to execute the digital content file.

That is, the client 104 extracts system information for generating a decryption key of the downloaded digital content file, and transmits a token request signal including the extracted system information.

In addition, the system information is information that a client system requesting a token has, including information such as the type, number of CPUs, and page size of the hard disk.

The authentication server 100 generates the first token key LKey1 by encrypting the service providing server number, the social security number, and the system information transmitted from the client 104 by the first setting key value aulKey, as shown in Equation 4. do.

LKey1 = E _auLKey [System Information (16)]

Where E is an abbreviation for encryption, the algorithm used for encryption is a two-fiche algorithm, and the numbers in parentheses indicate bytes.

The authentication server 100 generates a second token key SLKey1 by encrypting the 16 byte random value of the authentication server 100 using the generated first token key LKey1. At this time, the authentication server 100 checks whether or not it is normal by comparing the generated second token key SLKey1 with the verification key value generated by encrypting a null of 16 bytes with the previous second token key. do.

Here, the random value of the authentication server 100 is a value randomly formed by a certain program in the authentication server 100.

The authentication server 100 encrypts the 16-byte second file encryption key UKey1 generated by the seed key Cap ID of the client 104 using the second token key SLKey1 to generate a third token key ( Create EncUKey1).

Here, since the second file encryption key UKey1 is generated in the digital content providing server 102, the detailed description thereof will be omitted.

The authentication server 100 configures a token formed in the form of [Digital Content Encryption Server Random 16 ∥ Third Token 16] in which a 16-byte authentication server random value is added to the third token key EncUKey1. Send to.

In this case, the token is downloaded and stored in the storage area of the terminal, and the number of downloading of the token may be limited.

The client 104 extracts system information of the terminal and generates the first decryption key LKey2 by encrypting the extracted system information with a preset key value aulKey.

In addition, the client 104 generates a second decryption key SLKey2 by encrypting the random value in the token with the first decryption key LKey2.

Here, the first decryption key LKey2 and the second decryption key SLKey2 generated by the client 104 may be compared with the first token key LKey1 and the second token key SLKey1 generated by the authentication server 100. The same is true for the production process.

The client 104 decrypts the third token key EncUKey1 by the second decryption key SLKey2 to generate a third decryption key UKey2. At this time, it is apparent that the third decryption key UKey2 is the same key as the second file encryption key UKey1.

In addition, the client 104 generates a fourth file key (DauFKey) by encrypting the service providing server random extracted from the encrypted digital content file header with the third setting key (auFKey).

At this time, the third setting key (auFKey) may be configured in the same manner as the first setting key (auLKey) or the second setting key (asUKey) or may be configured in a different form.

As shown in Equation 3, the client 104 encrypts the file ID extracted from the encrypted digital content file, the digital content providing server random, and the third decryption key UKey2 by using the fourth decryption key DaufKey. Generate a decryption key (FKey2).

At this time, the client 104 checks whether it is normal by comparing the verification key value in the downloaded digital content file header with the generated file decryption key FKey2.

The client 104 decrypts the encrypted digital content file using the generated file decryption key FKey2, and executes the digital content file by the execution program.

Here, it is obvious that the file decryption key FKey2 is the same as the file encryption key FKey1 which encrypts the digital content file in the digital content providing server 102.

A process of performing the digital content copy protection device according to the present invention configured and operated as described above will be described with reference to FIG. 7.

7 is a flowchart for performing digital content copy protection according to the present invention.

First, the digital content providing server 102 transmits a service registration request signal according to input of user information from the client 104 connected through a network to the authentication server, and the authentication server 100 receives a seed key according to the user information. To generate and transmit to the digital content providing server 102 (S700).

The digital content providing server 102 multiplies the seed key Cap ID to generate a file encryption key FKey1, and encrypts the digital content file requested from the client 104 by the generated file encryption key FKey1. (S702).

Subsequently, the authentication server 100 transmits the user authorization key (token) generated by multi-level encryption of the system information of the client 104 terminal to the client 104 (S704).

Here, the system information is unique information that only the client 104 terminal has, and the token generated by the system information has unique characteristics for each terminal of the client.

The client 104 generates a file decryption key FKey2 by encryption and decryption using the token, and decrypts the digital content file encrypted by the generated file decryption key FKey2 (S706).

In this case, an algorithm used for encryption and decryption for generating a seed key, a file encryption key, a token, and a file decryption key is a two-pass algorithm.

In addition, the decrypted digital content file is executed by the corresponding execution program installed in the client 104 terminal.

The file encryption key generation process of the digital content copy protection process according to the present invention configured as described above will be described with reference to FIG. 8.

8 is a flowchart for performing file encryption key generation for digital content file encryption.

The digital content providing server 102 generates a first file encryption key DasUKey1 by encrypting a seed key from the authentication server 100 using a key value pre-set, i.e., hard-coded on a code by a programmer or the like (see FIG. S800).

Subsequently, the seed key, the social security number of the client 104, and the digital content providing server number are encrypted using the first file encryption key DasUKey1 to generate a second file encryption key UKey1 (S802).

A digital file providing server random value randomly formed by a predetermined program is encrypted with the second file encryption key UKey1 to generate a third file encryption key DaufKey1 (S804).

The second file encryption key UKey1, the ID and the random value of the digital content file requested from the client 104 are encrypted using the third file encryption key DaufKey1 to generate the file encryption key FKey1 (S806).

Next, the file encryption key (FKey1) generated by comparing a file encryption key (KVC) and a file encryption key (FKey1) formed by encrypting a null function with a previous file encryption key is checked to check whether it is normal. (S808).

The digital content file is encrypted by the file encryption key FKey1 which is confirmed to be normal and transmitted to the client 104 (S810).

Here, the algorithm used in encryption for generating the first to third file encryption keys and the file encryption key is a two-pass algorithm.                     

In addition, a process for generating user authority information, that is, a token in FIG. 7 will be described in more detail with reference to the accompanying drawings.

9 is a flowchart for generating user authority information by the authentication server.

First, the authentication server 100 encrypts the system information from the client 104 with a preset key value aulKey to generate a first token key LKey1 (S900), and generates the first token key LKey1. By encrypting the random value of the authentication server 100 to generate a second token key (SLKey1) (S902).

Subsequently, the second file encryption key UKey1 generated using the seed key Cap ID is encrypted using the second token key SLKey1 to generate a third token key EncUKey1 (S904).

Here, since the second file encryption key UKey1 is generated by the same process as in FIG. 8, a detailed description thereof will be omitted.

The authentication server 100 generates a token having a form in which a random value of 16 bytes is added to the generated third token key EncUKey1 and transmits it to the client 104 (S906).

The decryption process of the encrypted digital content file by the client will be described in detail with reference to FIG. 10.

10 is a flowchart for decoding a digital content file according to the present invention.

The client 104 extracts the system information of the terminal and generates the first decryption key LKey2 by encrypting the extracted system information with a preset key value aulKey (S1000).

Subsequently, the second decryption key SLKey2 is generated by encrypting a random value among tokens transmitted from the authentication server 100 and stored in the predetermined storage area of the terminal with the first decryption key LKey2 (S1002).

The third token key EncUKey1 among the tokens is decrypted by the second decryption key SLKey2 to generate a third decryption key UKey2 (S1004), and the verification key value KVC and the generated third decryption key UKey2. ), It is determined whether the third decryption key (UKey2) is normal (S1006).

Here, the confirmation key value KVC is a key value generated by encrypting a null composed of all bytes '0' by the previous third decryption key UKey2.

The fourth decryption key DaufKey2 is generated by encrypting a random value of the tokens by the third decryption key UKey2 generated in the above step S1004 (S1008).

Subsequently, the third decryption key UKey2, the file ID, and the random value are encrypted by the fourth decryption key DaFKey2 to generate the file decryption key FKey2 (S1010), and for checking the stored digital content file header. It is checked whether the file decryption key FKey2 is normal by comparing with the key value KVC (S1012).

The digital content file encrypted by the file decryption key FKey2 having been confirmed as normal is decrypted, and the digital content file is executed by the corresponding execution program installed in the terminal (S1014).

Here, it is apparent that the third decryption key UKey2 is the same as the second file encryption key FKey1, and the file decryption key FKey2 and the file encryption key FKey1 are the same.

The apparatus and method for copy protection of digital content according to the present invention comprises a multi-step encryption process for a file encryption key for encrypting digital content, user authority information for downloading a digital content file, or decrypting the downloaded digital content file. Create via

Therefore, in the present invention, since the file encryption key, the user authority information, and the file decryption key are generated through a multi-step encryption process, the decryption of the key is almost impossible, thereby preventing the copying of the digital content file.

In addition, since the user authority information is generated by a key value including system information of the terminal, the digital content file downloaded to the terminal of the client can be prevented from being copied to another terminal.

Claims (21)

In the copy protection method of the digital content file by the authentication server connected to the digital content providing server through a network, the digital content providing server provides an encrypted digital content file to the client, Generating a service registration key according to user information from the client and transmitting the generated service registration key to the digital content providing server; Generating a user authorization key according to system information of the client terminal and transmitting the generated user authorization key to the client; The digital content providing server encrypts the digital content file by generating a file encryption key using the service registration key using multi-level encryption, And the client generates a file decryption key corresponding to the file encryption key through multi-level encryption by the user authorization key to decrypt the encrypted digital content file. The method of claim 1, Generating a service registration key according to the user information from the client and transmitting to the digital content providing server Receiving user information of the client through the digital content providing server; Generating the service registration key by encrypting the user information and the information of the digital content providing server by a predetermined encryption algorithm; Storing the user information, the digital content providing server information, and the service registration key; Transmitting the service registration key to the digital content providing server. Digital content copy protection method by the authentication server comprising a. The method according to claim 1 or 2, And the user information includes a social security number and name information of the client. The method of claim 2, And the digital content providing server information comprises the digital content providing server number information. The method of claim 2, The encryption algorithm is a digital content duplication prevention method by an authentication server, characterized in that the two-fish (twofish) algorithm. The method of claim 1, Generating a user authorization key according to the system information of the client terminal and transmitting to the client Generating a first token key according to encrypting the system information by applying a predetermined encryption algorithm by a preset key value; Generating a second token key by encrypting a predetermined random value with the first token key using the algorithm; Generating the digital content file encryption initial key by encrypting the service registration key using the algorithm; Encrypting the generated file encryption initial key with the second token key using the algorithm to generate a third token key; Generating a user authorization key by adding the random value to the third token key; Transmitting the user authorization key to the client Digital content copy protection method by the authentication server comprising a. The method of claim 6, And the system information includes at least the type, number of CPUs, and page size information of a hard disk. The method of claim 6, The encryption algorithm is a digital content duplication prevention method by an authentication server, characterized in that the two-time algorithm. Method for preventing copying of a digital content file by a client connected to a digital content providing server through a network, wherein the digital content providing server receives a service registration key from an authentication server connected through a network, and the digital content providing server provides the service. Encrypting the digital content file using a file encryption key generated by multi-level encryption of a registration key, Transmitting system information of the client terminal to the authentication server; Receiving a user authorization key generated by the system information from the authentication server; Generating a file decryption key corresponding to the file encryption key by the user right key; Encrypting the encrypted digital content file by the generated file decryption key Including but not limited to: And the authentication server generates the service registration key by encrypting the information of the user connected to the digital content providing server and the digital content providing server information. The method of claim 9, And the system information includes at least the type, number of CPUs, and page size information of a hard disk. The method of claim 9, The user authorization key includes a file encryption initial key generated using a predetermined encryption algorithm and a random value of the authentication server. The file encryption initial key is generated by encrypting user information of the client and the digital content providing server information by using a first file encryption key generated by encrypting the service registration key using a preset key value. Digital content copy protection method by. The method of claim 9, Generating a file decryption key corresponding to the file encryption key by the user authorization key Generating a first file decryption key by encrypting the system information by using a preset first key value; Generating a second file decryption key by encrypting the authentication server random value among the user authorization keys with a first file decryption key; Generating a file encryption initial key by decrypting the encrypted file encryption initial key of the user right key with the second file decryption key; Generating a third file decryption key by encrypting the authentication server random value using a preset second key value; Encrypting the file encryption initial key, the digital content file ID, and the authentication server random value by the third file decryption key to generate a file decryption key corresponding to the file encryption key Digital content copy protection by the client comprising a. An apparatus for preventing copying of a digital content file by an authentication server connected to a digital content providing server through a network, the digital content providing server providing an encrypted digital content file to a client. Means for generating a service registration key according to user information from the client and transmitting the generated service registration key to the digital content providing server; Means for generating a user authorization key according to system information of the client terminal and transmitting it to the client, The digital content providing server encrypts the digital content file by generating a file encryption key using the service registration key using multi-level encryption, And the client generates a file decryption key corresponding to the file encryption key through multi-level encryption by the user authorization key to decrypt the encrypted digital content file. The method of claim 13, Means for generating a service registration key according to the user information from the client to transmit to the digital content providing server Means for receiving user information of the client through the digital content providing server; Means for encrypting the user information and the information of the digital content providing server by a predetermined encryption algorithm to generate the service registration key; Means for storing the user information and the digital content providing server information and the service registration key; Means for transmitting the service registration key to the digital content providing server Digital content copy protection device comprising a. The method of claim 14, And the user information comprises a social security number and name information of the client. The method of claim 14, And the digital content providing server information comprises the digital content providing server number information. The method of claim 14, And the encryption algorithm is a twofish algorithm. The method of claim 13, Means for generating a user authorization key according to the system information of the client terminal to transmit to the client Means for generating a first token key according to encrypting the system information by using a predetermined encryption algorithm by a preset key value; Means for generating a second token key using the algorithm to encrypt a predetermined random value with the first token key; Means for generating the digital content file encryption initial key by encrypting the service registration key using the algorithm; Means for encrypting the generated file encryption initial key with the second token key using the algorithm to generate a third token key; Means for generating a user authorization key by adding the random value to the third token key; Means for transmitting the user authorization key to the client Digital content copy protection device comprising a. The method of claim 18, And the system information includes at least the type, number of CPUs, and page size information of a hard disk. The method of claim 18, The encryption algorithm is a digital content copy protection device, characterized in that the two-peech algorithm. Device for preventing copying of a digital content file by a client connected to a digital content providing server through a network, wherein the digital content providing server receives a service registration key from an authentication server connected through a network, and the digital content providing server provides the service. Encrypting the digital content file using a file encryption key generated by multi-level encryption of a registration key, Means for transmitting system information of the client terminal to the authentication server; Means for receiving a user authorization key generated by the system information from the authentication server; Means for generating a file decryption key corresponding to the file encryption key by the user right key Including, And the authentication server generates the service registration key by encrypting the information of the user connected to the digital content providing server and the digital content providing server information.

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