KR100833902B1 - DRM system for supporting a safe superdistribution and method for managing the same - Google Patents

Abstract

A DRM system for safely redistributing content and a method of managing the same, the method comprising: transmitting a license request and first identification information to a primary distributor server for distributing at least one content; Extracting the key from the received license and decrypting the content, redistributing the encrypted content and the second identification information, storing the received third identification information, and distributing the license request and fourth identification information to the primary distributor. Receiving the secondary distributor server, including encrypted content and second identification information, transmitting the third identification information to the secondary distributor server, and transmitting a key from the received license. Extracting and decrypting the content, including the final distributor server, the license request from the primary distributor server, 4 may be configured to include a license server that receives identification information, generates corresponding licenses respectively, and transmits the generated licenses to the secondary distributor and the final distributor server, respectively.

License server, key, identifier, content, distributor, consumer

Description

Drm system supporting safe redistribution and its management method {DRM system for supporting a safe superdistribution and method for managing the same}

1 is a view for explaining a DRM system according to the present invention;

2 is a view showing the configuration of the secondary and final distributor server of FIG.

3 is a diagram illustrating a configuration of a license server of FIG. 1;

4 is a flowchart illustrating a method of managing a DRM system according to the present invention;

5 and 6 are flowcharts for describing a process of generating the first and second licenses of FIG. 4;

7 and 8 are flowcharts illustrating a process of extracting a key and decrypting content from the first and second licenses of FIG. 4;

9 is a diagram illustrating an embodiment of a DRM system according to the present invention.

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

1: primary distributor server 2: secondary distributor server

3: final distributor server 4: license server

11: transmitter 12: receiver

13 extractor 14 decoding unit

15: storage

21: first decoding unit 22: comparison unit

23: second decoding unit

31: receiver 32: generator

33: transmission unit

41: first encryption unit 42: connection unit

43: second encryption unit

The present invention relates to a DRM (Digital Rights Management) system, and more particularly to a DRM system and its management method for redistributing content securely.

In general, unlike tangible merchandise, intangible merchandise can be easily replicated.

Like tangible commodities, these digital contents are produced with a lot of capital, labor, and knowledge, but have the disadvantage of being illegally distributed and reproduced very easily and quickly through computer systems and computer communication networks.

Recently, the use and distribution of digital content is increasing due to the development of the Internet and communication, and the illegal copying and distribution of digital content is also increasing, making it difficult to generate revenue for content providers.

Due to the necessity of copyright protection technology to block such indiscriminate piracy distribution, a management system for distribution of profits of copyright holders, producers, owners, etc. has been required, which has resulted in the development of a digital rights management (DRM) system.

DRM is one of the representative security techniques for the protection of digital content and defines the right to use digital content as information that is combined inside the digital content.

For example, the DRM defines the number of times that the digital content can be played, whether or not it can be copied, or the like.

However, in the existing DRM systems, if the consumer who purchased the content redistributes the content to other consumers, the redistributed consumer must purchase a license.

This may prevent illegal use of content and increase profits for the content service provider, which is a distributor, but may give up the use of content because of the hassle of purchasing a license.

Since this is a factor that prevents smooth and rapid distribution of content, there is a demand for a technology for safely redistributing content without purchasing a license.

In addition, in the process of redistributing content, the existing DRM system has difficulty in generating revenue of a content service provider because it is difficult to identify a distributor who illegally distributes content if the redistributed content is illegal distribution.

Therefore, there is a demand for technologies that can confirm that consumers who redistribute content and consumers who have distributed content are legitimately authorized consumers, and identify distributors when illegally distributing content.

An object of the present invention is to solve the problems of the prior art, and to provide a DRM system and a management method thereof that can safely redistribute content regardless of whether a license is purchased.

Another object of the present invention is to provide a DRM system and a method of managing the same, which can confirm that consumers who redistribute the content and consumers who have distributed the content are legitimately authorized consumers.

Still another object of the present invention is to provide a DRM system and a management method thereof, which can immediately identify a distributor when illegal content is distributed.

The DRM system according to the present invention is a primary distributor server for distributing at least one content, transmitting the license request and the first identification information of the distributed content to the primary distributor server, and extracting a key from the received license And decrypting the content, redistributing the encrypted content and the second identification information, storing the received third identification information, and storing the license request and the fourth identification information of the redistributed content. Receiving the secondary distributor server, the encrypted content and the second identification information, transmitting the third identification information to the secondary distributor server, including transmitting to the distributor server; Extracting a key from the license and decrypting the content to the final distributor server and the primary distributor server. Emitter may be the license request and the generated license to the receiving the first and fourth identification information, respectively, and comprises a respective transfer license server that the generated license to the second distributor and the final distributor server.

The secondary distributor server transmits the license request and the first identification information of the distributed content to the primary distributor server, and sends the license request and the fourth identification information of the redistributed content to the primary distributor server. A transmission unit that transmits the encrypted content and the second identification information to the final distributor server, receives the content from the primary distributor server, receives third identification information from the final distributor server, and receives the license. A receiving unit for receiving a license from a server, an extracting unit for extracting a key from the received license, a decrypting unit for decrypting the content with the extracted key, the distributed and encrypted contents, the first to fourth identifications It may be configured to include a storage unit for storing information and licenses.

Here, the extracting unit decrypts the encrypted key from the received license and the accumulated hardware identifier connected to the encrypted key with the private key of the secondary distributor server, and the accumulated decrypted from the first decryption unit. And a second decoder for decrypting the encrypted key with a hardware identifier of the secondary distributor server according to a comparison result of the comparison unit. It may be configured.

The final distributor server may further include a transmission unit for transmitting the third identification information to the secondary distributor server, the encrypted content and the second identification information from the secondary distributor server, and receive a license from the license server. A receiving unit for receiving, an extracting unit for extracting a key from the received license, a decrypting unit for decrypting the contents with the extracted key, and storing the distributed and encrypted contents, the second identification information and a license It may be configured to include a part.

Here, the extracting unit decrypts the encrypted key from the received license and the accumulated hardware identifier connected to the encrypted key with the private key of the final distributor server, and the accumulated decrypted from the first decryption unit. A comparator for comparing a hardware identifier with a hardware identifier accumulated in the final distributor server, and a second decoder for decrypting the encrypted key with the hardware identifier of the final distributor server according to a comparison result of the comparator. It may be.

The license server may further include a receiver configured to receive the license request and the first and fourth identification information from the primary distributor server, a generator configured to generate a corresponding license according to the license request, and the generated license. It may be configured to include a transmission unit for transmitting to the primary distributor and the final distributor server, respectively.

Here, the generation unit connects the first encryption unit encrypting the key with the hardware identifier of the secondary distributor or the final distributor server, and the accumulated hardware identifiers included in the first or fourth identification information to the encrypted key. It may be configured to include a connecting unit and a second encryption unit for encrypting the encrypted key associated with the accumulated hardware identifiers with the public key of the secondary distributor or the final distributor server.

The management method of the DRM system according to the present invention comprises the steps of: transmitting the at least one content from the primary distributor server to the secondary distributor server, license request and first identification information of the content from the secondary distributor server; Transmitting the license request and the first identification information from the primary distributor server to the license server, generating a corresponding first license, and generating from the license server. Transmitting the first license to the secondary distributor server, extracting the key and decrypting the content, transmitting encrypted content and second identification information from the secondary distributor server to the final distributor server; Transmitting third identification information from the final distributor server to the secondary distributor server; Transmitting the license request and the fourth identification information from the spore server to the primary distributor server, and transmitting the license request and the fourth identification information from the primary distributor server to the license server, thereby obtaining the corresponding second license. And generating a second license from the license server and transmitting the second license to the final distributor server to extract a key and decrypt the content.

The generating of the first license may include receiving a license request including a hardware identifier of the secondary distributor server and the content header, encrypting a key with a hardware identifier of the secondary distributor server; Connecting the hardware identifier of the secondary distributor server to the encrypted key, and encrypting the encrypted key to which the hardware identifier of the secondary distributor server is linked with the public key of the secondary distributor server. .

The generating of the second license may include receiving a license request including hardware identifiers of the secondary and final distributor servers and the content header, encrypting a key with the hardware identifier of the final distributor server, Connecting the hardware identifiers of the secondary distributor server and the final distributor server, that is, the accumulated hardware identifiers, to the encrypted key, and encrypting the encrypted key associated with the accumulated hardware identifier with the public key of the final distributor server. It may be made, including.

In addition, extracting a key from the first license and decrypting the content may include decrypting the key encrypted from the first license and the hardware identifier of the secondary distributor server with the private key of the secondary distributor server, Comparing whether the hardware identifier of the secondary distributor server and the hardware identifier stored in the secondary distributor server match and decrypting the encrypted key with the hardware identifier of the secondary distributor server if the comparison result matches. And decrypting the content with the decrypted key.

The extracting of the key from the second license and decrypting the content may include decrypting the encrypted key and the accumulated hardware identifier from the second license with the private key of the final distributor server, and the decrypted accumulated hardware. Comparing the hardware identifier of the final distributor server that is part of an identifier with the hardware identifier of the final distributor server that is part of the accumulated hardware identifier stored in the final distributor server; and, if the comparison result matches, the decrypted accumulated hardware Comparing the hardware identifier of the secondary distributor server, which is part of the identifier, with the hardware identifier of the secondary distributor server, which is part of the accumulated hardware identifier stored in the final distributor server, and if the result of the comparison matches, from the second licenseAnd the expensive key decoding a hardware identifier of the final distributor server, may be made, including the step of decrypting the content key, the decrypted.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention accumulates the hardware identifiers of the consumers who redistribute, includes the accumulated hardware identifiers in the license, and finally, the consumer who redistributed the content also stores the accumulated hardware identifiers to accumulate the hardware identifiers between the license and the consumer. By comparing the results, first, the method of confirming that the consumer who distributed the content and the distributed consumer is the authorized consumer, second, the method of identifying the leaker when the content is leaked, and third, the encryption process using the hardware identifier after the verification process We propose a method of decoding a content.

In the present invention, the accumulated hardware identifiers mean that hardware identifiers of consumers who have redistributed have been accumulated.

The present invention is characterized by being able to monitor and manage the distribution path of the content by transmitting the accumulated hardware identifiers in the license.

1 is a view for explaining a DRM system according to the present invention.

As shown in FIG. 1, the present invention may be largely composed of a primary distributor server 1, a secondary distributor server 2, a final distributor server 3, and a license server 4.

Here, the secondary distributor server 2 may be at least one.

In the system of the present invention, the number of distributor servers capable of directly distributing content from the primary or secondary distributor servers (1, 2) is preferably at least five or less, and the first through the primary distributor server (1). Except for content distribution, the entire delivery stage of content distribution is preferably limited to three or less stages.

Here, the primary distributor server 1 distributes at least one content and transmits a license request and identification information provided from the secondary distributor server 2 to the license server 4.

The secondary distributor server 2 transmits the license request and the first identification information of the distributed content to the primary distributor server 1, extracts the key from the received license, decrypts the content, and encrypts the encrypted content and the first. 2 Redistribute identification information, store the received third identification information, and transmit a license request for the redistributed content, and fourth identification information to the primary distributor server 1.

In addition, the final distributor server 3 receives the encrypted content and the second identification information from the secondary distributor server 2, transmits the third identification information to the secondary distributor server 2, and receives a key from the received license. It serves to extract and decrypt content.

The license server 4 receives the license request and the first and fourth identification information from the primary distributor server 1 to generate corresponding licenses, respectively, and generates the licenses to the secondary distributor and the final distributor server, respectively. It serves to transmit.

Here, the first identification information includes the hardware identifier and content header of the secondary distributor server 2, the second identification information includes the hardware identifier of the secondary distributor server 2, and the third identification information is the final distributor. The hardware identifier of the server 3 may be included, and the fourth identification information may include a content header and hardware identifiers of the secondary distributor server 2 and the final distributor server 3.

FIG. 2 is a diagram illustrating the configuration of the secondary and final distributor servers of FIG. 1. As illustrated in FIG. 2, the secondary distributor server includes a transmitter 11, a receiver 12, an extractor 13, and a decoder. The unit 14 and the storage unit 15 may be configured.

Here, the transmitting unit 11 transmits the license request of the distributed content and the first identification information to the primary distributor server 1, and transmits the license request and the fourth identification information of the redistributed content to the primary distributor server 1. It transmits the encrypted content and the second identification information to the final distributor server (3).

In addition, the receiving unit 12 may receive content from the primary distributor server 1, receive third identification information from the final distributor server 3, and receive a license from the license server 4. have.

In addition, the extraction unit 13 extracts the key from the received license, the decryption unit 14 decrypts the content with the extracted key, and the storage unit 15 distributes and encrypts the contents, the first to fourth identifications. It is responsible for storing information and licenses.

Here, the extractor 13 may further include a first decoder 21, a comparator 22, and a second decoder 23.

The first decryption unit 21 decrypts the encrypted key from the received license and the accumulated hardware identifiers (hardware identifiers of consumers who have redistributed) into the private key of the secondary distributor server 2, and the comparison unit 22. Compares the accumulated hardware identifier decoded from the first decoder 21 with the hardware identifier accumulated in the secondary distributor server 2.

The second decryption unit 23 decrypts the key encrypted with the hardware identifier of the secondary distributor server 2 according to the comparison result of the comparison unit 22.

Meanwhile, as shown in FIG. 2, the final distributor server may include a transmitter 11, a receiver 12, an extractor 13, a decoder 14, and a storage 15.

Here, the transmission unit 11 transmits the third identification information to the secondary distributor server 2, the receiver 12 receives the encrypted content and the second identification information from the secondary distributor server 2, The license is received from the license server 4.

Then, the extraction unit 13 extracts the key from the received license, the decryption unit 14 decrypts the content with the extracted key, and the storage unit 15 distributes and encrypts the contents, the second identification information and the license. It plays a role of storing.

Here, the extractor 13 may further include a first decoder 21, a comparator 22, and a second decoder 23.

The first decryption unit 21 decrypts the encrypted key from the received license and the accumulated hardware identifiers (hardware identifiers of consumers who have redistributed) into the private key of the final distributor server 3, and the comparison unit 22 The accumulated hardware identifier decoded from the first decoder 21 is compared with the hardware identifier accumulated in the final distributor server 3.

The second decryption unit 23 decrypts the key encrypted with the hardware identifier of the final distributor server 3 according to the comparison result of the comparison unit 22.

FIG. 3 is a diagram illustrating a configuration of the license server of FIG. 1, and as shown in FIG. 3, the license server 4 may include a receiver 31, a generator 32, and a transmitter 33. .

Here, the receiver 31 receives the license request and the first and fourth identification information from the primary distributor server 1, the generator 32 generates a corresponding license according to the license request, and the transmitter 33 ) Transmits the generated licenses to the secondary and final distributor servers 2 and 3, respectively.

In addition, the generation unit 32 may be composed of a first encryption unit 41, a connection unit 42, a second encryption unit 43.

Here, the first encryption unit 41 encrypts the key with the hardware identifiers of the secondary or final distributor servers 2 and 3, and the connection unit 42 connects the hardware identifiers accumulated in the encrypted key, and the second encryption. The unit 43 performs a role of encrypting the encrypted key to which the accumulated hardware identifiers are connected with the public key of the secondary or final distributor server 2.

Thus, the management method of the DRM system of the present invention configured as follows.

4 is a flowchart illustrating a method of managing a DRM system according to the present invention. FIGS. 5 and 6 are flowcharts for describing a process of generating the first and second licenses of FIG. 4, and FIGS. 7 and 8. FIG. 4 is a flowchart illustrating a process of extracting a key and decrypting content from the first and second licenses of FIG. 4.

As shown in FIG. 4, the present invention first transmits at least one content from a primary distributor server to a secondary distributor server (S100).

Subsequently, the license request and the first identification information of the content are transmitted from the secondary distributor server to the primary distributor server (S101).

Here, the first identification information includes the hardware identifier of the secondary distributor server and the content header.

The license request and the first identification information are transmitted from the primary distributor server to the license server to generate a corresponding first license (S102).

Next, the first license generated from the license server is transmitted to the secondary distributor server, the key extraction and the content are decrypted (S103), and the encrypted content and the second identification information from the secondary distributor server are transmitted to the final distributor server. (S104)

Here, the second identification information includes the hardware identifier of the secondary distributor server.

Subsequently, the third identification information is transmitted from the final distributor server to the secondary distributor server (S105).

Here, the third identification information includes a hardware identifier of the final distributor server.

Then, the license request and the fourth identification information are transmitted from the secondary distributor server to the primary distributor server (S106).

Here, the fourth identification information includes a content header and hardware identifiers of the secondary distributor server and the final distributor server.

Next, the license request and the fourth identification information are transmitted from the primary distributor server to the license server to generate a corresponding second license (S107).

Then, the second license generated from the license server is transmitted to the final distributor server to extract the key and decrypt the content (S108).

5 is a flowchart illustrating a process of generating a first license of FIG. 4.

As shown in FIG. 5, first, a license request including a hardware identifier and a content header of a secondary distributor server is received (S109).

Subsequently, the key is encrypted using the hardware identifier of the secondary distributor server (S110).

Then, the hardware identifier of the secondary distributor server is connected to the encrypted key. (S111)

Next, the encrypted key associated with the hardware identifier of the secondary distributor server is encrypted with the public key of the secondary distributor server (S112).

FIG. 6 is a flowchart illustrating a process of generating the second license of FIG. 4. As shown in FIG. 6, a license request including hardware identifiers and a content header of a secondary and final distributor server is received. (S113)

Subsequently, the key is encrypted using the hardware identifier of the final distributor server (S114).

Next, the hardware identifiers of the secondary and final distributor servers are accumulated (S115).

Then, the accumulated hardware identifiers are connected to the encrypted key (S116).

Next, the encrypted key to which the identifiers of the secondary and final distributor servers are connected are encrypted with the public key of the final distributor server (S117).

FIG. 7 is a flowchart illustrating a process of extracting a key and decrypting content from the first license of FIG. 4.

As shown in Fig. 7, the key encrypted from the first license and the hardware identifier of the secondary distributor server are decrypted with the private key of the secondary distributor server (S118).

Subsequently, the hardware identifier of the decrypted secondary distributor server and the hardware identifier stored in the secondary distributor server are compared with each other (S119).

If the comparison result matches, the key encrypted with the hardware identifier of the secondary distributor server is decrypted (S120), and the content is decrypted with the decrypted key (S121).

However, if the result of the comparison in step S119 does not match, the license key extraction process is terminated.

FIG. 8 is a flowchart for describing a process of extracting a key and decrypting content from the second license of FIG. 4.

As shown in Fig. 8, the key encrypted from the second license and the accumulated hardware identifier are decrypted with the private key of the final distributor server (S122).

The decoded accumulated hardware identifier and the accumulated hardware identifier stored in the final distributor server are compared with each other (S123).

As a result of the comparison, if it matches, the key encrypted from the second license is decrypted by the hardware identifier of the final distributor server (S124), and the content is decrypted by the decrypted key (S125).

However, in step S123, if the comparison does not match, the license key extraction process is terminated.

9 is a diagram illustrating an embodiment of a DRM system according to the present invention.

9 shows the process from the initial distribution of content and redistribution of two stages to the distribution and licensing of contents, and shows the process of delivering hardware identifiers to consumers in each stage of distribution.

Here, the delivery of the hardware identifier between the consumers can be performed only by the client manager of the DRM system.

Security of hardware identifiers is the responsibility of the client administrator.

As a hardware identifier, one that may be used may be a device model number or serial number or an identifier arbitrarily generated by a client administrator.

In addition, the content header includes an identifier of the content provider so that it is possible to track the original provider of the content.

As shown in Fig. 9, in the initial distribution, the content is first sent from the distributor to the consumer i, and the consumer i pays a fee, and then with his request for a license, his hardware identifier (HIDi) and the content header (H). To the distributor.

The distributor then transfers the information received from consumer i to the license server, and a license containing the encrypted key is generated and issued to consumer i.

Next, the consumer i can extract the key from the license according to the key extraction process, and decrypt and execute the content.

In a first stage redistribution, consumer i transmits its hardware identifier (HIDi) with content to consumer i + 1.

Subsequently, the consumer i + 1 who received the content passes its hardware identifier (HIDi + 1) to the consumer i, and the consumer i receives the hardware of the header (H) itself and the consumer i + 1 together with the license request for the redistributed content. The identifier (HIDi, HIDi + 1) is transmitted to the distributor, and when the license is requested, the distributor transmits the received information to the license server.

Next, the license server issues a license and sends it to the consumer i + 1.

Subsequently, in the second stage redistribution, the content consumer i + 1 transmits the content and the hardware identifiers (HIDi and HIDi + 1) of itself and the consumer i to the consumer i + 2.

In addition, the consumer i + 2 having distributed the content from the consumer i + 1 transmits the hardware identifier HIDi + 2 to the consumer i + 1.

Next, the consumer i + 1 has its own hardware identifier (HIDi + 1), the hardware identifier (HIDi) of the consumer i who received the content, the hardware identifier (HIDi + 2) of the consumer i + 2 that delivered the content, and the header. Send the license request to the distributor.

The distributor then sends this information to the license server.

The license server issues a license and sends it to the consumer i + 2.

As such, in the present invention, the number of consumers in the next stage that can be directly redistributed by one consumer is limited to 5 or less, and the overall delivery stage is preferably 3 or less.

On the other hand, the license server encrypts the key with a hardware identifier, and accumulates hardware identifiers of consumers included in the redistribution path and includes the license keys.

That is, the key is encrypted by the hardware identifier (HIDi) of the consumer i, the final content recipient of the redistribution path, and encrypts the encrypted key and the hardware identifiers of the consumers included in the redistribution path with the public key of the consumer i.

As such, consumers can extract and compare the accumulated hardware identifiers and decrypt the encrypted key from the generated license.

In the redistribution path, if consumer i, the final content recipient, is issued a license, the accumulated hardware identifiers contained in the license are translated into consumer i's private key and accumulated hardware identifiers managed by consumer i's client manager. Compare with

If the comparison is consistent, the key is decrypted with the hardware identifier HIDi of consumer i.

If redistribution goes one step further, if consumer i distributes content to consumer i + 1, consumer i + 1 compares the accumulated HIDs up to HIDi + 1 included in the license with those stored in consumer i + 1. If it matches, the key is decrypted with HIDi + 1.

By comparing the accumulated hardware identifiers, two things can be identified.

First, the match between HIDi and HIDi-1 means that the content received by consumer i is from the right consumer and that HIDi-1 has distributed the content to the right consumer.

Second, all accumulated hardware identifiers match indicates that all consumers in the redistribution stage are authorized consumers with redistribution rights and that the content has been redistributed through the authorized consumers.

As such, if the accumulated hardware identifiers match, the key is decrypted, and the key is decrypted only when it is confirmed that redistribution of the content is not illegal, so that secure key management can be achieved.

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

The DRM system and its management method according to the present invention has the following effects.

The present invention can safely redistribute the content regardless of whether or not the license is purchased to enable a smooth and rapid content distribution.

In addition, the present invention can confirm that the redistributor and the consumer of the content are legitimately authorized consumers, and in the case of illegal distribution of content, the distributor can be immediately identified, thereby preventing illegal use of the content and increasing profit realization. You can.

Claims (19)

A primary distributor server for distributing at least one content; Transmitting to the primary distributor server a license request for the distributed content and first identification information including a hardware identifier and a content header of a secondary distributor server, extracting a key from the received license and decrypting the content; Redistributing second identification information including the encrypted content and a hardware identifier of a secondary distributor server, storing third identification information including a hardware identifier of a received final distributor server, and storing the redistributed content. Transmitting to the primary distributor server fourth identification information including a license request and a content header and hardware identifiers of the secondary distributor server and the final distributor server; Receiving second identification information including redistributed encrypted content at the secondary distributor server and a hardware identifier of the secondary distributor server, and receiving third identification information including the hardware identifier of the final distributor server. A final distributor server, including transmitting to the distributor server, extracting a key from the received license, and decrypting the content; And, First identification information including a hardware identifier and a content header of the license request and a secondary distributor server from the primary distributor server, and fourth identification information including a hardware identifier of the secondary distributor server and the final distributor server; And receiving a license server for generating corresponding licenses and transmitting the generated licenses to the secondary distributor and the final distributor server, respectively. The method of claim 1, DRM system, characterized in that the number of distributor servers that can receive content directly from the primary or secondary distributor server is at least five or less. The method of claim 1, DRM system, characterized in that the entire delivery step of the content distribution except the first content distribution through the primary distributor server is limited to three or less steps. delete The method of claim 1, The secondary distributor server, Transmit the first identification information including the license request of the distributed content and the hardware identifier and content header of the secondary distributor server to the primary distributor server, and license request and content header of the redistributed content and secondary distributor server And transmit fourth identification information including a hardware identifier of the final distributor server to the primary distributor server, and transmit second identification information including the encrypted content and a hardware identifier of the secondary distributor server to the final distributor server. A transmission unit; A receiving unit for receiving content from the primary distributor server, receiving third identification information including a hardware identifier of a final distributor server from the final distributor server, and receiving a license from the license server; An extraction unit for extracting a key from the received license; A decoder which decrypts the content with the extracted key; And, And a storage unit for storing the distributed and encrypted contents, the first to fourth identification information, and a license. The method of claim 5, The extraction unit A first decryption unit for decrypting the encrypted key and the accumulated hardware identifier from the received license with a private key of the secondary distributor server; A comparison unit comparing the accumulated hardware identifier decoded from the first decoder with the hardware identifier accumulated in the secondary distributor server; And a second decryption unit for decrypting the encrypted key with a hardware identifier of the secondary distributor server according to a comparison result of the comparison unit. The method of claim 1, The final distributor server, A transmission unit for transmitting the third identification information to the secondary distributor server; A receiving unit for receiving the encrypted content and the second identification information from the secondary distributor server and receiving a license from the license server; An extraction unit for extracting a key from the received license; A decoder which decrypts the content with the extracted key; And, And a storage unit for storing the distributed and encrypted contents, the second identification information, and a license. The method of claim 7, wherein The extraction unit A first decryption unit for decrypting the encrypted key and the accumulated hardware identifier from the received license into a private key of the final distributor server; A comparison unit for comparing the accumulated hardware identifier decoded from the first decoder with the hardware identifier accumulated in the final distributor server; And a second decryption unit for decrypting the encrypted key with a hardware identifier of the final distributor server according to a comparison result of the comparison unit. The method of claim 1, The license server First identification information including a hardware identifier and a content header of the license request and a secondary distributor server, and fourth identification information including a hardware identifier of a secondary distributor server and a final distributor server from the primary distributor server; Receiving unit for receiving; A generation unit generating a corresponding license according to the license request; And a transmission unit for transmitting the generated license to the secondary distributor and the final distributor server, respectively. The method of claim 9, The generation unit A first encryption unit for encrypting a key with a hardware identifier of the secondary distributor or the final distributor server; A connection unit connecting the accumulated hardware identifiers to the encrypted key; And a second encryption unit for encrypting the encrypted key to which the accumulated hardware identifiers are connected with the public key of the secondary distributor or the final distributor server. In the method of managing a DRM system comprising a primary distributor server for providing content, a secondary distributor server and a final distributor server for receiving a license of the content, and a license server for generating a license of the content, Transmitting the at least one content from the primary distributor server to the secondary distributor server; Transmitting, from the secondary distributor server, first identification information including a license request for the content and a hardware identifier and a content header of the secondary distributor server to the primary distributor server; Transmitting the first identification information including the hardware request and the content header of the license request and the secondary distributor server from the primary distributor server to the license server to generate a corresponding first license; Transmitting a first license generated from the license server to the secondary distributor server to extract a key and decrypt the content; Transmitting second identification information including encrypted content from the secondary distributor server and a hardware identifier of the secondary distributor server to the final distributor server; Transmitting, from the final distributor server, third identification information including a hardware identifier of the final distributor server to the secondary distributor server; Transmitting, from the secondary distributor server, fourth identification information including a license request and a content header and hardware identifiers of the secondary distributor server and the final distributor server to the primary distributor server; Transmitting, from the primary distributor server, fourth license information including the license request and content header and hardware identifiers of the secondary distributor server and the final distributor server to the license server to generate a corresponding second license; And, And transmitting the second license generated from the license server to the final distributor server, extracting a key and decrypting the content. The method of claim 11, The first identification information includes a hardware identifier of the secondary distributor server and the content header, the second identification information includes a hardware identifier of the secondary distributor server, and the third identification information is a final distributor server. And the fourth identification information includes the content header and hardware identifiers of the secondary distributor server and the final distributor server. The method of claim 11, Generating the first license, Receiving a license request including a hardware identifier of the secondary distributor server and the content header; Encrypting a key with a hardware identifier of the secondary distributor server; Associating a hardware identifier of the secondary distributor server with the encrypted key; And encrypting an encrypted key connected to a hardware identifier of the secondary distributor server with a public key of the secondary distributor server. The method of claim 11, Generating the second license, Receiving a license request comprising hardware identifiers of the secondary and final distributor servers and the content header; Encrypting a key with a hardware identifier of the final distributor server and concatenating the accumulated hardware identifiers of the secondary and final distributor servers to the encrypted key; And encrypting an encrypted key connected with identifiers of the secondary and final distributor servers with a public key of the final distributor server. The method of claim 11, Extracting the key from the first license and decrypting the content, Decrypting the encrypted key from the first license and the hardware identifier of the secondary distributor server with the private key of the secondary distributor server; Comparing the hardware identifier of the decrypted secondary distributor server with the hardware identifier stored in the secondary distributor server; Decrypting the encrypted key with a hardware identifier of the secondary distributor server, if the result of the comparison matches; And, And decrypting the content with the decrypted key. The method of claim 15, Comparing the decoded hardware identifier of the secondary distributor server with the hardware identifier stored in the secondary distributor server; If it is not matched, the key extracting process of the license is terminated. The method of claim 11, Extracting the key from the second license and decrypting the content, Decrypting the encrypted key and the accumulated hardware identifier from the second license into a private key of the final distributor server; Comparing the decrypted hardware identifier of the final distributor server with the hardware identifier of the final distributor server stored in the final distributor server; Comparing the decoded hardware identifier of the secondary distributor server with the hardware identifier of the secondary distributor server stored in the final distributor server, if a match is found; Decrypting the encrypted key from the second license with the hardware identifier of the final distributor server, if it is matched; And And decrypting the content with the decrypted key. The method of claim 17, Comparing the decoded hardware identifier of the final distributor server with the hardware identifier of the last distributor server stored in the final distributor server, If it is not matched, the key extracting process of the license is terminated. The method of claim 17, Comparing the decoded hardware identifier of the secondary distributor server with the hardware identifier of the secondary distributor server stored in the final distributor server; If it is not matched, the key extracting process of the license is terminated.

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