JP4195984B2 - Encryption key distribution server and content distribution method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an encryption key distribution server and a content distribution method for encrypting and distributing data using a communication line.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a content distribution system using the Internet, as a method of charging, charging is performed by distributing pre-encrypted content and managing a decryption key for decrypting the content encryption (for example, Patent Documents) 1).
[0003]
[Patent Document 1]
JP 2000-78555 A (Claims 1 to 5)
[0004]
[Problems to be solved by the invention]
However, the above technique has the following problems. The above description is based on the assumption that the content has been transmitted correctly. However, in a service where the content must be played at the same time as when the content is received, such as streaming streaming, There is no time for resending even if it is lost. For this reason, even if an encryption key for decrypting the content is acquired, the content itself is incomplete, so that the video may be interrupted or noise noise may occur while the user is viewing. Even in such a case, the content distributor pays based on the fact that the encryption key has been acquired, so that trouble occurs between the viewer and the content distributor. In order to eliminate such troubles, a means for content distributors to detect missing content is required.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, a first aspect of the present invention (corresponding to claim 1) divides content into predetermined data blocks, encrypts the data blocks with different encryption keys, and distributes them. An encryption key distribution server that distributes the encryption key, and holds a correspondence table of information indicating that the data block has been correctly received and encryption keys of data blocks distributed after the data block, and the data block An encryption key distribution server that distributes an encryption key of a data block distributed after the corresponding data block when information indicating that it is received correctly is received.
[0006]
According to a second aspect of the present invention (corresponding to claim 2), the correspondence table includes an identifier of the data block, and receives the information indicating that the identifier of the data block and the data block have been correctly received. The encryption key distribution server according to claim 1, wherein the encryption key of the data block distributed after the corresponding data block is distributed.
[0007]
According to a third aspect of the present invention (corresponding to claim 3), a content is distributed from a content server to a terminal using a communication line, and the content server divides the content into predetermined data blocks. The data block is encrypted with different encryption keys and distributed to the terminal, and the terminal transmits information indicating that the data block has been correctly received to the encryption key distribution server, and the encryption key distribution The server is a content distribution method in which an encryption key obtained by encrypting a data block distributed after the data block is distributed to the terminal.
[0008]
According to a fourth aspect of the present invention (corresponding to claim 4), when the content server encrypts and distributes the data block, the content server adds the identifier of the data block and distributes the data block. 4. The content distribution method according to claim 3, wherein an identifier of the data block is added to information indicating that the block has been correctly received and transmitted to the encryption key distribution server.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIG. 1 and FIG. FIG. 2 is a configuration diagram of the content distribution system in the present embodiment.
[0011]
In FIG. 2, 1000 is a streaming server, 1010 is video content, 1011 to 1016 are data blocks obtained by dividing the video content 1010 in advance, 2000 is a key distribution server, and 2010 is An encryption key table, 2020 is an encryption key distribution program that acquires and distributes the corresponding encryption key from the encryption key table 2010, 3000 is a streaming terminal, and 3010 is a checksum when data blocks 1011 to 1016 are received. 3030 is an encryption key acquisition program for transmitting the checksum obtained by the checksum calculation program to the key distribution server 2000 and acquiring an encryption key, and 3030 is an encryption key acquisition program 3020 acquired A program for decoding a data block from 1011 to 1016 by using the encryption key, 4000 is connected to and the streaming server 1000, the key distribution server 2000 and streaming device 3000, the Internet.
[0012]
As shown in FIG. 1, the encryption key table 2010 includes a checksum 2011, an encryption key 2012 corresponding to the checksum 2011, and a check column 2013 indicating whether or not the corresponding encryption key has been distributed. In the encryption key table 2010, the checksum of each data block corresponds to the encryption key of the data block distributed after the data block. That is, the encryption key of the data block 1012 corresponds to the checksum of the data block 1011. Similarly, the checksum of the data block 1012 and the encryption key of the data block 1013, and the checksum and data of the data block 1013 are the same. The correspondence of the encryption key of block 1014 is registered.
[0013]
The reason why the checksum of a data block corresponds to the encryption key of the data block after the data block, not the encryption key of the data block is that the data block is encrypted after the data block is acquired in streaming. The reason for acquiring the key is that the delay time between receiving the data block and reproducing it increases. In the present embodiment, for ease of explanation, the encryption key of the data block to be distributed one after is described. However, in actuality, the content to be distributed and the characteristics of the network to be used Determined by.
[0014]
The operation of the streaming distribution system configured as described above will be described below.
[0015]
Step 1-1:
The streaming terminal 3000 acquires information on the streaming server 1000 and the key distribution server 2000 and the encryption key of the data block 1011 distributed first, and makes a distribution request to the streaming server 1000.
[0016]
Step 1-2:
The streaming server 1000 transmits the data block 1011 of the video content 1010 to the streaming terminal 3000. Thereafter, the streaming server 1000 periodically transmits data blocks after the data block 1012 of the video content.
[0017]
Step 1-3:
The checksum calculation program 3010 of the streaming terminal 3000 calculates the checksum of the received data block 1011 and passes it to the encryption key acquisition program 3020. Further, the received data block 1011 is transferred to the decryption program 3030.
[0018]
Step 1-4:
The decryption program 3030 of the streaming 3000 decrypts the data block 1011 using the encryption key of the data block 1011 acquired in advance and reproduces the video.
[0019]
Step 1-5:
The encryption key acquisition program 3020 of the streaming terminal 3000 transmits the acquired checksum of the data block 1011 to the key distribution server 2000.
[0020]
Step 1-6:
The encryption key distribution program 2020 of the key distribution server 2000 searches the encryption key table 2010 from the checksum of the acquired data block 1011 to acquire the encryption key of the data block 1012 and simultaneously checks the check column 2013 to determine the streaming terminal 3000. To pass.
[0021]
Step 1-7:
The encryption key acquisition program 3020 of the streaming terminal 3000 passes the acquired encryption key of the data block 1012 to the decryption program 3030.
[0022]
Step 1-8:
Steps 1-3 to 1-7 are repeated to sequentially decode the data blocks after the data block 1012 and reproduce the video.
[0023]
Here, when a part of the data block is missing or an error occurs in the data block, the key distribution server 2000 can detect the missing data block by the check column 2013 of the encryption key table 2010.
[0024]
As described above, in the key distribution server, in order to distribute the encryption key for decrypting the data block, delivery confirmation is performed by requesting a checksum indicating that the corresponding data block has been received correctly, and content distribution The trader can confirm whether the video content is missing.
[0025]
In the present embodiment, the checksum calculation program 3010, the encryption key acquisition program 3020, and the decryption program 3030 of the streaming terminal 3000 are described as separate programs, but the same effect can be obtained even if one program is used. .
[0026]
In this embodiment, the encryption key of the data block 1011 is distributed in advance. However, the same effect can be obtained even if the data block 1011 is distributed without being encrypted as free content such as CM. It is done.
[0027]
In the present embodiment, the streaming server and the encryption key distribution server have been described as separate devices. However, the same effect can be obtained even when the same device is used. An embodiment in this case will be described in Embodiment 2.
[0028]
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a configuration diagram of the live video distribution system.
[0029]
In FIG. 3, 1100 is a streaming server, 1110 is an encryption key table, 1120 is an encryption key distribution program for obtaining and distributing an encryption key from the encryption key table, and 1130 is an MPEG2 that captures a moving image from a video camera. 1140 is an encryption program that encrypts data encoded by the encoder 1130 with an encryption key acquired from the encryption key table 1110 for each predetermined data block, and distributes the data. A streaming receiving terminal, 3110 is a CRC (Cyclic Redundancy Check) calculation program, 3120 is an encryption key acquisition program, 3130 is a decryption program, and 3140 is an encryption key acquisition program 312. There is an encryption key table for storing the acquired encryption key, 4000 is the Internet, which connects the streaming server 1100 and streaming device 3100.
[0030]
The video content in the present embodiment is a data block that is generated by the encoder 1130 and is obtained by dividing the data generated by the 1130 with a data length of, for example, 1000 bytes.
[0031]
As shown in FIG. 4, the encryption key table 1110 includes a data block serial number 1111, a CRC 1112 of the data block, a data block number 1113 corresponding to the encryption key, an encryption key 1114, and a check column for recording whether the encryption key has been distributed. 1115. In this encryption key table, the encryption key used for the data block of the number 00000004 can be acquired from the CRC of the data block of the number 00000001. However, the encryption keys of the data blocks with numbers 00000001 to 00000003 need to be transmitted to the streaming terminal 3100 in advance.
[0032]
The encryption key table 3140 includes an encryption key number 3141 and an encryption key 3142 as shown in FIG. The encryption key table 3140 is dynamically created by the encryption key acquisition program 3120.
[0033]
The operation of the live video distribution system configured as described above will be described below.
[0034]
Step 2-1
The streaming terminal 3100 acquires the information of the streaming server 1100 and the encryption key of the data block of the numbers 00000001 to 00000003 to be distributed first, and makes a distribution request to the streaming server 1100.
[0035]
Step 2-2:
In the streaming server 1100, the encoder 1130 generates a data block and periodically transmits it to the encryption program 1140.
[0036]
Step 2-3:
In the streaming server 1100, the encryption program 1140 first assigns a number 00000001 to the data block by a counter, acquires the encryption key corresponding to the data block number from the encryption key table 1110, and encrypts the data block. (In this case, the number 00000001 corresponds to the data block number 1113 corresponding to the encryption key.)
Step 2-4:
In the streaming server 1100, the encryption program 1140 then calculates the CRC of the encrypted data block and registers it in the encryption key table 1110. (In this case, the number 00000001 corresponds to the serial number 1111 of the data block.)
Step 2-5:
In the streaming server 1100, the encryption program 1140 finally adds the data block number 00000001 to the encrypted data block and transmits it to the streaming terminal 3100.
[0037]
Step 2-6:
In the streaming terminal 3100, when the CRC calculation program 3110 receives the data block to which the data block number 00000001 is added, the CRC calculation program 3110 calculates the CRC of the data block, and sends the CRC and the data block number 00000001 to the encryption key acquisition program 3120. hand over. Furthermore, the CRC calculation program 3110 passes the data block and the data block number 00000001 to the decryption program 3130.
[0038]
Step 2-7:
In the streaming terminal 3100, the encryption key acquisition program 3120 transmits the data block number 00000001 and CRC to the streaming server 1100.
[0039]
Step 2-8:
In the streaming server 1100, the encryption key distribution program 1120 acquires the CRC of the data block corresponding to the received data block number 000000001, the data block number corresponding to the encryption key, and the encryption key from the encryption key table 1110, and streaming. When the CRC transmitted from the terminal 3100 matches the CRC acquired from the encryption key table 1110, the check column 1115 of the encryption key table 1110 is checked, and the data block number 00000004 corresponding to the encryption key is sent to the streaming server 3100. And send the encryption key.
[0040]
Step 2-9:
In the streaming terminal 3100, the encryption key acquisition program 3120 acquires the block number 00000004 corresponding to the encryption key and the encryption key, and registers them in the encryption key table 3140.
[0041]
Step 2-10:
In the streaming terminal 3100, the decryption program 3130 acquires the encryption key corresponding to the received data block number 00000001 from the encryption key table 3140, decrypts the data block, and reproduces the video.
[0042]
Step 2-11:
Thereafter, Step 2-2 to Step 10 are repeated to sequentially decode the data blocks and reproduce the video.
[0043]
Here, when a part of the data block is missing or an error occurs in the data block, the stream server 1100 can detect the missing data block by the check column 1115 of the encryption key table 1110.
[0044]
As described above, in the key distribution server, in order to distribute the encryption key for decrypting the data block, delivery confirmation is performed by requesting a checksum indicating that the corresponding data block has been received correctly, and content distribution The trader can confirm whether the video content is missing. Further, by adding the data block number to the data block, the streaming terminal can know which data block encryption key can be acquired from the received data block.
[0045]
【The invention's effect】
As is apparent from the above description, in the streaming distribution service according to the present invention, the streaming distributor can detect that the data received by the streaming receiving terminal has been lost, and can eliminate trouble in billing.
[Brief description of the drawings]
FIG. 1 is a block diagram of an encryption key table 2010 in Embodiment 1 of the present invention. FIG. 2 is a block diagram of a content distribution system in Embodiment 1 of the present invention. FIG. 4 is a block diagram of the encryption key table 1110 according to the second embodiment of the present invention. FIG. 5 is a block diagram of the encryption key table 3140 according to the second embodiment of the present invention.
1000 Streaming server 1010 Video content 1011 to 1016 Data block 1100 Streaming server 1110 Encryption key table 1111 Data block sequence number 1112 CRC of data block
1113 Data block number corresponding to encryption key 1114 Encryption key 1115 Check column 1120 Encryption key distribution program 1130 Encoder 1140 Encryption distribution program 2000 Key distribution server 2010 Encryption key table 2011 Checksum 2012 Encryption key 2013 Check column 2020 Encryption key distribution program 3000 Streaming Terminal 3010 Checksum calculation program 3020 Encryption key acquisition program 3030 Decryption program 3100 Streaming terminal 3110 CRC calculation program 3120 Encryption key acquisition program 3130 Decryption program 3140 Encryption key table 3141 Data block number 3142 Encryption key 4000 Internet

Claims (2)

An encryption key distribution server that distributes the encryption key to the streaming terminal in a system that divides one content into predetermined data blocks, encrypts the data block with different encryption keys, and distributes the content to the streaming terminal. ,
Holding a correspondence table of information for determining whether or not the data block is correctly received and an encryption key of a data block distributed after the data block;
The correspondence table stores information for determining whether or not the data block is correctly received and the encryption key of the data block distributed after the data block as a pair ,
When it is determined that the data block is correctly received using the correspondence table when receiving information for determining whether or not the data block is correctly received from the streaming terminal, the correspondence The encryption key of the data block distributed after the data block , which is the encryption key stored in a pair with the information for determining whether or not the data block is correctly received in the table, is distributed to the streaming terminal An encryption key distribution server characterized by: The encryption key distribution server according to claim 1, wherein the first block among the plurality of divided data blocks to be distributed by streaming is transmitted without being encrypted.

Images