JP2000322321A - Method for protecting transmission data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure security necessary for copy right protection using electronic watermarking in a system in which contents are transmitted and received through a network. SOLUTION: At a transmission side 400, contents obtained by operating processing for embedding information being a key are enciphered by an electronic watermarking processor 600, and transmitted to a reception side 404. At the transmission side 404, the transmitted contents are deciphered, and certification data are enciphered by using information detected by an electronic watermarking detector 501, and transmitted to the transmission side 400. At the transmission side 400, the contents transmitted from the reception side are detected by an electronic watermarking detector 500, and the presence or absence of the electronic watermarking processing system in the reception side 404 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission data protection method, and more particularly to a transmission system for improving the security of transmission data by utilizing a digital watermarking technique for embedding information in the content and a digital signature. It's about things

[0002]

2. Description of the Related Art Electronic transmission of requests for contents desired by a user who is a receiving side via a network to a transmitting side having contents has been advanced. However, the network is easily accessible, and it is necessary to prevent the plundering of the copyrighted content from the network and the illegal copying on the receiving side.

[0003] A conventional content transmission method will be described below with reference to the drawings. FIG. 19 is a diagram showing the encoding / decoding relationship between an encryption key and a decryption key in an authentication system based on a public key system using a digital signature. The transmission side and the reception side have a public key and a private key, respectively. The public key B ′ on the receiving side is given by signing (encrypting) the public key B with the public key A on the transmitting side. Therefore, the content encrypted using the public key B ′ on the receiving side can be decrypted using the secret key A on the transmitting side.

[0004] Fig. 20 is a conceptual diagram showing a connection state between a transmitting side provided with contents and a user who is a receiving side via a network. In the figure, reference numeral 400 denotes a transmitting side provided with contents, for example, a data server. 401, a public key (PKa) of the transmitting side, and 402, a secret key (SKa) of the transmitting side.
a) and 403 are networks such as the Internet and a satellite communication network. Reference numeral 404 denotes a receiving side as a user, for example, a set-top box (STB); 405, a receiving side public key (PKbx) digitally signed with a transmitting side public key (PKa); Key (SKb). Reference numeral 407 denotes an analog output to a television or a speaker after decoding the received content, and reference numeral 408 denotes a digital output after decoding the content.

[0005] Electronic transmission using the content transmission method configured as described above will be described with reference to the flowcharts of FIGS. Hereinafter, data encryption or decryption will be described as follows. Function name = E / D (A, B) In the equation, E: encryption, D = decryption, A indicates a key in encryption or decryption, and B indicates plaintext or ciphertext. For example, to generate a ciphertext C by encrypting a plaintext B with a key A, C = E (A, B). In addition, decoding is expressed as B = D (A, C).

As shown in FIG. 21, step A1, step A3, and step A5 are performed on the receiving side 404, step A2 and step A4 are performed on the transmitting side 400, and processing is sequentially performed according to the above-described steps A1 to A5. .

That is, on the receiving side 404, step A
Step a101 according to FIG.
In step a1, the password of the receiving side 404, which proves that it is registered in the transmitting side 400, is encrypted using the secret key SKb406 as a key to generate E1, and
02, start signal to start communication, receiving side 40
4 The ID (Identify) indicating the unique identification, the public key PKbx 405, the encrypted password E1, and the request name of the content are transmitted to the transmission side 400.

Next, on the transmitting side 400, in step a201 according to FIG.
The transmitted start signal, ID, and public key PKbx4
05, the encrypted password E1, the request name of the content are received, and in step a202, the received public key PKbx405 is replaced with the secret key SKa402 of the transmission side.
By generating a public key PKb by decrypting
In step a203, the encrypted password E1 is decrypted using the generated public key PKb as a key to generate D1 (corresponding to a password).
04, using the D1 and the ID,
Then, the password on the receiving side registered in the database or the like is compared with the above D1.

As a result of the above comparison, if they match (YES), the receiving side 404 is authenticated and step a
In step 205, an encryption key CK1 is generated, and step a2
In step 06, E2 is generated by encrypting the encryption key CK1 using the generated public key PKb as a key, and E2 is transmitted to the receiving side 404 in step a207.

On the other hand, as a result of the comparison, if it is determined that the two do not match (NO), the receiving side 404 is determined to be unauthenticated, and in step a208, the communication end is notified to the receiving side 404.
And the communication ends in step a209.

Next, on the receiving side 404, in step a301 according to FIG. 24 which is the processing of step A3,
If E2 or communication end is received, and it is determined in step a302 that communication has ended (YES), step a3
03, the communication is terminated, or the process is restarted from step A1. On the other hand, if it is determined in step a302 that the communication is not terminated (NO), the process proceeds to step a304, and the received E2 is received using the secret key SKb406 as a key.
Is decoded to generate D2 (equivalent to CK1).

Next, on the transmitting side 400, in step a401 according to FIG. 25 which is the processing of step A4,
Assuming that the request name of the content received in step a201 is content 0, the content 0 is stored in step A2.
By encrypting using the encryption key CK1 generated in the above as a key,
E3 is generated, and E3 is transmitted to the receiving side 404 in step a402.

Next, on the receiving side 404, according to FIG.
In step a502, D3, that is, content 0, is obtained by decrypting E3 using the generated D2 (corresponding to CK1) as a key.
03, the content 0 is reproduced, and the analog output 40
7 outputs the content in an analog format, and the digital output 408 outputs the content in a digital format.

[0014]

The conventional transmission data protection system is configured as described above, and encrypts the content and transmits the content from the transmission side to the reception side so that the content requested by a specific recipient can be obtained. In the conventional configuration described above, the security of the content transmission from the transmitting side to the receiving side can be established, but the illegal copying of the content on the receiving side is easy in digital and analog. Yes, security was low and there was a problem in terms of copyright protection.

Further, when a plurality of contents are requested, in order to enhance the security, in order to transmit the contents by changing the encryption key for each content and transmitting the contents, the above protocol requires the transmitting side to transmit the contents. There is a problem in that the receiving side needs to transmit the encryption key for each content, which involves an increase in the number of processing steps.

As described in Japanese Patent Application Laid-Open No. H10-145557 and the like, by embedding identification information without affecting the contents of the contents, the analogized contents data is digitized again. There is a technique called digital watermark that can extract the identification information. This technique is based on the premise that an information protection system using a digital watermark exists on the receiving side, and an information protection system using a digital watermark on the receiving side. In the case where the file does not exist, the content can be copied after reception.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is directed to a system for transmitting and receiving contents using a network. It is an object of the present invention to provide a transmission data protection method which does not require a complicated protocol even when the content is requested, and is effective even when the digital watermarking system is not provided on the receiving side.

[0018]

A transmission data protection method according to a first aspect of the present invention is a transmission data protection method for protecting the copyright of a content when transmitting / receiving the content using a network. Before transmitting the content requested by the receiving side on the transmitting side,
A step of transmitting authentication content obtained by embedding specific information in predetermined content using a pseudo-random number as a key, called a digital watermark; and, on the receiving side, the specific content obtained by decrypting the authentication content. Transmitting information to the transmitting side, and detecting, on the transmitting side, the content of the specific information transmitted from the receiving side, and detecting whether or not to perform the digital watermarking process on the receiving side. Including.

According to a second aspect of the present invention, there is provided the transmission data protection method according to the first aspect, wherein a plurality of contents are requested by the receiving side, and the digital watermark processing on the receiving side is performed. In the step of detecting whether or not to apply, when it is determined that the digital watermarking process is possible, the transmitting side sends, to each content,
Following this, the method includes a step of encrypting and adding key information for decrypting the next content and transmitting it to the receiving side.

A transmission data protection method according to a third aspect of the present invention is a transmission data protection method for protecting a copyright of a content when transmitting / receiving the content using a network, Transmitting the specific information to the receiving side before transmitting the content requested by the receiving side; and receiving the specific information on the receiving side, and using the pseudo random number as a key, called a digital random number, as a key. Creating an authentication content that has been subjected to a process of embedding the information in the predetermined content, and transmitting the authentication content to the transmitting side; and transmitting, on the transmitting side, the specific information of the specific information obtained by decoding the authentication content. Detecting the contents and detecting whether or not to perform the digital watermarking process on the receiving side.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 shows a transmission side provided with contents using a transmission data protection method according to Embodiment 1 of the present invention;
FIG. 1 is a conceptual diagram of a case where a user on the receiving side receiving the connection makes a connection via a network. In FIG. 1, reference numeral 500 denotes a digital watermark detector on a transmitting side;
Is a digital watermark detector on the receiving side. Also, 60
Reference numeral 0 denotes a digital watermark processor on the transmission side, and reference numeral 601 denotes a digital watermark processor on the reception side. Here, the same portions as those in FIG. 19 are denoted by the same reference numerals, and description of overlapping portions will be omitted.

Hereinafter, the electronic transmission operation by the transmission data protection system configured as described above will be described with reference to flowcharts shown in FIGS. 2 to 13, focusing on the communication protocol. In the following drawings, 図 面
Is a symbol for performing an exclusive OR operation.

As shown in FIG. 2, steps B1, B3, B5, and B7 are performed on the receiving side 404, and steps B2, B4, and B6 are performed on the transmitting side 400.

That is, on the receiving side 404, step B
According to FIG. 3 which is the processing of No. 1, in step b101, a random number 1 (hereinafter referred to as R1) is generated, and in step b1
02, the ID (Id
Enty) and the result of exclusive OR of the random number R1 are encrypted using the secret key (SKb) 406 of the receiving side as a key to generate E5, and in step b103, the fact that the E5 is registered with the transmitting side 400 is confirmed. Proving recipient 404
Is encrypted using the secret key (SKb) 406 as a key to generate E6. In step b104, a start signal (content request: for example, using the address of the transmission side) for starting communication, an ID (Identify) indicating a unique identification of the reception side, a public key (PKbx) 405, and the above E5 and E6 are transmitted to the transmission side. 400
Send to

Next, on the transmitting side 400, according to FIG. 4, which is the processing of step B2, in step b201, the start signal, ID, public key (PKbx) 405, E5,
E6 is received. Then, in step b202,
The public key (PKbx) 405 is decrypted using the secret key (SKa) 402 as a key to generate a public key (PKb). In step b203, the result of decrypting E5 using the public key (PKb) as a key and the ID The exclusive OR is used to generate D5, and in step b204, the result obtained by decrypting E6 using the public key (PKb) as a key and the above generated D5 are exclusive ORed to obtain D6. Generate Then, in step b205, D6 and ID
Then, the password registered in the database or the like of the transmission side 400 is compared with D6.

If the result of this comparison is determined to match the two,
(YES), receiving side 404 is authenticated, and step b206 is performed.
Generates a random number 2 (hereinafter referred to as R2), and in step b207, encrypts the result of exclusive OR of the random number R2 and D5 with the public key (PKb) as a key to generate E7, In step b208, I
The result of exclusive OR between D and the random number R2 is given to the public key (P
E8 is generated by encrypting using Kb) as a key, and the generated E7 and E8 are transmitted to the receiving side 404 in step b209.

On the other hand, if it is determined in the comparison result that they do not match (NO), the receiving side 404 is not authenticated, and in step b210, the end of communication is notified to the receiving side 40.
4 and terminates the communication in step b211.

Next, on the receiving side 404, according to FIG. 5, which is the processing of step B3, in step b301, E
7, E8 or communication end is received, and step b302
If it is determined that the communication has been completed in (NO), step b
Proceeding to 306, the communication is terminated, or the process is restarted from step B1, while if it is determined in step b302 that the communication is not terminated (YES), step b30
Then, the process goes to 3 to obtain an exclusive OR of the result obtained by decrypting E7 using the secret key (SKb) 306 as a key and the random number R1, thereby generating D7. SKb) The exclusive OR of the result of decryption using 406 as a key and D7 gives
8 is generated. In step b305, the generated D8 and the ID indicating the unique identification of the receiving side 404 are set.
And if it is determined that they do not match (N
O), the transmitting side 400 is set as non-authenticated, and step b306
To end the communication, and if it is determined in step b305 that they match (YES), the transmitting side 400 is authenticated and communication is continued.

The transmitting side 400 waits for a while after step b209 of step B2 is completed,
6, a random number R3 is generated in step b401. In step b402, the result of the exclusive OR of D5 and the random number R3 is used by the digital watermark processor 600 for the content prepared by the transmission side 400. To generate the content X, and
In step b404, E9 is generated by encrypting the content X using the random number R2 as a key, and the generated E9 is transmitted to the receiving side 404 in step b404.

Next, on the receiving side 404, step B5
According to FIG. 7, which is the processing of step (b), E9 is received in step b501, and D9 is generated by decrypting E9 in step b502 using D7 as a key, thereby generating step d9.
In step 503, the information embedded in D9 generated by the digital watermark detector 501 is extracted, and the
By taking the exclusive OR with 1, a random number R3 is generated,
In step b504, E10 is generated by encrypting the result of exclusive OR of the random numbers R1 and D7 with the random number R3 as a key, and in step b505,
E11 is generated by encrypting the requested content list using the random number R3 as a key, and step b5
At 06, E10 and E11 are transmitted to the transmission side 400.

Next, on the transmitting side 400, step B6
According to FIG. 8A, which is the process of (a), E10 and E11 are received in step b601, and in step b602, the result obtained by decrypting E10 using the random number R3 as a key and the random number R2 are exclusive-ORed. , D10. Then, in step b603, the generated D
If 10 and D5 are compared and it is determined that they do not match (NO), a communication end is transmitted to the receiving side 404 in step b606, and the communication is ended in step b607.

On the other hand, if it is determined in step b603 that there is a match (YES), in step b604, D11 is generated by decoding E11 with a random number R3, and the content request list is confirmed as follows. .

That is, when there is one requested content, as shown in FIG.
, Copyright information is embedded in the content 1 in response to D11 (content request) by the digital watermark processor 600, and in step x101, the content 1 is encrypted by using the random number R3 as a key to obtain the E2.
In step x102, E20 is transmitted to the receiving side 404.

Next, step b606 of step B6
When the communication end is transmitted in step S7, the receiving side 404 determines that the number of the requested contents is one according to FIG.
In step 200, if E20 or the communication end is received, and it is determined that the communication is not ended in step x201 (YES), in step x202, E20 is set to a random number R.
3 is decrypted using the key to generate D20,
If there is no request, the communication ends in step b702 of FIG. On the other hand, if the communication is terminated in step x201 (NO), step b in FIG.
Proceeding to 702, the communication ends.

By the above operation, the data D5 (R1) of the receiving side 404 decrypted in step b203 in step b603 and the data D10 (R1) transmitted using the information embedded in the content of step b402 of the transmitting side 400 as a key. By comparing with the above, it is possible to detect the presence or absence of the digital watermark detector on the receiving side 404.
Also, the receiving side 404 transmits, to the transmitting side 400, the E11 obtained by encrypting the content name requested in step b506 using the R3 generated in step b503 as a key, thereby releasing the privacy information called the request name of the receiving side 404. Has been prevented.

As described above, according to the first embodiment, the digital watermark detector 5 is provided on the receiving side 404 and the transmitting side 400, respectively.
01, 500, and before transmitting the requested content, the transmitting side 400 transmits the predetermined test content (content X) encrypted by the digital watermarking process to the receiving side, and the receiving side transmits this. Since the digital watermark processing and decryption are returned to the transmitting side 400 to confirm that the digital watermark processing unit 601 on the receiving side is present.
1 can be suppressed from being output in digital format on the receiving side 404, digital copying can be prevented, and copyright information can be embedded in the content by digital watermarking technology, so that analog Even if copied, since the copyright information can be detected by re-digitization, illegal content duplication can be easily found.

In this embodiment, in FIG.
In steps B1 to B3, the authentication processing of the transmission side 400 on the reception side 404 is performed, but this processing is not always necessary and may be omitted.

Embodiment 2 Next, Embodiment 2 of the present invention
Will be described. As shown in FIG. 10, steps B1 to B5 perform the same processing as shown in FIG. 2 of the first embodiment. In addition, step b shown in FIG.
The operation up to 604 is the same as that of the first embodiment, but in the second embodiment, even when there are a plurality of content requests, the key for decrypting the content is efficiently changed for each content unit. Can be done.

That is, FIG. 13 is a diagram conceptually showing a state of a key embedded in a content when a plurality of contents are transmitted by the transfer data protection method according to the second embodiment. As shown in FIG. For the content request (content 2 and content 3), the decryption key (R10, R11) of the content is included in the content (content 1 and content 2) transmitted immediately before the content.

Hereinafter, description will be made with reference to the flowcharts of FIGS. In the case where there are a plurality of requested contents, for example, in the case of three, as shown in FIG. 11B which is the processing of step B6 ′, following step b604, in step x300, a random number 1 is set.
0 (R10) and random number 11 (R11) are generated, and in step x301, the random number R10 is embedded in the content 1 corresponding to D11 (request 1) by the digital watermark processor 600, and in step x302, D11 (request 2) The digital watermark processor 600 embeds a random number R12 in the content 2 corresponding to
In step, E30 is generated by encrypting the content 1 using the random number R3 as a key, and in step x304, E31 is generated by encrypting the content 2 using the random number R10 as a key. In step x305,
E32 is generated by encrypting the content 3 using the random number R11 as a key. In step x306, the generated E30, E31, and E32 are transmitted.

Next, on the receiving side 404, step B7 '
According to FIG. 12B, which is the process of FIG. 12B, when there are three requested contents, in step x400, E30, E31, E32, or communication end is received.
S) When it is determined, D30 is generated by decrypting E30 using the random number R3 as a key in step x402, and the digital watermark detector 50 is generated in step x403.
Random number R embedded in D30 (content 1) by 0
In step x404, D31 is generated by decrypting E31 using the random number R10 as a key, and in step x405, D32 (content 2)
To generate a random number R11 embedded in. In step x406, D32 is generated by decoding E32 using the random number R11 as a key. If there is no request, the communication is terminated in step b702.
On the other hand, if the communication ends in step x401 (NO), the process proceeds to step b702 in FIG. 12A to end the communication.

As described above, according to the second embodiment, in the case where there are a plurality of content requests, the key information necessary for decrypting the content is embedded by the digital watermark processing unit. By using the key R10 extracted from the content 1 for decrypting the content 2 in step x404, a plurality of content requests can be sequentially and efficiently transmitted for each content unit without transmitting a decryption key separately from the content. Can be changed, so that highly secure transmission is possible.

Embodiment 3 Next, Embodiment 3 of the present invention
Will be described. In the first embodiment, the key information included in the content X transmitted from the transmission side is decrypted and returned to the transmission side again, thereby confirming the presence or absence of the digital watermark processor. In the third embodiment, the presence of a digital watermark processor is confirmed by transmitting a content from the receiving side and verifying the content on the transmitting side. That is, in FIG.
3 performs the same processing as shown in FIG. 2 of the first embodiment.

Next, the transmitting side 400 generates a random number R12 in step x501 and generates a random number R12 in step x502 in accordance with FIG.
12 is encrypted using the random number R3 as a key,
0, and in step x503, the generated E
40 is transmitted to the receiving side 404.

Next, the receiving side 404 receives E40 in step x601 according to the processing in step F5 shown in FIG. 16, and generates D40 by decoding E40 using the random number R3 as a key in step x602. In x603, the above D40 (R1
2) is embedded in the content prepared by the receiving side by the digital watermark processor 601 to generate the content Y,
In step x604, the content Y is encrypted using the random number R3 as a key to generate E41, in step x605, the request is encrypted using D40 (R12) as a key, and E42 is generated. In step x606, E41 and E42 are transmitted. To the side 400.

Next, the transmitting side 400 receives E41 and E42 in step x701 according to the processing in step F6 shown in FIG.
D41 is generated by decrypting the digital watermark 41 using the random number 3 as a key.
00, D43 embedded in D41 (contents Y) is extracted. In step x704, the digital watermark detector 500 compares the D43 with the random number R12. If it is determined that they match, the process proceeds to step x704. Proceeding to x705, D42 is generated by decrypting E42 using the random number R12 as a key, and step x706 is performed.
In step, the digital watermark processor 600 embeds the copyright information in the content corresponding to D42 (request), generates the E44 by encrypting the content using the random number R12 as a key in step x707, and transmits the E44 to the receiving side 404 in step x708. I do. On the other hand, if it is determined in step x704 that they do not match (NO), the flow advances to step x709 to transmit the end of communication, and ends the communication in step x710.

Next, the receiving side 404 receives E44 in step x801 according to the processing of step F7 shown in FIG. 18, and if it is determined in step x802 that the communication is not to be ended (YES), the E44 is converted to D40 (R12) in step x803. D44 is generated by decrypting as a key, and if there is no request, step x
At 804, the communication ends. On the other hand, the above step x
If it is determined in 802 that communication has ended (NO),
Proceed to step x804 to end the communication.

As described above, according to the third embodiment, in the first embodiment, the key information included in the content X transmitted from the transmitting side 400 is decrypted and returned to the transmitting side 400 again. Thus, the presence / absence of the digital watermark processor is checked. However, in the third embodiment, the random number R12 reproduced in step x501 is transmitted to the receiving side 404.
At the receiving side 404, the digital watermark processor 601 detects D40 (R12) information embedded in the content, and the detected information and the random number R12 are compared by the digital watermark detector 500 of the transmitting side 400. By that
Whether or not the digital watermark processor 601 exists can be confirmed.

[0049]

As described above, according to the transmission data protection method according to the present invention, the receiving side and the transmitting side are each provided with the digital watermark detector, and the transmission is performed before transmitting the requested content. Side transmits the predetermined test content encrypted by the digital watermarking process to the receiving side, and the receiving side digitally watermarks the decrypted test content and sends it back to the transmitting side, or from the transmitting side to the receiving side. The specific information is transmitted, and the receiving side receives the information, creates an authentication content in which the specific information is embedded in the predetermined content using a digital watermark, transmits the authentication content to the transmitting side, and transmits the authentication content to the transmitting side. Then, by detecting the above-mentioned specific information, it is confirmed that the digital watermark processor on the receiving side is present. More secure data transmitting network, there is an effect that the sending and receiving via a network performed can improve the safety of the system.

Also, key information necessary to decrypt the next encrypted content to be transmitted to the receiving side is embedded in the content sequentially transmitted from the transmitting side by a digital watermark. By doing so, it is not necessary to transmit key information separately from data, and content can be transmitted on a public network by performing encryption using a different key for each content. Therefore, there is an effect that a complicated protocol is not required and the number of processing steps can be reduced.

[0051]

[Brief description of the drawings]

FIG. 1 is a diagram showing a concept when a network connection is performed using a transmission data protection method according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an overall flow when data is transmitted and received using the transmission data protection method according to the first embodiment.

FIG. 3 is a flowchart illustrating a process of step B1 when transmitting and receiving data using the transmission data protection method according to the first embodiment;

FIG. 4 is a diagram showing a flowchart for describing in detail a process of step B2 when transmitting and receiving data using the transmission data protection method according to the first embodiment.

FIG. 5 is a diagram showing a flowchart for describing in detail a process of step B3 when transmitting and receiving data using the transmission data protection method according to the first embodiment.

FIG. 6 is a diagram showing a flowchart for describing in detail a process of step B4 when transmitting and receiving data using the transmission data protection method according to the first embodiment.

FIG. 7 is a diagram showing a flowchart for describing in detail a process of step B5 when transmitting and receiving data using the transmission data protection method according to the first embodiment.

FIG. 8 is a diagram showing a flowchart for explaining in detail a process of step B6 when transmitting and receiving data using the transmission data protection method according to the first embodiment.

FIG. 9 is a diagram showing a flowchart for describing in detail a process of step B7 when transmitting and receiving data using the transmission data protection method according to the first embodiment.

FIG. 10 is a diagram for explaining an overall flow when data is transmitted and received using the transmission data protection method according to the second embodiment.

FIG. 11 is a diagram showing a flowchart for describing in detail a process of step B6 ′ when transmitting and receiving data using the transmission data protection method according to the second embodiment.

FIG. 12 is a diagram showing a flowchart for describing in detail a process of step B7 ′ when transmitting and receiving data using the transmission data protection method according to the second embodiment.

FIG. 13 is a diagram showing a concept of content content transmitted from a transmission side to a reception side using the transmission data protection method according to the second embodiment of the present invention.

FIG. 14 is a diagram for explaining an overall flow when data is transmitted and received using the transmission data protection method according to the third embodiment.

FIG. 15 is a diagram showing a flowchart for explaining in detail the process of step F4 when transmitting and receiving data using the transmission data protection method according to the third embodiment.

FIG. 16 is a diagram illustrating a flowchart for describing in detail a process of step F5 when transmitting and receiving data using the transmission data protection method according to the third embodiment.

FIG. 17 is a diagram illustrating a flowchart for describing in detail a process of step F6 when transmitting and receiving data using the transmission data protection method according to the third embodiment.

FIG. 18 is a diagram showing a flowchart for describing in detail the process of step F7 when transmitting and receiving data using the transmission data protection method according to the third embodiment.

FIG. 19 is a diagram showing the encoding / decoding relationship between an encryption key and a decryption key in an authentication system based on a public key system using a digital signature.

FIG. 20 is a diagram showing a concept when a network connection is performed using a conventional transmission data protection method.

FIG. 21 is a diagram for explaining an overall flow when data is transmitted and received using a conventional transmission data protection method.

FIG. 22 is a diagram showing a flowchart for explaining in detail the processing of step A1 when transmitting and receiving data using the conventional transmission data protection method.

FIG. 23 is a diagram showing a flowchart for explaining in detail the processing of step A2 when transmitting and receiving data using the conventional transmission data protection method.

FIG. 24 is a diagram showing a flowchart for explaining in detail the process of step A3 when transmitting and receiving data using the conventional transmission data protection method.

FIG. 25 is a diagram showing a flowchart for explaining in detail the process of step A4 when transmitting and receiving data using the conventional transmission data protection method.

FIG. 26 is a diagram showing a flowchart for explaining in detail the process of step A5 when transmitting and receiving data using the conventional transmission data protection method.

[Explanation of symbols]

400 sender 401 public key (PKa) of sender 402 secret key (SKa) of sender 403 network 404 receiver 405 receiver's public key (PKbx) digitally signed with public key (PKa) 406 receiver's secret Key (SKb) 407 Analog output 408 Digital output 500 Digital watermark detector at transmitting side 501 Digital watermark detector at receiving side 600 Digital watermark processing unit at transmitting side 601 Digital watermark processing unit at receiving side

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 9/08 H04N 7/16 Z 9/32 H04L 9/00 601B // H04N 7/16 675B F term ( Reference) 5B017 AA06 BA05 BA07 BB03 BB07 CA16 5B082 AA01 AA13 EA12 GA02 GC05 HA05 5C064 CA18 CB01 CC02 5J104 AA07 AA08 AA14 BA01 CA01 KA02 KA05 KA06 KA11 NA05 NA36 PA00 PA07

Claims (3)

[Claims] 1. A transmission data protection method for protecting a copyright of a content when transmitting / receiving the content using a network, wherein a transmission side transmits a content requested by a reception side before transmitting the content. Transmitting an authentication content that has been subjected to a process of embedding specific information in predetermined content using a pseudo-random number as a key, which is called a digital watermark, and, on the receiving side, the identification obtained by decrypting the authentication content. Transmitting the information to the transmitting side, and detecting, on the transmitting side, the content of the specific information transmitted from the receiving side, and detecting whether the digital watermarking process can be performed on the receiving side. A transmission data protection method, comprising: 2. The transmission data protection method according to claim 1, wherein a plurality of contents are requested from the receiving side, and in the step of detecting whether or not to perform digital watermarking on the receiving side, digital watermarking is possible. If determined, the transmitting side encrypts and attaches to each content key information for decrypting the next content following the content, and transmits the encrypted content to the receiving side. To protect transmitted data. 3. A transmission data protection method for protecting a copyright of a content when transmitting / receiving the content using a network, wherein the transmission side transmits the content requested by the reception side before transmitting the content. Transmitting the specific information to the receiving side, and receiving, on the receiving side, the specific information, and performing processing for embedding the specific information in predetermined content using a pseudo random number as a key, which is called a digital watermark. Creating the content for use and transmitting the content to the transmitting side; detecting the content of the specific information obtained by decoding the content for authentication on the transmitting side; Detecting whether or not to perform transmission data protection.