JP2002051039A - Contents reproduction method and contents reproduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contents reproduction method and a contents reproduction device that can reduce a discrimination time at least when contents are illegal in the case of verifying the validity of contents. SOLUTION: The reproduction device compares illegal signature information recorded in a signature information memory 28 with signature information 24 read from a recording medium 12, and discriminates contents 15 to be illegal contents without investigating contents themselves of the signature information 24 by a signature verification section 22 when information coincident with the signature information 24 is recorded in the signature information memory 28 as illegal signature information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a content reproducing method and a content reproducing apparatus for verifying the validity of a content based on signature information and controlling the reproduction of the content. It is another object of the present invention to provide a content reproducing method and a content reproducing apparatus capable of shortening the time required for judging that the content is illegal in verifying the validity of the content.

[0002]

2. Description of the Related Art One of the effective means for preventing the use of a recording medium in which digital content having copyright is illegally copied is authentication by signature. In this method, in addition to digital content,
Signature information indicating that the recording medium or the content is valid is also recorded. In a device for reproducing digital content, when a user performs a reproducing operation, first, it is verified whether or not the signature is valid, and only when the signature is valid, reproduction of the digital content is permitted. Also, as disclosed in Japanese Patent Application Laid-Open No. 2000-22680, there is known a method of reflecting a verification result of a signature on whether or not to decrypt a key necessary for decrypting digital content at least partially encrypted. Have been.

[0003]

However, in the case of the signature method used in the above method, if the copyright protection capability of a certain level or more is to be ensured, the amount of data required for the signature information becomes large, The calculation used for the calculation becomes complicated. Unlike a PC or the like, a digital content reproducing apparatus that can be used by general users often has a low processing capacity for signature verification, and performs verification processing on signature information having a large data amount (verification processing of the content of the signature information itself). It takes time. Conventionally, such a time-consuming signature verification process (a process of verifying the content of the signature information itself) is always performed every time a reproducing operation is performed, and a considerable amount of time is always required until a verification result of improper or legitimate is obtained. I needed it. In particular, even when reproducing legitimate content, the user had to wait a considerable amount of time from when the user performed the reproduction operation to when the content was actually displayed until a verification result that the content was valid was obtained. .

An object of the present invention is to provide a content reproducing method and a content reproducing apparatus which can shorten at least the time required for judging that the content is illegal in the verification of the validity of the content. In addition, the present invention
It eliminates the inconvenience that the user has to wait for the reproduction of the legitimate content until the result of the legitimacy verification is obtained, without improving the content validity verification processing capability (verification process of the content of the signature information itself), and It is another object of the present invention to provide a content reproducing method and a content reproducing apparatus which can restrict the reproduction of an illegal content.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides the following content reproducing method and content reproducing apparatus. (1) In a content reproduction method for controlling the reproduction of the content by verifying the validity of the content based on the signature information A indicating the validity of the content to be reproduced, the validity of the content based on the signature information A Verification of the content and the reproduction of the content are started once, and the verification of the validity of the content based on the signature information A is performed by using the signature information A and the signature information already stored in the built-in memory, which are to be fraudulent. If the information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the contents of the signature information A are not verified without verifying the content itself. Information that matches the signature information A is not stored in the built-in memory as the signature information to be fraudulent. In this case, the content of the signature information A is verified, and when the content is determined to be illegal content, the signature information A is newly stored in the internal memory as signature information to be illegal. A content reproducing method, wherein, as a result of the validity verification of the content, if the content is determined to be an illegal content, the reproduction of the content is stopped and the reproduction is not permitted. (2) In the content reproduction method for controlling the reproduction of the content by verifying the validity of the content based on the signature information A indicating the validity of the content to be reproduced, the validity of the content based on the signature information A The verification of the property is performed by comparing the signature information A already stored in the built-in memory with the signature information A and the signature information A, and storing information matching the signature information A in the built-in memory as the signature information to be fraudulent. If the content has not been verified, the content itself is not verified, and the content is determined to be unauthorized content, and information that matches the signature information A is stored in the internal memory as the signature information to be unauthorized. If the content is not stored, verification of the content of the signature information A is performed, and when the content is determined to be illegal content, The signature information A is newly stored in the built-in memory as signature information to be fraudulent, and if the content is determined to be invalid as a result of the validity verification of the content, the content is reproduced. Content reproduction method, wherein the content is not permitted. (3) When a flag indicating that there is signature information A indicating the validity of the content to be reproduced is detected, verification of the validity of the content based on the signature information A is started, and reproduction of the content is performed once. The verification of the validity of the content based on the signature information A is performed by comparing the signature information A with the signature information already stored in the built-in memory and targeted for injustice, and matches the signature information A. If the information is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined to be fraudulent without verifying the content itself of the signature information A, and it is determined that the content matches the signature information A. If the information to be executed is not stored in the internal memory as the signature information to be fraudulent, the content itself of the signature information A is verified and the When the content is determined to be illegal content, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the validity verification of the content, the content is identified as illegal content. If it is determined, the reproduction of the content is stopped and the reproduction is not permitted. (4) If a flag indicating that there is signature information A indicating the validity of the content to be reproduced is detected, verification of the validity of the content based on the signature information A is started, and Verifying the validity of the content based on the signature information A, which is stored in the built-in memory and is to be fraudulent, and compares the signature information A;
If information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined to be invalid without verifying the content itself of the signature information A. If the information that matches the signature information A is not stored in the internal memory as the signature information to be fraudulent, the content itself of the signature information A is verified and the content is determined to be unauthorized content. Then, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and if the content is determined to be invalid as a result of the validity verification of the content, the content A content reproduction method, wherein reproduction of a content is not permitted. (5) In a content reproducing apparatus that controls the reproduction of the content by verifying the validity of the content based on the signature information A indicating the validity of the content to be reproduced, the validity of the content based on the signature information A Verification of the content and the reproduction of the content are started once, and the verification of the validity of the content based on the signature information A is performed by using the signature information A and the signature information already stored in the built-in memory, which are to be fraudulent. If the information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the contents of the signature information A are not verified without verifying the content itself. Information that matches the signature information A is not stored in the built-in memory as the signature information to be fraudulent. In this case, the content of the signature information A is verified, and when the content is determined to be illegal content, the signature information A is newly stored in the internal memory as signature information to be illegal. A content reproducing apparatus, wherein as a result of the validity verification of the content, if the content is determined to be an illegal content, the reproduction of the content is stopped and the reproduction is not permitted. (6) In a content reproducing apparatus that verifies the validity of the content based on the signature information A indicating the validity of the content to be reproduced and controls the reproduction of the content, the validity of the content based on the signature information A The verification of the property is performed by comparing the signature information A already stored in the built-in memory with the signature information A and the signature information A, and storing information matching the signature information A in the built-in memory as the signature information to be fraudulent. If the content has not been verified, the content itself is not verified, and the content is determined to be unauthorized content, and information that matches the signature information A is stored in the internal memory as the signature information to be unauthorized. If the content is not stored, verification of the content of the signature information A is performed, and when the content is determined to be illegal content, The signature information A is newly stored in the built-in memory as signature information to be fraudulent, and if the content is determined to be invalid as a result of the validity verification of the content, the content is reproduced. A content reproducing device, wherein (7) When a flag indicating that the signature information A indicating the validity of the content to be reproduced exists is detected, verification of the validity of the content based on the signature information A is started, and reproduction of the content is performed once. The verification of the validity of the content based on the signature information A is performed by comparing the signature information A with the signature information already stored in the built-in memory and targeted for injustice, and matches the signature information A. If the information is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined to be fraudulent without verifying the content itself of the signature information A, and it is determined that the content matches the signature information A. If the information to be executed is not stored in the internal memory as the signature information to be fraudulent, the content itself of the signature information A is verified and the When the content is determined to be illegal content, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the validity verification of the content, the content is identified as illegal content. If it is determined, the reproduction of the content is stopped and the reproduction is not permitted. (8) If a flag indicating that there is signature information A indicating the validity of the content to be reproduced is detected, verification of the validity of the content based on the signature information A is started, and Verifying the validity of the content based on the signature information A, which is stored in the built-in memory and is to be fraudulent, and compares the signature information A;
If information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined to be invalid without verifying the content itself of the signature information A. If the information that matches the signature information A is not stored in the internal memory as the signature information to be fraudulent, the content itself of the signature information A is verified and the content is determined to be unauthorized content. Then, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and if the content is determined to be invalid as a result of the validity verification of the content, the content A content reproducing apparatus, wherein reproduction of a content is not permitted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The recording medium 12 for digital contents may be any of a magnetic tape, an optical disk, and a semiconductor memory. The digital content to be recorded may be any digital data such as video and audio and PC programs.

In the recording apparatus, the digital content 01, the copy control flag 03, the signature information 08, and the signature information flag 09 are recorded on the recording medium 12 by the recording head 11. The copy control flag 03 is a flag indicating whether or not the content 01 recorded on the recording medium 12 can be digitally copied. The copy control flag 03 is, for example, CGMS, and is set from the copy control flag setting unit 02.

[0008] The signature information 08 indicates the validity of the digital content 01 to be recorded. This signature information 08
A message digest (hereinafter referred to as MD) 05 created from the digital content 01 by the hash function operation unit 04 is applied to a general digital signature method (RSA signature, DSS signature, etc.) using the secret key 07 of the copyright holder. ). The signature information flag 09 is a flag indicating whether or not the signature information 08 is recorded. It is assumed that 1-bit binary data indicates that there is no signature information and “1” indicates that there is signature information. The signature information 08 and the signature information flag 09 are created by the signature creation unit 06. FIG. 3A shows an operation flow of the printing apparatus.

Next, the reproducing apparatus shown in FIG. 1 will be described. FIG. 3B is a diagram showing an operation flow of the reproducing apparatus. The reproducing apparatus for reproducing the recording medium 12 first reads the digital content 15, the signature information flag 20, and the copy control flag 25 from the recording medium 12 by the read head 16.
(Here, the digital content 01, the copy control flag 03, the signature information 08, and the signature information flag 09 recorded on the recording medium 12 are stored in the digital content 15, the copy control flag 25, the signature information 24, and the signature information flag 20, respectively.
And )

When the signature information flag 20 is “0”, no signature information is recorded on the recording medium 12, and the signature verification unit 22 causes the decoder 14 to reproduce the digital content 15. If the signature information flag 20 is “1”, the signature verification unit 22 starts verifying the validity of the content 15 based on the signature information, and temporarily decodes the content 15
Start playback by 14. To verify the validity, first, the signature information 24 is read from the recording medium 12 and supplied to the signature verification unit 22 (a verification unit that verifies the content of the signature information itself) and the signature information comparison unit 27.

The signature information comparing section 27 compares the signature information 24 read from the recording medium 12 with the signature information recorded in the signature information memory 28 capable of recording two or more signature information. . If information matching the signature information 24 is recorded in the signature information memory 28 as unauthorized signature information, the signature verification section 22 does not verify the content itself of the signature information 24, and the signature information comparison section 27 outputs the content 15 Is determined to be illegal content. Then, the signature information comparing unit 27 transmits to the decoder control unit 17 as the reproduction permission / prohibition information 21, an instruction signal for stopping reproduction of the content and disabling subsequent reproduction.

On the other hand, if information matching the signature information 24 is not recorded in the signature information memory 28 as unauthorized signature information, the signature information comparison unit 27 transmits a signature content verification execution instruction signal to the signature verification unit 22. .

[0013] The signature verification unit 22 receives the signature verification instruction signal and verifies the MD 19 and the signature information 24 created from the digital content 15 by the hash function operation unit 18 using the public key 21 of the copyright holder. I do. As a result of the signature content verification, if it is determined that the content is valid, the signature verification unit 22 sends to the decoder control unit 17 the reproduction permission / prohibition information 21 permitting the reproduction of the already reproduced content. The decoder control unit 17 controls the decoder 14 so as to continue reproduction.

When the signature content verification shows that the content is illegal, the signature verification unit 22 sends, as the reproduction permission / prohibition information 21, an instruction signal for stopping the reproduction of the content and disallowing the subsequent reproduction. This is transmitted to the decoder control unit 17.

At the same time, the signature verification unit 22 uses the signature information 24 determined as an unauthorized object as the unauthorized signature information 30 as a signature information memory.
Send to 28. In the signature information memory 28, the history management unit 31
Then, if there is an area where the unauthorized signature information can still be recorded in the memory 28, the unauthorized signature information 30 is recorded. If there is no recordable area, the oldest unauthorized signature information (the first unauthorized signature information recorded in chronological order) is erased from the memory 28, and the newly received unauthorized signature information 30 is recorded. I do. When it is determined that the content is unauthorized, the display unit 13 may display that the content is unauthorized, and notify the user.

The external output control unit 26 determines whether or not the content can be digitally copied based on the copy control flag 25 read from the recording medium 12, and outputs the content to another recording device if the digital copy is possible. I do.

In the above embodiment, the case where digital content is recorded without encryption has been described. However, at least a part of the digital content is encrypted and recorded by the recording device, and the digital content is decrypted and reproduced by the reproducing device. Good.

As described above, in the present embodiment, the unauthorized signature information recorded in the signature information memory 28 is compared with the signature information 24 read from the recording medium, and information matching the signature information 24 is determined to be invalid. When the signature information is recorded in the signature information memory 28, the content 15 of the signature information 24 is not verified by the signature verification unit 22, and the content 15 is determined to be an illegal content. Therefore, a part of the determination of the injustice in the verification of the validity of the content becomes possible without performing the verification processing of the content itself of the signature information every time the reproduction operation is performed, and is an injustice in the verification of the validity of the content. And the time required for the determination can be reduced. Signature information memory
In the memory 28, two or more signature information to be fraudulent are stored in memory, so that it is possible to judge the fraud in correspondence with a plurality of fraudulent signature information.

Further, in this embodiment, at the time of reproduction, verification of the validity of the content based on the signature information is started, and
Since the reproduction of the content is started once, the user is required to wait for the reproduction of the valid content until the result of the verification of the validity is obtained, without improving the capability of the reproduction device to verify the validity of the content. Inconvenience can be eliminated. Of course, the reproduction of the illegal content can be stopped when the result of the verification of the validity is obtained, and the subsequent reproduction can be rejected, so that sufficient copyright protection capability can be secured.

In addition, by starting the verification of the validity of the content based on the signature information and once permitting the reproduction of the content, a certain amount of time is left in the validity verification time of the content. Therefore, in the present embodiment, it is possible to further improve the copyright protection capability by using signature information that requires a long time to verify the content itself and has a large amount of information.
Furthermore, in the present embodiment, it is possible to distribute signature information (divided recording of signature information) on the recording medium, which requires some time for reading from the recording medium. As a result,
Even on a tape-shaped recording medium such as a video tape, it is not necessary to record the signature information over the entire medium portion on which the content is recorded. (Conventionally, in a tape-shaped recording medium such as a video tape which is wound and stored, all of the recorded portions of the content are stored in such a manner that the signature information can be immediately read no matter where the reproduction is started. It was necessary to record the signature information over.)

In the above embodiment, the signature information flag
Although the use of the signature information 20 is used to instantaneously determine the presence or absence of the signature information, the speed up to the start of content playback is further improved, but the signature information itself is actually recorded on the recording medium without using the signature information flag 20. Alternatively, it may be determined by searching from the list. Further, in the above embodiment, the digital content, the copy control flag, the signature information, and the signature information flag are described as being transmitted via the recording medium. However, as shown in FIG. A configuration in which the data is directly transmitted to the reproducing apparatus through a transmission path by communication or broadcasting without intervening may be used. (FIG. 2 is the same as FIG. 1 except that the recording medium 12 in FIG. 1 is changed to a transmission line 120.)

Further, when the copyright protection capability of the copyright is more emphasized, the content is not reproduced until the result of the verification of the validity of the content based on the signature information is obtained.
When it is determined that the content is an illegal content, a reproduction non-permission instruction signal may be transmitted to the decoder control unit 17 as the reproduction permission / prohibition information 21.

[0023]

As described above, the present invention has the following effects. (B) The unauthorized signature information recorded in the signature information memory is compared with the signature information read from the recording medium, and information matching the signature information is recorded in the signature information memory as the unauthorized signature information. In such a case, the content is determined to be invalid without verifying the content of the signature information itself in the signature verification unit. Therefore, a part of the determination of the injustice in the verification of the validity of the content becomes possible without performing the verification processing of the content itself of the signature information every time the reproduction operation is performed, and is an injustice in the verification of the validity of the content. And the time required for the determination can be reduced. (B) In the case where the verification of the validity of the content based on the signature information is started at the time of reproduction and the reproduction of the content is started once, even if the capability of the reproduction device to verify the validity of the content is not improved. In addition, it is possible to eliminate the inconvenience that the user has to wait for the reproduction of the legitimate content until a validity verification result is obtained. Of course, the reproduction of the illegal content can be stopped when the result of the verification of the validity is obtained, and the subsequent reproduction can be rejected, so that sufficient copyright protection capability can be secured. (C) In the case where the verification of the validity of the content based on the signature information is started at the time of reproduction and the reproduction of the content is started once, there is a certain amount of time for the validity verification time of the content. Therefore, in the present invention, it is possible to further improve the copyright protection capability by using signature information having a large amount of information that requires time for verification of the content itself. Further, in the present invention, it is possible to distribute signature information (divided recording of signature information) on a recording medium, which requires a certain amount of time to read from the recording medium. As a result, it is not necessary to record the signature information even on a tape-shaped recording medium such as a video tape over the entire area where the content is recorded. (D) When the presence / absence of signature information is determined using the signature information flag, the presence / absence of signature information can be instantaneously determined, and the speed up to the start of content reproduction can be further increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a flowchart showing a main operation of the embodiment shown in FIG. 1;

[Explanation of symbols]

 02 Copy control flag setting section 04 Hash function calculation section 06 Signature creation section 11 Recording head 12 Recording medium 13 Display section 14 Decoder 16 Read head 17 Control section 18 Hash function calculation section 22 Signature verification section 26 External output control section 27 Signature information comparison Part 28 Signature information memory 31 History management part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // H04N 5/91 H04N 5/91 PF term (reference) 5B017 AA03 BA07 CA06 CA09 CA11 5B049 AA05 EE03 EE09 FF04 GG10 5C053 FA13 FA22 FA23 FA27 GB11 HA40 JA21 JA30 KA05 5J104 AA09 LA03 LA06 PA14

Claims (8)

[Claims] 1. A content reproducing method for verifying the validity of a content based on signature information A indicating the validity of the content to be reproduced and controlling reproduction of the content, wherein the content based on the signature information A is Verification of the content and the reproduction of the content are started once, and the verification of the validity of the content based on the signature information A is performed by using the signature information and the signature which are already stored in the built-in memory and are to be fraudulent. The information A is compared with the signature information A, and if the information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the content of the signature information A is not verified and the content itself is not verified. Is determined to be illegal content, and information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent. If not, the content itself of the signature information A is verified, and when the content is determined to be unauthorized content, the signature information A is newly stored in the built-in memory as signature information to be unauthorized. And a content reproduction method, wherein as a result of the content validity verification, if the content is determined to be invalid content, the reproduction of the content is stopped and the reproduction is not permitted. 2. A content reproduction method for verifying the validity of the content based on signature information A indicating the validity of the content to be reproduced and controlling the reproduction of the content, wherein the content based on the signature information A is Is verified by comparing the signature information A already stored in the built-in memory with the signature information to be fraudulent, and information matching the signature information A is regarded as the signature information to be fraudulently stored in the built-in memory. If the content is stored in the signature information A, the content itself is not verified, and the content is determined to be an unauthorized content, and information that matches the signature information A is stored as the signature information to be illegal. If the content is not stored in the memory, the content itself of the signature information A is verified, and the content is determined to be an illegal content. Sometimes, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the validity verification of the content, if the content is determined to be fraudulent, the content A content reproduction method characterized in that reproduction is not permitted. 3. When a flag indicating that signature information A indicating the validity of the content to be reproduced exists is detected, verification of the validity of the content based on the signature information A is started, and the content is temporarily checked. Is started, and the verification of the validity of the content based on the signature information A is performed by comparing the signature information A with the signature information already stored in the built-in memory and targeted for injustice. When the matching information is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined as an unauthorized content without verifying the content itself of the signature information A, and the signature information A If the information corresponding to the signature information A is not stored in the internal memory as the signature information to be fraudulent, the content of the signature information A is verified, When the content is determined to be illegal content, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the content validity verification, the content is And determining that the reproduction of the content is stopped and the reproduction is not permitted. 4. When a flag indicating the presence of signature information A indicating the validity of the content to be reproduced is detected, verification of the validity of the content based on the signature information A is started, and The verification of the validity of the content based on A compares the signature information A already stored in the built-in memory with the signature information A and the information that matches the signature information A becomes the fraudulent target. When the content is stored in the built-in memory as the signature information, the content itself is determined as unauthorized content without verifying the content itself of the signature information A, and information matching the signature information A is determined as the unauthorized target. If the signature information A is not stored in the built-in memory, the content itself of the signature information A is verified, and the content is determined to be an illegal content. Sometimes, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the validity verification of the content, if the content is determined to be fraudulent, the content A content reproduction method characterized in that reproduction is not permitted. 5. A content reproducing apparatus which controls the reproduction of the content by verifying the validity of the content based on signature information A indicating the validity of the content to be reproduced. And the reproduction of the content is started once, and the verification of the validity of the content based on the signature information A is performed based on the signature information and the signature which are already stored in the built-in memory and which are to be fraudulent. Compare with information A,
If information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined to be invalid without verifying the content itself of the signature information A. If the information that matches the signature information A is not stored in the internal memory as the signature information to be fraudulent, the content itself of the signature information A is verified and the content is determined to be unauthorized content. Then, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and if the content is determined to be invalid as a result of the validity verification of the content, the content A content reproduction apparatus for stopping reproduction of the content and disabling the reproduction. 6. A content reproducing apparatus that verifies the validity of the content based on signature information A indicating the validity of the content to be reproduced and controls the reproduction of the content. Is verified by comparing the signature information A already stored in the built-in memory with the signature information to be fraudulent and the signature information A,
If information matching the signature information A is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined to be invalid without verifying the content itself of the signature information A. If the information that matches the signature information A is not stored in the internal memory as the signature information to be fraudulent, the content itself of the signature information A is verified and the content is determined to be unauthorized content. Then, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and if the content is determined to be invalid as a result of the validity verification of the content, the content A content reproducing apparatus, wherein reproduction of a content is not permitted. 7. When a flag indicating that there is signature information A indicating the validity of the content to be reproduced is detected, verification of the validity of the content based on the signature information A is started, and once the content is verified. Is started, and the verification of the validity of the content based on the signature information A is performed by comparing the signature information A with the signature information already stored in the built-in memory and targeted for injustice. When the matching information is stored in the built-in memory as the signature information to be fraudulent, the content itself is determined as an unauthorized content without verifying the content itself of the signature information A, and the signature information A If the information corresponding to the signature information A is not stored in the internal memory as the signature information to be fraudulent, the content of the signature information A is verified, When the content is determined to be illegal content, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the content validity verification, the content is A content reproduction device that stops the reproduction of the content and prohibits the reproduction. 8. When a flag indicating that signature information A indicating the validity of the content to be reproduced exists is detected, verification of the validity of the content based on the signature information A is started, and the signature information is verified. The verification of the validity of the content based on A compares the signature information A already stored in the built-in memory with the signature information A and the information that matches the signature information A becomes the fraudulent target. When the content is stored in the built-in memory as the signature information, the content itself is determined as unauthorized content without verifying the content itself of the signature information A, and information matching the signature information A is determined as the unauthorized target. If the signature information A is not stored in the built-in memory, the content itself of the signature information A is verified, and the content is determined to be an illegal content. Sometimes, the signature information A is newly stored in the built-in memory as signature information to be fraudulent, and as a result of the validity verification of the content, if the content is determined to be fraudulent, the content A content reproducing apparatus for which reproduction is not permitted.