JP2008301204A - Reproducing device and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reproducing device and a reproducing method for easily reproducing content information including an ARF (Advanced Resource File) encrypted in a CBC (Cipher Block Chaining) mode. <P>SOLUTION: The reproducing device comprises: a reading part (11) which outputs the content information including the ARF encrypted in the CBC mode; a buffer part (5) which stores the read information in a storage area; and a processing part (21) which extracts data to be a header and an initial vector, stores the data in a buffer, extracts key information from the header stored in the buffer, decodes the initial vector and data to be reproduced, decodes encrypted data of the next block into plain text data by the decoded initial vector and sequentially performs decoding processing of the next piece of encrypted data by the decoded plain text data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a playback apparatus and a playback method for decrypting a part of content data (ARF (Advanced Resource File)) encrypted in a CBC (Cipher Block Chaining) mode.

  In recent years, with the development of digital technology, playback devices and recording devices using many encryption technologies have become widespread. For example, a device that reproduces content encrypted in a CBC mode, which is one method of encryption technology, is known.

Patent Document 1 discloses a stream recording / playback apparatus capable of decrypting data encrypted particularly in the CBC mode.
JP 2006-331483 A

  However, in the prior art of Patent Document 1, even when part of the data is decoded, the data must be read sequentially from the top for decoding, and it is necessary to read data unnecessary for reproduction. It is.

  An object of the present invention is to provide a playback device and a playback method for easily playing back content information including ARF encrypted in the CBC mode.

One embodiment for solving the problem is:
A reading unit (11) for outputting content information including ARF encrypted in CBC mode;
A buffer unit (5) for storing the content information in a storage area;
In order to reproduce the ARF encrypted in the CBC mode of the content information, the header and the data one block before the data to be reproduced are extracted from the ARF stored in the buffer unit,
Key information is extracted from the header, and by this key information, the data one block before the data to be reproduced and the data to be reproduced are decrypted;
Decoding the data to be reproduced one block before the decoded data to be reproduced;
And a processing unit (7, 14) for sequentially performing subsequent data decoding processing based on the decoded data.

  A specific and detailed description is given of how content information including ARF encrypted in the CBC mode is played back by a playback device using a small-capacity buffer.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<An example of a playback apparatus according to an embodiment of the present invention>
First, an example of a playback apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Here, the present invention will be described in detail using an optical disk device as an example of a playback device. FIG. 1 is a block diagram showing an example of the configuration of an optical disc apparatus according to an embodiment of the present invention.

(Constitution)
As shown in FIG. 1, an optical disc apparatus 1 according to an embodiment of the present invention includes an optical disc D, a control unit 3 that controls the overall operation, and a signal used for recording as a signal used for recording processing A recording signal processing circuit 4 for conversion, a buffer 5 for storing a stream read from the optical disc D, etc., an LDD 6 for controlling the laser beam of the optical pickup, an optical pickup head, and a PUH actuator for controlling the position of the optical pickup head 8 and PD 10 for receiving a detection signal detected from the optical pickup head and outputting the signal.

  Further, as shown in FIG. 1, the optical disc apparatus 1 includes a preamplifier 12 that appropriately amplifies the detected signal, an AACS processing circuit 14 that decodes content information by an AACS (Advanced Access Content System) process, and a given read-out. An address signal processing circuit 16 that acquires an appropriate address according to a command, a reproduction circuit 17 that processes a video signal and an audio signal that are decoded read signals, and a servo circuit that controls the spindle motor 20 at an appropriate speed. 18, a spindle motor 20, a removable memory 21 that is a removable memory for storing a stream and the like, and a communication unit 22 for acquiring the stream and the like via a network such as the Internet.

  An optical disc apparatus 1 according to an embodiment of the present invention collects laser light emitted from an optical pick-up head PUH actuator 8 in an information recording layer in an optical disc D that is rotationally driven by a spindle motor 20. Information is recorded and reproduced by shining light (focusing on the target recording layer by a focus servo). The light reflected from the optical disk D passes through the optical system of the PUH actuator 8 again and is detected as an electric signal by the PD (photo detector) 10.

  The detected electrical signal is amplified by the preamplifier 12 and output to the servo circuit 18, the AACS processing circuit 14, and the address signal processing circuit 16. The servo circuit 18 generates servo signals such as focus, tracking, tilt, and rotation speed, and outputs each servo signal to a focus, tracking, and tilt actuator (not shown) in the PUH actuator 8. The servo signal of the rotational speed is sent to the drive circuit system of the spindle motor 20, and the linear velocity of the laser beam spot on the recording layer of the disk is controlled to a predetermined value.

  The address signal processing circuit 16 processes the detected signal to read “physical address information” indicating the recording position on the optical disc and output it to the control unit 3. Based on this address information, the control unit 3 reads data at a desired address position (user data or the like) or records data at a desired address position. At that time, the recording data is modulated into a recording waveform control signal suitable for optical disc recording by a recording waveform circuit (not shown) in the recording signal processing circuit 4 or in the LDD (laser diode drive circuit) 6. Based on the modulated signal, the LDD 6 causes the laser diode to emit light and records information on the optical disc D.

(Operation)
Next, in such a playback apparatus, a procedure for playing back content including ARF encrypted in the CBC mode when fast-forwarding (fast-rewinding) a stream will be described in detail with reference to flowcharts.

  FIG. 3 is a flowchart showing an example of ARF reproduction processing in the optical disc apparatus according to the embodiment of the present invention. FIG. 4 is a flowchart showing an example of reproduction processing of ARF supplied from the network. FIG. 5 is also a flowchart showing an example of a reproduction process of ARF supplied from the memory. FIG. 6 is a flowchart showing another example of ARF reproduction processing.

  Each step in the flowcharts of FIGS. 3 to 6 below can be replaced with a circuit block. Therefore, all steps in each flowchart can be redefined as blocks.

  Here, the encrypted ARF 50 has a data configuration as shown in FIG. 2, and includes, for example, a 282 byte header 51 and resource data 52.

  Here, the header 51 has a file ID 61, protection type information 62, a reserve area 63, title key information 64, a resource file size 65, and a resource file name area 66, and the resource file name area 66 Only is encrypted. Further, the resource data 52 is encrypted in the CBC mode in units of 16 bytes, and the data 67 of the previous 16-byte block that becomes the IV (initial vector) and the data 68 after that are shown.

When playing a file from an optical disc First, a case of playing a file from an optical disc will be described with reference to the flowchart of FIG. In the flowchart of FIG. 3, when the control unit 3 receives an operation signal such as fast-forwarding of a file, for example, the control unit 3 interprets the file as reproduction of a part of ARF encrypted in the CBC mode (step S11).

  The control unit 3 and the access management unit 7 obtain the ARF header encrypted in the CBC mode from the drive of the optical disc D, and store it in a buffer (the access management unit 7 may be a buffer (not shown) or a buffer 5). Store (step S12). Further, the access management unit 7 acquires, from the drive of the optical disc D, a part of the multiple of 16 bytes at an address that is a multiple of 16 bytes from the beginning of the data area of the data portion of the ARF encrypted in the CBC mode. (Step S13). This partial data is data from one block (16 bytes) before the position to be reproduced.

  Next, the control unit 3 and the access management unit 7 supply the title key information 64 indicated by the header to the AACS processing circuit 14 (step S14). The AACS processing circuit 14 acquires key data based on the title key information 64 in the header, and decrypts the ARF encrypted data encrypted in the CBC mode (step S15).

  Then, the data to be reproduced is decoded by the data one block (16 bytes) before the data to be reproduced, and thereafter, the process of decoding the next block data using the decoded data is successively performed. To go. The decoded data is supplied to the reproduction circuit 17 to reproduce audio information and video information.

  By such a procedure, content information that is a large ARF of a file size encrypted in the CBC mode stored in the optical disc can be smoothly reproduced even if a relatively small buffer is used.

When playing a file via a network Next, a case of playing a file via a network will be described with reference to the flowchart of FIG. The flowchart in FIG. 4 is essentially the same as the flowchart in FIG. 3, and the description of the common parts is omitted.

  That is, in the case where the file is reproduced through the network in step S22, the header of the ARF encrypted in the CBC mode from an external server or the like using the communication unit 22 or the like, for example, via the network such as the Internet. Are first downloaded and held in a buffer (a buffer (not shown) of the access management unit 7 or a buffer 5 may be used).

  Next, a part of the size of a multiple of 16 bytes is downloaded from the network at a multiple of 16 bytes from the beginning of the data area of the data portion of the ARF encrypted in the CBC mode (step S23). As an example, this part is data to be reproduced and data that becomes an initial vector IV one block before this data.

  The other processes are essentially the same as those in the flowchart of FIG. 3, and description of common parts is omitted.

  As described above, even in the case of content information including ARF encrypted in the CBC mode acquired via a network, content information that is ARF having a large file size is relatively small in capacity as in the case of an optical disc. Even with this buffer, it can be played back smoothly.

Case of Reproducing File Stored in Memory Next, a case of reproducing a file via a network will be described with reference to the flowchart of FIG. The flowchart in FIG. 5 is essentially the same as the flowchart in FIG. 3, and description of common parts is omitted.

  That is, when playing back a file stored in the memory, content information including the ARF encrypted in the CBC mode is obtained by accessing the removable memory 21, and a buffer (not shown in the access management unit 7) is obtained. It may be held in a buffer or buffer 5 (step S32).

  Next, a part of the size of a multiple of 16 bytes is read from the removable memory 21 at an address that is a multiple of 16 bytes from the beginning of the data area of the data portion of the ARF encrypted in the CBC mode (step S33). As an example, this part is data to be reproduced and data that becomes an initial vector IV one block before this data.

  The other processes are essentially the same as those in the flowchart of FIG. 3, and description of common parts is omitted.

  As described above, even if the content information includes the encrypted ARF stored in the removable memory, the content information that is an ARF having a large file size is compared with the case of the content information including the optical disc or the network. Even if a small-capacity buffer is used, it can be reproduced smoothly.

When the file is advanced or retracted by the instruction time Next, the case where the file is advanced or retracted by the instruction time will be described with reference to the flowchart of FIG. The flowchart in FIG. 6 is essentially the same as the flowchart in FIG. 3, and description of common parts is omitted.

  That is, when the playback position is moved forward or backward for a specified time in step S42, it is preferable to jump the ARF read position forward or backward in multiples of 16 bytes. This is based on the fact that the ARF data is CBC encrypted for each 16-byte block.

  As a result, in the ARF playback scene in which the playback position (time) of the file can be specified from the position (number of bytes) from the beginning of the file, when the playback position is jumped back and forth for a specified time, the data of the section not played back is acquired Is no longer necessary. As a result, the reaction speed of the device in the special regeneration can be improved.

  With the various embodiments described above, those skilled in the art can realize the present invention. However, it is easy for those skilled in the art to come up with various modifications of these embodiments, and have the inventive ability. It is possible to apply to various embodiments at least. Therefore, the present invention covers a wide range consistent with the disclosed principle and novel features, and is not limited to the above-described embodiments.

1 is a block diagram showing an example of the configuration of an optical disc device according to an embodiment of the present invention. Explanatory drawing which shows an example of the data structure of the content which the optical disc device concerning one Embodiment of this invention handles. 6 is a flowchart showing an example of ARF reproduction processing in the optical disc apparatus according to the embodiment of the present invention. 6 is a flowchart showing an example of a reproduction process of ARF supplied from a network in the optical disc apparatus according to the embodiment of the present invention. 6 is a flowchart showing an example of a reproduction process of ARF supplied from a memory in the optical disc apparatus according to the embodiment of the present invention. 10 is a flowchart showing another example of ARF reproduction processing in the optical disc apparatus according to the embodiment of the present invention.

Explanation of symbols

  D ... Optical disc, 3 ... Control unit, 4 ... Recording signal processing circuit, 5 ... Buffer, 6 ... LDD, 7 ... Access management unit, 8 ... PUH actuator, 10 ... PD, 12 ... Preamplifier, 14 ... AACS processing circuit, 16 DESCRIPTION OF SYMBOLS ... Address signal processing circuit, 17 ... Reproduction circuit, 18 ... Servo circuit, 20 ... Spindle motor, 21 ... Detachable memory, 22 ... Communication part.

Claims (10)

A reading unit that outputs content information including ARF encrypted in CBC mode;
A buffer unit for storing the content information in a storage area;
In order to reproduce the ARF encrypted in the CBC mode of the content information, a header is extracted from the ARF and stored in the buffer unit.
Obtain the data one block before the data to be reproduced and the data to be reproduced,
Key information is extracted from the header stored in the buffer unit, and based on the key information, the data one block before the data to be reproduced and the data to be reproduced are decrypted;
Decoding the data to be reproduced one block before the decoded data to be reproduced;
A processing unit for sequentially performing subsequent decoding processing of the data with the decoded data;
A playback apparatus comprising:   2. The reproducing apparatus according to claim 1, wherein the processing unit accesses the data every multiple of 16 bits.   2. The reproducing apparatus according to claim 1, wherein the reading unit reads content information including ARF encrypted in the CBC mode from an optical disc. A communication unit that communicates with an external device via a network;
The playback apparatus according to claim 1, wherein the reading unit reads content information including ARF encrypted in the CBC mode from the external device via the network by the communication unit. It further has an interface part with a removable or non-removable memory,
2. The reproducing apparatus according to claim 1, wherein the reading unit reads content information including ARF encrypted in the CBC mode from the memory.   The playback apparatus according to claim 1, wherein the processing unit plays back the ARF in the content information in response to a fast-forward or rewind instruction for the content. Content information playback processing,
Receive content information including ARF encrypted in CBC mode,
Extract the header and the data one block before the data to be reproduced from the ARF,
Key information is extracted from the header, and by this key information, the data one block before the data to be reproduced and the data to be reproduced are decrypted;
Decoding the data to be reproduced one block before the decoded data to be reproduced;
A reproduction method characterized by sequentially performing subsequent data decoding processing based on the decoded data.   8. The reproducing method according to claim 7, wherein the encrypted data is accessed every multiple of 16 bits.   8. The reproducing method according to claim 7, wherein content information including ARF encrypted in the CBC mode is read from an optical disc.   8. The reproduction method according to claim 7, wherein content information including ARF encrypted in the CBC mode is read from an external device via a network.

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