JP2008283463A - Encryption processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encryption processor capable of enhancing confidentiality of secret key data. <P>SOLUTION: The encryption processor includes: an encryption processing part which uses key data to encrypt or decrypt input data and outputs encrypted or decrypted data; and a control part which inputs not only encrypted secret key data resulting from encryption with prescribed key data as key data and with secret key data but also prescribed key data to the encryption processing part as input data and key data respectively to cause the encryption processing part to generate secret key data and inputs not only encrypted data encrypted by using the secret key data but also the generated secret key data to the encryption processing part as input data and key data respectively to cause the encryption processing part to generate decrypted data obtained by decrypting encrypted data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cryptographic processing apparatus.

CPRM (Content Protection for Recordable Media) is one of the mechanisms for preventing illegal copying of DVDs (Digital Versatile Disks). In a playback apparatus compatible with CPRM, data recorded on a DVD is decrypted using secret key data called a device key assigned to each apparatus (for example, Patent Document 1). In general, a device key used in a playback apparatus is assigned to each playback apparatus from a licensor and is written in a non-volatile memory in a production process of the playback apparatus.
JP 2007-60627 A

  Since the device key is confidential information, it must be managed robustly so as not to be leaked. However, when the device key assigned by the licensor is written in the nonvolatile memory as it is, if the playback device is disassembled, the device key is removed from the nonvolatile memory. The device key can be read, and confidentiality is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an encryption processing apparatus capable of enhancing the confidentiality of secret key data.

  In order to achieve the above object, the cryptographic processing apparatus of the present invention uses a key data to encrypt or decrypt input data and output the data, and a predetermined key data as the key data. The encrypted secret key data obtained by encrypting the secret key data as the input data is input to the encryption processing unit as the input data, and the predetermined key data is input to the encryption processing unit as the key data. Thus, the secret key data is generated, the encrypted data encrypted using the secret key data is input to the encryption processing unit as the input data, and the generated secret key data is input to the key And a control unit that generates decrypted data obtained by decrypting the encrypted data by inputting the data to the encryption processing unit as data.

  It is possible to provide an encryption processing apparatus capable of enhancing the confidentiality of secret key data.

  FIG. 1 is a diagram illustrating a configuration example of a cryptographic processing apparatus according to an embodiment of the present invention. The cryptographic processing device 10a includes a cryptographic processing unit 20, a user code storage unit 21, an encryption key storage unit 22, selectors 23 to 25, a register 26, and a selector control unit 30.

  The encryption processing unit 20 is a processing unit that performs encryption and decryption using secret key data such as C2 (Cryptomeria Cipher) and DES (Data Encryption Standard). The cryptographic processing unit 20 can be realized by hardware, or can be realized by a processor (not shown) included in the cryptographic processing device 10a executing a program.

  The user code storage unit 21 is a storage area in which key data (predetermined key data) arbitrarily determined by a user (for example, the manufacturer of the cryptographic processing device 10a) is stored. For example, the user code storage unit 21 is configured by a non-volatile memory such as a flash memory. Realized.

  The encryption key storage unit 22 is a storage area for storing encrypted secret key data obtained by encrypting secret key data provided from a licensor, and is realized by a non-volatile memory such as a flash memory, for example. FIG. 2 is a diagram illustrating an example of a flow of processing for encrypting secret key data. As shown in FIG. 2, the secret key data given from the licensor is encrypted by the encryption processing unit 20 using the user code stored in the user code storage unit 21 and stored in the encryption key storage unit 22. Is done. In the cryptographic processing apparatus 10a, the secret key data given from the licensor is only input when generating the encrypted secret key data, and is always stored in a non-volatile memory such as a flash memory. is not.

  The selectors 23 to 25 perform input / output selection control based on an instruction from the selector control unit 30. The selectors 23 to 25 can be realized by hardware, or can be realized by a processor (not shown) executing a program. The selector 23 (key selection unit) outputs either the user code stored in the user code storage unit 21 or the data stored in the register 26 to the encryption processing unit 20 as secret key data. The selector 24 (input selection unit) encrypts encrypted private key data stored in the encryption key storage unit 22 or encrypted with the private key data input from the licensor input to the cryptographic processing device 10a. Either one of the data is input to the encryption processing unit 20 as data to be decrypted. The selector 25 (output selection unit) stores the decrypted data output from the encryption processing unit 20 in the register 26 as the secret key data obtained by decrypting the encrypted secret key data stored in the encryption key storage unit 22. Or output as decrypted data obtained by decrypting the encrypted data input to the cryptographic processing apparatus 10a.

  The register 26 is a storage area for temporarily storing data, and stores secret key data generated by decrypting the encrypted secret key data stored in the encryption key storage unit 22 by the encryption processing unit 20. The

  The selector control unit 30 (selection control unit) decrypts the encrypted data input to the cryptographic processing apparatus 10a by using the secret key data given from the licensor by controlling the selection operation of the selectors 23 to 25. The decoded data is output. The selectors 23 to 25 and the selector control unit 30 correspond to the control unit of the present invention.

  A flow of decryption processing in the cryptographic processing apparatus 10a will be described. First, under the control of the selector control unit 30, the selector 23 outputs the user code stored in the user code storage unit 21 to the encryption processing unit 20 as secret key data, and the selector 24 is stored in the encryption key storage unit 22. The encrypted private key data is output to the encryption processing unit 20 as data to be decrypted. As a result, the encryption processing unit 20 decrypts the encrypted secret key data using the user code, and generates and outputs the secret key data given from the licensor. The selector 25 stores the decrypted secret key data output from the encryption processing unit 20 in the register 26 under the control of the selector control unit 30.

  Next, under the control of the selector control unit 30, the selector 23 outputs the secret key data stored in the register 26 to the encryption processing unit 20, and the selector 24 decrypts the encrypted data input to the encryption processing device 10a. The data is output to the encryption processing unit 20 as target data. As a result, the encryption processing unit 20 decrypts the encrypted data using the secret key data given from the licensor, and outputs the decrypted data. Then, under the control of the selector control unit 30, the selector 25 outputs the decrypted data output from the cryptographic processing unit 20 as data obtained by decrypting the encrypted data input to the cryptographic processing device 10a.

  As described above, in the cryptographic processing device 10a, the secret key data given from the licensor is encrypted with an arbitrary user code as the secret key data and stored in the encryption key storage unit 22. Then, when decrypting the input encrypted data, the encrypted private key data stored in the encryption storage unit 22 is decrypted using the user code, so that the private key given from the licensor is obtained. Data is generated and used as secret key data for decrypting the input encrypted data. In other words, the secret key data given by the licensor is not always stored in a non-volatile memory such as a flash memory, but is encrypted using secret key data called a user code, and the input encrypted data It is only temporarily generated when decoding is performed. Therefore, in the cryptographic processing device 10a, it is possible to improve the confidentiality of the secret key data given from the licensor.

  FIG. 3 is a diagram showing another configuration example of the cryptographic processing apparatus according to the embodiment of the present invention. The cryptographic processing device 10b includes rearrangement circuits 31 and 32 in addition to the components of the cryptographic processing device 10a shown in FIG. FIG. 4 is a diagram showing an example of the flow of processing for encrypting secret key data.

  The rearrangement circuit 31 rearranges and outputs each bit of the input data according to a predetermined rule. Then, the rearrangement circuit 32 rearranges each bit of the input data in accordance with a rule according to a predetermined rule in the rearrangement circuit 31 and outputs it. For example, the rearrangement circuit 31 may be a circuit that cyclically shifts input data n bits to the right and outputs the data, and the rearrangement circuit 32 may be a circuit that cyclically shifts input data n bits to the left and outputs the data. it can. The rearrangement circuit 31 can be realized by changing the order of connection between the encryption key storage unit 22 and the selector 24, for example. Similarly, the rearrangement circuit 32 can be realized by changing the order of connection between the output of the encryption processing unit 20 and the selector 25. Note that the same function as that of the rearrangement circuits 31 and 32 can be realized by using software. In addition to data rearrangement, an encryption unit / decryption unit that performs encryption / decryption according to a predetermined rule may be used instead of the rearrangement circuits 31 and 32.

  As shown in FIG. 4, the secret key data given from the licensor is rearranged by the rearrangement circuit 31, encrypted by the encryption processing unit 20, rearranged again by the rearrangement circuit 32, and encrypted. It is stored in the key storage unit 22. Then, during the decryption process in the cryptographic processing apparatus 10b, the encrypted secret key data stored in the encryption key storage unit 22 is rearranged by the rearrangement circuit 31 and output, and is decrypted by the encryption processing unit 20 Are rearranged by the rearrangement circuit 32 and output.

  Thus, in the cryptographic processing apparatus 10b, when the secret key data given from the licensor is decrypted, in addition to the decryption in the cryptographic processing unit 20, the rearrangement (encryption) in the rearrangement circuit 31 and Rearrangement (decoding) is performed in the rearrangement circuit 32. Therefore, the decryption process of the encrypted data input to the encryption processing device 10b is different from the decryption process of the encrypted private key data stored in the encryption key storage unit 22, and the decryption in the encryption processing unit 20 is performed. This logic can be difficult to analyze by a third party.

  FIG. 5 is a diagram illustrating a configuration example of a reproducing apparatus to which the cryptographic processing apparatus according to the present embodiment is applied. The playback device 40 is a device for playing back data stored in a media 45 such as a DVD (Digital Versatile Disk) that supports CPRM (Content Protection for Recordable Media). The user code storage unit 21 and the encryption key storage described above. In addition to the unit 22, the selectors 23 to 25, the register 26, and the selector control unit 30, the MKB processing unit 50, the C2_G processing units 51 and 52, the C2_D processing unit 53, and the C2_DCBC processing unit 54 are included. Further, the media 45 records an MKB 60, a media ID 61, an encrypted title key 62, a CCI 63, and an encrypted content 64.

  The MKB processing unit 50 performs encryption / decryption by C2 using the device key given from the licensor for each playback device 40 as secret key data, and decrypts the MKB (Media Key Block) 60 using the device key. To generate a media key. The MKB processing unit 50 corresponds to the cryptographic processing unit 20 in the cryptographic processing apparatus 10a. In addition, the encryption key storage unit 22 of the playback device 40 stores encrypted secret key data obtained by encrypting the device key using the user code stored in the user code storage unit 21 as the secret key data. .

  In the playback device 40, first, the encrypted private key data stored in the encryption key storage unit 22 is decrypted by the MKB processing unit 50 using the user code stored in the user code storage unit. A device key is generated and temporarily stored in the register 26. Thereafter, the MKB processing unit 50 decrypts the MKB 60 using the device key stored in the register 26 as secret key data, thereby generating a media key. The C2_G processing unit 51 generates a media unique key using the media key and the media ID 61. Further, the C2_D processing unit 53 generates a title key by decrypting the encrypted title key 62 with the media unique key. The C2_G processing unit 52 generates a content key using CCI (Copy Control Information) and a title key. Then, in the C2_DCBC processing unit 54, the encrypted content 64 is decrypted with the content key, whereby the content is generated and processed as video data or audio data.

  As described above, in the playback device 40, the device key given from the licensor is not always stored in the non-volatile memory such as the flash memory, so that the confidentiality of the device key given from the licensor can be improved. It becomes.

  The present embodiment and application examples have been described above. As described above, in the cryptographic processing devices 10a and 10b, it is not necessary to always store the secret key data necessary for decrypting the encrypted data in a nonvolatile memory such as a flash memory. It is possible to improve confidentiality. The secret key data is encrypted with the key data arbitrarily determined by the user as the secret key data, so that the strength of the encryption is high. In addition, the encryption processing unit 20 used for encryption / decryption of the secret key data is originally provided for the encryption processing devices 10a and 10b to decrypt the encrypted data. It is possible to suppress an increase in size.

  Then, in the cryptographic processing devices 10a and 10b, the selectors 23 to 25 are used to switch between the decryption processing of the secret key data and the decryption processing of the encrypted data, thereby using the cryptographic processing unit 20 necessary for decrypting the encrypted data. The confidentiality of the private key data is improved.

  Further, like the cryptographic processing device 10b, the encrypted private key data is encrypted and then input to the cryptographic processing unit 20, and the data output from the cryptographic processing unit 20 is decrypted to generate the private key data. By doing so, the decryption process of the encrypted data and the decryption process of the encrypted private key data are different, and the encryption / decryption logic of the encryption processing unit 20 is difficult to be analyzed by a third party. Can do.

  Then, as shown in the cryptographic processing device 10b, by realizing encryption / decryption by the rearrangement circuits 31 and 32, it is possible to suppress an increase in circuit scale.

  In addition, the said Example is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  For example, the playback device 40, which is an application example of the cryptographic processing device 10a, has been described. However, the same applies to the cryptographic processing device 10b. Further, the reproducing apparatus 40 using C2 has been described as an example of an encryption algorithm using secret key data, but the applicable encryption algorithm is not limited to C2, and any algorithm using secret key data may be used. For example, the present invention can be similarly applied to DES (Data Encryption Standard), AES (Advanced Encryption Standard), and the like.

It is a figure which shows the structural example of the encryption processing apparatus which is embodiment of this invention. It is a figure which shows an example of the flow of a process which encrypts secret key data. It is a figure which shows the other structural example of the encryption processing apparatus which is embodiment of this invention. It is a figure which shows an example of the flow of a process which encrypts secret key data. It is a figure which shows the structural example of the reproducing | regenerating apparatus to which the encryption processing apparatus of this embodiment is applied.

Explanation of symbols

10a, 10b Cryptographic processing device 20 Cryptographic processing unit 21 User code storage unit 22 Encryption key storage unit 23-25 Selector 26 Register 30 Selector control unit 31, 32 Rearrangement circuit 40 Playback device 45 Media 50 MKB processing unit 51-53 C2_G Processing unit 54 C2_D processing unit 60 MKB
61 Media ID
62 Encrypted title key 63 CCI
64 Encrypted content

Claims (4)

Using the key data, encrypting or decrypting the input data and outputting the encrypted data; and
Encrypted secret key data obtained by encrypting predetermined key data as the key data and secret key data as the input data is input to the encryption processing unit as the input data, and the predetermined key data is input to the key The secret key data is generated by inputting the data to the encryption processing unit, and the encrypted data encrypted using the secret key data is input to the encryption processing unit as the input data, and the generation A controller that generates decrypted data obtained by decrypting the encrypted data by inputting the secret key data that has been performed to the encryption processor as the key data;
A cryptographic processing apparatus comprising: The cryptographic processing device according to claim 1,
The controller is
An input selection unit that outputs either the encrypted secret key data or the encrypted data to the encryption processing unit as the input data;
An output selection unit that selects whether to output the data output from the encryption processing unit as the secret key data or the decrypted data;
A key selection unit that outputs either the predetermined key data or the secret key data output from the output selection unit to the encryption processing unit as the key data;
The secret key data output from the encryption processing unit is output to the output selection unit by causing the input selection unit to output the encrypted secret key data and causing the key selection unit to output the predetermined key data. And causing the input selection unit to output the encrypted data and causing the key selection unit to output the secret key data to cause the output selection unit to output the decrypted data output from the encryption processing unit. A selection control unit;
A cryptographic processing device comprising: The cryptographic processing device according to claim 2,
The encrypted secret key data corresponds to the predetermined encryption after the predetermined key data is used as the key data, and data obtained by performing predetermined encryption on the secret key data is encrypted as the input data. Data that has been subjected to predetermined decryption,
An encryption unit that performs the predetermined encryption on the encrypted secret key data and outputs the encrypted data to the input selection unit;
A decryption unit that performs the predetermined decryption on the secret key data generated by the encryption processing unit and outputs the decrypted data to the output selection unit;
The cryptographic processing apparatus further comprising: The cryptographic processing device according to claim 3,
The encryption unit is a circuit that outputs and sorts input data according to a predetermined rule,
The decryption unit is a circuit that outputs and sorts input data according to a rule according to the predetermined rule;
A cryptographic processing device characterized by the above.

Images