Device for reproducing data

A data reproducing device (100) for decrypting encrypted content data to reproduce content data, comprising:

• a data storing portion (110) for holding said encrypted content data and a license key for decrypting said encrypted content data, outputting said license key in an encrypted form and being removably attached to said data reproducing device;
• a data reproducing portion for receiving the output of said data storing portion, and reproducing said encrypted content data;
• and
• a first control portion (1106) for controlling transmission of data between said data storing portion and said data reproducing portion, wherein
• said data producing portion includes:
• a first decryption processing portion (1516) for receiving said license key and said encrypted content data read from said data storing portion, and decrypts said encrypted content data with said license key to extract the content data,
• an authentication data holding portion (1500) for holding authentication data ({KPp(1)}KPma) prepared by encrypting a public key (KPp(1)) preapplied to said data reproducing portion into a form decodable with a public authentication key (KPma) for outputting the encrypted authentication data to said data storing portion,
• a private key holding portion (1502) for holding a private key used for decrypting data encrypted with said preapplied public key,
• a second decryption processing portion (1504) for receiving a first session key (Ks3) encrypted with said public key and supplied from said data storing portion, performing decryption with said private key to extract said first session key, and holding the extracted first session key,
• a first session key generating portion (1508) for producing a second session key (Ks4) to be updated upon every access to said data storing portion for obtaining said license key,
• a first encryption processing portion (1506) for encrypting said second session key with said first session key held by said second decryption processing portion for output to said data storing portion, and,
• a third decryption processing portion (1510) for receiving said license key (Kc) encrypted with said second session key and supplied from said data storing portion, performing the decryption with said second session key to extract said license key, and supplying the extracted license key to said first decryption processing portion;
• said data storing portion includes;
• a recording portion (1415) for recording said encrypted content data and said license key,
• a fourth decryption processing portion (1408) for receiving said authentication data, and decrypting said authentication data with said public authentication key to extract the public key,
• a second control portion (1420) for performing authentication processing based on results of the decryption processing by said fourth decryption processing portion to determine whether said license key is to be output to said data reproducing portion or not,
• a second session key generating portion (1418) for producing and holding said second session key (Ks4) to be updated every time said second control portion determines that said license key is to be output to said data reproducing portion,
• a second encryption processing portion (1410) for encrypting said second session key with said public key for applying said second session key to said data reproducing portion,
• a fifth decryption processing portion (1412) for decrypting, with said first session key, said second session key applied from said data reproducing portion and encrypted with said first session key to extract said first session key, and
• a third encryption processing portion (1406) for encrypting said license key with said second session key for applying said license key to said data reproducing portion;
• and
• said first control portion performs the control to utilize said first session key common to processing of supplying the plurality of license keys to said content reproducing portion from said data storing portion corresponding to the plurality of continuous reproduction operations of the encrypted content data, to utilize, in each of said plurality of license key supply operations, said second session key different from those for the other license key supply operations, and controls said second decryption processing portion to hold said first session key during a predetermined period common to said plurality of license key supply operations.