Storage medium conversion method, non-transitory computer readable storage medium and device

A non-transitory computer readable storage medium storing program instructions which when executed by a computer of a user terminal converts stored contents of a first memory comprising a first user data area and a first protected area where authentication between a host and the first memory is required for access to the first protected area, in a manner of providing compatibility between,

• a first encryption system which uses the first memory for prestoring media identifier data, media unique key data generated based on the media identifier data, encrypted user key data stored in the first protected area and obtained by encrypting user key data in a decryptable manner based on the media unique key data, and first encrypted content key data obtained by encrypting content key data stored in the first user data area and in a decryptable manner based on the user key data, and the user terminal for storing first encrypted content obtained by encrypting content data in a decryptable manner based on the content key data, and
• a second encryption system which uses a second memory for storing, different from the first encryption system, encrypted title key data stored in a second protected area and obtained by encrypting title key data equivalent to the content key data in a decryptable manner based on the media unique key data, and second encrypted content obtained by encrypting the content data in a decryptable manner based on the title key data,
• the program instructions comprising:
• first program code for causing the computer to execute processing of generating the media unique key data based on the media identifier data read from the first memory;
• second program code for causing the computer to execute processing of decrypting the encrypted user key data read from the first memory based on the media unique key data to obtain user key data;
• third program code for causing the computer to execute processing of decrypting the first encrypted content key data read from the first memory based on the user key data to obtain content key data;
• fourth program code for causing the computer to execute processing of encrypting the content key data in a decryptable manner based on the media unique key data, thereby obtaining second encrypted content key data equivalent to the encrypted title key data;
• fifth program code for causing the computer to execute processing of writing the second encrypted content key data in the first memory;
• and
• sixth program code for causing the computer to execute processing of writing the first encrypted content in the first memory.

An electronic device capable of decrypting content encrypted based on content key data, comprising:

• a holding device configured to detachably hold a storage medium having a first area for storing media identifier data, a second area for storing media unique key data generated in connection with the media identifier data, a third area for storing encrypted user key data obtained by encrypting user key data in a decryptable manner based on the media unique key data, where an authentication between a host and the storage medium is required for access to the third area, and a fourth area for storing content key data encrypted based on the user key data;
• a first writing device configured to write content encrypted based on the content key data in the fourth area of the storage medium;
• a second writing device configured to write the content key data encrypted based on the media unique key data generated in connection with the media identifier data in the third area in response to the writing by the first writing device;
• a first deleting device configured to delete the encrypted content in the fourth area by an operation from the outside;
• and
• a second deleting device configured to delete the content key data encrypted based on the media unique key data from the third area in response to the deletion by the first deleting device.