Data terminal device providing backup of uniquely existable content data

A data terminal device generating encrypted content data that is an encrypted version of content data obtained in plaintext, and a license key required to decrypt said encrypted content data, and transferring said encrypted content data and said license key between a data recording apparatus, said data terminal device comprising:

• an operation unit to input a designation,
• an interface to transfer data with said data recording apparatus,
• a storage unit to store said content data in plaintext,
• an encrypted content generation unit generating said license key, and generating said encrypted content data by encrypting said content data using the generated license key,
• a license generation unit generating a license including said license key and control information restricting the number of times of output of said license key from said data recording apparatus to once,
• an encryption/decryption processing unit encrypting the license generated by said license generation unit to generate an encrypted license, or receiving and decrypting another encrypted license stored in said data recording apparatus and including another license key,
• a content data decryptor receiving another encrypted content data stored in said data recording apparatus, and decrypting said received another encrypted content data using another license key decrypted by and extracted from said encryption/decryption processing unit and
• a control unit,
• wherein said control unit responds to a transmission request of said content data to said data recording apparatus input via said operation unit to read out said content data in plaintext from said storage unit into said encrypted content generation unit, transmitting said encrypted content data and said encrypted license to said data recording apparatus via said interface, and deleting the content data in plaintext stored in said storage unit.