Method of and system for recording and reproducing information data

A method for making a legal backup of a first recording medium using a second recording medium each having its own identification data, said method comprising:

• each recording medium has identification data in a fixed area of the recording medium that cannot be altered unless the recording medium is destroyed;
• mutual confirmation is performed between the first recording medium and the second recording medium to confirm whether these recording mediums are formally registered, an encrypted information data is read out from the first recording medium or the second recording medium if the mutual confirmation shows that the first and second recording mediums are formally registered;
• reading first encrypted information data encrypted in accordance with an identification data of the first recording medium and recorded in said first recording medium;
• encrypting the first encrypted information data in accordance with an identification data of the second recording medium, wherein the identification data of the second recording medium is different from the identification data of the first recording medium so as to produce second encrypted information data;
• recording the second encrypted information data in the second recording medium;
• when the first encrypted information recorded in the first recording medium is damaged, reading the second encrypted information data from the second recording medium and decoding the second encrypted information data in accordance with the identification data of the second recording medium;
• and
• wherein the second encrypted information data is decoded in accordance with the identification information data of the second recording medium so as to be restored into the first encrypted information data without being again encrypted in accordance with the identification data of the first recording medium
• whereby the second encrypted information data recorded in the second recording medium is different from the first encrypted information data recorded in the first recording medium.