| 摘要 |
<p>An information recording or reproducing device in which key distribution is effected by KRB distribution as a key distributing configuration of a tree structure. In this information recording or reproducing device, a key, such as a master key, a media key or a content key, is transmitted along with the KRB (key renewal block) by the key distributing configuration of the tree structure. After a given recording and/or reproducing device has acquired a key of a given recording medium on calculations, based on the KRB as received, the so acquired key is encrypted with a cipher key unique to the recording or reproducing device, such as a leaf key, so as to be then stored in a recording medium or in a memory of the recording or reproducing device. Thus, when the recording and/or reproducing device next uses the recording medium or the content, the recording or reproducing device is able to calculate the key on decrypting the cipher key only once. So, the volume of processing such as KRB decrypting processing needed when the recording and/or reproducing device accesses a recording medium or uses the content may be diminished to improve the efficiency in the processing on the KRB receipt side. <IMAGE></p> |
