| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a communication technology with which, even in a case where reachers share a plurality of pieces as a part of contents distributed in a content distribution system, when a key is disclosed, the effect can be reduced. <P>SOLUTION: A preferential piece index selecting section 522 selects, as a preferential piece index, a piece index (j) in an encryption piece column having most non-transmitted encryption pieces among encryption pieces stored in a seeder 52. When a piece request is received, a piece index determining section 523 determines a piece index (j) of an encryption piece with the piece index (j) selected as the preferential piece index as a transmission candidate. A variation index determining section 524 determines an encryption piece to be transmitted, from among encryption pieces which belong to an encryption piece column corresponding to the determined piece index (j) and that the variation index determining selection itself is holding. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
