Memory card and data distribution system using it

摘要

A memory card ( 110 ) conducts an authentication process with a server based on data stored in an authentication data hold unit ( 1400 ). The memory card ( 110 ) extracts a first session key (Ks 1 ) from a server by a decryption process and a transaction ID from the data applied on a data bus (BS 3 ). The memory card ( 110 ) generates a second session key (Ks 2 ) through a session key generation unit ( 1418 ), and transmits to the server, as the keys to encrypt content data in receiving decryption of content data, the second session key (Ks 2 ) and a key (KPm( 1 )) unique to the memory card ( 110 ) in an encrypted state with the first session key (Ks 1 ). The transaction ID and the second session key (Ks 2 ) stored in the log memory ( 1460 ) are used in the redistribution process.