Patent ID: 7676042

Claim:
A terminal apparatus that transmits a content key request message to a server apparatus, receives a response message to the content key request message from the server apparatus, and uses content, wherein the content key request message includes a transaction flag that is associated with a content key request process currently in execution and takes a value of 0 or 1, the response message includes a content key and a transaction flag storage requirement flag, the transaction flag storage requirement flag indicating whether or not the transaction flag needs to be stored, said terminal apparatus comprises: a message transmission and reception unit configured to perform message transmission and reception with the server apparatus; a transaction flag storage unit configured to store the transaction flag therein; and a transaction flag writing unit configured to write the transaction flag into said transaction flag storage unit, and said transaction flag writing unit is configured to write the transaction flag into said transaction flag storage unit, when (1) said message transmission and reception unit receives the response message, and (2) the transaction flag storage requirement flag included in the response message indicates that the transaction flag needs to be stored.