To provide a data processor which can effectively protect the profit of a provider of content data.

A SAM 1051 inputs a secure container 104 containing content data ciphered by using content key data, the mentioned ciphered content key data, and title deed data showing the handling of the content data and determines at least one of the purchase style and use style of the content data according to the handling that the title deed data indicate. Further, the SAM 1051 functions as a slave of a host CPU 810 and also has a common memory shared with the host CPU 810.