A content key, an authentication key, and a program data etc. are transmitted with an enabling key block (EKB) in an encrypted key constitution of a tree structure. The EKB has a constitution in which a device as a leaf of the tree holds a leaf key and a limited node key, and a specific enabling key block (EKB) is generated and distributed to a group specified by a specific node to limit devices that can be renewed. As the devices that do not belong to the group cannot perform decryption, the security for distributing keys etc. can be secured. Thus, distribution of various kinds of keys or data is executed in an encryption key constitution of a tree structure to realize an information processing system and method enabling to distribute data efficiently and safely.