Method for encrypting and decrypting metadata and method for managing metadata and system thereof

PURPOSE: A method for encrypting/decrypting metadata, and the method and a system for managing the encrypted metadata are provided to minimize management information for protecting the metadata, and effectively protect/manage the metadata by encrypting/decrypting the metadata of a node as using a one-direction function, the key information of an upper node, and the position information of the node. CONSTITUTION: An application(820) receives a use request for the node of the encrypted metadata. A metadata license storage(842) stores a user license matched with the metadata. A metadata RMP(Right Management Protecting) system(840) outputs the decrypted metadata if the license of the metadata is existed by confirming the license for the metadata use request as referring the metadata license stored in the metadata license storage. The metadata on the node of the tree structure metadata is encrypted by a password key generated by using the function. The function uses the password key of the upper node and the information specifying the node as an input value.