Content (120) is divided (401) into a of partial contents (500). Next, each of the partial contents (500) is encrypted (403) using a browsing-control-use secret key (508). Also, an editing-control-use secret key (506) and a partial-content validation key (507) are generated (402), then generating the feature value (505) for each of the partial content (500). Moreover, key-encrypted data (503) is generated (405) by encrypting the browsing-control-use secret key (508) and the editing-control-use secret key (506) corresponding to each of the browsable and editable partial contents, using the public key (511) of a user. Finally, encrypted content (121) is generated (407) from the key-encrypted data (503), encrypted partial contents (504), and the partial-content validation key (507).