To solve a problem of a conventional reproduction device in which all contents are decoded and illegally distributed when a key used to encrypt a contents key is leaked because the key to encrypt the contents key used to encrypt contents is constant.

The information terminal (2) of this invention is provided with a particular key basic data generating means (12) that obtains particular key basic data depending on information other than particular information of the information terminal (2), a particular key generating means (16) that generates a particular key from the particular key basic data and the particular information and a contents key encryption means (7) that uses the particular key to encrypt the contents key.