Storage device, storage system, and authentication method

A storage device comprising:

• a nonvolatile semiconductor memory configured to store user data;
• an apparatus authenticator configured to execute apparatus authentication on the basis of an apparatus authentication information received from a currently connected host device;
• a portion key storage configured to store a first portion key;
• a portion key writer configured to generate a third portion key on the basis of a second portion key received from the currently connected host device and the first portion key stored in the portion key storage, after the apparatus authentication;
• a user authenticator configured to execute user authentication on the basis of a user authentication information received from the currently connected host device and the third portion key;
• and
• a data read controller configured to output user data stored in the nonvolatile semiconductor memory to the currently connected host device if both of the apparatus authentication and user authentication are passed,
• wherein the apparatus authenticator destructs the first portion key, if the apparatus authentication is failed.