Storage device, storage system, and authentication method

A storage system comprising:

• a storage device;
• and
• an authorized host device having connection authority with respect to the storage device,
• wherein the storage device comprises
• a nonvolatile semiconductor memory configured to store user data received from the authorized host device,
• an authentication information storage configured to store first apparatus authentication information to authenticate the authorized host device and first user authentication information to authenticate an authorized user who uses the authorized host device,
• an apparatus authenticator configured to execute apparatus authentication according to whether-second apparatus authentication information received from a currently connected host device matches the first apparatus authentication information stored in the authentication information storage,
• a user authenticator configured to execute user authentication, after the apparatus authentication, according to whether second user authentication information received from the currently connected host device matches the first user authentication information stored in the authentication information storage,
• a data read controller configured to output user data stored in the nonvolatile semiconductor memory to the currently connected host device, in response to a read request therefrom, if both of the apparatus authentication and user authentication are passed and the currently connected host device is authorized as the authorized host device,
• a user data invalidator configured to execute an invalidation process for physically corrupting the user data stored in the nonvolatile semiconductor memory thereby the user data cannot be read out as its original form, if at least one of the apparatus authentication and user authentication is failed, and
• a volatile memory in which data is erased when a power supply is turned off,
• portion key storage configured to store a first portion key constituting a portion of an encryption key written in the volatile memory, and
• 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 authentication information storage, after the apparatus authentication and before the user authentication, and to write the generated third portion key in the volatile memory,
• wherein the apparatus authenticator destructs the first portion key, if the apparatus authentication is failed, and
• the user authenticator uses the third portion key in the user authentication,
• wherein the authorized host device comprises
• an apparatus authentication information storage configured to store the second apparatus authentication information,
• an apparatus authentication information transmitter configured to transmit the second apparatus authentication information stored in the apparatus authentication information storage to the storage device, according to a predetermined authentication sequence of the apparatus authentication executed by the apparatus authenticator, when the storage device is connected,
• a user authentication information receiver configured to receive an input of the second user authentication information, according to an operation from a user,
• a user authentication information transmitter configured to transmit the second user authentication information to the storage device,
• a read request receiver configured to receive an input of a read request, according to an operation from the user, and
• a read request transmitter configured to transmit the received read request to the storage device.

An authentication method in a storage device comprising a nonvolatile semiconductor memory configured to store user data received from an authorized host device and a volatile memory in which data is erased when a power supply is turned off, the authentication method comprising:

• storing first apparatus authentication information to authenticate the authorized host device and first user authentication information to authenticate an authorized user who uses the authorized host device in an authentication information storage;
• executing apparatus authentication according to whether second apparatus authentication information received from a currently connected host device matches the first apparatus authentication information stored in the authentication information storage;
• executing user authentication, after the apparatus authentication, according to whether second user authentication information received from the currently connected host device matches the first user authentication information stored in the authentication information storage;
• outputting user data stored in the nonvolatile semiconductor memory to the currently connected host device, in response to a read request therefrom, if both of the apparatus authentication and user authentication are passed and the currently connected host device is authorized as the authorized host device;
• executing an invalidation process for physically corrupting the user data stored in the nonvolatile semiconductor memory thereby the user data cannot be read out as its original form, if at least one of the apparatus authentication and user authentication is failed;
• storing a first portion key constituting a portion of an encryption key written in the volatile memory;
• generating 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 authentication information storage, after the apparatus authentication and before the user authentication, and writing the generated third portion key in the volatile memory;
• and
• destructing the first portion key, if the apparatus authentication is failed,
• wherein the third portion key is used in the user authentication.