Method for authentication between apparatuses using challenge and response system

A second apparatus for being authenticated by a first apparatus using a challenge and response system, a relation between a first conversion and a second conversion being identical or reverse, the second apparatus comprising:

• a challenge data receiving unit operable to receive a piece of challenge data sent from the first apparatus;
• a response data generating unit operable to generate a piece of response data by performing the second conversion on the piece of challenge data received by the challenge data receiving unit;
• a response data sending unit operable to send the piece of response data generated by the response data generating unit to the first apparatus;
• and
• a setting unit operable to, after performing the second conversion in the response data generating unit, set a second conversion to be used in a next authentication instead of the second conversion used in the current authentication, a content of the second conversion for the next authentication being different from a content of the second conversion used in the current authentication, and a relation between a first conversion and the second conversion for the next authentication being the same as the relation between the first conversion and the second conversion used in the current authentication.

An authentication system using a challenge and response system between a first apparatus and a second apparatus, a relation between a first conversion and a second conversion being identical or reverse, the authentication system comprising:

• an authenticating unit operable to send a piece of challenge data from the first apparatus to the second apparatus, send a piece of response data from the second apparatus to the first apparatus, the piece of response data having been converted from the piece of challenge data by the second conversion, judge in the first apparatus, based on the first conversion, whether the piece of response data is converted from the piece of challenge data by the second conversion, and authenticate the second apparatus if a result of the judgment is affirmative;
• and
• a setting unit operable to, when the result of the judgment in the authenticating unit is affirmative, set a first conversion and a second conversion to be used in a next authentication, instead of the first conversion and the second conversion used in the current authentication, respectively, a content of the first conversion and the second conversion for the next authentication being different from a content of the first conversion and the second conversion used in the current authentication, and a relation between the first conversion and the second conversion for the next authentication being the same as the relation between the first conversion and the second conversion used in the current authentication.

A keyless entry system using a challenge and response system between an in-vehicle unit and a remote controller, a relation between a first conversion and a second conversion being identical or reverse, the keyless entry system comprising:

• an authenticating unit operable to send a piece of challenge data from the in-vehicle unit to the remote controller, send a piece of response data from the remote controller to the in-vehicle unit, the piece of response data having been converted from the piece of challenge data by the second conversion, judge in the in-vehicle unit, based on the first conversion, whether the piece of response data is converted from the piece of challenge data by the second conversion, and authenticate the remote controller if a result of the judgment is affirmative;
• and
• a setting unit operable to, when the result of the judgment in the authenticating unit is affirmative, set a first conversion and a second conversion to be used in a next authentication, instead of the first conversion and the second conversion used in the current authentication, respectively, a content of the first conversion and the second conversion for the next authentication being different from a content of the first conversion and the second conversion used in the current authentication, and a relation between the first conversion and the second conversion for the next authentication being the same as the relation between the first conversion and the second conversion used in the current authentication.

A vehicle equipped with a keyless entry system using a challenge and response system between an in-vehicle unit and a remote controller, a relation between a first conversion and a second conversion being identical or reverse, the keyless entry system comprising:

• an authenticating unit operable to send a piece of challenge data from the in-vehicle unit to the remote controller, send a piece of response data from the remote controller to the in-vehicle unit, the piece of response data having been converted from the piece of challenge data by the second conversion, judge in the in-vehicle unit, based on the first conversion, whether the piece of response data is converted from the piece of challenge data by the second conversion, and authenticate the remote controller if a result of the judgment is affirmative;
• and
• a setting unit operable to, when the result of the judgment in the authenticating unit is affirmative, set a first conversion and a second conversion to be used in a next authentication, instead of the first conversion and the second conversion used in the current authentication respectively, a content of the first conversion and the second conversion for the next authentication being different from a content of the first conversion and the second conversion used in the current authentication, and a relation between the first conversion and the second conversion for the next authentication being the same as the relation between the first conversion and the second conversion used in the current authentication.