Method and apparatus for performing cross-authentication based on secret information

A method of performing cross-authentication in an external device interworking with a vehicle controller via a wired or wireless connection, the method comprising:

• transmitting, by the external device, an authentication request message to the vehicle controller;
• receiving, at the external device, a random number S from the vehicle controller;
• generating, by a repeat count generator of the external device, a variable i using a first function having the random number S as a parameter, wherein a random number R and the random number S are set as parameters of the first function to generate the variable i when the random number R is included in the authentication request message, and the variable i is calculated using a function for cyclic-shifting the random number R by a specified number of bits of the random number S;
• generating, by a session key generator of the external device, a first session key Ks using a second function having the variable i and a pre-stored secret key K as parameters;
• generating, by a response key generator of the external device, a first response key using a third function having the random number S, the variable i and the first session key Ks as parameters;
• transmitting, by the external device, the first response key to the vehicle controller;
• and
• accessing, by the external device, the vehicle controller when the external device is granted access to the vehicle controller in response to authentication of the external device.

An apparatus for performing cross-authentication with an external device, the apparatus comprising:

• a communication unit performing communication with the external device via a wired or wireless connection;
• a random number generator generating a random number S in response to an authentication request message received from the external device;
• a repeat count generator generating a variable i using a first function having the random number S as a parameter, wherein a random number R and the random number S are set as parameters of the first function to generate the variable i when the random number R is included in the authentication request message, and the variable i is calculated using a function for cyclic-shifting the random number R by a specified number of bits of the random number S;
• a session key generator generating a first session key Ks using a second function having the variable i and a pre-stored secret key K as parameters;
• a response key generator generating a second response key using a third function having the random number S, the variable i and the first session key Ks as parameters, upon receiving a first response key from the external device;
• and
• an authentication unit authenticating the external device based on whether the first response key is equal to the second response key,
• wherein the apparatus grants the external device access to the vehicle controller when the external device is authenticated.

An apparatus for performing cross-authentication with a vehicle controller, the apparatus comprising:

• a communication unit transmitting an authentication request message to the vehicle controller and receiving a random number S from the vehicle controller via a wired or wireless connection;
• a repeat count generator generating a variable i using a first function having the random number S as a parameter, wherein a random number R and the random number S are set as parameters of the first function to generate the variable i when the random number R is included in the authentication request message, and the variable i is calculated using a function for cyclic-shifting the random number R by a specified number of bits of the random number S;
• a session key generator generating a first session key Ks using a second function having the variable i and a pre-stored secret key K as parameters;
• a response key generator generating a first response key using a third function having the variable i, the first session key Ks and the random number S as parameters;
• and
• an authentication unit determining whether the first response key transmitted to the vehicle controller is equal to a third response key received from the vehicle controller and authenticating the vehicle controller based on the determination,
• wherein the apparatus accesses the vehicle controller when the apparatus is granted access to the vehicle controller in response to authentication of the apparatus S.

A non-transitory computer readable medium containing program instructions for performing cross-authentication in a vehicle controller interworking with an external device via a wired or wireless connection, the computer readable medium comprising:

• program instructions that generate a random number S and transmit the random number S to the external device in response to an authentication request message received from the external device;
• program instructions that generate a variable i using a first function having the random number S as a parameter, wherein a random number R and the random number S are set as parameters of the first function to generate the variable i when the random number R is included in the authentication request message, and the variable i is calculated using a function for cyclic-shifting the random number R by a specified number of bits of the random number S;
• program instructions that generate a first session key Ks using a second function having the variable i and a pre-stored secret key K as parameters;
• program instructions that receive a first response key from the external device;
• program instructions that generate a second response key using a third function having the random number S, the variable i and the first session key Ks as parameters;
• program instructions that authenticate the external device based on whether the first response key is equal to the second response key;
• and
• program instructions that grant the external device access to the vehicle controller when the external device is authenticated.

A non-transitory computer readable medium containing program instructions for performing cross-authentication in a vehicle controller interworking with an external device via a wired or wireless connection, the computer readable medium comprising:

• program instructions that transmit an authentication request message to the vehicle controller;
• program instructions that receive a random number S from the vehicle controller;
• program instructions that generate a variable i using a first function having the random number S as a parameter, wherein a random number R and the random number S are set as parameters of the first function to generate the variable i when the random number R is included in the authentication request message, and the variable i is calculated using a function for cyclic-shifting the random number R by a specified number of bits of the random number S;
• program instructions that generate a first session key Ks using a second function having the variable i and a pre-stored secret key K as parameters;
• program instructions that generate a first response key using a third function having the random number S, the variable i and the first session key Ks as parameters;
• program instructions that transmit the first response key to the vehicle controller;
• and
• program instructions that access the vehicle controller when the external device is granted access to the vehicle controller in response to authentication of the external device.