Keyless motor vehicle entry and ignition system

A method for remotely operating locks of a motor vehicle with a keyless entry system that includes a control circuit in the motor vehicle and a remote control for carrying by a user, said method comprising the steps of:

• storing identical seed data in both the control circuit and the remote control;
• in response to the user activating the remote control, generating and exchanging challenge data between the control circuit and the remote control;
• the control circuit executing an encryption algorithm which uses the seed data and the challenge data to produce a first answer;
• the remote control executing the encryption algorithm which uses the seed data and the challenge data to produce a second answer;
• the remote control transmitting the second answer to the control circuit;
• the control circuit comparing the first and second answers and producing a first indication when a match occurs;
• and
• in response to the first indication, unlocking a door on the motor vehicle.

A method for remotely operating a motor vehicle with a keyless control system that includes a control circuit in the motor vehicle and a remote control for carrying by a user, said method comprising the steps of:

• the control circuit transmitting an interrogation signal;
• in response to receiving the interrogation signal, the remote control transmitting an initial signal;
• the control circuit responding to the initial signal by transmitting challenge data to the remote control;
• the control circuit executing an encryption algorithm which uses seed data and the challenge data to produce a first answer;
• the remote control executing the encryption algorithm which uses the seed data and the challenge data to produce a second answer;
• the remote control transmitting the second answer to the control circuit;
• the control circuit comparing the first and second answers and producing a first indication when a match occurs;
• and
• in response to the first indication, performing a function on the motor vehicle.

A method for operating a keyless motor vehicle control system including a portable remote control on which a user selects a function for the motor vehicle to perform, and including a control circuit in the motor vehicle, said method comprising the steps of:

• storing seed data in the control circuit;
• storing the seed data in the portable remote control;
• programming a remote control identification into the portable remote control;
• storing the remote control identification into the control circuit;
• thereafter
• in response to a user selecting a function on the portable remote control, transmitting an initial signal to the control circuit;
• the control circuit responding to receiving the initial signal by generating challenge data and transmitting the challenge data to the portable remote control;
• the control circuit executing an encryption algorithm which uses the seed data and the challenge data to produce a first answer;
• the portable remote control executing the encryption algorithm which uses the seed data and the challenge data to produce a second answer;
• the portable remote control transmitting the second answer and the remote control identification to the control circuit;
• the control circuit comparing the first and second answers and producing a first indication when a match occurs;
• determining whether the remote control identification received from the portable remote control matches a remote control identification previously stored in the control circuit and if so producing a second indication;
• and
• in response to presence of both the first and second indications, producing a control signal for activating the function selected by the user.