Security system for a moveable barrier operator

A system comprising:

• a first device comprising a first transmitter, a first receiver, and a first controller operatively connected to the first transmitter and the first receiver, the first controller configured to:
• determine a first public key and a first private key;
• control the first transmitter to transmit the first public key of the first device to a second device;
• receive through the first receiver a second public key of the second device;
• determine a shared secret session key based at least in part upon the first private key and the second public key;
• control the first transmitter to transmit to the second device a first message encrypted using the shared secret session key, the first message including a first fixed code and a first changing code;
• receive through the first receiver a second message from the second device;
• control the first transmitter to transmit to the second device a third message encrypted using the shared secret session key, the third message including the first fixed code and a changed version of the first changing code;
• receive through the first receiver a fourth message from the second device;
• wherein the second device comprises a second transmitter, a second receiver, and a second controller operatively connected to the second transmitter and the second receiver, the second controller configured to:
• determine the second public key and a second private key;
• receive through the second receiver the first public key from the first device;
• control the second transmitter to transmit the second public key to the first device;
• determine the shared secret session key based at least in part upon the second private key and the first public key;
• receive through the second receiver the first message;
• control the second transmitter to transmit to the first device the second message encrypted using the shared secret session key, the second message including a second fixed code and a second changing code;
• receive through the second receiver the third message;
• validate the third message based at least in part on the first fixed code, the first changing code, and the changed version of the first changing code;
• control the second transmitter to transmit to the first device the fourth message encrypted using the shared secret session key, the fourth message including the second fixed code, a changed version of the second changing code, and a long-term key;
• wherein the first controller is further configured to control the first transmitter to transmit a fifth message encrypted using the long-term key to the second device in response to a user interface receiving a user input;
• and
• wherein second controller is further configured to decrypt the fifth message using the long-term key and cause the second device to perform an action in response to validating the fifth message.

An apparatus for communicating with a second device to cause the second device to perform an action, the apparatus comprising:

• a transmitter;
• a receiver;
• a memory;
• and
• a controller operatively connected to the transmitter, the receiver, and the memory, the controller configured to:
• determine a first public key and a first private key;
• control the transmitter to transmit the first public key to the second device;
• receive through the receiver a second public key of the second device;
• determine a shared secret session key based at least in part upon the first private key and the second public key;
• control the transmitter to transmit to the second device a first message encrypted using the shared secret session key, the first message including a first fixed code and a first changing code;
• receive through the receiver a second message from the second device, the second message encrypted using the shared secret session key and including a second fixed code and a second changing code;
• control the transmitter to transmit to the second device a third message encrypted using the shared secret session key, the third message including the first fixed code and a changed version of the first changing code;
• receive through the receiver a fourth message from the second device, the fourth message encrypted using the shared secret session key and including the second fixed code, a changed version of the second changing code, and a long-term key;
• store the long-term key in the memory for encryption of subsequent communications to the second device;
• and
• transmit a fifth message encrypted using the long-term key to the second device in response to a user interface receiving a user input,
• wherein the fifth message is configured to, upon decryption using the long-term key and validation by the second device, cause the second device to perform an action.