Certificate-based pairing of key fob device and control unit
An electronic device, in disclosed embodiments, includes an antenna, transceiver circuitry coupled to the antenna, a memory configured to store a first operation key and instructions, and a processor coupled to the transceiver and to the memory. The processor is configured to execute the instructions stored in the memory to cause the electronic device to, in response to receiving a first transmission containing an encrypted version of a second operation key that is encrypted by the first operation key, decrypt the encrypted version of the second operation key using the first operation key to recover the second operation key, store the second operation key in the memory, transmitting, by a transmitter of the electronic device, a second transmission that contains the first operation key and a command.
1. A method comprising:
storing a first key in a memory of a key fob;
executing an authenticated challenge-response protocol with the first key;
receiving, by a receiver of the key fob after storing the first key, a first transmission from a control unit, wherein the first transmission includes an encrypted version of a second key that is encrypted by the first key;
decrypting the encrypted version of the second key using the first key to recover the second key, wherein the second key is a replacement key for the first key;
restoring the second key in the memory of the key fob; and
executing the authenticated challenge-response protocol with the second key.
2. The method of claim 1 further comprising, after decrypting the encrypted version of the second key using the first key, deleting the first key from the memory of the key fob.
3. The method of claim 2 , further comprising, after decrypting the encrypted version of the second key using the first key, deleting the first key from a second key fob.
4. The method of claim 1 , wherein the first key is a first random number and the second key is a second random number that differs from the first random number.
5. The method of claim 4 , wherein the first and second random numbers are 128-bit random numbers.
6. The method of claim 1 , wherein the second key is not stored in the memory of the key fob prior to receiving the first transmission.
7. The method of claim 1 , wherein executing the authenticated challenge-response protocol with the first key is between the key fob and a pairing device, and wherein executing the authenticated challenge-response protocol with the second key is between the key fob and the control unit.
8. The method of claim 1 , further comprising providing, from the control unit to a second key fob, a signal including a request to change the first key.
9. The method of claim 1 , wherein the key fob is associated with a garage door system, hotel entrance system, or home entrance system.
10. A key fob comprising:
an antenna;
transceiver circuitry coupled to the antenna;
a memory configured to store a first key and instructions; and
a processor coupled to the transceiver circuitry and to the memory, the processor being configured to execute the instructions stored in the memory to cause the key fob to:
execute an authenticated challenge-response protocol with the first key;
receive, via the transceiver circuitry and the antenna, a first transmission from a control unit, wherein the first transmission includes an encrypted version of a second key that is encrypted by the first key;
decrypt the encrypted version of the second key using the first key to recover the second key, wherein the second key is a replacement key for the first key;
store the second key in the memory; and
execute the authenticated challenge-response protocol with the second key.
11. The key fob of claim 10 , wherein the second key is not stored in the memory prior to receipt of the first transmission.
12. The key fob of claim 10 , wherein the execution of the instructions by the processor further cause the key fob to delete the first key from the memory after recovering the second key.
13. The key fob of claim 10 , wherein the first key is a first random number and the second key is a second random number that differs from the first random number.
14. The key fob of claim 13 , wherein the first and second random numbers are 128-bit random numbers.
15. The key fob of claim 10 , wherein the instructions further cause the key fob to execute the authenticated challenge-response protocol with the first key between the key fob and a pairing device, and to execute the authenticated challenge-response protocol with the second key between the key fob and the control unit.
16. The key fob of claim 10 , wherein the transceiver circuitry is configured to transmit the first key to establish a valid operation with the control unit.
17. The key fob of claim 10 , wherein the control unit is onboard a vehicle.