5 ms·

how do you put a real time clock into a key fob that can actually keep time?

• mrex 4y ago
  RSA SecureID has been doing this for decades and decades. They use a not-tremendously-accurate battery backed quartz RTC with some drift compensation built into the server side. There are a ton of other options though. Atomic clock signals are broadcast nationwide in the US. GPS, Glonass, etc. signals broadcast the time. Cellular networks broadcast the time.
• buescher 4y ago
  If you can synchronize the clocks in the car and the key fob, it doesn't matter if you know the delta to UTC or not.
  • mmebane 4y ago
    Isn't any method of synchronizing clocks likely to be vulnerable to the same sort of counter resynchronization issue that this attack exploits?
    • buescher 4y ago
      Good question.
  • amluto 4y ago
    If you can do that, you probably have two-way communication, and this issue should be moot.
• iso1631 4y ago
  ...and doesn't run the battery down in a couple of months