When you click on the open button on the fob, you send
SHA256(key)
Car responds with a random challenge
RND
Fob sends
SHA256(key XOR RND)
Car does the same calculation and compares.
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I approach my car, I press the button on the fob to open it, and your attack does what exactly?
When you click on the open button on the fob, you send
SHA256(key)
Car responds with a random challenge
RND
Fob sends
SHA256(key XOR RND)
Car does the same calculation and compares.