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by dfox 675 days ago
Non trivial amount of RFID access cards work the wrong way around, ie. the reader authenticates to the card.
1 comments

These systems usually do mutual authentication, and that's as much a side effect of the cryptographic primitives used as it is an intentional feature:

They're often using symmetric cryptography (even ECC is orders of magnitude more complex than a simple block cipher), and you get mutual authentication "for free" that way, in exchange for having to guard the keys on both the card and the reader to prevent a total compromise.