A rollback attack is always possible: the bad guy backs up his&#x2F;her device, does a transaction, and restores the device.  (A replay protected memory block + secure enclave can make this hard, but never impossible, to do.)  This means that you can&#x27;t make an ironclad assertion that the very last transaction the bank sees was fraudulent, because you can&#x27;t be trusted to make such an assertion.<p>But you&#x27;re still protected against transactions alleged to have occurred before your last real transaction or, equivalently, you&#x27;re guaranteed to (in theory) notice the fraud the next time you try to do a genuine transaction.