Please check the following text for errors. Please only output the errors themselves. Do not repeat the whole document..

- Requires additional setup - can't be used with existing transponders which have not been set up.
- Requires additional AES key(s).
  - These can either be set up "globally", i.e. at PICC level, or
  - at app level. That is, whoever sets up the app needs to configure the keys.
  - The latter might be more suitable for systems / customers with more than one app per transponder?.
    I have no idea how much effort each approach takes. In any case, our tooling needs to be adjusted.
    For most systems, card writing is done at the customer's site anyway?
    So it's actually not in our influence.
- The keys must be configured both on the transponder and on the locking unit.
  - The locking unit needs the key to encrypt/decrypt the message exchange for "Proximity Check"
- We need to find a suitable threshold time. Maybe make it configurable?
  - If Proximity Check messages have a "round-trip-time" higher than the threshold,
    the transponder will be rejected (by our firmware)
- Caution must be taken, transponders can be configured to require a PC.
  Not sure if we can find that out, or if we even need to do that.
  - If the card is configured in that way, it will reject all Authentication attempts.
- Feature needs to be implemented in the firmware, but that should be the least problem. Avoid using the following keywords: writing, message, case, unit
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