▲ 6 r/Tangem
BTC UTXO signing limitation?
I have a technical question regarding BTC transaction signing on iOS using NFC.
From what I understand, iOS NFC APDU communication sessions have a limited active time window (around ~20 seconds for continuous APDU exchanges per session, depending on system constraints).
In a BTC transaction scenario where there are 30+ UTXOs to sign, I’m concerned whether the signing process can be completed within a single NFC session.
I also noticed in your documentation that a single signing flow can theoretically handle ~700 inputs within ~1 minute. This seems to exceed the practical iOS NFC session time window.
My questions are:
- If a transaction requires 30+ UTXOs, can all signing APDU commands reliably complete within one iOS NFC session?
- If the NFC session times out before all signatures are completed, what happens to the transaction process?
- Does it fail completely?
- Or can it resume/retry from the last state?
- Are there any internal batching / chunking mechanisms on the card side to mitigate NFC timeout constraints?
Thanks in advance.
u/Right-Ad465 — 4 days ago