firmware/psbt: add BTCSignNeedsNonWitnessUTXOs() helper
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api/firmware/psbt_test.go
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| // All inputs are Taproot, but the change output is not Taproot. Some BitBox firmwares erroneouslyc |
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| // All inputs are Taproot, but the change output is not Taproot. Some BitBox firmwares erroneouslyc | |
| // All inputs are Taproot, but the change output is not Taproot. Some BitBox firmwares erroneously |
BitBox needs access to the input's previous transactions (NonWitnessUTXO in PSBT-jargon) if not all inputs are Taproot. Since it can be costly to retrieve them, client's can check if they are needed using this function before providing them. When signing using `BTCSign()` directly, one could do this with `BTCSignNeedsPrevTxs()`, but that is not compatible with PSBT signing workflow. A small complication: BitBox has a bug (to be fixed in a future FW version) where the previous transactions are required, even if all inputs are Taproot - when an output is marked as belonging to the same account (change or otherwise) but the output is a non-Taproot output. The function as it is now aligns with this bug, and will be extended/corrected once the FW with the bugfix is available. When that happens, the `TestSimulatorBTCPSBTTaprootSpendsToNonTaproot` can be adjusted.
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BitBox needs access to the input's previous
transactions (NonWitnessUTXO in PSBT-jargon) if not all inputs are Taproot. Since it can be costly to retrieve them, client's can check if they are needed using this function before providing them.
When signing using
BTCSign()directly, one could do this withBTCSignNeedsPrevTxs(), but that is not compatible with PSBT signing workflow.A small complication: BitBox has a bug (to be fixed in a future FW version) where the previous transactions are required, even if all inputs are Taproot - when an output is marked as belonging to the same account (change or otherwise) but the output is a non-Taproot output. The function as it is now aligns with this bug, and will be extended/corrected once the FW with the bugfix is available. When that happens, the
TestSimulatorBTCPSBTTaprootSpendsToNonTaprootcan be adjusted.