Non-default sighash type

[ik105]

I created an unsigned transaction in Sparrow wallet with SIGHASH_NONE, then imported the psbt into Electrum and was surprised that Electrum didn't show any warning about the unusual sighash type. It becomes possible to steal coins with malware even from cold or multisig storage.

Please add a warning when signing a transaction with a non-default sighash type.

[SomberNight]

Good point. Do you know how it works/looks in other programs when trying to sign a tx with a non-sighash_all input?

[ik105]

Sparrow wallet doesn't warn, but there is an option to select the type of sighash (I don't think it's enough, you can ignore it). Trezor seems to just not accept such transactions. Ledger shows "Non-default sighash - > Reject if you're not sure -> Continue/Reject". Coldcard shows this:

[ecdsa]

I guess there is no use case for sighash_none at the moment, so we can forbid it.
There are use cases for sighash_all|anyonecanpay

[SomberNight]

note: related commits in #8699 and #8743