fn verify_interactive_tx_signatures(
	&mut self, witnesses: &Vec<Witness>,
) -> Result<(), APIError> {
	if let Some(ref mut signing_session) = self.interactive_tx_signing_session {
		// We get the (already sorted) inputs' prevout scriptpubkeys corresponding to the provided
		// witnesses.
		let script_pubkeys = signing_session
			.unsigned_tx()
			.inputs()
			.filter(|input| matches!(input, InteractiveTxInput::Local(_)))
			.map(|input| &input.prev_output().script_pubkey);
		for (idx, (script_pubkey, witness)) in script_pubkeys.zip(witnesses).enumerate() {
			// Check ECDSA signatures (P2WPKH, P2WSH)
			if script_pubkey.is_p2wpkh() {
				if witness
					.iter()
					.next()
					.and_then(|sig_bytes| {
						bitcoin::ecdsa::Signature::from_slice(sig_bytes)
							.ok()
							.map(|sig| matches!(sig.sighash_type, EcdsaSighashType::All))
					})
					.unwrap_or(false)
				{
					continue;
				} else {
					return Err(APIError::APIMisuseError {
						err:
							format!("The signature in the P2WPKH witness at index {idx} does not use SIGHASH_ALL")
					});
				}
			}

			if script_pubkey.is_p2wsh() {
				for instruction in
					witness.witness_script().iter().flat_map(|script| script.instructions())
				{
					match instruction {
						Ok(bitcoin::script::Instruction::PushBytes(push_bytes)) => {
							if let Some(sig) =
								bitcoin::ecdsa::Signature::from_slice(push_bytes.as_bytes())
									.ok()
							{
								if !matches!(sig.sighash_type, EcdsaSighashType::All) {
									return Err(APIError::APIMisuseError {
										err:
											format!("A signature in the P2WSH witness at index {idx} does not use SIGHASH_ALL")
									});
								}
							}
						},
						_ => continue,
					}
				}
			}

			if script_pubkey.is_p2tr() {
				// If the witness contains a single element, it corresponds to a P2TR key path spend
				if witness.len() == 1 {
					if let Some(sig) = bitcoin::taproot::Signature::from_slice(&witness[0]).ok()
					{
						if !matches!(
							sig.sighash_type,
							TapSighashType::Default | TapSighashType::All
						) {
							return Err(APIError::APIMisuseError {
								err:
									format!("The signature for the key path spend in the P2TR witness at index {idx} does not use SIGHASH_ALL or SIGHASH_DEFAULT")
							});
						}
					}
				}

				// Else we assume a script path spend
				for instruction in witness
					.taproot_leaf_script()
					.iter()
					.flat_map(|leaf_script| leaf_script.script.instructions())
				{
					match instruction {
						Ok(bitcoin::script::Instruction::PushBytes(push_bytes)) => {
							if let Some(sig) =
								bitcoin::taproot::Signature::from_slice(push_bytes.as_bytes())
									.ok()
							{
								if !matches!(
									sig.sighash_type,
									TapSighashType::All | TapSighashType::Default
								) {
									return Err(APIError::APIMisuseError {
										err:
											format!("A signature for the script path spend in the P2TR witness at index {idx} does not use SIGHASH_ALL or SIGHASH_DEFAULT")
									});
								}
							}
						},
						_ => continue,
					}
				}
			}
		}
	}
	Ok(())
}