Is there Bitcoin Taproot Schnorr Signature support in Wallet Core

[punithbm]

How to Generate Pre Sign Transaction hashes for the Bitcoin Taproot Address

[0xharsha]

@satoshiotomakan, can you confirm whether it is possible to generate pre-sign hashes to obtain a Schnorr signature from an external wallet?

[satoshiotomakan]

Hi @0xharsha, yes it's possible, please take a look at the example.
Note that it's a BRC20 reveal transaction test, but P2TR works similar.

wallet-core/rust/tw_tests/tests/chains/bitcoin/bitcoin_compile/brc20.rs

Lines 96 to 171 in 4af0ee3

	// There is only need to test if `TransactionCompiler` works with schnorr signatures.
	// Please find other transactions at `bitcoin_sign/brc20.rs`.
	#[test]
	fn test_bitcoin_compile_brc20_transfer_reveal() {
	// Successfully broadcasted: https://www.blockchain.com/explorer/transactions/btc/7046dc2689a27e143ea2ad1039710885147e9485ab6453fa7e87464aa7dd3eca
	let my_private_key = "e253373989199da27c48680e3a3fc0f648d50f9a727ef17a7fe6a4dc3b159129";
	let my_private_key = schnorr::PrivateKey::try_from(my_private_key)
	.unwrap()
	// Disable aux rand for the test.
	.no_aux_rand();
	let my_pubkey = my_private_key.public().compressed();
	assert_eq!(
	my_pubkey.to_hex(),
	"030f209b6ada5edb42c77fd2bc64ad650ae38314c8f451f3e36d80bc8e26f132cb"
	);
	let brc20_inscribed_amount = 7_000;
	let tx_fee = brc20_inscribed_amount - DUST;
	// Spend `797d17d47ae66e598341f9dfdea020b04d4017dcf9cc33f0e51f7a6082171fb1` BRC20 commit output.
	let utxo_hash_0 = "797d17d47ae66e598341f9dfdea020b04d4017dcf9cc33f0e51f7a6082171fb1";
	let utxo_0 = Proto::Input {
	out_point: input::out_point(utxo_hash_0, 0),
	value: brc20_inscribed_amount,
	sighash_type: SIGHASH_ALL,
	claiming_script: input::brc20_inscribe(my_pubkey.to_vec(), "oadf", "20"),
	..Default::default()
	};
	let out_0 = Proto::Output {
	value: DUST,
	// Reveal to my address.
	to_recipient: output::p2wpkh(my_pubkey.to_vec()),
	};
	let builder = Proto::TransactionBuilder {
	version: Proto::TransactionVersion::V2,
	inputs: vec![utxo_0],
	outputs: vec![out_0],
	input_selector: Proto::InputSelector::UseAll,
	dust_policy: dust_threshold(DUST),
	..Default::default()
	};
	let signing = Proto::SigningInput {
	public_keys: vec![my_pubkey.to_vec().into()],
	chain_info: btc_info(),
	transaction: TransactionOneof::builder(builder),
	..Default::default()
	};
	let sighash_0 = H256::from("3fd1a453f68dadba110a5b18798a06458e5f3d84dbb6f4f33334fa440a4a2530");
	preimage::BitcoinPreImageHelper::new(&signing)
	.coin(CoinType::Bitcoin)
	.add_expected_taproot(my_pubkey.to_vec(), sighash_0.to_vec(), None)
	.pre_image();
	// Sign the given sighash with the non-tweaked private key.
	let signature_0 = my_private_key.sign(sighash_0).unwrap();
	assert_eq!(signature_0.to_vec().to_hex(), "6a35548b8fa4620028e021a944c1d3dc6e947243a7bfc901bf63fefae0d2460efa149a6440cab51966aa4f09faef2d1e5efcba23ab4ca6e669da598022dbcfe3");
	// Compile the transaction.
	compile::BitcoinCompileHelper::new(&signing)
	.coin(CoinType::Bitcoin)
	.add_pubkey_sig(my_pubkey.to_vec(), signature_0.to_vec())
	.compile(compile::Expected {
	encoded: "02000000000101b11f1782607a1fe5f033ccf9dc17404db020a0dedff94183596ee67ad4177d790000000000ffffffff012202000000000000160014e311b8d6ddff856ce8e9a4e03bc6d4fe5050a83d03406a35548b8fa4620028e021a944c1d3dc6e947243a7bfc901bf63fefae0d2460efa149a6440cab51966aa4f09faef2d1e5efcba23ab4ca6e669da598022dbcfe35b0063036f7264010118746578742f706c61696e3b636861727365743d7574662d3800377b2270223a226272632d3230222c226f70223a227472616e73666572222c227469636b223a226f616466222c22616d74223a223230227d6821c00f209b6ada5edb42c77fd2bc64ad650ae38314c8f451f3e36d80bc8e26f132cb00000000",
	txid: BRC20_REVEAL_TX_ID,
	inputs: vec![brc20_inscribed_amount],
	outputs: vec![DUST],
	vsize: 131,
	weight: 522,
	fee: tx_fee,
	});
	}

[0xharsha]

Thank you @satoshiotomakan.