Merge bitcoin/bitcoin#23578: Add external signer taproot support

796b020 wallet: add taproot support to external signer (Sjors Provoost)

Pull request description:

  Builds on #22558 (merged on 2022-06-28).

  [HWI 2.1.0](https://github.com/bitcoin-core/HWI/releases/tag/2.1.0) or newer is required to import and use taproot descriptors. Older versions will work, but won't import a taproot descriptor.

  Tested with HWI 2.1.1:
  * Trezor T (firmware v2.5.1) on Signet: signs, change detection works
  * Ledger Nano S (firmware 2.1.0, Bitcoin app 2.0.6): signs, change detection works

  Only the most basic `tr(key)` descriptor is supported, script path spending is completely untested (if it works at all).

ACKs for top commit:
  jb55:
    utACK 796b020
  achow101:
    ACK 796b020

Tree-SHA512: 6dcb7eeb45421a3bbf2bdabeacd29979867db69077d7bf192bb77faa4bfefe446487b8df07bc40f9457009a88e598bdc09f769e6106fed2833ace7ef205a157a

Author: fanquake

src/external_signer.cpp

@@ -81,6 +81,9 @@ bool ExternalSigner::SignTransaction(PartiallySignedTransaction& psbtx, std::str
         for (const auto& entry : input.hd_keypaths) {
             if (parsed_m_fingerprint == MakeUCharSpan(entry.second.fingerprint)) return true;
         }
+        for (const auto& entry : input.m_tap_bip32_paths) {
+            if (parsed_m_fingerprint == MakeUCharSpan(entry.second.second.fingerprint)) return true;
+        }
         return false;
     };
 

test/functional/mocks/signer.py

@@ -27,12 +27,15 @@ def getdescriptors(args):
         "receive": [
             "pkh([00000001/44'/1'/" + args.account + "']" + xpub + "/0/*)#vt6w3l3j",
             "sh(wpkh([00000001/49'/1'/" + args.account + "']" + xpub + "/0/*))#r0grqw5x",
-            "wpkh([00000001/84'/1'/" + args.account + "']" + xpub + "/0/*)#x30uthjs"
+            "wpkh([00000001/84'/1'/" + args.account + "']" + xpub + "/0/*)#x30uthjs",
+            "tr([00000001/86'/1'/" + args.account + "']" + xpub + "/0/*)#sng9rd4t"
         ],
         "internal": [
             "pkh([00000001/44'/1'/" + args.account + "']" + xpub + "/1/*)#all0v2p2",
             "sh(wpkh([00000001/49'/1'/" + args.account + "']" + xpub + "/1/*))#kwx4c3pe",
-            "wpkh([00000001/84'/1'/" + args.account + "']" + xpub + "/1/*)#h92akzzg"
+            "wpkh([00000001/84'/1'/" + args.account + "']" + xpub + "/1/*)#h92akzzg",
+            "tr([00000001/86'/1'/" + args.account + "']" + xpub + "/1/*)#p8dy7c9n"
+
         ]
     }))
 
@@ -44,7 +47,8 @@ def displayaddress(args):
         return sys.stdout.write(json.dumps({"error": "Unexpected fingerprint", "fingerprint": args.fingerprint}))
 
     expected_desc = [
-        "wpkh([00000001/84'/1'/0'/0/0]02c97dc3f4420402e01a113984311bf4a1b8de376cac0bdcfaf1b3ac81f13433c7)#0yneg42r"
+        "wpkh([00000001/84'/1'/0'/0/0]02c97dc3f4420402e01a113984311bf4a1b8de376cac0bdcfaf1b3ac81f13433c7)#0yneg42r",
+        "tr([00000001/86'/1'/0'/0/0]c97dc3f4420402e01a113984311bf4a1b8de376cac0bdcfaf1b3ac81f13433c7)#4vdj9jqk",
     ]
     if args.desc not in expected_desc:
         return sys.stdout.write(json.dumps({"error": "Unexpected descriptor", "desc": args.desc}))

test/functional/wallet_signer.py

@@ -98,7 +98,7 @@ def test_valid_signer(self):
         # )
         # self.clear_mock_result(self.nodes[1])
 
-        assert_equal(hww.getwalletinfo()["keypoolsize"], 30)
+        assert_equal(hww.getwalletinfo()["keypoolsize"], 40)
 
         address1 = hww.getnewaddress(address_type="bech32")
         assert_equal(address1, "bcrt1qm90ugl4d48jv8n6e5t9ln6t9zlpm5th68x4f8g")
@@ -121,6 +121,13 @@ def test_valid_signer(self):
         assert_equal(address_info['ismine'], True)
         assert_equal(address_info['hdkeypath'], "m/44'/1'/0'/0/0")
 
+        address4 = hww.getnewaddress(address_type="bech32m")
+        assert_equal(address4, "bcrt1phw4cgpt6cd30kz9k4wkpwm872cdvhss29jga2xpmftelhqll62ms4e9sqj")
+        address_info = hww.getaddressinfo(address4)
+        assert_equal(address_info['solvable'], True)
+        assert_equal(address_info['ismine'], True)
+        assert_equal(address_info['hdkeypath'], "m/86'/1'/0'/0/0")
+
         self.log.info('Test walletdisplayaddress')
         result = hww.walletdisplayaddress(address1)
         assert_equal(result, {"address": address1})
@@ -133,7 +140,7 @@ def test_valid_signer(self):
         self.clear_mock_result(self.nodes[1])
 
         self.log.info('Prepare mock PSBT')
-        self.nodes[0].sendtoaddress(address1, 1)
+        self.nodes[0].sendtoaddress(address4, 1)
         self.generate(self.nodes[0], 1)
 
         # Load private key into wallet to generate a signed PSBT for the mock
@@ -142,14 +149,14 @@ def test_valid_signer(self):
         assert mock_wallet.getwalletinfo()['private_keys_enabled']
 
         result = mock_wallet.importdescriptors([{
-            "desc": "wpkh([00000001/84'/1'/0']tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/0/*)#rweraev0",
+            "desc": "tr([00000001/86'/1'/0']tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/0/*)#0jtt2jc9",
             "timestamp": 0,
             "range": [0,1],
             "internal": False,
             "active": True
         },
         {
-            "desc": "wpkh([00000001/84'/1'/0']tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/*)#j6uzqvuh",
+            "desc": "tr([00000001/86'/1'/0']tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/*)#7xw2h8ga",
             "timestamp": 0,
             "range": [0, 0],
             "internal": True,