Merge bitcoin/bitcoin#29130: wallet: Add `createwalletdescriptor` and `gethdkeys` RPCs for adding new automatically generated descriptors

746b6d88395607abbd3c13bbdcdd4ca83e9bc9e4 test: Add test for createwalletdescriptor (Ava Chow)
2402b6306215a9ee8d5f4068ea81f4e7f324adeb wallet: Test upgrade of pre-taproot wallet to have tr() descriptors (Ava Chow)
460ae1bf67c0051033c1802d44787d173abb9248 wallet, rpc: Add createwalletdescriptor RPC (Ava Chow)
8e1a475062e62321e58a0624385cc3fa0885aa12 wallet: Be able to retrieve single key from descriptors (Ava Chow)
85b1fb19dd3a3f3c68da1c5e60a6eb911e1119a6 wallet: Add GetActiveHDPubKeys to retrieve xpubs from active descriptors (Ava Chow)
73926f2d31b61ff78d5f0c8f9b5e3130fb1f9620 wallet, descspkm: Refactor wallet descriptor generation to standalone func (Andrew Chow)
54e74f46ea10e479be682750c1279165f29bb2f4 wallet: Refactor function for single DescSPKM setup (Andrew Chow)
3b09d0eb7f2c1d6ebdab73d18db28e5bf7d74f18 tests: Test for gethdkeys (Ava Chow)
5febe28c9e131fb93fac9c35f80c42759654f150 wallet, rpc: Add gethdkeys RPC (Ava Chow)
66632e5c24c1b59afef1e89b562fbd0117ab6ef5 wallet: Add IsActiveScriptPubKeyMan (Ava Chow)
fa6a259985b61235ebc21eae2a76014cc9437d5f desc spkm: Add functions to retrieve specific private keys (Ava Chow)
fe67841464cc0f970a1c233caba92cb78e9c78dc descriptor: Be able to get the pubkeys involved in a descriptor (Ava Chow)
ef6745879d87cdb6f1061337867a689167e965a1 key: Add constructor for CExtKey that takes CExtPubKey and CKey (Ava Chow)

Pull request description:

  This PR adds a `createwalletdescriptor` RPC which allows users to add new automatically generated descriptors to their wallet, e.g. to upgrade a 0.21.x wallet to contain a taproot descriptor. This RPC takes 3 arguments: the output type to create a descriptor for, whether the descriptor will be internal or external, and the HD key to use if the user wishes to use a specific key. The HD key is an optional parameter. If it is not specified, the wallet will use the key shared by the active descriptors, if they are all single key. For most users in the expected upgrade scenario, this should be sufficient. In more advanced cases, the user must specify the HD key to use.

  Currently, specified HD keys must already exist in the wallet. To make it easier for the user to know, `gethdkeys` is also added to list out the HD keys in use by all of the descriptors in the wallet. This will include all HD keys, whether we have the private key, for it, which descriptors use it and their activeness, and optionally the extended private key. In this way, users with more complex wallets will be still be able to get HD keys from their wallet for use in other scenarios, and if they want to use `createwalletdescriptor`, they can easily get the keys that they can specify to it.

  See also https://github.com/bitcoin/bitcoin/pull/26728#issuecomment-1866961865

ACKs for top commit:
  Sjors:
    re-utACK 746b6d88395607abbd3c13bbdcdd4ca83e9bc9e4
  furszy:
    ACK 746b6d8
  ryanofsky:
    Code review ACK 746b6d88395607abbd3c13bbdcdd4ca83e9bc9e4, and this looks ready to merge. There were various suggested changes since last review where main change seems to be switching `gethdkeys` output to use normalized descriptors (removing hardened path components).

Tree-SHA512: f2849101e6fbf1f59cb031eaaaee97af5b1ae92aaab54c5716940d210f08ab4fc952df2725b636596cd5747b8f5beb1a7a533425bc10d09da02659473516fbda

4 files changed, 329 insertions, 0 deletions

diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 1408854e02..3f6e47d410 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -181,6 +181,8 @@ BASE_SCRIPTS = [
     'wallet_keypool_topup.py --legacy-wallet',
     'wallet_keypool_topup.py --descriptors',
     'wallet_fast_rescan.py --descriptors',
+    'wallet_gethdkeys.py --descriptors',
+    'wallet_createwalletdescriptor.py --descriptors',
     'interface_zmq.py',
     'rpc_invalid_address_message.py',
     'rpc_validateaddress.py',
diff --git a/test/functional/wallet_backwards_compatibility.py b/test/functional/wallet_backwards_compatibility.py
index 4d6e6024c5..ab008a40cd 100755
--- a/test/functional/wallet_backwards_compatibility.py
+++ b/test/functional/wallet_backwards_compatibility.py
@@ -355,6 +355,25 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
             down_wallet_name = f"re_down_{node.version}"
             down_backup_path = os.path.join(self.options.tmpdir, f"{down_wallet_name}.dat")
             wallet.backupwallet(down_backup_path)
+
+            # Check that taproot descriptors can be added to 0.21 wallets
+            # This must be done after the backup is created so that 0.21 can still load
+            # the backup
+            if self.options.descriptors and self.major_version_equals(node, 21):
+                assert_raises_rpc_error(-12, "No bech32m addresses available", wallet.getnewaddress, address_type="bech32m")
+                xpubs = wallet.gethdkeys(active_only=True)
+                assert_equal(len(xpubs), 1)
+                assert_equal(len(xpubs[0]["descriptors"]), 6)
+                wallet.createwalletdescriptor("bech32m")
+                xpubs = wallet.gethdkeys(active_only=True)
+                assert_equal(len(xpubs), 1)
+                assert_equal(len(xpubs[0]["descriptors"]), 8)
+                tr_descs = [desc["desc"] for desc in xpubs[0]["descriptors"] if desc["desc"].startswith("tr(")]
+                assert_equal(len(tr_descs), 2)
+                for desc in tr_descs:
+                    assert info["hdmasterfingerprint"] in desc
+                wallet.getnewaddress(address_type="bech32m")
+
             wallet.unloadwallet()
 
             # Check that no automatic upgrade broke the downgrading the wallet
diff --git a/test/functional/wallet_createwalletdescriptor.py b/test/functional/wallet_createwalletdescriptor.py
new file mode 100755
index 0000000000..18e1703da3
--- /dev/null
+++ b/test/functional/wallet_createwalletdescriptor.py
@@ -0,0 +1,123 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test wallet createwalletdescriptor RPC."""
+
+from test_framework.descriptors import descsum_create
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
+from test_framework.wallet_util import WalletUnlock
+
+
+class WalletCreateDescriptorTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        self.add_wallet_options(parser, descriptors=True, legacy=False)
+
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def run_test(self):
+        self.test_basic()
+        self.test_imported_other_keys()
+        self.test_encrypted()
+
+    def test_basic(self):
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet("blank", blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("blank")
+
+        xpub_info = def_wallet.gethdkeys(private=True)
+        xpub = xpub_info[0]["xpub"]
+        xprv = xpub_info[0]["xprv"]
+        expected_descs = []
+        for desc in def_wallet.listdescriptors()["descriptors"]:
+            if desc["desc"].startswith("wpkh("):
+                expected_descs.append(desc["desc"])
+
+        assert_raises_rpc_error(-5, "Unable to determine which HD key to use from active descriptors. Please specify with 'hdkey'", wallet.createwalletdescriptor, "bech32")
+        assert_raises_rpc_error(-5, f"Private key for {xpub} is not known", wallet.createwalletdescriptor, type="bech32", hdkey=xpub)
+
+        self.log.info("Test createwalletdescriptor after importing active descriptor to blank wallet")
+        # Import one active descriptor
+        assert_equal(wallet.importdescriptors([{"desc": descsum_create(f"pkh({xprv}/44h/2h/0h/0/0/*)"), "timestamp": "now", "active": True}])[0]["success"], True)
+        assert_equal(len(wallet.listdescriptors()["descriptors"]), 1)
+        assert_equal(len(wallet.gethdkeys()), 1)
+
+        new_descs = wallet.createwalletdescriptor("bech32")["descs"]
+        assert_equal(len(new_descs), 2)
+        assert_equal(len(wallet.gethdkeys()), 1)
+        assert_equal(new_descs, expected_descs)
+
+        self.log.info("Test descriptor creation options")
+        old_descs = set([(d["desc"], d["active"], d["internal"]) for d in wallet.listdescriptors(private=True)["descriptors"]])
+        wallet.createwalletdescriptor(type="bech32m", internal=False)
+        curr_descs = set([(d["desc"], d["active"], d["internal"]) for d in wallet.listdescriptors(private=True)["descriptors"]])
+        new_descs = list(curr_descs - old_descs)
+        assert_equal(len(new_descs), 1)
+        assert_equal(len(wallet.gethdkeys()), 1)
+        assert_equal(new_descs[0][0], descsum_create(f"tr({xprv}/86h/1h/0h/0/*)"))
+        assert_equal(new_descs[0][1], True)
+        assert_equal(new_descs[0][2], False)
+
+        old_descs = curr_descs
+        wallet.createwalletdescriptor(type="bech32m", internal=True)
+        curr_descs = set([(d["desc"], d["active"], d["internal"]) for d in wallet.listdescriptors(private=True)["descriptors"]])
+        new_descs = list(curr_descs - old_descs)
+        assert_equal(len(new_descs), 1)
+        assert_equal(len(wallet.gethdkeys()), 1)
+        assert_equal(new_descs[0][0], descsum_create(f"tr({xprv}/86h/1h/0h/1/*)"))
+        assert_equal(new_descs[0][1], True)
+        assert_equal(new_descs[0][2], True)
+
+    def test_imported_other_keys(self):
+        self.log.info("Test createwalletdescriptor with multiple keys in active descriptors")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet("multiple_keys")
+        wallet = self.nodes[0].get_wallet_rpc("multiple_keys")
+
+        wallet_xpub = wallet.gethdkeys()[0]["xpub"]
+
+        xpub_info = def_wallet.gethdkeys(private=True)
+        xpub = xpub_info[0]["xpub"]
+        xprv = xpub_info[0]["xprv"]
+
+        assert_equal(wallet.importdescriptors([{"desc": descsum_create(f"wpkh({xprv}/0/0/*)"), "timestamp": "now", "active": True}])[0]["success"], True)
+        assert_equal(len(wallet.gethdkeys()), 2)
+
+        assert_raises_rpc_error(-5, "Unable to determine which HD key to use from active descriptors. Please specify with 'hdkey'", wallet.createwalletdescriptor, "bech32")
+        assert_raises_rpc_error(-4, "Descriptor already exists", wallet.createwalletdescriptor, type="bech32m", hdkey=wallet_xpub)
+        assert_raises_rpc_error(-5, "Unable to parse HD key. Please provide a valid xpub", wallet.createwalletdescriptor, type="bech32m", hdkey=xprv)
+
+        # Able to replace tr() descriptor with other hd key
+        wallet.createwalletdescriptor(type="bech32m", hdkey=xpub)
+
+    def test_encrypted(self):
+        self.log.info("Test createwalletdescriptor with encrypted wallets")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet("encrypted", blank=True, passphrase="pass")
+        wallet = self.nodes[0].get_wallet_rpc("encrypted")
+
+        xpub_info = def_wallet.gethdkeys(private=True)
+        xprv = xpub_info[0]["xprv"]
+
+        with WalletUnlock(wallet, "pass"):
+            assert_equal(wallet.importdescriptors([{"desc": descsum_create(f"wpkh({xprv}/0/0/*)"), "timestamp": "now", "active": True}])[0]["success"], True)
+        assert_equal(len(wallet.gethdkeys()), 1)
+
+        assert_raises_rpc_error(-13, "Error: Please enter the wallet passphrase with walletpassphrase first.", wallet.createwalletdescriptor, type="bech32m")
+
+        with WalletUnlock(wallet, "pass"):
+            wallet.createwalletdescriptor(type="bech32m")
+
+
+
+if __name__ == '__main__':
+    WalletCreateDescriptorTest().main()
diff --git a/test/functional/wallet_gethdkeys.py b/test/functional/wallet_gethdkeys.py
new file mode 100755
index 0000000000..f09b8c875a
--- /dev/null
+++ b/test/functional/wallet_gethdkeys.py
@@ -0,0 +1,185 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test wallet gethdkeys RPC."""
+
+from test_framework.descriptors import descsum_create
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
+from test_framework.wallet_util import WalletUnlock
+
+
+class WalletGetHDKeyTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        self.add_wallet_options(parser, descriptors=True, legacy=False)
+
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def run_test(self):
+        self.test_basic_gethdkeys()
+        self.test_ranged_imports()
+        self.test_lone_key_imports()
+        self.test_ranged_multisig()
+        self.test_mixed_multisig()
+
+    def test_basic_gethdkeys(self):
+        self.log.info("Test gethdkeys basics")
+        self.nodes[0].createwallet("basic")
+        wallet = self.nodes[0].get_wallet_rpc("basic")
+        xpub_info = wallet.gethdkeys()
+        assert_equal(len(xpub_info), 1)
+        assert_equal(xpub_info[0]["has_private"], True)
+
+        assert "xprv" not in xpub_info[0]
+        xpub = xpub_info[0]["xpub"]
+
+        xpub_info = wallet.gethdkeys(private=True)
+        xprv = xpub_info[0]["xprv"]
+        assert_equal(xpub_info[0]["xpub"], xpub)
+        assert_equal(xpub_info[0]["has_private"], True)
+
+        descs = wallet.listdescriptors(True)
+        for desc in descs["descriptors"]:
+            assert xprv in desc["desc"]
+
+        self.log.info("HD pubkey can be retrieved from encrypted wallets")
+        prev_xprv = xprv
+        wallet.encryptwallet("pass")
+        # HD key is rotated on encryption, there should now be 2 HD keys
+        assert_equal(len(wallet.gethdkeys()), 2)
+        # New key is active, should be able to get only that one and its descriptors
+        xpub_info = wallet.gethdkeys(active_only=True)
+        assert_equal(len(xpub_info), 1)
+        assert xpub_info[0]["xpub"] != xpub
+        assert "xprv" not in xpub_info[0]
+        assert_equal(xpub_info[0]["has_private"], True)
+
+        self.log.info("HD privkey can be retrieved from encrypted wallets")
+        assert_raises_rpc_error(-13, "Error: Please enter the wallet passphrase with walletpassphrase first", wallet.gethdkeys, private=True)
+        with WalletUnlock(wallet, "pass"):
+            xpub_info = wallet.gethdkeys(active_only=True, private=True)[0]
+            assert xpub_info["xprv"] != xprv
+            for desc in wallet.listdescriptors(True)["descriptors"]:
+                if desc["active"]:
+                    # After encrypting, HD key was rotated and should appear in all active descriptors
+                    assert xpub_info["xprv"] in desc["desc"]
+                else:
+                    # Inactive descriptors should have the previous HD key
+                    assert prev_xprv in desc["desc"]
+
+    def test_ranged_imports(self):
+        self.log.info("Keys of imported ranged descriptors appear in gethdkeys")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet("imports")
+        wallet = self.nodes[0].get_wallet_rpc("imports")
+
+        xpub_info = wallet.gethdkeys()
+        assert_equal(len(xpub_info), 1)
+        active_xpub = xpub_info[0]["xpub"]
+
+        import_xpub = def_wallet.gethdkeys(active_only=True)[0]["xpub"]
+        desc_import = def_wallet.listdescriptors(True)["descriptors"]
+        for desc in desc_import:
+            desc["active"] = False
+        wallet.importdescriptors(desc_import)
+        assert_equal(wallet.gethdkeys(active_only=True), xpub_info)
+
+        xpub_info = wallet.gethdkeys()
+        assert_equal(len(xpub_info), 2)
+        for x in xpub_info:
+            if x["xpub"] == active_xpub:
+                for desc in x["descriptors"]:
+                    assert_equal(desc["active"], True)
+            elif x["xpub"] == import_xpub:
+                for desc in x["descriptors"]:
+                    assert_equal(desc["active"], False)
+            else:
+                assert False
+
+
+    def test_lone_key_imports(self):
+        self.log.info("Non-HD keys do not appear in gethdkeys")
+        self.nodes[0].createwallet("lonekey", blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("lonekey")
+
+        assert_equal(wallet.gethdkeys(), [])
+        wallet.importdescriptors([{"desc": descsum_create("wpkh(cTe1f5rdT8A8DFgVWTjyPwACsDPJM9ff4QngFxUixCSvvbg1x6sh)"), "timestamp": "now"}])
+        assert_equal(wallet.gethdkeys(), [])
+
+        self.log.info("HD keys of non-ranged descriptors should appear in gethdkeys")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        xpub_info = def_wallet.gethdkeys(private=True)
+        xpub = xpub_info[0]["xpub"]
+        xprv = xpub_info[0]["xprv"]
+        prv_desc = descsum_create(f"wpkh({xprv})")
+        pub_desc = descsum_create(f"wpkh({xpub})")
+        assert_equal(wallet.importdescriptors([{"desc": prv_desc, "timestamp": "now"}])[0]["success"], True)
+        xpub_info = wallet.gethdkeys()
+        assert_equal(len(xpub_info), 1)
+        assert_equal(xpub_info[0]["xpub"], xpub)
+        assert_equal(len(xpub_info[0]["descriptors"]), 1)
+        assert_equal(xpub_info[0]["descriptors"][0]["desc"], pub_desc)
+        assert_equal(xpub_info[0]["descriptors"][0]["active"], False)
+
+    def test_ranged_multisig(self):
+        self.log.info("HD keys of a multisig appear in gethdkeys")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet("ranged_multisig")
+        wallet = self.nodes[0].get_wallet_rpc("ranged_multisig")
+
+        xpub1 = wallet.gethdkeys()[0]["xpub"]
+        xprv1 = wallet.gethdkeys(private=True)[0]["xprv"]
+        xpub2 = def_wallet.gethdkeys()[0]["xpub"]
+
+        prv_multi_desc = descsum_create(f"wsh(multi(2,{xprv1}/*,{xpub2}/*))")
+        pub_multi_desc = descsum_create(f"wsh(multi(2,{xpub1}/*,{xpub2}/*))")
+        assert_equal(wallet.importdescriptors([{"desc": prv_multi_desc, "timestamp": "now"}])[0]["success"], True)
+
+        xpub_info = wallet.gethdkeys()
+        assert_equal(len(xpub_info), 2)
+        for x in xpub_info:
+            if x["xpub"] == xpub1:
+                found_desc = next((d for d in xpub_info[0]["descriptors"] if d["desc"] == pub_multi_desc), None)
+                assert found_desc is not None
+                assert_equal(found_desc["active"], False)
+            elif x["xpub"] == xpub2:
+                assert_equal(len(x["descriptors"]), 1)
+                assert_equal(x["descriptors"][0]["desc"], pub_multi_desc)
+                assert_equal(x["descriptors"][0]["active"], False)
+            else:
+                assert False
+
+    def test_mixed_multisig(self):
+        self.log.info("Non-HD keys of a multisig do not appear in gethdkeys")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet("single_multisig")
+        wallet = self.nodes[0].get_wallet_rpc("single_multisig")
+
+        xpub = wallet.gethdkeys()[0]["xpub"]
+        xprv = wallet.gethdkeys(private=True)[0]["xprv"]
+        pub = def_wallet.getaddressinfo(def_wallet.getnewaddress())["pubkey"]
+
+        prv_multi_desc = descsum_create(f"wsh(multi(2,{xprv},{pub}))")
+        pub_multi_desc = descsum_create(f"wsh(multi(2,{xpub},{pub}))")
+        import_res = wallet.importdescriptors([{"desc": prv_multi_desc, "timestamp": "now"}])
+        assert_equal(import_res[0]["success"], True)
+
+        xpub_info = wallet.gethdkeys()
+        assert_equal(len(xpub_info), 1)
+        assert_equal(xpub_info[0]["xpub"], xpub)
+        found_desc = next((d for d in xpub_info[0]["descriptors"] if d["desc"] == pub_multi_desc), None)
+        assert found_desc is not None
+        assert_equal(found_desc["active"], False)
+
+
+if __name__ == '__main__':
+    WalletGetHDKeyTest().main()