Add register command for BIP388 policies

Author: Sjors

hwilib/_cli.py

@@ -12,6 +12,7 @@
     getdescriptors,
     prompt_pin,
     toggle_passphrase,
+    register,
     restore_device,
     send_pin,
     setup_device,
@@ -22,6 +23,7 @@
 )
 from .common import (
     AddressType,
+    BIP388Policy,
     Chain,
 )
 from .errors import (
@@ -59,6 +61,10 @@ def backup_device_handler(args: argparse.Namespace, client: HardwareWalletClient
 def displayaddress_handler(args: argparse.Namespace, client: HardwareWalletClient) -> Dict[str, str]:
     return displayaddress(client, desc=args.desc, path=args.path, addr_type=args.addr_type)
 
+def register_handler(args: argparse.Namespace, client: HardwareWalletClient) -> Dict[str, str]:
+    policy = BIP388Policy(name=args.name, descriptor_template=args.desc, keys_info=args.key)
+    return register(client, bip388_policy=policy)
+
 def enumerate_handler(args: argparse.Namespace) -> List[Dict[str, Any]]:
     return enumerate(password=args.password, expert=args.expert, chain=args.chain, allow_emulators=args.allow_emulators)
 
@@ -197,6 +203,12 @@ def get_parser() -> HWIArgumentParser:
     displayaddr_parser.add_argument("--addr-type", help="The address type to display", type=AddressType.argparse, choices=list(AddressType), default=AddressType.WIT) # type: ignore
     displayaddr_parser.set_defaults(func=displayaddress_handler)
 
+    register_parser = subparsers.add_parser('register', help='Register a BIP388 wallet policy')
+    register_parser.add_argument('--name', help='Name for the policy')
+    register_parser.add_argument('--desc', help='Descriptor template, e.g. tr(musig(@0,@1)')
+    register_parser.add_argument('--key', help='Key information, e.g. [00000000/84h/0h/0h]xpub...', action='append')
+    register_parser.set_defaults(func=register_handler)
+
     setupdev_parser = subparsers.add_parser('setup', help='Setup a device. Passphrase protection uses the password given by -p. Requires interactive mode')
     setupdev_parser.add_argument('--label', '-l', help='The name to give to the device', default='')
     setupdev_parser.add_argument('--backup_passphrase', '-b', help='The passphrase to use for the backup, if applicable', default='')

hwilib/commands.py

@@ -52,6 +52,7 @@
 from .devices import __all__ as all_devs
 from .common import (
     AddressType,
+    BIP388Policy,
     Chain,
 )
 from .hwwclient import HardwareWalletClient
@@ -494,6 +495,23 @@ def displayaddress(
             return {"address": client.display_singlesig_address(pubkey.get_full_derivation_path(0), addr_type)}
     raise BadArgumentError("Missing both path and descriptor")
 
+def register(
+    client: HardwareWalletClient,
+    bip388_policy: BIP388Policy,
+) -> Dict[str, str]:
+    """
+    Register a BIP388 policy on the device for client.
+
+    :param name: Name for the policy
+    :param desc: Descriptor template
+    :return: A dictionary containing policy HMAC.
+        Returned as ``{"hmac": <hex string>}``.
+    :raises: BadArgumentError: if an argument is malformed, missing, or conflicts.
+    """
+    assert bip388_policy.hmac is None
+
+    return {"hmac": client.register_bip388_policy(bip388_policy)}
+
 def setup_device(client: HardwareWalletClient, label: str = "", backup_passphrase: str = "") -> Dict[str, bool]:
     """
     Setup a device that has not yet been initialized.

hwilib/devices/ledger.py

@@ -31,6 +31,7 @@
 )
 from ..common import (
     AddressType,
+    BIP388Policy,
     Chain,
 )
 from .ledger_bitcoin.client import (
@@ -479,6 +480,24 @@ def format_key_info(pubkey: PubkeyProvider) -> str:
 
         return self.client.get_wallet_address(multisig_wallet, registered_hmac, change, address_index, True)
 
+    @ledger_exception
+    def register_bip388_policy(
+        self,
+        bip388_policy: BIP388Policy,
+    ) -> str:
+        if isinstance(self.client, LegacyClient):
+            raise BadArgumentError("Registering a BIP388 policy not supported by this version of the Bitcoin App")
+
+        wallet_policy = WalletPolicy(
+            name=bip388_policy.name,
+            descriptor_template=bip388_policy.descriptor_template,
+            keys_info=bip388_policy.keys_info
+        )
+
+        _, registered_hmac = self.client.register_wallet(wallet_policy)
+
+        return registered_hmac.hex()
+
     def setup_device(self, label: str = "", passphrase: str = "") -> bool:
         """
         Ledgers do not support setup via software.

hwilib/hwwclient.py

@@ -17,7 +17,11 @@
     get_bip44_chain,
 )
 from .psbt import PSBT
-from .common import AddressType, Chain
+from .common import (
+    AddressType,
+    BIP388Policy,
+    Chain,
+)
 
 
 class HardwareWalletClient(object):
@@ -135,6 +139,17 @@ def display_multisig_address(
         raise NotImplementedError("The HardwareWalletClient base class "
                                   "does not implement this method")
 
+    def register_bip388_policy(
+        self,
+        bip388_policy: BIP388Policy,
+    ) -> str:
+        """
+        Register a BIP388 policy.
+
+        :return: The policy HMAC
+        """
+        raise NotImplementedError("This device does not support BIP388 policies or it's not yet implemented")
+
     def wipe_device(self) -> bool:
         """
         Wipe the device.