python/trezorctl: support multisig addresses in get-address

python/CHANGELOG.md

@@ -12,6 +12,7 @@ _At the moment, the project does **not** adhere to [Semantic Versioning](https:/
 ### Added
 
 - `trezorctl set unsafe-prompts` controls the new "unsafe prompts" feature.  [#1126]
+- `trezorctl btc get-address` can create multisig addresses.
 
 ### Changed
 

python/src/trezorlib/cli/btc.py

@@ -18,6 +18,7 @@ import base64
 import json
 
 import click
+import construct as c
 
 from .. import btc, messages, protobuf, tools
 from . import ChoiceType, with_client
@@ -37,6 +38,34 @@ OUTPUT_SCRIPTS = {
 DEFAULT_COIN = "Bitcoin"
 
 
+XpubStruct = c.Struct(
+    "version" / c.Int32ub,
+    "depth" / c.Int8ub,
+    "fingerprint" / c.Int32ub,
+    "child_num" / c.Int32ub,
+    "chain_code" / c.Bytes(32),
+    "key" / c.Bytes(33),
+    c.Terminated,
+)
+
+
+def xpub_deserialize(xpubstr):
+    xpub_bytes = tools.b58check_decode(xpubstr)
+    data = XpubStruct.parse(xpub_bytes)
+    node = messages.HDNodeType(
+        depth=data.depth,
+        fingerprint=data.fingerprint,
+        child_num=data.child_num,
+        chain_code=data.chain_code,
+    )
+    if data.key[0] == 0:
+        node.private_key = data.key[1:]
+    else:
+        node.public_key = data.key
+
+    return data.version, node
+
+
 @click.group(name="btc")
 def cli():
     """Bitcoin and Bitcoin-like coins commands."""
@@ -52,13 +81,66 @@ def cli():
 @click.option("-n", "--address", required=True, help="BIP-32 path")
 @click.option("-t", "--script-type", type=ChoiceType(INPUT_SCRIPTS), default="address")
 @click.option("-d", "--show-display", is_flag=True)
+@click.option("-x", "--multisig-xpub", multiple=True, help="XPUBs of multisig owners")
+@click.option("-m", "--multisig-threshold", type=int, help="Number of signatures")
+@click.option(
+    "-N",
+    "--multisig-suffix-length",
+    help="BIP-32 suffix length for multisig",
+    type=int,
+    default=2,
+)
 @with_client
-def get_address(client, coin, address, script_type, show_display):
-    """Get address for specified path."""
+def get_address(
+    client,
+    coin,
+    address,
+    script_type,
+    show_display,
+    multisig_xpub,
+    multisig_threshold,
+    multisig_suffix_length,
+):
+    """Get address for specified path.
+
+    To obtain a multisig address, provide XPUBs of all signers (including your own) in
+    the intended order. All XPUBs should be on the same level. By default, it is assumed
+    that the XPUBs are on the account level, and the last two components of --address
+    should be derived from all of them.
+
+    For BIP-45 multisig:
+
+    $ trezorctl btc get-public-node -n m/45h/0
+    xpub0101
+    $ trezorctl btc get-address -n m/45h/0/0/7 -m 3 -x xpub0101 -x xpub0202 -x xpub0303
+
+    This assumes that the other signers also created xpubs at address "m/45h/i".
+    For all the signers, the final keys will be derived with the "/0/7" suffix.
+
+    You can specify a different suffix length by using the -N option. For example, to
+    use final xpubs, specify '-N 0'.
+    """
     coin = coin or DEFAULT_COIN
     address_n = tools.parse_path(address)
+
+    if multisig_xpub:
+        if multisig_threshold is None:
+            raise click.ClickException("Please specify signature threshold")
+
+        multisig_suffix = address_n[-multisig_suffix_length:]
+        nodes = [xpub_deserialize(x)[1] for x in multisig_xpub]
+        multisig = messages.MultisigRedeemScriptType(
+            nodes=nodes, address_n=multisig_suffix, m=multisig_threshold
+        )
+        if script_type == messages.InputScriptType.SPENDADDRESS:
+            script_type = messages.InputScriptType.SPENDMULTISIG
     return btc.get_address(
-        client, coin, address_n, show_display, script_type=script_type
+        client,
+        coin,
+        address_n,
+        show_display,
+        script_type=script_type,
+        multisig=multisig,
     )