signing/multisig: get_address for change outputs, address_n check

src/apps/wallet/sign_tx/addresses.py

@@ -19,7 +19,7 @@ class AddressError(Exception):
     pass
 
 
-def get_address(script_type: InputScriptType, coin: CoinType, node) -> str:
+def get_address(script_type: InputScriptType, coin: CoinType, node, multisig=None) -> str:
 
     if script_type == InputScriptType.SPENDADDRESS:  # p2pkh
         return node.address(coin.address_type)
@@ -36,6 +36,21 @@ def get_address(script_type: InputScriptType, coin: CoinType, node) -> str:
                                'Segwit not enabled on this coin')
         return address_p2wpkh_in_p2sh(node.public_key(), coin.address_type_p2sh)
 
+    elif script_type == InputScriptType.SPENDMULTISIG:  # multisig
+        if multisig is None:
+            raise AddressError(FailureType.ProcessError,
+                               'Multisig details required')
+        pubkey = node.public_key()
+        index = multisig_pubkey_index(multisig, pubkey)
+        if index is None:
+            raise AddressError(FailureType.ProcessError,
+                               'Public key not found')
+        if coin.address_type_p2sh is None:
+            raise AddressError(FailureType.ProcessError,
+                               'Multisig not enabled on this coin')
+
+        return address_multisig_p2sh(multisig_get_pubkeys(multisig), multisig.m, coin.address_type_p2sh)
+
     else:
         raise AddressError(FailureType.ProcessError,
                            'Invalid script type')

src/apps/wallet/sign_tx/multisig.py

@@ -29,3 +29,10 @@ def multisig_get_pubkey(hd: HDNodePathType) -> bytes:
 
 def multisig_get_pubkeys(multisig: MultisigRedeemScriptType):
     return [multisig_get_pubkey(hd) for hd in multisig.pubkeys]
+
+
+def check_address_n_against_pubkeys(multisig: MultisigRedeemScriptType, address_n) -> bool:
+    for p in multisig.pubkeys:
+        if p.address_n == address_n:
+            return True
+    return False

src/apps/wallet/sign_tx/scripts.py

@@ -122,14 +122,14 @@ def input_script_multisig(current_signature, other_signatures, pubkeys, m: int):
 
 
 # returns a ripedm(sha256()) hash of a multisig script used in P2SH
-def output_script_multisig_p2sh(pubkeys, m) -> HashWriter:
+def output_script_multisig_p2sh(pubkeys, m) -> bytes:
     script = script_multisig(pubkeys, m)
     h = sha256(script).digest()
     return ripemd160(h).digest()
 
 
 # returns a sha256() hash of a multisig script used in native P2WSH
-def output_script_multisig_p2wsh(pubkeys, m) -> HashWriter:
+def output_script_multisig_p2wsh(pubkeys, m) -> bytes:
     for pubkey in pubkeys:
         if len(pubkey) != 33:
             raise Exception  # only compressed public keys are allowed for P2WSH
@@ -137,7 +137,7 @@ def output_script_multisig_p2wsh(pubkeys, m) -> HashWriter:
     return sha256(script).digest()
 
 
-def script_multisig(pubkeys, m) -> bytes:
+def script_multisig(pubkeys, m) -> bytearray:
     n = len(pubkeys)
     if n < 1 or n > 15:
         raise Exception

src/apps/wallet/sign_tx/signing.py

@@ -438,6 +438,10 @@ def output_derive_script(o: TxOutputType, coin: CoinType, root) -> bytes:
     if o.address_n:  # change output
         if o.address:
             raise SigningError(FailureType.DataError, 'Address in change output')
+        if o.multisig:
+            if not check_address_n_against_pubkeys(o.multisig, o.address_n):
+                raise AddressError(FailureType.ProcessError,
+                                   'address_n must match one of the address_n in the MultisigRedeemScriptType pubkeys')
         o.address = get_address_for_change(o, coin, root)
     else:
         if not o.address:
@@ -471,7 +475,7 @@ def get_address_for_change(o: TxOutputType, coin: CoinType, root):
         input_script_type = InputScriptType.SPENDP2SHWITNESS
     else:
         raise SigningError(FailureType.DataError, 'Invalid script type')
-    return get_address(input_script_type, coin, node_derive(root, o.address_n))
+    return get_address(input_script_type, coin, node_derive(root, o.address_n), o.multisig)
 
 
 def output_is_change(o: TxOutputType, wallet_path: list, segwit_in: int) -> bool: