signing: code style

src/apps/wallet/sign_tx/signing.py

@@ -1,22 +1,21 @@
 from micropython import const
 
-from trezor.crypto.hashlib import sha256
+from trezor.crypto import base58, bip32, der
 from trezor.crypto.curve import secp256k1
-from trezor.crypto import base58, der
+from trezor.crypto.hashlib import sha256
 
-from trezor.messages.TxRequestSerializedType import TxRequestSerializedType
-from trezor.messages.TxRequestDetailsType import TxRequestDetailsType
 from trezor.messages import OutputScriptType
+from trezor.messages.TxRequestDetailsType import TxRequestDetailsType
+from trezor.messages.TxRequestSerializedType import TxRequestSerializedType
 
-from apps.common import address_type
+from apps.common import address_type, coins
-from apps.common import coins
+from apps.common.hash_writer import HashWriter
 from apps.wallet.sign_tx.addresses import *
 from apps.wallet.sign_tx.helpers import *
-from apps.wallet.sign_tx.segwit_bip143 import *
 from apps.wallet.sign_tx.scripts import *
-from apps.wallet.sign_tx.writers import *
+from apps.wallet.sign_tx.segwit_bip143 import *
 from apps.wallet.sign_tx.tx_weight_calculator import *
-from apps.common.hash_writer import HashWriter
+from apps.wallet.sign_tx.writers import *
 
 # the number of bip32 levels used in a wallet (chain and address)
 _BIP32_WALLET_DEPTH = const(2)
@@ -44,7 +43,7 @@ class SigningError(ValueError):
 # - check inputs, previous transactions, and outputs
 # - ask for confirmations
 # - check fee
-async def check_tx_fee(tx: SignTx, root):
+async def check_tx_fee(tx: SignTx, root: bip32.HDNode):
     coin = coins.by_name(tx.coin_name)
 
     # h_first is used to make sure the inputs and outputs streamed in Phase 1
@@ -53,13 +52,9 @@ async def check_tx_fee(tx: SignTx, root):
     h_first = HashWriter(sha256)  # not a real tx hash
 
     bip143 = Bip143()  # bip143 transaction hashing
-    multifp = MultisigFingerprint()  # control fp of multisig inputs
+    multifp = MultisigFingerprint()  # control checksum of multisig inputs
     weight = TxWeightCalculator(tx.inputs_count, tx.outputs_count)
 
-    txo_bin = TxOutputBinType()
-    tx_req = TxRequest()
-    tx_req.details = TxRequestDetailsType()
-
     total_in = 0  # sum of input amounts
     segwit_in = 0  # sum of segwit input amounts
     total_out = 0  # sum of output amounts
@@ -67,6 +62,11 @@ async def check_tx_fee(tx: SignTx, root):
     wallet_path = []  # common prefix of input paths
     segwit = {}  # dict of booleans stating if input is segwit
 
+    # output structures
+    txo_bin = TxOutputBinType()
+    tx_req = TxRequest()
+    tx_req.details = TxRequestDetailsType()
+
     for i in range(tx.inputs_count):
         # STAGE_REQUEST_1_INPUT
         txi = await request_tx_input(tx_req, i)
@@ -115,11 +115,14 @@ async def check_tx_fee(tx: SignTx, root):
         txo_bin.amount = txo.amount
         txo_bin.script_pubkey = output_derive_script(txo, coin, root)
         weight.add_output(txo_bin.script_pubkey)
-        if (change_out == 0) and is_change(txo, wallet_path, segwit_in, multifp):
+
+        if change_out == 0 and is_change(txo, wallet_path, segwit_in, multifp):
+            # output is change and does not need confirmation
             change_out = txo.amount
         elif not await confirm_output(txo, coin):
             raise SigningError(FailureType.ActionCancelled,
                                'Output cancelled')
+
         write_tx_output(h_first, txo_bin)
         bip143.add_output(txo_bin)
         total_out += txo_bin.amount
@@ -142,7 +145,7 @@ async def check_tx_fee(tx: SignTx, root):
     return h_first, bip143, segwit, total_in, wallet_path
 
 
-async def sign_tx(tx: SignTx, root):
+async def sign_tx(tx: SignTx, root: bip32.HDNode):
     tx = sanitize_sign_tx(tx)
 
     # Phase 1
@@ -281,7 +284,7 @@ async def sign_tx(tx: SignTx, root):
 
             # if multisig, check if singing with a key that is included in multisig
             if txi_sign.multisig:
-                pubkey_idx = multisig_pubkey_index(txi_sign.multisig, key_sign_pub)
+                multisig_pubkey_index(txi_sign.multisig, key_sign_pub)
 
             # compute the signature from the tx digest
             signature = ecdsa_sign(key_sign, get_tx_hash(h_sign, True))
@@ -416,7 +419,7 @@ def get_hash_type(coin: CoinType) -> int:
     return hashtype
 
 
-def get_tx_header(tx: SignTx, segwit=False):
+def get_tx_header(tx: SignTx, segwit: bool = False):
     w_txi = bytearray()
     write_uint32(w_txi, tx.version)
     if segwit:
@@ -430,14 +433,17 @@ def get_tx_header(tx: SignTx, segwit=False):
 # ===
 
 
-def output_derive_script(o: TxOutputType, coin: CoinType, root) -> bytes:
+def output_derive_script(o: TxOutputType, coin: CoinType, root: bip32.HDNode) -> bytes:
+
     if o.script_type == OutputScriptType.PAYTOOPRETURN:
+        # op_return output
         if o.amount != 0:
             raise SigningError(FailureType.DataError,
                                'OP_RETURN output with non-zero amount')
         return output_script_paytoopreturn(o.op_return_data)
 
-    if o.address_n:  # change output
+    if o.address_n:
+        # change output
         if o.address:
             raise SigningError(FailureType.DataError, 'Address in change output')
         o.address = get_address_for_change(o, coin, root)
@@ -445,24 +451,27 @@ def output_derive_script(o: TxOutputType, coin: CoinType, root) -> bytes:
         if not o.address:
             raise SigningError(FailureType.DataError, 'Missing address')
 
-    if coin.bech32_prefix and o.address.startswith(coin.bech32_prefix):  # p2wpkh or p2wsh
+    if coin.bech32_prefix and o.address.startswith(coin.bech32_prefix):
+        # p2wpkh or p2wsh
         witprog = decode_bech32_address(coin.bech32_prefix, o.address)
         return output_script_native_p2wpkh_or_p2wsh(witprog)
 
     raw_address = base58.decode_check(o.address)
 
-    if address_type.check(coin.address_type, raw_address):  # p2pkh
+    if address_type.check(coin.address_type, raw_address):
+        # p2pkh
         pubkeyhash = address_type.strip(coin.address_type, raw_address)
         return output_script_p2pkh(pubkeyhash)
 
-    elif address_type.check(coin.address_type_p2sh, raw_address):  # p2sh
+    elif address_type.check(coin.address_type_p2sh, raw_address):
+        # p2sh
         scripthash = address_type.strip(coin.address_type_p2sh, raw_address)
         return output_script_p2sh(scripthash)
 
     raise SigningError(FailureType.DataError, 'Invalid address type')
 
 
-def get_address_for_change(o: TxOutputType, coin: CoinType, root):
+def get_address_for_change(o: TxOutputType, coin: CoinType, root: bip32.HDNode):
     if o.script_type == OutputScriptType.PAYTOADDRESS:
         input_script_type = InputScriptType.SPENDADDRESS
     elif o.script_type == OutputScriptType.PAYTOMULTISIG:
@@ -498,10 +507,15 @@ def output_is_change(o: TxOutputType, wallet_path: list, segwit_in: int) -> bool
 
 def input_derive_script(coin: CoinType, i: TxInputType, pubkey: bytes, signature: bytes=None) -> bytes:
     if i.script_type == InputScriptType.SPENDADDRESS:
-        return input_script_p2pkh_or_p2sh(pubkey, signature, get_hash_type(coin))  # p2pkh or p2sh
+        # p2pkh or p2sh
+        return input_script_p2pkh_or_p2sh(
+            pubkey, signature, get_hash_type(coin))
+
+    if i.script_type == InputScriptType.SPENDP2SHWITNESS:
+        # p2wpkh or p2wsh using p2sh
 
-    if i.script_type == InputScriptType.SPENDP2SHWITNESS:  # p2wpkh or p2wsh using p2sh
+        if i.multisig:
-        if i.multisig:  # p2wsh in p2sh
+            # p2wsh in p2sh
             pubkeys = multisig_get_pubkeys(i.multisig)
             witness_script = output_script_multisig(pubkeys, i.multisig.m)
             witness_script_hash = sha256(witness_script).digest()
@@ -510,14 +524,16 @@ def input_derive_script(coin: CoinType, i: TxInputType, pubkey: bytes, signature
         # p2wpkh in p2sh
         return input_script_p2wpkh_in_p2sh(ecdsa_hash_pubkey(pubkey))
 
-    elif i.script_type == InputScriptType.SPENDWITNESS:  # native p2wpkh or p2wsh
+    elif i.script_type == InputScriptType.SPENDWITNESS:
+        # native p2wpkh or p2wsh
         return input_script_native_p2wpkh_or_p2wsh()
 
-    # multisig
     elif i.script_type == InputScriptType.SPENDMULTISIG:
+        # p2sh multisig
         signature_index = multisig_pubkey_index(i.multisig, pubkey)
         return input_script_multisig(
             i.multisig, signature, signature_index, get_hash_type(coin))
+
     else:
         raise SigningError(FailureType.ProcessError, 'Invalid script type')
 
@@ -544,19 +560,23 @@ def input_check_wallet_path(txi: TxInputType, wallet_path: list) -> list:
                            'Transaction has changed during signing')
 
 
-def node_derive(root, address_n: list):
+def node_derive(root: bip32.HDNode, address_n: list):
     node = root.clone()
     node.derive_path(address_n)
     return node
 
 
-def ecdsa_sign(node, digest: bytes) -> bytes:
+def ecdsa_sign(node: bip32.HDNode, digest: bytes) -> bytes:
     sig = secp256k1.sign(node.private_key(), digest)
     sigder = der.encode_seq((sig[1:33], sig[33:65]))
     return sigder
 
 
-def is_change(txo: TxOutputType, wallet_path, segwit_in: int, multifp: MultisigFingerprint) -> bool:
+def is_change(
+        txo: TxOutputType,
+        wallet_path: list,
+        segwit_in: int,
+        multifp: MultisigFingerprint) -> bool:
     if txo.multisig:
         if not multifp.matches(txo.multisig):
             return False

src/apps/wallet/sign_tx/writers.py

@@ -1,8 +1,8 @@
-
 from trezor.crypto.hashlib import sha256
 
 from apps.wallet.sign_tx.writers import *
 
+
 # TX Serialization
 # ===