utils: simplify HashWriter interface

src/apps/common/signverify.py

@@ -8,9 +8,9 @@ from apps.wallet.sign_tx.signing import write_varint
 
 def message_digest(coin, message):
     if coin.decred:
-        h = HashWriter(blake256)
+        h = HashWriter(blake256())
     else:
-        h = HashWriter(sha256)
+        h = HashWriter(sha256())
     write_varint(h, len(coin.signed_message_header))
     h.extend(coin.signed_message_header)
     write_varint(h, len(message))

src/apps/ethereum/sign_message.py

@@ -10,7 +10,7 @@ from apps.common.signverify import split_message
 
 
 def message_digest(message):
-    h = HashWriter(sha3_256, keccak=True)
+    h = HashWriter(sha3_256(keccak=True))
     signed_message_header = "\x19Ethereum Signed Message:\n"
     h.extend(signed_message_header)
     h.extend(str(len(message)))

src/apps/ethereum/sign_tx.py

@@ -61,7 +61,7 @@ async def sign_tx(ctx, msg):
 
     total_length = get_total_length(msg, data_total)
 
-    sha = HashWriter(sha3_256, keccak=True)
+    sha = HashWriter(sha3_256(keccak=True))
     sha.extend(rlp.encode_length(total_length, True))  # total length
 
     if msg.tx_type is not None:

src/apps/lisk/sign_message.py

@@ -13,7 +13,7 @@ from apps.wallet.sign_tx.signing import write_varint
 
 
 def message_digest(message):
-    h = HashWriter(sha256)
+    h = HashWriter(sha256())
     signed_message_header = "Lisk Signed Message:\n"
     write_varint(h, len(signed_message_header))
     h.extend(signed_message_header)

src/apps/lisk/sign_tx.py

@@ -25,7 +25,7 @@ async def sign_tx(ctx, msg):
     await layout.require_confirm_fee(ctx, transaction.amount, transaction.fee)
 
     txbytes = _get_transaction_bytes(transaction)
-    txhash = HashWriter(sha256)
+    txhash = HashWriter(sha256())
     for field in txbytes:
         txhash.extend(field)
     digest = txhash.get_digest()

src/apps/wallet/sign_tx/decred_prefix_hasher.py

@@ -30,7 +30,7 @@ class DecredPrefixHasher:
     """
 
     def __init__(self, tx: SignTx):
-        self.h_prefix = HashWriter(blake256)
+        self.h_prefix = HashWriter(blake256())
         self.last_output_bytes = None
         write_uint32(self.h_prefix, tx.version | DECRED_SERIALIZE_NO_WITNESS)
         write_varint(self.h_prefix, tx.inputs_count)

src/apps/wallet/sign_tx/multisig.py

@@ -50,7 +50,7 @@ def multisig_fingerprint(multisig: MultisigRedeemScriptType) -> bytes:
     # casting to bytes(), sorting on bytearray() is not supported in MicroPython
     pubkeys = sorted(pubkeys, key=lambda hd: bytes(hd.node.public_key))
 
-    h = HashWriter(sha256)
+    h = HashWriter(sha256())
     write_uint32(h, m)
     write_uint32(h, n)
     for hd in pubkeys:

src/apps/wallet/sign_tx/segwit_bip143.py

@@ -25,9 +25,9 @@ class Bip143Error(ValueError):
 
 class Bip143:
     def __init__(self):
-        self.h_prevouts = HashWriter(sha256)
-        self.h_sequence = HashWriter(sha256)
-        self.h_outputs = HashWriter(sha256)
+        self.h_prevouts = HashWriter(sha256())
+        self.h_sequence = HashWriter(sha256())
+        self.h_outputs = HashWriter(sha256())
 
     def add_prevouts(self, txi: TxInputType):
         write_bytes_reversed(self.h_prevouts, txi.prev_hash)
@@ -56,7 +56,7 @@ class Bip143:
         pubkeyhash: bytes,
         sighash: int,
     ) -> bytes:
-        h_preimage = HashWriter(sha256)
+        h_preimage = HashWriter(sha256())
 
         ensure(not tx.overwintered)
 

src/apps/wallet/sign_tx/signing.py

@@ -64,7 +64,7 @@ async def check_tx_fee(tx: SignTx, root: bip32.HDNode):
     # h_first is used to make sure the inputs and outputs streamed in Phase 1
     # are the same as in Phase 2.  it is thus not required to fully hash the
     # tx, as the SignTx info is streamed only once
-    h_first = HashWriter(sha256)  # not a real tx hash
+    h_first = HashWriter(sha256())  # not a real tx hash
 
     if coin.decred:
         hash143 = DecredPrefixHasher(tx)  # pseudo bip143 prefix hashing
@@ -333,7 +333,7 @@ async def sign_tx(tx: SignTx, root: bip32.HDNode):
             else:
                 raise ValueError("Unknown input script type")
 
-            h_witness = HashWriter(blake256)
+            h_witness = HashWriter(blake256())
             write_uint32(h_witness, tx.version | DECRED_SERIALIZE_WITNESS_SIGNING)
             write_varint(h_witness, tx.inputs_count)
 
@@ -348,7 +348,7 @@ async def sign_tx(tx: SignTx, root: bip32.HDNode):
                 h_witness, double=coin.sign_hash_double, reverse=False
             )
 
-            h_sign = HashWriter(blake256)
+            h_sign = HashWriter(blake256())
             write_uint32(h_sign, DECRED_SIGHASHALL)
             write_bytes(h_sign, prefix_hash)
             write_bytes(h_sign, witness_hash)
@@ -380,9 +380,9 @@ async def sign_tx(tx: SignTx, root: bip32.HDNode):
 
         else:
             # hash of what we are signing with this input
-            h_sign = HashWriter(sha256)
+            h_sign = HashWriter(sha256())
             # same as h_first, checked before signing the digest
-            h_second = HashWriter(sha256)
+            h_second = HashWriter(sha256())
 
             if tx.overwintered:
                 write_uint32(
@@ -575,9 +575,9 @@ async def get_prevtx_output_value(
     tx = await request_tx_meta(tx_req, prev_hash)
 
     if coin.decred:
-        txh = HashWriter(blake256)
+        txh = HashWriter(blake256())
     else:
-        txh = HashWriter(sha256)
+        txh = HashWriter(sha256())
 
     if tx.overwintered:
         write_uint32(txh, tx.version | OVERWINTERED)  # nVersion | fOverwintered

src/apps/wallet/sign_tx/zcash.py

@@ -46,9 +46,9 @@ def derive_script_code(txi: TxInputType, pubkeyhash: bytes) -> bytearray:
 
 class Zip143:
     def __init__(self):
-        self.h_prevouts = HashWriter(blake2b, outlen=32, personal=b"ZcashPrevoutHash")
-        self.h_sequence = HashWriter(blake2b, outlen=32, personal=b"ZcashSequencHash")
-        self.h_outputs = HashWriter(blake2b, outlen=32, personal=b"ZcashOutputsHash")
+        self.h_prevouts = HashWriter(blake2b(outlen=32, personal=b"ZcashPrevoutHash"))
+        self.h_sequence = HashWriter(blake2b(outlen=32, personal=b"ZcashSequencHash"))
+        self.h_outputs = HashWriter(blake2b(outlen=32, personal=b"ZcashOutputsHash"))
 
     def add_prevouts(self, txi: TxInputType):
         write_bytes_reversed(self.h_prevouts, txi.prev_hash)
@@ -78,7 +78,7 @@ class Zip143:
         sighash: int,
     ) -> bytes:
         h_preimage = HashWriter(
-            blake2b, outlen=32, personal=b"ZcashSigHash\x19\x1b\xa8\x5b"
+            blake2b(outlen=32, personal=b"ZcashSigHash\x19\x1b\xa8\x5b")
         )  # BRANCH_ID = 0x5ba81b19 / Overwinter
 
         ensure(tx.overwintered)
@@ -123,7 +123,7 @@ class Zip243(Zip143):
         sighash: int,
     ) -> bytes:
         h_preimage = HashWriter(
-            blake2b, outlen=32, personal=b"ZcashSigHash\xbb\x09\xb8\x76"
+            blake2b(outlen=32, personal=b"ZcashSigHash\xbb\x09\xb8\x76")
         )  # BRANCH_ID = 0x76b809bb / Sapling
 
         ensure(tx.overwintered)

src/trezor/utils.py

@@ -62,11 +62,8 @@ def format_ordinal(number):
 
 
 class HashWriter:
-    def __init__(self, hashfunc, *hashargs, **hashkwargs):
-        if callable(hashfunc):
-            self.ctx = hashfunc(*hashargs, **hashkwargs)
-        else:
-            self.ctx = hashfunc
+    def __init__(self, ctx):
+        self.ctx = ctx
         self.buf = bytearray(1)  # used in append()
 
     def extend(self, buf: bytearray):

tests/test_apps.wallet.address.py

@@ -1,8 +1,8 @@
 from common import *
+from trezor.crypto import bip32, bip39
 
-from apps.wallet.sign_tx.signing import *
 from apps.common import coins
-from trezor.crypto import bip32, bip39
+from apps.wallet.sign_tx.signing import *
 
 
 class TestAddress(unittest.TestCase):
@@ -59,7 +59,7 @@ class TestAddress(unittest.TestCase):
 
         # pubkey OP_CHECKSIG
         script = unhexlify('210279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798ac')
-        h = HashWriter(sha256)
+        h = HashWriter(sha256())
         write_bytes(h, script)
 
         address = address_p2wsh(