From b7c7190573cd1f163226f156b6075d31f6fb51d1 Mon Sep 17 00:00:00 2001
From: matejcik <ja@matejcik.cz>
Date: Fri, 20 Apr 2018 17:23:43 +0200
Subject: [PATCH] trezorlib: remove Hash to btc_hash, prepare for moving it
 away from things

---
 tools/signtest.py                     | 2 +-
 trezorlib/client.py                   | 4 ++--
 trezorlib/tests/support/ckd_public.py | 4 ++--
 trezorlib/tools.py                    | 7 +++++--
 4 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/tools/signtest.py b/tools/signtest.py
index 547c3c6953..1fbdd6e2e3 100755
--- a/tools/signtest.py
+++ b/tools/signtest.py
@@ -110,7 +110,7 @@ class MyTxApiBitcoin(object):
                     o.script_pubkey = b'\x76\xa9\x14' + pubkey + b'\x88\xac'
 
             txser = self.serialize_tx(t)
-            txhash = tools.Hash(txser)[::-1]
+            txhash = tools.btc_hash(txser)[::-1]
             self.inputs.append(
                 proto_types.TxInputType(
                     address_n=self.client.expand_path("44'/0'/0'/0/%d" % idx),
diff --git a/trezorlib/client.py b/trezorlib/client.py
index f5bdd973d1..8a0bb46a9e 100644
--- a/trezorlib/client.py
+++ b/trezorlib/client.py
@@ -1029,7 +1029,7 @@ class ProtocolMixin(object):
         if xprv[0:4] not in ('xprv', 'tprv'):
             raise ValueError("Unknown type of xprv")
 
-        if len(xprv) < 100 and len(xprv) > 112:
+        if not 100 < len(xprv) < 112:  # yes this is correct in Python
             raise ValueError("Invalid length of xprv")
 
         node = proto.HDNodeType()
@@ -1038,7 +1038,7 @@ class ProtocolMixin(object):
         if data[90:92] != b'00':
             raise ValueError("Contain invalid private key")
 
-        checksum = binascii.hexlify(hashlib.sha256(hashlib.sha256(binascii.unhexlify(data[:156])).digest()).digest()[:4])
+        checksum = binascii.hexlify(tools.btc_hash(binascii.unhexlify(data[:156]))[:4])
         if checksum != data[156:]:
             raise ValueError("Checksum doesn't match")
 
diff --git a/trezorlib/tests/support/ckd_public.py b/trezorlib/tests/support/ckd_public.py
index e377cf05a9..cb4f2fa5ba 100644
--- a/trezorlib/tests/support/ckd_public.py
+++ b/trezorlib/tests/support/ckd_public.py
@@ -126,14 +126,14 @@ def serialize(node, version=0x0488B21E):
         s += b'\x00' + node.private_key
     else:
         s += node.public_key
-    s += tools.Hash(s)[:4]
+    s += tools.btc_hash(s)[:4]
     return tools.b58encode(s)
 
 
 def deserialize(xpub):
     data = tools.b58decode(xpub, None)
 
-    if tools.Hash(data[:-4])[:4] != data[-4:]:
+    if tools.btc_hash(data[:-4])[:4] != data[-4:]:
         raise ValueError("Checksum failed")
 
     node = messages.HDNodeType()
diff --git a/trezorlib/tools.py b/trezorlib/tools.py
index 8029cb1cbf..bb24e9dd63 100644
--- a/trezorlib/tools.py
+++ b/trezorlib/tools.py
@@ -35,7 +35,10 @@ def H_(x: int) -> int:
     return x | HARDENED_FLAG
 
 
-def Hash(data):
+def btc_hash(data):
+    """
+    Double-SHA256 hash as used in BTC
+    """
     return hashlib.sha256(hashlib.sha256(data).digest()).digest()
 
 
@@ -47,7 +50,7 @@ def hash_160(public_key):
 
 def hash_160_to_bc_address(h160, address_type):
     vh160 = struct.pack('<B', address_type) + h160
-    h = Hash(vh160)
+    h = btc_hash(vh160)
     addr = vh160 + h[0:4]
     return b58encode(addr)