From 1f677306a16b5bcc6bd1234fc2d81cf286e5b675 Mon Sep 17 00:00:00 2001
From: Tomas Susanka <tsusanka@gmail.com>
Date: Thu, 21 Dec 2017 15:59:38 +0100
Subject: [PATCH] ethereum/signing: streaming; all tests passing

---
 src/apps/ethereum/ethereum_sign_tx.py | 43 +++++++++++++++++++++------
 src/trezor/crypto/rlp.py              | 21 +++++++++++--
 2 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/src/apps/ethereum/ethereum_sign_tx.py b/src/apps/ethereum/ethereum_sign_tx.py
index ce8851ab..7378acad 100644
--- a/src/apps/ethereum/ethereum_sign_tx.py
+++ b/src/apps/ethereum/ethereum_sign_tx.py
@@ -45,24 +45,49 @@ async def ethereum_sign_tx(ctx, msg):
     data += msg.data_initial_chunk
     data_left = data_total - len(msg.data_initial_chunk)
 
+    total_length = get_total_length(msg, data_total)
+
+    sha = sha3_256()
+    sha.update(rlp.encode_length(total_length, True))  # total length
+
+    for field in [msg.nonce, msg.gas_price, msg.gas_limit, msg.to, msg.value]:
+        sha.update(rlp.encode(field))
+
+    if data_left == 0:
+        sha.update(rlp.encode(data))
+    else:
+        sha.update(rlp.encode_length(data_total, False))
+        sha.update(rlp.encode(data, False))
+
     while data_left > 0:
         resp = await send_request_chunk(ctx, data_left, data_total)
-        data += resp.data_chunk
         data_left -= len(resp.data_chunk)
-        # todo stream
+        sha.update(resp.data_chunk)
 
+    # eip 155 replay protection
     if msg.chain_id:
-        fields = [msg.nonce, msg.gas_price, msg.gas_limit, msg.to, msg.value, data, msg.chain_id, 0, 0]
-    else:
-        fields = [msg.nonce, msg.gas_price, msg.gas_limit, msg.to, msg.value, data]
-    rlp_encoded = rlp.encode(fields)
-    sha256 = sha3_256()
-    sha256.update(rlp_encoded)
-    digest = sha256.digest(True)
+        sha.update(rlp.encode(msg.chain_id))
+        sha.update(rlp.encode(0))
+        sha.update(rlp.encode(0))
 
+    digest = sha.digest(True)
     return await send_signature(ctx, msg, digest)
 
 
+def get_total_length(msg: EthereumSignTx, data_total: int) -> int:
+    length = 0
+    for field in [msg.nonce, msg.gas_price, msg.gas_limit, msg.to, msg.value]:
+        length += rlp.field_length(len(field), field[:1])
+
+    if msg.chain_id:  # forks replay protection
+        length += rlp.field_length(1, [msg.chain_id])
+        length += rlp.field_length(0, 0)
+        length += rlp.field_length(0, 0)
+
+    length += rlp.field_length(data_total, msg.data_initial_chunk)
+    return length
+
+
 async def send_request_chunk(ctx, data_left: int, data_total: int):
     from trezor.messages.wire_types import EthereumTxAck
     # todo layoutProgress ?
diff --git a/src/trezor/crypto/rlp.py b/src/trezor/crypto/rlp.py
index 94340510..1f13bd7b 100644
--- a/src/trezor/crypto/rlp.py
+++ b/src/trezor/crypto/rlp.py
@@ -20,13 +20,13 @@ def encode_length(l: int, is_list: bool) -> bytes:
         raise ValueError('Input too long')
 
 
-def encode(data) -> bytes:
+def encode(data, include_length=True) -> bytes:
     if isinstance(data, int):
         return encode(int_to_bytes(data))
     if isinstance(data, bytearray):
         data = bytes(data)
     if isinstance(data, bytes):
-        if len(data) == 1 and ord(data) < 128:
+        if (len(data) == 1 and ord(data) < 128) or not include_length:
             return data
         else:
             return encode_length(len(data), is_list=False) + data
@@ -34,6 +34,21 @@ def encode(data) -> bytes:
         output = b''
         for item in data:
             output += encode(item)
-        return encode_length(len(output), is_list=True) + output
+        if include_length:
+            return encode_length(len(output), is_list=True) + output
+        else:
+            return output
     else:
         raise TypeError('Invalid input of type ' + str(type(data)))
+
+
+def field_length(length: int, first_byte: bytearray) -> int:
+    if length == 1 and first_byte[0] <= 0x7f:
+        return 1
+    elif length <= 55:
+        return 1 + length
+    elif length <= 0xff:
+        return 2 + length
+    elif length <= 0xffff:
+        return 3 + length
+    return 4 + length