From 00fb2520631967d43fc09e0b53efa1b315f80a0b Mon Sep 17 00:00:00 2001
From: Tomas Susanka <tsusanka@gmail.com>
Date: Thu, 17 May 2018 14:24:37 +0200
Subject: [PATCH] stellar: signing init

---
 src/apps/stellar/__init__.py       |   7 ++
 src/apps/stellar/get_public_key.py |   1 -
 src/apps/stellar/sign_tx.py        | 112 +++++++++++++++++++++++++++++
 src/apps/stellar/writers.py        |  26 +++++++
 4 files changed, 145 insertions(+), 1 deletion(-)
 create mode 100644 src/apps/stellar/sign_tx.py
 create mode 100644 src/apps/stellar/writers.py

diff --git a/src/apps/stellar/__init__.py b/src/apps/stellar/__init__.py
index eb8ca62500..a1a032999b 100644
--- a/src/apps/stellar/__init__.py
+++ b/src/apps/stellar/__init__.py
@@ -1,5 +1,6 @@
 from trezor.wire import register, protobuf_workflow
 from trezor.messages.wire_types import StellarGetPublicKey
+from trezor.messages.wire_types import StellarSignTx
 
 
 def dispatch_StellarGetPublicKey(*args, **kwargs):
@@ -7,5 +8,11 @@ def dispatch_StellarGetPublicKey(*args, **kwargs):
     return get_public_key(*args, **kwargs)
 
 
+def dispatch_StellarSignTx(*args, **kwargs):
+    from .sign_tx import sign_tx_loop
+    return sign_tx_loop(*args, **kwargs)
+
+
 def boot():
     register(StellarGetPublicKey, protobuf_workflow, dispatch_StellarGetPublicKey)
+    register(StellarSignTx, protobuf_workflow, dispatch_StellarSignTx)
diff --git a/src/apps/stellar/get_public_key.py b/src/apps/stellar/get_public_key.py
index 4ced0caa70..9bd5958abf 100644
--- a/src/apps/stellar/get_public_key.py
+++ b/src/apps/stellar/get_public_key.py
@@ -49,7 +49,6 @@ def _address_from_public_key(pubkey: bytes):
     address.extend(pubkey)
     address.extend(ustruct.pack("<H", _crc16_checksum(address)))  # checksum
 
-    print(base32.encode(address))
     return base32.encode(address)
 
 
diff --git a/src/apps/stellar/sign_tx.py b/src/apps/stellar/sign_tx.py
new file mode 100644
index 0000000000..e8e03c38bd
--- /dev/null
+++ b/src/apps/stellar/sign_tx.py
@@ -0,0 +1,112 @@
+from trezor.messages.StellarAccountMergeOp import StellarAccountMergeOp
+from trezor.messages.StellarSignTx import StellarSignTx
+from trezor.messages.StellarTxOpRequest import StellarTxOpRequest
+from trezor.messages.StellarSignedTx import StellarSignedTx
+from trezor.messages import wire_types
+from .writers import *
+from ..common import seed
+from trezor.crypto.curve import ed25519
+from trezor.crypto.hashlib import sha256
+
+STELLAR_CURVE = 'ed25519'
+TX_TYPE = bytearray('\x00\x00\x00\x02')
+
+
+async def sign_tx_loop(ctx, msg: StellarSignTx):
+    signer = sign_tx(msg, msg)
+    res = None
+    while True:
+        req = signer.send(res)
+        if isinstance(req, StellarTxOpRequest):
+            res = await ctx.call(req, wire_types.StellarAccountMergeOp)
+        elif isinstance(req, StellarSignedTx):
+            break
+        else:
+            raise TypeError('Invalid Stellar signing instruction')
+    return req
+
+
+async def sign_tx(ctx, msg):
+    network_passphrase_hash = sha256(msg.network_passphrase).digest()
+
+    # Stellar transactions consist of sha256 of:
+    # - sha256(network passphrase)
+    # - 4-byte unsigned big-endian int type constant (2 for tx)
+    # - public key
+
+    w = bytearray()
+    write_bytes(w, network_passphrase_hash)
+    write_bytes(w, TX_TYPE)
+
+    node = await seed.derive_node(ctx, msg.address_n, STELLAR_CURVE)
+    pubkey = seed.remove_ed25519_public_key_prefix(node.public_key())
+    write_pubkey(w, pubkey)
+
+    write_uint32(w, msg.fee)
+    write_uint64(w, msg.sequence_number)
+
+    # timebounds are only present if timebounds_start or timebounds_end is non-zero
+    if msg.timebounds_start or msg.timebounds_end:
+        write_bool(w, True)
+        # timebounds are sent as uint32s since that's all we can display, but they must be hashed as 64bit
+        write_uint64(w, msg.timebounds_start)
+        write_uint64(w, msg.timebounds_end)
+    else:
+        write_bool(w, False)
+
+    write_uint32(w, msg.memo_type)
+    if msg.memo_type == 1:  # nothing is needed for memo_type = 0
+        # Text: 4 bytes (size) + up to 28 bytes
+        write_bytes(w, bytearray(msg.memo_text))  # todo trim to 28 bytes? yes max 28 bytes!
+    elif msg.memo_type == 2:
+        # ID: 64 bit unsigned integer
+        write_uint64(w, msg.memo_id)
+    elif msg.memo_type in [3, 4]:
+        # Hash/Return: 32 byte hash
+        write_bytes(w, bytearray(msg.memo_hash))
+
+    write_uint32(w, msg.num_operations)
+    for i in range(msg.num_operations):
+        op = yield StellarTxOpRequest()
+        # todo ask
+        # todo serialize OP
+        if isinstance(op, StellarAccountMergeOp):
+            serialize_account_merge_op(w, op)
+
+    # # Determine what type of network this transaction is for  - todo used for layout
+    # if msg.network_passphrase == "Public Global Stellar Network ; September 2015":
+    #     network_type = 1
+    # elif msg.network_passphrase == "Test SDF Network ; September 2015":
+    #     network_type = 2
+    # else:
+    #     network_type = 3
+    # # todo use network_type in layout
+
+    # 4 null bytes representing a (currently unused) empty union
+    write_uint32(w, 0)
+
+    # sign
+    # (note that the signature does not include the 4-byte hint since it can be calculated from the public key)
+    digest = sha256(w).digest()
+    signature = ed25519.sign(node.private_key(), digest)
+
+    # Add the public key for verification that the right account was used for signing
+    resp = StellarSignedTx()
+    resp.public_key = pubkey
+    resp.signature = signature
+
+    yield resp
+
+
+def serialize_account_merge_op(w, msg: StellarAccountMergeOp):
+    if not msg.source_account:
+        write_bool(w, False)  # todo move this to stellar_confirmSourceAccount
+    #else: todo ask and hash the address
+    write_uint32(w, 8)  # merge op todo
+    write_pubkey(w, msg.destination_account)
+
+
+def node_derive(root, address_n: list):
+    node = root.clone()
+    node.derive_path(address_n)
+    return node
diff --git a/src/apps/stellar/writers.py b/src/apps/stellar/writers.py
new file mode 100644
index 0000000000..db633b3f96
--- /dev/null
+++ b/src/apps/stellar/writers.py
@@ -0,0 +1,26 @@
+import ustruct
+
+
+def write_uint32(w, n: int):
+    write_bytes(w, ustruct.pack('>L', n))
+
+
+def write_uint64(w, n: int):
+    write_bytes(w, ustruct.pack('>Q', n))
+
+
+def write_bytes(w, buf: bytearray):
+    w.extend(buf)
+
+
+def write_bool(w, val: True):
+    if val:
+        write_uint32(w, 1)
+    else:
+        write_uint32(w, 0)
+
+
+def write_pubkey(w, pubkey: bytes):
+    # first 4 bytes of an address are the type, there's only one type (0)
+    write_uint32(w, 0)
+    write_bytes(w, bytearray(pubkey))