fix SPV.hash_merkle_root, add tests/test_verifier.py

electrum/tests/test_verifier.py

@@ -0,0 +1,78 @@
+# -*- coding: utf-8 -*-
+
+from electrum.bitcoin import hash_encode
+from electrum.transaction import Transaction
+from electrum.util import bfh
+from electrum.verifier import SPV, InnerNodeOfSpvProofIsValidTx
+
+from . import TestCaseForTestnet
+
+
+TST_MBRANCH = [
+    'f2994fd4546086b21b4916b76cf901afb5c4db1c3ecbfc91d6f4cae1186dfe12',
+    '6b65935528311901c7acda7db817bd6e3ce2f05d1c62c385b7caadb65fac7520']
+
+TST_R = '11dbac015b6969ea75509dd1250f33c04ec4d562c2d895de139a65f62f808254'
+
+TEST_T_TX_RAW = ('0200000001cb659c5528311901a7aada'
+                 '7db817bd6e3ce2f05d1c62c385b7caad'
+                 'b65fac75201234000000fabcdefa01ab'
+                 'cd1234010000000405060708fabcdefa')
+
+ORIG_RAISE_IF_VALID_TX = SPV._raise_if_valid_tx
+
+
+class VerifierTestCase(TestCaseForTestnet):
+
+    def test_verify_ok_t_tx(self):
+        '''test vefify ok forged T tx'''
+        assert len(TEST_T_TX_RAW) == 128
+        t_tx = Transaction(TEST_T_TX_RAW)
+        t_tx_hash = t_tx.txid()
+        assert SPV.hash_merkle_root(TST_MBRANCH, t_tx_hash, 3) == TST_R
+
+    def test_verify_ok_f_tx(self):
+        '''test verify ok forged F tx (fake)'''
+        SPV._raise_if_valid_tx = lambda raw_tx: None
+        t_tx = Transaction(TEST_T_TX_RAW)
+        # first 32 bytes of T encoded as hash
+        fake_branch_node = hash_encode(bfh(TEST_T_TX_RAW[:64]))
+        fake_mbranch = [fake_branch_node] + TST_MBRANCH
+        # last 32 bytes of T encoded as hash
+        f_tx_hash = hash_encode(bfh(TEST_T_TX_RAW[64:]))
+        assert SPV.hash_merkle_root(fake_mbranch, f_tx_hash, 7) == TST_R
+        SPV._raise_if_valid_tx = ORIG_RAISE_IF_VALID_TX
+
+    def test_verify_fail_f_tx(self):
+        '''test verify fail forged F tx (fake)'''
+        t_tx = Transaction(TEST_T_TX_RAW)
+        # first 32 bytes of T encoded as hash
+        fake_branch_node = hash_encode(bfh(TEST_T_TX_RAW[:64]))
+        fake_mbranch = [fake_branch_node] + TST_MBRANCH
+        # last 32 bytes of T encoded as hash
+        f_tx_hash = hash_encode(bfh(TEST_T_TX_RAW[64:]))
+        with self.assertRaises(InnerNodeOfSpvProofIsValidTx):
+            assert SPV.hash_merkle_root(fake_mbranch, f_tx_hash, 7) == TST_R
+
+    def test_verify_ok_f_tx_even(self):
+        '''test verify ok forged F tx (fake) with even fake txpos'''
+        SPV._raise_if_valid_tx = lambda raw_tx: None
+        t_tx = Transaction(TEST_T_TX_RAW)
+        # last 32 bytes of T encoded as hash
+        fake_branch_node = hash_encode(bfh(TEST_T_TX_RAW[64:]))
+        fake_mbranch = [fake_branch_node] + TST_MBRANCH
+        # first 32 bytes of T encoded as hash
+        f_tx_hash = hash_encode(bfh(TEST_T_TX_RAW[:64]))
+        assert SPV.hash_merkle_root(fake_mbranch, f_tx_hash, 6) == TST_R
+        SPV._raise_if_valid_tx = ORIG_RAISE_IF_VALID_TX
+
+    def test_verify_fail_f_tx_even(self):
+        '''test verify fail forged F tx (fake) with even fake txpos'''
+        t_tx = Transaction(TEST_T_TX_RAW)
+        # last 32 bytes of T encoded as hash
+        fake_branch_node = hash_encode(bfh(TEST_T_TX_RAW[64:]))
+        fake_mbranch = [fake_branch_node] + TST_MBRANCH
+        # first 32 bytes of T encoded as hash
+        f_tx_hash = hash_encode(bfh(TEST_T_TX_RAW[:64]))
+        with self.assertRaises(InnerNodeOfSpvProofIsValidTx):
+            assert SPV.hash_merkle_root(fake_mbranch, f_tx_hash, 6) == TST_R

electrum/verifier.py

@@ -149,9 +149,10 @@ class SPV(NetworkJobOnDefaultServer):
         for item in merkle_branch_bytes:
             if len(item) != 32:
                 raise MerkleVerificationFailure('all merkle branch items have to 32 bytes long')
-            h = sha256d(item + h) if (index & 1) else sha256d(h + item)
+            inner_node = item + h if index & 1 else h + item
+            cls._raise_if_valid_tx(bh2u(inner_node))
+            h = sha256d(inner_node)
             index >>= 1
-            cls._raise_if_valid_tx(bh2u(h))
         if index != 0:
             raise MerkleVerificationFailure(f'leaf_pos_in_tree too large for branch')
         return hash_encode(h)