text: # -*- coding: utf-8 -*-
  
  from electrum_onion.bitcoin import hash_encode
  from electrum_onion.transaction import Transaction
  from electrum_onion.util import bfh
  from electrum_onion.verifier import SPV, InnerNodeOfSpvProofIsValidTx
  
  from . import TestCaseForTestnet
  
  
  MERKLE_BRANCH = [
      'f2994fd4546086b21b4916b76cf901afb5c4db1c3ecbfc91d6f4cae1186dfe12',
      '6b65935528311901c7acda7db817bd6e3ce2f05d1c62c385b7caadb65fac7520']
  
  MERKLE_ROOT = '11dbac015b6969ea75509dd1250f33c04ec4d562c2d895de139a65f62f808254'
  
  VALID_64_BYTE_TX = ('0200000001cb659c5528311901a7aada7db817bd6e3ce2f05d1c62c385b7caad'
                      'b65fac75201234000000fabcdefa01abcd1234010000000405060708fabcdefa')
  assert len(VALID_64_BYTE_TX) == 128
  
  
  class VerifierTestCase(TestCaseForTestnet):
      # these tests are regarding the attack described in
      # https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2018-June/016105.html
  
      def test_verify_ok_t_tx(self):
          """Actually mined 64 byte tx should not raise."""
          t_tx = Transaction(VALID_64_BYTE_TX)
          t_tx_hash = t_tx.txid()
          self.assertEqual(MERKLE_ROOT, SPV.hash_merkle_root(MERKLE_BRANCH, t_tx_hash, 3))
  
      def test_verify_fail_f_tx_odd(self):
          """Raise if inner node of merkle branch is valid tx. ('odd' fake leaf position)"""
          # first 32 bytes of T encoded as hash
          fake_branch_node = hash_encode(bfh(VALID_64_BYTE_TX[:64]))
          fake_mbranch = [fake_branch_node] + MERKLE_BRANCH
          # last 32 bytes of T encoded as hash
          f_tx_hash = hash_encode(bfh(VALID_64_BYTE_TX[64:]))
          with self.assertRaises(InnerNodeOfSpvProofIsValidTx):
              SPV.hash_merkle_root(fake_mbranch, f_tx_hash, 7)
  
      def test_verify_fail_f_tx_even(self):
          """Raise if inner node of merkle branch is valid tx. ('even' fake leaf position)"""
          # last 32 bytes of T encoded as hash
          fake_branch_node = hash_encode(bfh(VALID_64_BYTE_TX[64:]))
          fake_mbranch = [fake_branch_node] + MERKLE_BRANCH
          # first 32 bytes of T encoded as hash
          f_tx_hash = hash_encode(bfh(VALID_64_BYTE_TX[:64]))
          with self.assertRaises(InnerNodeOfSpvProofIsValidTx):
              SPV.hash_merkle_root(fake_mbranch, f_tx_hash, 6)
  