4 from electrum import Interface
6 """validate a transaction (SPV)"""
9 Hash = lambda x: hashlib.sha256(hashlib.sha256(x).digest()).digest()
12 return s.decode('hex')[::-1].encode('hex')
14 def int_to_hex(i, length=1):
15 s = hex(i)[2:].rstrip('L')
16 s = "0"*(2*length - len(s)) + s
20 i = Interface({'server':'ecdsa.org:50002:s'})
24 def get_header(i, block_height):
25 i.send([('blockchain.block.get_header',[block_height])])
27 r = i.responses.get(True, 100000000000)
28 method = r.get('method')
29 if method == 'blockchain.block.get_header':
31 return r.get('result')
35 def get_merkle(i, tx_hash):
37 i.send([('blockchain.transaction.get_merkle',[tx_hash])])
39 r = i.responses.get(True, 100000000000)
40 method = r.get('method')
41 if method == 'blockchain.transaction.get_merkle':
44 return r.get('result')
47 def merkle_root(merkle):
49 merkle = map (lambda tx_hash: tx_hash.decode('hex')[::-1], merkle)
50 while len(merkle) != 1:
51 if len(merkle)%2: merkle.append( merkle[-1] )
54 n.append( Hash( merkle[0] + merkle[1] ) )
59 return merkle[0][::-1].encode('hex')
63 header = int_to_hex(res.get('version'),4) \
64 + rev_hex(res.get('prev_block_hash')) \
65 + rev_hex(res.get('merkle_root')) \
66 + int_to_hex(int(res.get('timestamp')),4) \
67 + int_to_hex(int(res.get('bits')),4) \
68 + int_to_hex(int(res.get('nonce')),4)
69 return rev_hex(Hash(header.decode('hex')).encode('hex'))
72 def verify_tx(tx_hash):
73 res = get_merkle(i, tx_hash)
74 assert tx_hash in res.get('merkle')
75 assert res.get('merkle_root') == merkle_root(res['merkle'])
76 block_height = res.get('block_height')
78 for height in range(block_height-10,block_height+10):
79 header = get_header(i, height)
80 if _hash: assert _hash == header.get('prev_block_hash')
81 _hash = hash_header(header)
83 if height==block_height:
84 assert header.get('merkle_root') == res.get('merkle_root')
91 tx = '587430e52af2cec98b3fd543083469ffa7a5f5dd2bd569898a7897a64e2eb031'