commit 633a65878f024dc686542d1a18171fc58d86a3be
parent 11a8e04dd07f39988a278f907d2d9dd8a9e12949
Author: thomasv <thomasv@gitorious>
Date: Thu, 18 Oct 2012 17:07:27 +0200
SPV example script (first commit)
Diffstat:
| A | scripts/validate_tx | | | 93 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 93 insertions(+), 0 deletions(-)
diff --git a/scripts/validate_tx b/scripts/validate_tx
@@ -0,0 +1,93 @@
+#!/usr/bin/env python
+
+import sys, hashlib
+from electrum import Interface
+
+"""validate a transaction (SPV)"""
+
+
+Hash = lambda x: hashlib.sha256(hashlib.sha256(x).digest()).digest()
+
+def rev_hex(s):
+ return s.decode('hex')[::-1].encode('hex')
+
+def int_to_hex(i, length=1):
+ s = hex(i)[2:].rstrip('L')
+ s = "0"*(2*length - len(s)) + s
+ return rev_hex(s)
+
+
+i = Interface({'server':'ecdsa.org:50002:s'})
+i.start()
+
+
+def get_header(i, block_height):
+ i.send([('blockchain.block.get_header',[block_height])])
+ while True:
+ r = i.responses.get(True, 100000000000)
+ method = r.get('method')
+ if method == 'blockchain.block.get_header':
+ break
+ return r.get('result')
+
+
+
+def get_merkle(i, tx_hash):
+
+ i.send([('blockchain.transaction.get_merkle',[tx_hash])])
+ while True:
+ r = i.responses.get(True, 100000000000)
+ method = r.get('method')
+ if method == 'blockchain.transaction.get_merkle':
+ break
+
+ return r.get('result')
+
+
+def merkle_root(merkle):
+
+ merkle = map (lambda tx_hash: tx_hash.decode('hex')[::-1], merkle)
+ while len(merkle) != 1:
+ if len(merkle)%2: merkle.append( merkle[-1] )
+ n = []
+ while merkle:
+ n.append( Hash( merkle[0] + merkle[1] ) )
+ merkle = merkle[2:]
+
+ merkle = n
+
+ return merkle[0][::-1].encode('hex')
+
+
+def hash_header(res):
+ header = int_to_hex(res.get('version'),4) \
+ + rev_hex(res.get('prev_block_hash')) \
+ + rev_hex(res.get('merkle_root')) \
+ + int_to_hex(int(res.get('timestamp')),4) \
+ + int_to_hex(int(res.get('bits')),4) \
+ + int_to_hex(int(res.get('nonce')),4)
+ return rev_hex(Hash(header.decode('hex')).encode('hex'))
+
+
+def verify_tx(tx_hash):
+ res = get_merkle(i, tx_hash)
+ assert res.get('merkle_root') == merkle_root(res['merkle'])
+ block_height = res.get('block_height')
+ _hash = None
+ for height in range(block_height-10,block_height+10):
+ header = get_header(i, height)
+ if _hash: assert _hash == header.get('prev_block_hash')
+ _hash = hash_header(header)
+ #print _hash
+ if height==block_height:
+ assert header.get('merkle_root') == res.get('merkle_root')
+
+
+
+try:
+ tx = sys.argv[1]
+except:
+ tx = '587430e52af2cec98b3fd543083469ffa7a5f5dd2bd569898a7897a64e2eb031'
+
+verify_tx(tx)
+
