Verify Merkle Root of 7 Transactions

This section describes how to verify the Merkle Root of 7 transactions in a Bitcoin block.

Now let's try a block with more transactions.

Get the block # 500 from Bitcoin Test Network:

C:\>\local\bitcoin-0.15.1\bin\bitcoin-cli -testnet getblockhash 500
00000000a2424460c992803ed44cfe0c0333e91af04fde9a6a97b468bf1b5f70

C:\>\local\bitcoin-0.15.1\bin\bitcoin-cli -testnet getblock
   00000000a2424460c992803ed44cfe0c0333e91af04fde9a6a97b468bf1b5f70

   ...
  "height": 500,
  "merkleroot": 
     "dd3f288510dd3b632940bd3fb1db162d3ff99b19ddb0c586cfa3ac9a76d42517",
  "tx": [
    "a647d0c4112b4727f3c856782ff6bbaf099be929b27214a8e0dfedee4383eb68", 
    "24b8a4c788b8c805b810438ddd99e569e184ff20f4394ac49a6d832e69f57242", 
    "c5ffd70c3bc4998465cef55ed6d5d831ab3a550406423eb611117ed8ee41c278", 
    "4692772a73ea834c836915089acf97f2c790380a2b8fd32f82729da72545d8c5", 
    "82d6d88081e3e0eb36730f7f3aedb17228142b9e00a6dbaab4b53b798d0742c1", 
    "fc407d7a3b819daa5cf1ecc2c2a4b103c3782104d1425d170993bd534779a0da", 
    "95ad3ffb2a9426d6f5f5b97a134d90153ae16c9375f74eb385f481cff2771d77"
  ],
  ...

Here is my Python script and test result:

C:\>type Merkle-Root-Hash-of-Test-500.py
#- Merkle-Root-Hash-of-Test-500.py
#- Copyright (c) 2018, HerongYang.com, All Rights Reserved.

import hashlib
import binascii
 
def doubleSha256(hex): 
   bin = binascii.unhexlify(hex)
   hash = hashlib.sha256(bin).digest()
   hash2 = hashlib.sha256(hash).digest()
   return binascii.hexlify(hash2)

# Getting transaction hashes from blockexplorer
h1 = "a647d0c4112b4727f3c856782ff6bbaf099be929b27214a8e0dfedee4383eb68" 
h2 = "24b8a4c788b8c805b810438ddd99e569e184ff20f4394ac49a6d832e69f57242" 
h3 = "c5ffd70c3bc4998465cef55ed6d5d831ab3a550406423eb611117ed8ee41c278" 
h4 = "4692772a73ea834c836915089acf97f2c790380a2b8fd32f82729da72545d8c5" 
h5 = "82d6d88081e3e0eb36730f7f3aedb17228142b9e00a6dbaab4b53b798d0742c1" 
h6 = "fc407d7a3b819daa5cf1ecc2c2a4b103c3782104d1425d170993bd534779a0da" 
h7 = "95ad3ffb2a9426d6f5f5b97a134d90153ae16c9375f74eb385f481cff2771d77"

# Converting them in little-endian hex notation
h1 = binascii.hexlify(binascii.unhexlify(h1)[::-1])
h2 = binascii.hexlify(binascii.unhexlify(h2)[::-1])
h3 = binascii.hexlify(binascii.unhexlify(h3)[::-1])
h4 = binascii.hexlify(binascii.unhexlify(h4)[::-1])
h5 = binascii.hexlify(binascii.unhexlify(h5)[::-1])
h6 = binascii.hexlify(binascii.unhexlify(h6)[::-1])
h7 = binascii.hexlify(binascii.unhexlify(h7)[::-1])

# Rount #1 
h1 = doubleSha256(h1+h2)
h2 = doubleSha256(h3+h4)
h3 = doubleSha256(h5+h6)
h4 = doubleSha256(h7+h7)

# Rount #2
h1 = doubleSha256(h1+h2)
h2 = doubleSha256(h3+h4)

# Rount #3
hash = doubleSha256(h1+h2)

# Converting result to big-endian hex notation
root = binascii.hexlify(binascii.unhexlify(hash)[::-1])
root = str(root,"ascii")

# Comparing with Merkle Root on Bitcoin Core
exp = "dd3f288510dd3b632940bd3fb1db162d3ff99b19ddb0c586cfa3ac9a76d42517";
print("Match the Bitcoin network: "+str(root==exp))
print("Merkle Root:\n   "+root)

C:\>Python Merkle-Root-Hash-of-testnet-500.py
Match the Bitcoin network: True
Merkle Root:
   dd3f288510dd3b632940bd3fb1db162d3ff99b19ddb0c586cfa3ac9a76d42517

Cool. You should be able to make a generic script to verify the Merkle Root of any Bitcoin block now.

Last update: 2018.

Table of Contents

 About This Book

 Introduction of Bitcoin

 Bitcoin Blockchain

 Bitcoin Wallet

 Bitcoin Core

 Bitcoin Transaction

 Bitcoin-Qt - Bitcoin Core GUI

 Bitcoin Mining

 Bitcoin Consensus Rules

Bitcoin Block Data Structure

 Data Components of Bitcoin Block

 Data Properties of Bitcoin Block

 Merkle Root of Bitcoin Block

 Calculate Double-SHA256 Hash with Python

 Verify Merkle Root of 2 Transactions

Verify Merkle Root of 7 Transactions

 Data Structure of Bitcoin Block

 "getblock blockhash 0" - Serialized Hex Block Data

 Block Hash Calculation Algorithm

 Block Hash Calculation in Python

 Calculate Double-SHA256 Hash with Java

 Bitcoin Transaction Data Structure

 blockexplorer.com API

 Copay - Bitcoin Wallet

 References

 PDF Printing Version