Verification

To verify the output, you can use the following code. Put the fields that you get in the required format, and match the serialized transaction that comes as the output.

Below is the Python program to verify the serialized transaction:

Python

import hashlib
import struct
import json

def serialize_tx(transaction):
    serialized = b""
    
    # Version
    serialized += struct.pack("<L", transaction["version"])  

    # Input count
    serialized += encode_varint(len(transaction["vin"]))  
    for inp in transaction["vin"]:
      
        # TXID in little-endian format
        txid_bytes = bytes.fromhex(inp["txid"])[::-1]  
        serialized += txid_bytes
        
        # Output index
        serialized += struct.pack("<L", inp["vout"])  
        
        # ScriptSig
        scriptsig_bytes = bytes.fromhex(inp.get("scriptsig", ""))
        
        # Script length
        serialized += encode_varint(len(scriptsig_bytes))  
        serialized += scriptsig_bytes
        
        # Sequence
        serialized += struct.pack("<L", inp["sequence"])  

    # Output count    
    serialized += encode_varint(len(transaction["vout"]))  
    for out in transaction["vout"]:
      
        # Output value
        serialized += struct.pack("<Q", out["value"])  
        
        # ScriptPubKey
        scriptpubkey_bytes = bytes.fromhex(out["scriptpubkey"])
        
        # ScriptPubKey size
        serialized += encode_varint(len(scriptpubkey_bytes))  
        serialized += scriptpubkey_bytes

    # Locktime
    serialized += struct.pack("<L", transaction["locktime"])  

    txid = hashlib.sha256(hashlib.sha256(serialized).digest()).digest()[::-1].hex()

    return serialized


def compact_size(value):
    if value < 0xFD:
        return value.to_bytes(1, "little")
    elif value <= 0xFFFF:
        return b"\xfd" + value.to_bytes(2, "little")
    elif value <= 0xFFFFFFFF:
        return b"\xfe" + value.to_bytes(4, "little")
    else:
        return b"\xff" + value.to_bytes(8, "little")


def encode_varint(n):
    if n < 0xFD:
        return struct.pack("<B", n)
    elif n <= 0xFFFF:
        return b"\xfd" + struct.pack("<H", n)
    elif n <= 0xFFFFFFFF:
        return b"\xfe" + struct.pack("<I", n)
    else:
        return b"\xff" + struct.pack("<Q", n)

# Example transaction
transaction = {
  "version": 1,
  "locktime": 0,
  "vin": [
    {
      "txid": "3b239ad258a308129049df85c03f97bd4f57b99825174ad2a50509a08ec2a2b9",
      "vout": 0,
      "prevout": {
        "scriptpubkey": "a914423877331b30a905240c7e1f2adee4ebaa47c5f687",
        "scriptpubkey_asm": "OP_HASH160 OP_PUSHBYTES_20 423877331b30a905240c7e1f2adee4ebaa47c5f6 OP_EQUAL",
        "scriptpubkey_type": "p2sh",
        "scriptpubkey_address": "37jAAWEdJ9D9mXybRobcveioxSkt7Lkwog",
        "value": 2504928
      },
      "scriptsig": "16001415ff0337937ecadd10ce56ffdfd4674817613223",
      "scriptsig_asm": "OP_PUSHBYTES_22 001415ff0337937ecadd10ce56ffdfd4674817613223",
      "witness": [
        "3044022037656a38eff538cb3ccdcd4f47ca80118bcfd60414363b7bc08b1469adedece902206f182c48452cf2b6e6897b03354ed32d0357fc3607f5089b509fef17c498a5cd01",
        "035658f6dd92339165f76caff02f63316433c4b68a247d40b1b323fb1690279e42"
      ],
      "is_coinbase": False,
      "sequence": 4294967280,
      "inner_redeemscript_asm": "OP_0 OP_PUSHBYTES_20 15ff0337937ecadd10ce56ffdfd4674817613223"
    },
    {
      "txid": "4f382663a4491570c2e01a4a5ae4cfcd3b11b52ed2124947816dba9f09e71584",
      "vout": 1,
      "prevout": {
        "scriptpubkey": "a914423877331b30a905240c7e1f2adee4ebaa47c5f687",
        "scriptpubkey_asm": "OP_HASH160 OP_PUSHBYTES_20 423877331b30a905240c7e1f2adee4ebaa47c5f6 OP_EQUAL",
        "scriptpubkey_type": "p2sh",
        "scriptpubkey_address": "37jAAWEdJ9D9mXybRobcveioxSkt7Lkwog",
        "value": 58711992
      },
      "scriptsig": "16001415ff0337937ecadd10ce56ffdfd4674817613223",
      "scriptsig_asm": "OP_PUSHBYTES_22 001415ff0337937ecadd10ce56ffdfd4674817613223",
      "witness": [
        "3044022040a303cd51c50bdf296e89661f8bb3ea411d639c5149cab461a63855d5bf97c502207ac0ce4133e22daba97abc5d65f219c49cea1959247ec398c9c6eaceb4fcd9d801",
        "035658f6dd92339165f76caff02f63316433c4b68a247d40b1b323fb1690279e42"
      ],
      "is_coinbase": False,
      "sequence": 4294967280,
      "inner_redeemscript_asm": "OP_0 OP_PUSHBYTES_20 15ff0337937ecadd10ce56ffdfd4674817613223"
    }
  ],
  "vout": [
    {
      "scriptpubkey": "76a91471a3d2f54b0917dc9d2c877b2861ac52967dec7f88ac",
      "scriptpubkey_asm": "OP_DUP OP_HASH160 OP_PUSHBYTES_20 71a3d2f54b0917dc9d2c877b2861ac52967dec7f OP_EQUALVERIFY OP_CHECKSIG",
      "scriptpubkey_type": "p2pkh",
      "scriptpubkey_address": "1BMscNZbFKdUDYi3bnF5XEmkWT3WPmRBDJ",
      "value": 28278016
    },
    {
      "scriptpubkey": "a914423877331b30a905240c7e1f2adee4ebaa47c5f687",
      "scriptpubkey_asm": "OP_HASH160 OP_PUSHBYTES_20 423877331b30a905240c7e1f2adee4ebaa47c5f6 OP_EQUAL",
      "scriptpubkey_type": "p2sh",
      "scriptpubkey_address": "37jAAWEdJ9D9mXybRobcveioxSkt7Lkwog",
      "value": 32928544
    }
  ]
}

Serialized=serialize_tx(transaction)
print("Serialized Transaction : ", Serialized.hex())
txid = hashlib.sha256(hashlib.sha256(serialize_tx(transaction)).digest()).digest()[::-1].hex()
print("TXID of transaction : ", txid)

Output:

The output is the same serialized transaction that we took in the beginning to deserialize.

Serialized Transaction

How to Decode Input Data from a Transaction?

When transactions are transmitted over the network or exchanged between applications, they are serialized. Serialization is most commonly used for encoding data structures for transmission over a network or for storage in a file. The serialization format of a transaction output is shown in Transaction output serialization. This article focuses on discussing steps to decode input data from a transaction.

Table of Content

What is Serialization?
Raw Bitcoin Transaction
Format of Various Fields in Serialized Transaction
Decoding the Transaction
Detailed Explanation
Verification
Conclusion

Verification

How to Decode Input Data from a Transaction?

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