How to get address from scriptSig?

Question

I'm looking for a way to get address from scriptSig. I want to know input address. Can you share how to do it? I prefer PHP library but any ways would be appreciated.

e.g.

I use bitwasp, a PHP library. I can see a scriptSig ("483...767") in vin. I want to decode it so that I can get the source addresses.

PHP sample

<?php

require_once 'vendor/autoload.php';

use BitWasp\BitcoinLib\RawTransaction;

$hex = '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';

$tx_data = RawTransaction::decode($hex);
print(json_encode($tx_data));

Output

{
   "txid":"55a8f0d5852745ab2d80358ff4ae6fdbfeab0e4dc94b3474d1c5538e0579bb95",
   "version":"1",
   "vin":[
      {
         "txid":"5941bb5472ce032a2affeac7de616240716da133a4992a05f43601a95f79bbe7",
         "vout":1,
         "scriptSig":{
            "asm":"3045022100f5b10c765ae5116917ddf9b8c4e8d07996b37ad934c005396e7dcda70e7621ee022014cf65f5cc46e229fbcfe7259b3f8c9d0b0c3cd446c4307a8872ad6cc0d538b401 0396f8781a4900372a5d72d84718d146170d5983e67dff8b4a28fef80690c09767",
            "hex":"483045022100f5b10c765ae5116917ddf9b8c4e8d07996b37ad934c005396e7dcda70e7621ee022014cf65f5cc46e229fbcfe7259b3f8c9d0b0c3cd446c4307a8872ad6cc0d538b401210396f8781a4900372a5d72d84718d146170d5983e67dff8b4a28fef80690c09767"
         },
         "sequence":4294967295
      }
   ],
   "vout":[
      {
         "value":"0.00005471",
         "vout":0,
         "scriptPubKey":{
            "asm":"OP_DUP OP_HASH160 3e37de641b25616304415a72bc556824f4420045 OP_EQUALVERIFY OP_CHECKSIG",
            "hex":"76a9143e37de641b25616304415a72bc556824f442004588ac",
            "type":"pubkeyhash",
            "reqSigs":1,
            "hash160":"3e37de641b25616304415a72bc556824f4420045",
            "addresses":[
               "16fypikbjmmfroCHUhDLhczngCfL6BgccH"
            ]
         }
      },
      {
         "value":"0.00000000",
         "vout":1,
         "scriptPubKey":{
            "asm":"OP_RETURN 54f55fe6f2a0f349e2921d06e63d58712a906fbb4231f1e943da82d6",
            "hex":"6a1c54f55fe6f2a0f349e2921d06e63d58712a906fbb4231f1e943da82d6",
            "message":"unable to decode tx type!"
         }
      },
      {
         "value":"0.01260849",
         "vout":2,
         "scriptPubKey":{
            "asm":"OP_DUP OP_HASH160 2f7dcdf7cda481fe0f123d4c62bf830605e9f54d OP_EQUALVERIFY OP_CHECKSIG",
            "hex":"76a9142f7dcdf7cda481fe0f123d4c62bf830605e9f54d88ac",
            "type":"pubkeyhash",
            "reqSigs":1,
            "hash160":"2f7dcdf7cda481fe0f123d4c62bf830605e9f54d",
            "addresses":[
               "15L7U55PAsHLEpQkZqz62e3eqWd9AHb2DH"
            ]
         }
      }
   ],
   "locktime":"0"
}

---

Update 1

The following is a screenshot of blockchain.info

https://blockchain.info/ja/tx/10857ad56f1695559562af8076aea4ccba625ba79a82f75e5658c0c2fa4336c0

I'm wondering how I can get the source address "1J16FUpZsS6My1FqHXpka5fztAnyFsBPf1".

---

Update 2

I found a similar question and retrieving previous transaction was proposed. It may work but I want to decode hex so that it can reduce cost to access bitcoind.

How to get the Input Address from vin where only a txid is given (Insight-Api)

---

Update 3

This is also taking same approach. It may impossible to decode the scriptsig...

How to findout the sender of a transaction

---

Update 4

This explains why it is impossible. Okay I give up decoding scriptsig. I'll retrieve it by txid.

Due to the nature of the pay-to-pubkey script, the script sig does not contain the pubkey anymore (just the signature).

https://stackoverflow.com/questions/29350766/extract-input-address-from-a-namecoin-transaction-given-a-name-operation

---

Update 5 (Solved)

theStack gave me the best answer. Following the answer, I tried it in PHP with Bitwasp.

<?php

require_once 'vendor/autoload.php';

use BitWasp\BitcoinLib\BitcoinLib;
use BitWasp\BitcoinLib\RawTransaction;

$hex = '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';

$tx = RawTransaction::decode($hex);

$asm = explode(' ', $tx['vin'][0]['scriptSig']['asm']);
$address = BitcoinLib::public_key_to_address($asm[1], '00');

print($address); // 15L7U55PAsHLEpQkZqz62e3eqWd9AHb2DHyusaku

Answer 1

The scriptSig needed for spending a P2PKH output (that is, an output of a standard address starting with '1...') consists of two parts, namely the signature and the public key. Looking at your example transaction 10857ad56f1695559562af8076aea4ccba625ba79a82f75e5658c0c2fa4336c0, the public key is 03d7b3bc2d0b4b72a845c469c9fee3c8cf475a2f237e379d7f75a4f463f7bd6ebd:

From this you can derive the address by first applying the HASH-160 (where HASH-160(x) = RIPEMD-160(SHA-256(x))), then adding network byte (prefix) and checksum (postfix), and finally converting the whole data into Base58 format. The detailed process of converting a public key to an address is described here: https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

Though you probably have Bitcoin libraries doing the dirty work, the following small Python script converts the public key to the address:

 #!/usr/bin/env python
 from hashlib import *
 from base58 import *

def SHA256D(bstr):
    return sha256(sha256(bstr).digest()).digest()

def ConvertPKHToAddress(prefix, addr):
    data = prefix + addr
    return b58encode(data + SHA256D(data)[:4])

def PubkeyToAddress(pubkey_hex):
    pubkey = bytearray.fromhex(pubkey_hex)
    round1 = sha256(pubkey).digest()
    h = new('ripemd160')
    h.update(round1)
    pubkey_hash = h.digest()
    return ConvertPKHToAddress(b'\x00', pubkey_hash)

pubkey = "03d7b3bc2d0b4b72a845c469c9fee3c8cf475a2f237e379d7f75a4f463f7bd6ebd"
print("Address: %s" % PubkeyToAddress(pubkey))

This leads to the following expected result:

$ ./pubkey_to_script.py
Address: 1J16FUpZsS6My1FqHXpka5fztAnyFsBPf1