How to generate fingerprint in xpub

Quote from: nc50lc on July 02, 2024, 05:38:15 AM

Quote from: DanielAThompson27@gmail.c on July 02, 2024, 03:54:45 AM

I want to know what the 5183a8d8 in the xpub above is generated based on, is this the fingerprint?

Just get the HASH160 of the compressed public key pair of ECDSA Private key part (without the 'Chain Code') of the "Master Private Key".
Given that your example has an "Extended Public Key" instead, you wont be able to compute the master fingerprint from it.

I'll provide you a valid example:
Descriptor (Master Fingerprint: de651e9f):

Code:

"wpkh([de651e9f/84h/1h/0h]tpubDDDduCzj2qe9kXmasbrKu8CxNG6LoueVcQbeb3mJ9nKC9m2UnwKxGupu83TKhq9EV4RCCXdsf5mVboMh5FBf5AC74PPHXh2fBrP47q7oqHx/1/*)

Descriptor with Master Private Key (private version of the above):

Code:

"wpkh(tprv8ZgxMBicQKsPfMMj4bdRMrXr3RMDCc24Pqqa3TAGHBrqgtSQ6mYnxzHLNPzSJD1m8hv3pEjiu3fYdGTcVzc8WNvfChULWAQAqojcimN4D4h/84'/1'/0'/1/*)

Now to compute the Master Fingerprint:

Decode the base58 tprv above and get the private key (teal colored):

04358394
00
00000000
00000000
f8f8553de856d4e29504423da00dad4067296c782213919c64bb98f41752c66f
00
56a85c89f1df3bd53d00723768357bcb02930b366c13e97170133c12c4344b1f
f9f0b48e

Compute its Compressed Public key pair:
02cd9776ca76833f399a5c0fa7af51edca0b1edaa24a09accc3f7568964fdbb0fc
Compute the HASH160 of the above; RIPEMD160[SHA256(PubKey)]:
de651e9fb4c50f68fe4be1ca9d6bb563a78307ce
Get the first four Bytes of the above (check if it's the same as the Master Fingerprint):
de651e9f

const bitcoin = require('bitcoinjs-lib');
const bip39 = require('bip39');
const bitcoinMessage = require('bitcoinjs-message');

const ecc = require('tiny-secp256k1')
const { BIP32Factory } = require('bip32')
const bip32 = BIP32Factory(ecc)
function computeFingerprintFromXPriv() {
  const mnemonic = "top ritual venue glad soon alcohol annual base tornado invest speak lpke";
  const seed = bip39.mnemonicToSeedSync(mnemonic);
  const network = bitcoin.networks.testnet;
  const root = bip32.fromSeed(seed, network);
  const path = "m/86'/1'/0'";
  const account = root.derivePath(path);
  const xpriv = account.toBase58()
  const extendedPublicKey = account.neutered().toBase58();
  console.log(extendedPublicKey)
  const node = bip32.fromBase58(xpriv,network);
  const compressedPublicKey = node.publicKey;
  const hash160 = bitcoin.crypto.hash160(compressedPublicKey);

  console.log(`Master fingerprint: ${hash160.toString('hex')}`);
  return hash160.toString('hex').substring(0, Cool

;
}

I successfully reproduced it using bitcoinjs of node, but the final result of hash160 does not correspond to the correct result. I don't know why
[133a3b35/86h/1h/0h]tpubDCynnv7orn7ymby6QpWMgw9DwJahdDzzgxARwSd4ipdJ9rv5na4ppub8Pv6346pWtigrNMFrnau uCgcsx1SrtaWqNuELKFGTeZYvAVhX3ES/<0;1;9;10>

The correct result is 133a3b35, but the final output is de404428. I have confirmed that the extended public key is consistent with the extended public key result above, but the fingerprint is different. I don't know why

prvKey: 072439bb6c3508a0b583c781a1fb787d173ea7619866d86a1d32d10be0310fa4
pubKey: 0330104bf9b299b41c775842dc22f26b420ce36e0787104bbc6ce2472f3447f88b
SHA256: 459c1f0d9f68e849dc245a8910763a0752358f2eb9fc3b797032ddc3917e1502
RIPEMD160: de4044283b4e32a35e1adfe6001a24eaf3fa8f76
Fingerprint: de404428