Crypto Flexs
  • DIRECTORY
  • CRYPTO
    • ETHEREUM
    • BITCOIN
    • ALTCOIN
  • BLOCKCHAIN
  • EXCHANGE
  • ADOPTION
  • TRADING
  • HACKING
  • SLOT
  • TRADE
Crypto Flexs
  • DIRECTORY
  • CRYPTO
    • ETHEREUM
    • BITCOIN
    • ALTCOIN
  • BLOCKCHAIN
  • EXCHANGE
  • ADOPTION
  • TRADING
  • HACKING
  • SLOT
  • TRADE
Crypto Flexs
Home»BITCOIN NEWS»sha256 – Compute block header hash
BITCOIN NEWS

sha256 – Compute block header hash

By Crypto FlexsNovember 29, 20232 Mins Read
Facebook Twitter Pinterest LinkedIn Tumblr Email
sha256 – Compute block header hash
Share
Facebook Twitter LinkedIn Pinterest Email

I use the following code to calculate the header hash:

function serializeBlockHeader(blockHeader) 
    const version = Buffer.alloc(4);
    version.writeUInt32LE(blockHeader.version);
    console.log('version length', version.length, version)

    const previousBlockHash = Buffer.from(blockHeader.previousblockhash, 'hex').reverse();
    console.log('previousBlockHash length', previousBlockHash.length, previousBlockHash)

    const merkleRoot = Buffer.from(blockHeader.merkleroot, 'hex').reverse();
    console.log('merkleRoot length', merkleRoot.length, merkleRoot)


    const time = Buffer.alloc(4);
    time.writeUInt32LE(blockHeader.time);
    console.log('time length', time.length, time)

    const bits = Buffer.from(blockHeader.bits, 'hex').reverse();
    console.log('bits length', bits.length, bits)


    const nonce = Buffer.alloc(4);
    nonce.writeUInt32LE(blockHeader.nonce);
    console.log('nonce length', nonce.length, nonce)

    const headerBuffer = Buffer.concat((
        version,
        previousBlockHash,
        merkleRoot,
        time,
        bits,
        nonce
    ));

    return headerBuffer.toString('hex');


function hash256(hexStr) 
    const data = Buffer.from(hexStr, 'hex')
    const hash1 = crypto.createHash('sha256').update(data).digest();
    const hash2 = crypto.createHash('sha256').update(hash1).digest();
    return hash2.toString('hex');


client.getBlockHash(600000) 
  .then((blockHash) => 
    client.getBlockHeader(blockHash)
      .then((blockHeader) => 
        console.log('Block Header:', blockHeader);
        const headerBytes = serializeBlockHeader(blockHeader)
        console.log("headerBytes", headerBytes)
        
        console.log('header hash:', hash256(headerBytes))
      )
      .catch((err) => 
        console.error('Error getting block header:', err);
      );
  )
  .catch((err) => 
    console.error('Error getting block hash:', err);
  );

The output is

Block Header: (Object: null prototype) 
  hash: '00000000000000000007316856900e76b4f7a9139cfbfba89842c8d196cd5f91',
  confirmations: 153235,
  height: 600000,
  version: 536870912,
  versionHex: '20000000',
  merkleroot: '66b7c4a1926b41ceb2e617ddae0067e7bfea42db502017fde5b695a50384ed26',
  time: 1571443461,
  mediantime: 1571440177,
  nonce: 1066642855,
  bits: '1715a35c',
  difficulty: '13008091666971.9',
  chainwork: '00000000000000000000000000000000000000000962281c680c87bdb11f440b',
  nTx: 1925,
  previousblockhash: '00000000000000000003ecd827f336c6971f6f77a0b9fba362398dd867975645',
  nextblockhash: '00000000000000000000817313d6b5fe4838ec6eff47fbe7c4b9f22a40c2a4f4'

version length 4 <Buffer 00 00 00 20>
previousBlockHash length 32 <Buffer 45 56 97 67 d8 8d 39 62 a3 fb b9 a0 77 6f 1f 97 c6 36 f3 27 d8 ec 03 00 00 00 00 00 00 00 00 00>
merkleRoot length 32 <Buffer 26 ed 84 03 a5 95 b6 e5 fd 17 20 50 db 42 ea bf e7 67 00 ae dd 17 e6 b2 ce 41 6b 92 a1 c4 b7 66>
time length 4 <Buffer 05 53 aa 5d>
bits length 4 <Buffer 5c a3 15 17>
nonce length 4 <Buffer a7 ad 93 3f>
headerBytes 0000002045569767d88d3962a3fbb9a0776f1f97c636f327d8ec0300000000000000000026ed8403a595b6e5fd172050db42eabfe76700aedd17e6b2ce416b92a1c4b7660553aa5d5ca31517a7ad933f
header hash: 915fcd96d1c84298a8fbfb9c13a9f7b4760e9056683107000000000000000000
reverse hash: 00000000000000000007316856900e76b4f7a9139cfbfba89842c8d196cd5f91

Why do I need to invert the result of a double hash to get the correct header hash?

Share. Facebook Twitter Pinterest LinkedIn Tumblr Email

Related Posts

Sequans starts $ 384M Bitcoin Treasury Initiative with Swan Bitcoin Partnership.

June 23, 2025

ECB Chairman Lagarde aims to seize the global order to strengthen the Euro’s global position.

June 17, 2025

Bitcoin aims for $ 115K after US CPI data prefers investors.

June 11, 2025
Add A Comment

Comments are closed.

Recent Posts

Checkpoint #4: Berlinterop | Ether Leeum Foundation Blog

June 28, 2025

TRON Price Propects USDT supply exceeded $ 80 billion

June 28, 2025

Stablecoin startups surpass 2021 venture capital peaks as institutional money spills.

June 28, 2025

No Altcoin Season 2025 ? Why Bitcoin Dominance Is Holding Strong In The Crypto Market

June 28, 2025

Why It Matters For Every Crypto Investor

June 27, 2025

Why It Matters For Every Crypto Investor

June 27, 2025

Safe smart account audit summary

June 27, 2025

CARV’s New Roadmap Signals Next Wave Of Web3 AI

June 27, 2025

CARV’s New Roadmap Signals Next Wave Of Web3 AI

June 27, 2025

Bybit Expands Global Reach With Credit Card Crypto Purchases In 25+ Currencies And Cashback Rewards

June 27, 2025

BYDFi Joins Seoul Meta Week 2025, Advancing Web3 Vision And South Korea Strategy

June 27, 2025

Crypto Flexs is a Professional Cryptocurrency News Platform. Here we will provide you only interesting content, which you will like very much. We’re dedicated to providing you the best of Cryptocurrency. We hope you enjoy our Cryptocurrency News as much as we enjoy offering them to you.

Contact Us : Partner(@)Cryptoflexs.com

Top Insights

Checkpoint #4: Berlinterop | Ether Leeum Foundation Blog

June 28, 2025

TRON Price Propects USDT supply exceeded $ 80 billion

June 28, 2025

Stablecoin startups surpass 2021 venture capital peaks as institutional money spills.

June 28, 2025
Most Popular

AI Token Surges, Market Dazzles in Amazing Rally – Blockchain News, Opinion, TV & Jobs

February 24, 2024

Bitcoin falls below $40,000 amid BTC ETF selling

January 22, 2024

SOL price has crossed the $200 milestone. What’s next for Solana?

March 18, 2024
  • Home
  • About Us
  • Contact Us
  • Disclaimer
  • Privacy Policy
  • Terms and Conditions
© 2025 Crypto Flexs

Type above and press Enter to search. Press Esc to cancel.