programming_bitcoin

🌅 Getting Started

Dependencies

Required

• rustc 1.69.0-nightly
  • to change to nighhtly version only on the current folder rustup override set nightly
• Cargo

🚀 Usage

How to create public/private keys

  let secret = BigInt::from(12345); // this should be a really large number
  let p = PrivateKey::new(e);

How to create a signature / verification

  let passphrase = "Programming Bitcoin!";
  let p = PrivateKey::new(PrivateKey::generate_secret(passphrase));
  let signature_hash = Signature::signature_hash(passphrase);
  let sig = p.sign(&signature_hash, None);
  p.point.verify(&signature_hash, sig)

How to create a private key and get the a valid compressed address for the testnet

  let passphrase = "[email protected] my secret";
  let p = PrivateKey::new(PrivateKey::generate_secret(passphrase));
  priva.point.address(Some(true), Some(true))  // mzzLk9MmXzmjCBLgjoeNDxrbdrt511t5Gm

• If the generated address is valid, it is possible to send some testnet coins to it.
• It is possible to use this service to test if the address is valid and send some testnet coins: https://testnet-faucet.com/btc-testnet/
• An example using the previous generated address: https://live.blockcypher.com/btc-testnet/address/mzzLk9MmXzmjCBLgjoeNDxrbdrt511t5Gm/

How to create script_pubkey, script_sig and evaluate the combined script

  let z = Signature::signature_hash_from_hex(
      "7c076ff316692a3d7eb3c3bb0f8b1488cf72e1afcd929e29307032997a838a3d",
  );
  let sec = "04887387e452b8eacc4acfde10d9aaf7f6d9a0f975aabb10d006e4da568744d06c61de6d95231cd89026e286df3b6ae4a894a3378e393e93a0f45b666329a0ae34";
  let sec_encode = hex::decode(sec).unwrap();
  let sig = "3045022000eff69ef2b1bd93a66ed5219add4fb51e11a840f404876325a1e8ffe0529a2c022100c7207fee197d27c618aea621406f6bf5ef6fca38681d82b2f06fddbdce6feab6";
  let sig_encode = hex::decode(sig).unwrap();
  let cmd = vec![
      Command::Element(sec_encode),
      Command::Operation(op::parse_raw_op_codes(0xac)), //OpChecksig
  ];
  let script_pubkey = Script::new(Some(cmd));
  let script_sig = Script::new(Some(vec![Command::Element(sig_encode)]));
  let combined_script = script_sig + script_pubkey;
  assert!(combined_script.evaluate(z))

How to create a raw TX

The first step is to define one or more inputs from where the coins have to come. It is also necessary to define which index has to be used:

  let prev_tx_faucet =
      hex::decode("177546b0d70663917f9dbe3dc6ddf05289d0a43d6cd721bf79f62581bc75a1cc")
          .unwrap();
  let prev_tx_faucet_index = BigInt::from(0);
  let prev_tx_ex4 =
      hex::decode("3fd155536987271e0f94358e9fa2e135bb620981ea8dbe8e60645d0daa2ffe3b")
          .unwrap();
  let prev_tx_ex4_index = BigInt::from(1);
  let mut tx_ins: Vec<TxIn> = Vec::new();
  tx_ins.push(TxIn::new(prev_tx_faucet, prev_tx_faucet_index, None, None));
  tx_ins.push(TxIn::new(prev_tx_ex4, prev_tx_ex4_index, None, None));

Then it is necessary to define the output or the outputs where we want to send the coins, and the ammount to transfer.

  let target_address = "mzzLk9MmXzmjCBLgjoeNDxrbdrt511t5Gm";
  let target_amount = 0.01728903;
  let mut tx_outs: Vec<TxOut> = Vec::new();
  let h160 = utils::decode_base58(target_address);
  let script_pubkey = utils::p2pkh_script(h160);
  let target_satoshis = BigInt::from((target_amount * 100_000_000_f64) as u64);
  tx_outs.push(TxOut::new(target_satoshis, script_pubkey));

After the input and output lists are ready, we can create a TX struct almost ready to be broadcasted.

  let mut tx_obj = Tx::new(BigInt::from(1), tx_ins, tx_outs, BigInt::from(0), true);

The last step is to sign each input. For this step is necessary to use the pair (private key) of the public key defined on the inputs (the outputs of previous TX) in which we were the recipients.

let secret = "[email protected] my secret";
let priva = PrivateKey::new(&PrivateKey::generate_secret(secret));
assert!(tx_obj.sign_input(0, priva.clone()));
assert!(tx_obj.sign_input(1, priva.clone()));

Finally, we can get the serialized TX ready for broadcasting.

  hex::encode(tx_obj.serialize())

Some useful links:

• An online TX decode
• For broadcast the TX

Testing

cargo test

TODOs

• implement deterministic_k
• using this simple service for checking the fee: https://blockstream.info/api/tx/d1c789a9c60383bf715f3f6ad9d14b91fe55f3deb369fe5d9280cb1a01793f81/hex
• update TX version to u32