script for signing a Bitcoin transaction

src/example-sign-transaction.js

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+/**
+ * Example: Signing a Bitcoin transaction using bitcoinjs-lib
+ *
+ * This demo creates a dummy transaction, signs it using a random private key,
+ * and prints both the raw transaction hex and the public address.
+ */
+
+import * as bitcoin from 'bitcoinjs-lib';
+import { ECPairFactory } from 'ecpair';
+import * as tinysecp from 'tiny-secp256k1';
+
+const ECPair = ECPairFactory(tinysecp);
+
+export function signExampleTx() {
+  const keyPair = ECPair.makeRandom();
+  const { address } = bitcoin.payments.p2wpkh({ pubkey: keyPair.publicKey });
+
+  // Create a fake transaction
+  const psbt = new bitcoin.Psbt({ network: bitcoin.networks.testnet });
+  psbt.addInput({
+    hash: 'ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
+    index: 0,
+    witnessUtxo: {
+      script: bitcoin.payments.p2wpkh({ pubkey: keyPair.publicKey }).output,
+      value: 10_000,
+    },
+  });
+  psbt.addOutput({
+    address: address,
+    value: 9_000,
+  });
+
+  // Sign & finalize
+  psbt.signAllInputs(keyPair);
+  psbt.finalizeAllInputs();
+
+  const txHex = psbt.extractTransaction().toHex();
+  console.log('Signed transaction (hex):', txHex);
+  console.log('Sender address:', address);
+  return txHex;
+}
+
+// Uncomment below for direct testing
+// signExampleTx();