Finalize & Extract

The finalize_and_extract function performs final validation and produces the raw transaction bytes ready to broadcast to the Zcash network.

Prerequisites

Before finalization, ensure:

✅ All transparent inputs are signed
✅ All Orchard proofs are generated

const info = t2z.inspect_pczt(pczt.to_hex());

if (!info.all_inputs_signed) {
  throw new Error('Not all inputs signed');
}
if (!info.has_orchard_proofs) {
  throw new Error('Orchard proofs not generated');
}

Function Signature

TypeScript
Go
Kotlin

// Get raw bytes
function finalize_and_extract(pczt: WasmPczt): Uint8Array

// Get hex string (convenient for broadcasting)
function finalize_and_extract_hex(pczt: WasmPczt): string

func FinalizeAndExtract(pczt *Pczt) ([]byte, error)
func FinalizeAndExtractHex(pczt *Pczt) (string, error)

fun finalizeAndExtract(pczt: Pczt): ByteArray
fun finalizeAndExtractHex(pczt: Pczt): String

Basic Usage

TypeScript
Go
Kotlin

// Get transaction as hex (most common)
const txHex = t2z.finalize_and_extract_hex(pczt);
console.log('Transaction ready:', txHex.length / 2, 'bytes');

// Or get raw bytes
const txBytes = t2z.finalize_and_extract(pczt);

txHex, err := t2z.FinalizeAndExtractHex(pczt)
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Transaction ready: %d bytes\n", len(txHex)/2)

val txHex = finalizeAndExtractHex(pczt)
println("Transaction ready: ${txHex.length / 2} bytes")

What Happens During Finalization

Spend Finalizer

Assembles final script signatures from partial signatures.

Validation

Verifies all required data is present and valid.

Transaction Extractor

Converts the PCZT into a raw Zcash transaction.

Serialization

Produces the final byte representation.

Broadcasting the Transaction

After extraction, broadcast the transaction to the Zcash network:

Using zcash-cli

zcash-cli sendrawtransaction "0500000..."

Using lightwalletd

// gRPC to lightwalletd
const response = await lightwalletClient.sendTransaction({
  data: hexToBytes(txHex)
});
console.log('Txid:', response.txid);

Using a Block Explorer

Many block explorers provide a “Broadcast” or “Push TX” feature where you can paste the raw transaction hex.

Using JSON-RPC

const response = await fetch('https://zcash-rpc.example.com', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    jsonrpc: '2.0',
    method: 'sendrawtransaction',
    params: [txHex],
    id: 1
  })
});

Complete Example

import * as t2z from '@d4mr/t2z-wasm';

async function buildAndBroadcast() {
  // 1. Create PCZT
  let pczt = t2z.propose_transaction(inputs, payments, changeAddr, network, expiry);
  
  // 2. Sign all inputs
  for (let i = 0; i < inputs.length; i++) {
    const sighash = t2z.get_sighash(pczt, i);
    const sig = await sign(sighash, keys[i]);
    pczt = t2z.append_signature(pczt, i, pubkeys[i], sig);
  }
  
  // 3. Generate proofs
  pczt = t2z.prove_transaction(pczt);
  
  // 4. Finalize
  const txHex = t2z.finalize_and_extract_hex(pczt);
  
  // 5. Broadcast
  const txid = await broadcast(txHex);
  console.log('Transaction broadcast:', txid);
  
  return txid;
}

Transaction Structure

The extracted transaction follows the v5 transaction format:

Field	Description
Header	Version, version group ID
Transparent	Inputs with signatures, outputs
Sapling	(empty in t2z transactions)
Orchard	Actions with proofs, binding signature
Expiry	Block height expiry

Typical sizes:

1 input → 1 Orchard output: ~2.5 KB
1 input → 2 Orchard outputs: ~5 KB

Common Errors

Missing signatures

Not all transparent inputs have been signed. Use inspect_pczt to check which inputs need signing.

const info = t2z.inspect_pczt(pczt.to_hex());
info.transparent_inputs.forEach((input, i) => {
  if (!input.is_signed) {
    console.log(`Input ${i} needs signature`);
  }
});

Missing proofs

Orchard proofs haven’t been generated. Call prove_transaction first.

Spend finalizer error

The PCZT couldn’t be finalized. This usually means something is inconsistent — try rebuilding from scratch.

After Broadcasting

After a successful broadcast:

Get the txid — Most broadcast methods return the transaction ID
Wait for confirmation — Monitor for inclusion in a block
Verify in explorer — Check the transaction on a block explorer

The recipient can view incoming shielded funds using their full viewing key (not spending key). For Orchard, viewing keys are encoded as uview1... (mainnet) or uviewtest1... (testnet).

🎉 Congratulations!

You’ve completed the full t2z transaction flow:

✅ Proposed the transaction
✅ Verified (optional)
✅ Signed all inputs
✅ Generated proofs
✅ Finalized and broadcast

Try the Demo

See this entire flow in action with the interactive demo.

Getting Started

Transaction Flow

Platform Guides

Advanced

Finalize & Extract

Prerequisites

Function Signature

Basic Usage

What Happens During Finalization

Broadcasting the Transaction

Using zcash-cli

Using lightwalletd

Using a Block Explorer

Using JSON-RPC

Complete Example

Transaction Structure

Common Errors

After Broadcasting

🎉 Congratulations!

Try the Demo

​Prerequisites

​Function Signature

​Basic Usage

​What Happens During Finalization

​Broadcasting the Transaction

​Using zcash-cli

​Using lightwalletd

​Using a Block Explorer

​Using JSON-RPC

​Complete Example

​Transaction Structure

​Common Errors

​After Broadcasting

​🎉 Congratulations!

Try the Demo

Prerequisites

Function Signature

Basic Usage

What Happens During Finalization

Broadcasting the Transaction

Using zcash-cli

Using lightwalletd

Using a Block Explorer

Using JSON-RPC

Complete Example

Transaction Structure

Common Errors

After Broadcasting

🎉 Congratulations!