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A t2z transaction goes through five distinct phases. Each phase can be performed by different parties or systems, enabling flexible transaction construction workflows.

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The Five Phases

Propose

Create the PCZTCombine transparent inputs and payment outputs into a Partially Constructed Zcash Transaction.
  • Define which UTXOs to spend
  • Specify recipient addresses and amounts
  • Set change address and expiry height
  • ZIP 317 fee is calculated automatically
Learn more →

Verify

Validate before signing (optional)Ensure the PCZT matches your original request — important if the PCZT was handled by a third party.
  • Confirm all payments are present
  • Verify amounts match
  • Check for unexpected outputs (malleation)
Learn more →

Sign

Add signaturesSign each transparent input with the corresponding private key.
  • Get sighash for each input
  • Sign externally (hardware wallet, HSM) or internally
  • Append signatures to the PCZT
Learn more →

Prove

Generate ZK proofsCreate Orchard zero-knowledge proofs for any shielded outputs.
  • First call builds proving key (~10 seconds)
  • Subsequent calls are fast (cached)
  • No trusted setup required (Halo 2)
Learn more →

Finalize

Extract transactionPerform final validation and extract the raw transaction bytes.
  • Verify all signatures present
  • Verify all proofs generated
  • Produce transaction ready for broadcast
Learn more →

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Parallel Operations

Signing and proving can be done in parallel since they don’t depend on each other: If signing and proving are done by the same party sequentially, the combine step can be skipped.

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Example: Complete Flow

  • TypeScript
  • Go
  • Kotlin
import * as t2z from '@d4mr/t2z-wasm';

// 1. PROPOSE
let pczt = t2z.propose_transaction(inputs, payments, changeAddr, network, expiry);

// 2. VERIFY (optional but recommended)
t2z.verify_before_signing(pczt, payments, expectedChange);

// 3. SIGN each input
for (let i = 0; i < inputs.length; i++) {
  const sighash = t2z.get_sighash(pczt, i);
  const signature = await externalSign(sighash, keys[i]);
  pczt = t2z.append_signature(pczt, i, pubkeys[i], signature);
}

// 4. PROVE
pczt = t2z.prove_transaction(pczt);

// 5. FINALIZE
const txHex = t2z.finalize_and_extract_hex(pczt);

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Inspecting the PCZT

At any point, you can inspect the PCZT to see its current state: 
const info = t2z.inspect_pczt(pczt.to_hex());

console.log({
  totalInput: info.total_input,
  totalOutput: info.total_orchard_output + info.total_transparent_output,
  fee: info.implied_fee,
  signed: info.all_inputs_signed,
  proved: info.has_orchard_proofs,
});
Learn more about inspect_pczt →