Withdraw Funds

Overview

Withdrawing from Private Channels is a two-step process. First, the user burns their channel-side token balance by calling WithdrawFunds on the Withdraw Program. Second, an operator calls ReleaseFunds on the Escrow Program (devnet, in this walkthrough) with a valid Sparse Merkle Tree exclusion proof to release the funds. The SMT proof ensures each withdrawal nonce can only be used once, preventing double-spend.

Step 1: Initiate Withdrawal on the Channel

Call WithdrawFunds on the Withdraw Program to burn your channel-side balance. Use the Async variant, which auto-derives the tokenAccount PDA and is the recommended form for production use:

import { getWithdrawFundsInstructionAsync } from "../private-channel-withdraw-program/clients/typescript/src/generated";
import {
  createSolanaRpc,
  address,
  pipe,
  createTransactionMessage,
  setTransactionMessageFeePayerSigner,
  setTransactionMessageLifetimeUsingBlockhash,
  appendTransactionMessageInstruction,
  signAndSendTransactionMessageWithSigners,
  assertIsTransactionMessageWithSingleSendingSigner,
  getBase58Decoder
} from "@solana/kit";

// Point to the gateway, not a public Solana RPC
const privateChannelRpc = createSolanaRpc("http://localhost:8899");

const withdrawIx = await getWithdrawFundsInstructionAsync({
  user: userSigner,
  mint: address(mintAddress),
  amount: 1_000_000n, // 1 USDC (6 decimals)
  destination: null // null = release to signer's devnet wallet
});

const { value: latestBlockhash } = await privateChannelRpc
  .getLatestBlockhash({ commitment: "confirmed" })
  .send();

// Sent to the Private Channels gateway (not Solana RPC directly), which
// expects the legacy transaction format - do not switch this to version 0.
const transactionMessage = pipe(
  createTransactionMessage({ version: "legacy" }),
  (m) => setTransactionMessageFeePayerSigner(userSigner, m),
  (m) => setTransactionMessageLifetimeUsingBlockhash(latestBlockhash, m),
  (m) => appendTransactionMessageInstruction(withdrawIx, m)
);

assertIsTransactionMessageWithSingleSendingSigner(transactionMessage);

const signatureBytes =
  await signAndSendTransactionMessageWithSigners(transactionMessage);
const signature = getBase58Decoder().decode(signatureBytes);
console.log("Withdrawal initiated:", signature);

Withdraw Program ID: J231K9UEpS4y4KAPwGc4gsMNCjKFRMYcQBcjVW7vBhVi
Submit this transaction to the gateway (http://localhost:8899), not to a public Solana RPC
If destination is provided, released funds go to that wallet instead of the signer's

What to Expect

No further action is required after calling WithdrawFunds. The operator services handle settlement automatically:

indexer-private-channel polls the channel every 1 second for burn events and writes a pending withdrawal record when yours is detected
operator-private-channel polls the database every 1 second for pending records and submits ReleaseFunds to the Escrow Program on Solana devnet with the required SMT exclusion proof; it polls for devnet confirmation up to 5 times at 400 ms intervals before retrying

Funds typically appear in your devnet wallet within a few seconds under normal conditions.

How the Operator Settles (Reference)

After the channel-side burn, a provisioned operator must call ReleaseFunds on the Escrow Program with a valid SMT exclusion proof; the operator cannot release funds without proving the withdrawal nonce has not been used before. This step is handled automatically by operator-private-channel; you do not need to call it yourself.

The operator provides:

amount: must match the burned amount
user: recipient wallet on devnet
new_withdrawal_root: updated SMT root after this withdrawal
transaction_nonce: unique nonce for this leaf
sibling_proofs: 512 bytes (16 x 32-byte sibling hashes for the tree proof)

Verify

After the operator call confirms, check your devnet token balance:

spl-token balance <MINT_ADDRESS> --owner <YOUR_WALLET>

Or via RPC:

import { createSolanaRpc, address } from "@solana/kit";
import { findAssociatedTokenPda } from "@solana-program/token";

const TOKEN_PROGRAM_ADDRESS = address(
  "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA"
);

// Query devnet directly; ReleaseFunds settles here, not through the gateway
const rpc = createSolanaRpc("https://api.devnet.solana.com");

const [yourDevnetAta] = await findAssociatedTokenPda({
  mint: address(mintAddress),
  owner: address(userSigner.address),
  tokenProgram: TOKEN_PROGRAM_ADDRESS
});

const balance = await rpc.getTokenAccountBalance(yourDevnetAta).send();
console.log(balance.value.uiAmountString);

Withdraw Funds

Overview

Step 1: Initiate Withdrawal on the Channel

What to Expect

How the Operator Settles (Reference)

Verify

You've Completed the Quickstart

Channel Lifecycle

Authentication & Roles

Release Funds Reference

Sparse Merkle Tree

목차