Deposit

Deposits shield ERC-20 tokens (or native ETH) into the privacy pool, creating a new UTXO commitment on-chain.

Overview

ERC-20 tokens → OCash Contract → UTXO commitment + encrypted memo

Unlike transfers and withdrawals, deposits go directly through the on-chain contract (not the relayer). The SDK handles:

1. Computing the deposit fee
2. ERC-20 approval (if needed)
3. Building the deposit transaction
4. Encrypting a memo for the recipient's wallet to discover the UTXO

Basic Usage

import { createPublicClient, createWalletClient, http } from 'viem';
import { sepolia } from 'viem/chains';

// viem clients
const publicClient = createPublicClient({ chain: sepolia, transport: http() });
const walletClient = createWalletClient({ chain: sepolia, transport: http(), account });

// Derive the owner's public key
const ownerPub = sdk.keys.getPublicKeyBySeed(seed, nonce);

// Prepare deposit
const prepared = await sdk.ops.prepareDeposit({
  chainId: 11155111,
  assetId: 'my-token-id',
  amount: 1000000n,         // In base units (e.g. 1 USDC = 1000000)
  ownerPublicKey: ownerPub,
  account: account.address,  // Depositor's EOA
  publicClient,
});

Handling Approval

For ERC-20 tokens, you may need to approve the contract first:

if (prepared.approveNeeded && prepared.approveRequest) {
  const approveTxHash = await walletClient.writeContract(prepared.approveRequest);
  await publicClient.waitForTransactionReceipt({ hash: approveTxHash });
}

// Execute deposit
const txHash = await walletClient.writeContract(prepared.depositRequest);
const receipt = await publicClient.waitForTransactionReceipt({ hash: txHash });

Using submitDeposit

For convenience, ops.submitDeposit handles approval + deposit in one call:

const result = await sdk.ops.submitDeposit({
  prepared,
  walletClient,
  publicClient,
  autoApprove: true,  // Automatically approve if needed
});

console.log('Deposit tx:', result.txHash);
console.log('Receipt:', result.receipt);

Fees

prepared includes fee information:

Field	Description
protocolFee	On-chain protocol fee (from depositFeeBps)
depositRelayerFee	Relayer deposit fee (if applicable)
payAmount	Total amount the depositor needs to pay
value	ETH value to send with the transaction (for native deposits)

After Deposit

After the deposit transaction confirms:

1. The UTXO commitment is stored on-chain in the Merkle tree
2. The encrypted memo is stored by the Entry Service
3. Run sdk.sync.syncOnce() to discover the new UTXO in your wallet
4. The balance updates to reflect the deposited amount

Native ETH Deposits

For native ETH (wrapped as a privacy token), the deposit value is sent as msg.value:

// prepared.value will be non-zero for native deposits
// The SDK sets this automatically in the depositRequest