> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/Privacy-Cash/privacy-cash/llms.txt
> Use this file to discover all available pages before exploring further.

# Security Best Practices

> Guidelines for safely using Privacy Cash

Follow these best practices to maximize your security and privacy when using Privacy Cash.

## Transaction Security

### Keep Your Secrets Safe

<Warning>
  **Never share your note secrets**: Each deposit generates a secret note. Anyone with this secret can withdraw your funds. Treat it like a private key.
</Warning>

<CardGroup cols={2}>
  <Card title="Store Secrets Offline" icon="vault">
    Keep your note secrets in a secure, offline location. Hardware wallets or encrypted files are recommended.
  </Card>

  <Card title="Use Multiple Notes" icon="layer-group">
    Split large amounts across multiple deposits to reduce risk and improve privacy.
  </Card>
</CardGroup>

### Verify Transaction Details

<Info>
  Always verify transaction parameters before signing:

  * **Recipient address**: Ensure the withdrawal address is correct
  * **Amount**: Confirm deposit/withdrawal amounts match your intent
  * **Fees**: Check that fees are within expected ranges (0.25% for withdrawals)
  * **Token type**: Verify you're transacting with the correct SPL token
</Info>

## Privacy Best Practices

### Timing and Anonymity Set

<Card title="Wait Before Withdrawing" icon="clock">
  For maximum privacy, wait for multiple other deposits before withdrawing. A larger anonymity set makes linking deposits to withdrawals more difficult.
</Card>

Recommendations:

* **Minimum wait**: Wait for at least 10-20 other deposits in the same denomination
* **Different amounts**: Avoid depositing and withdrawing the exact same amount
* **Time variation**: Don't withdraw at predictable intervals

### Network Privacy

<CardGroup cols={2}>
  <Card title="Use VPN or Tor" icon="shield">
    Protect your IP address when interacting with the protocol to prevent network-level correlation.
  </Card>

  <Card title="Different Wallets" icon="wallet">
    Consider using separate wallets for deposits and withdrawals to enhance privacy.
  </Card>
</CardGroup>

## Amount Management

### Deposit Limits

<Info>
  **Current Limits**:

  * **SOL**: Maximum 1,000 SOL per deposit
  * **SPL Tokens**: Limits vary by token (set by protocol authority)

  These limits protect against large-scale attacks and ensure system stability.

  Reference: `lib.rs:78`, `lib.rs:267-272`
</Info>

### Breaking Up Large Amounts

For amounts exceeding deposit limits or for better privacy:

1. **Split deposits**: Break large amounts into multiple smaller deposits
2. **Use different denominations**: Vary the amounts to avoid patterns
3. **Stagger timing**: Space out deposits over time
4. **Mix tokens**: Consider using multiple token types if appropriate

## Relayer Safety

### Using Relayers for Withdrawals

<Card title="Relayer Best Practices" icon="tower-broadcast">
  Relayers enable withdrawals to fresh addresses without linking to your deposit wallet.
</Card>

When using relayers:

<Warning>
  **Verify relayer fees**: Relayers charge a service fee on top of the protocol's 0.25% withdrawal fee. Check that the total fee is reasonable before proceeding.
</Warning>

* Use reputable relayers with transparent fee structures
* Understand that relayers know the withdrawal address (but not the deposit)
* Consider using multiple relayers for different withdrawals
* Verify the relayer's smart contract is correctly implemented

## Smart Contract Interaction

### Verifying Program Deployment

<Info>
  Before interacting with Privacy Cash, verify the on-chain program:

  **Program ID (Mainnet)**:

  ```
  9fhQBbumKEFuXtMBDw8AaQyAjCorLGJQiS3skWZdQyQD
  ```

  **Verified Hash**:

  ```
  c6f1e5336f2068dc1c1e1c64e92e3d8495b8df79f78011e2620af60aa43090c5
  ```

  Use Solana verification tools to ensure the deployed program matches the audited source code.
</Info>

### Approved Tokens Only

<Card title="Token Allowlist" icon="list-check">
  Only use approved SPL tokens listed in the protocol documentation.
</Card>

**Mainnet Approved Tokens**:

* USDC (Circle)
* USDT (Tether)
* ORE
* ZEC (Zcash)
* stORE (Staked ORE)
* jlUSDC (Jupiter LP USDC)
* jlWSOL (Jupiter LP Wrapped SOL)

Reference: `lib.rs:52-60`

<Warning>
  Attempting to use non-approved tokens will result in transaction failure. The protocol enforces a strict allowlist for security.
</Warning>

## Fee Management

### Understanding Fee Structure

<CardGroup cols={2}>
  <Card title="Deposits" icon="arrow-down">
    **Free** - No protocol fees for deposits (0%)
  </Card>

  <Card title="Withdrawals" icon="arrow-up">
    **0.25%** - Standard withdrawal fee (25 basis points)
  </Card>
</CardGroup>

Reference: `lib.rs:91-92`

### Fee Error Margin

The protocol allows a 5% error margin on fees to accommodate minor calculation differences:

```
Minimum acceptable fee = Expected fee × (1 - 5%)
                      = Expected fee × 0.95
```

This prevents legitimate transactions from failing due to rounding errors while still protecting against fee manipulation.

Reference: `lib.rs:93`, `utils.rs:148-212`

## Operational Security

### Wallet Security

<CardGroup cols={2}>
  <Card title="Hardware Wallets" icon="microchip">
    Use hardware wallets for signing transactions when possible.
  </Card>

  <Card title="Multi-Signature" icon="users">
    For large amounts, consider using multi-signature wallets for deposits.
  </Card>

  <Card title="Fresh Addresses" icon="plus">
    Withdraw to fresh addresses that haven't been publicly linked to you.
  </Card>

  <Card title="Regular Audits" icon="magnifying-glass">
    Periodically review your notes and transactions for any anomalies.
  </Card>
</CardGroup>

### Backup Your Data

<Warning>
  **Critical**: Back up all transaction data, including:

  * Note secrets and commitments
  * Merkle tree paths
  * Transaction hashes
  * Encrypted output data

  Loss of this data means permanent loss of funds.
</Warning>

Backup recommendations:

* Store encrypted backups in multiple secure locations
* Use different encryption keys for different backups
* Test recovery procedures periodically
* Consider using secret-sharing schemes (e.g., Shamir's Secret Sharing)

## Monitoring and Alerts

### Track Your Transactions

<Info>
  **Monitor these events**:

  * `CommitmentData`: Emitted when SOL deposits/withdrawals create new commitments
  * `SplCommitmentData`: Emitted for SPL token transactions

  These events help you track the state of the Merkle tree and verify your transactions were included.

  Reference: `lib.rs:351-361`, `lib.rs:505-517`
</Info>

### Merkle Root History

The protocol maintains a history of 100 recent Merkle roots:

* Transactions can reference any root from this history
* Older roots are automatically pruned from the history
* If your proof references a root outside the history window, the transaction will fail

<Warning>
  **Time-sensitive withdrawals**: If you generate a proof but don't submit it for an extended period, the referenced root may be pruned from history. Always submit proofs promptly after generation.

  Reference: `merkle_tree.rs:79-105`, `lib.rs:80`
</Warning>

## Common Pitfalls to Avoid

### Transaction Failures

<CardGroup cols={2}>
  <Card title="Double-Spend Attempts" icon="ban">
    Using the same nullifier twice will cause automatic transaction failure.
  </Card>

  <Card title="Invalid Proofs" icon="xmark">
    Ensure your zero-knowledge proof is correctly generated for the current circuit.
  </Card>

  <Card title="Unknown Roots" icon="question">
    Verify your Merkle root is still in the 100-entry history before submitting.
  </Card>

  <Card title="Insufficient Funds" icon="coins">
    Ensure the pool has enough liquidity for your withdrawal plus fees.
  </Card>
</CardGroup>

### Privacy Leaks

Avoid these common privacy mistakes:

1. **Same-amount patterns**: Don't deposit and withdraw identical amounts
2. **Immediate withdrawals**: Wait for more deposits to increase anonymity set
3. **Address reuse**: Don't withdraw to previously used addresses
4. **Metadata correlation**: Use different timestamps, gas prices, and wallet addresses
5. **Social correlation**: Don't discuss specific deposits/withdrawals publicly

## Emergency Procedures

### If You Lose Your Note Secret

<Warning>
  **Funds are irrecoverable**: If you lose your note secret and have no backup, your funds cannot be recovered. There is no password reset or recovery mechanism.
</Warning>

### If You Suspect Compromise

If you believe your note secret may be compromised:

1. **Immediately withdraw**: If possible, withdraw to a new, secure address
2. **Use a relayer**: Consider using a relayer to avoid exposing your IP
3. **Monitor the chain**: Watch for unauthorized withdrawal attempts
4. **Secure new funds**: Use different wallets and secrets for future deposits

## Additional Resources

<CardGroup cols={2}>
  <Card title="Security Audits" icon="shield-check" href="/security/audits">
    Review comprehensive security audits by multiple firms
  </Card>

  <Card title="Safety Features" icon="lock" href="/security/safety-features">
    Learn about built-in protocol security mechanisms
  </Card>

  <Card title="GitHub Repository" icon="github" href="https://github.com/Privacy-Cash">
    Examine the open-source code yourself
  </Card>

  <Card title="SDK Documentation" icon="code" href="https://github.com/Privacy-Cash/privacy-cash-sdk">
    Integrate Privacy Cash safely into your application
  </Card>
</CardGroup>