Privacy Cash Rust SDK

Pure Rust SDK for Privacy Cash - Privacy-preserving transactions on Solana using Zero-Knowledge Proofs.

Created by Nova Shield

Features

• Private Transactions - Send SOL and SPL tokens with complete privacy using ZK proofs
• Pure Rust ZK Proofs - Native Groth16 proof generation, no external dependencies
• Multi-Token Support - SOL, USDC, USDT, and more
• One Function API - send_privately() handles deposit + withdraw in one call
• Partner Fee Integration - Earn fees by integrating this SDK into your platform
• Configurable - Customize RPC, fees, and referrer via environment variables

Installation

Add to your Cargo.toml:

[dependencies]
privacy-cash = { git = "https://github.com/NovaShieldWallet/privacy-cash-rust-sdk" }
tokio = { version = "1", features = ["full"] }

Circuit Files (Required)

The SDK requires circuit files for ZK proof generation.

This repo vendors the required artifacts at:

• circuit/transaction2.wasm
• circuit/transaction2.zkey

See circuit/README.md for provenance and licensing details.

Quick Start - ONE Function!

use privacy_cash::send_privately;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Send 0.1 SOL privately - ONE function does everything!
    let result = send_privately(
        "your_base58_private_key",  // Private key
        "recipient_pubkey",          // Recipient address
        0.1,                         // Amount to send
        "sol",                       // Token: "sol", "usdc", "usdt"
        None,                        // Optional RPC URL
    ).await?;
    
    println!("Sent privately!");
    println!("Deposit TX: {}", result.deposit_signature);
    println!("Withdraw TX: {}", result.withdraw_signature);
    println!("Recipient received: {} lamports", result.amount_received);
    
    Ok(())
}

The send_privately() function automatically:

1. Deposits your tokens into Privacy Cash
2. Waits for blockchain confirmation
3. Withdraws the maximum amount to the recipient

API

SendPrivatelyResult

pub struct SendPrivatelyResult {
    pub deposit_signature: String,   // Deposit transaction
    pub withdraw_signature: String,  // Withdraw transaction
    pub amount_deposited: u64,       // Amount deposited
    pub amount_received: u64,        // Amount recipient received
    pub total_fees: u64,             // Total fees paid
    pub recipient: String,           // Recipient address
    pub token: String,               // Token type
}

Supported Tokens

Partner/Platform Fee Integration

Platforms integrating this SDK can earn fees on transactions. Configure via environment variables:

Example setup:

export PARTNER_FEE_WALLET="YourWalletAddressHere"
export PARTNER_FEE_RATE="0.005"  # 0.5% fee
export PARTNER_REFERRER="YourWalletAddressHere"

Configuration

All configuration can be set via environment variables:

Examples

Tip: Copy .env.local.example to .env.local (gitignored) and set your variables.

# Check balances
SOLANA_PRIVATE_KEY="your-key" cargo run --release --example check_balance

# Send 0.02 SOL privately
SOLANA_PRIVATE_KEY="your-key" cargo run --release --example send_privately -- 0.02 sol

# Send 10 USDC privately to a recipient
SOLANA_PRIVATE_KEY="your-key" cargo run --release --example send_privately -- 10 usdc RecipientPubkey

# Same send test via helper script (prompts for SOLANA_PRIVATE_KEY if not set)
bash scripts/send-test.sh RecipientPubkey 0.02 sol

Security

• Never hardcode private keys in your code
• Use environment variables or secure key management
• Private keys are used locally and never sent to any server
• All ZK proofs are generated client-side

License

SDK code is MIT-licensed (see LICENSE). Circuit artifacts in circuit/ have their own upstream license—see circuit/README.md.

Links

• Nova Shield
• Privacy Cash Protocol
• Privacy Cash GitHub
• SDK Repository