Kasbah: Privacy-Preserving Token Protocol for Solana

Kasbah is a privacy-focused confidential token protocol built on Solana that enables secure, private token transfers using zero-knowledge proofs.

Overview

Kasbah allows users to:

• Deposit tokens into commitment pools with zero-knowledge proofs
• Generate off-chain receipts that can be sent to recipients
• Redeem tokens without revealing the connection between deposit and withdrawal transactions

This ensures transaction privacy while maintaining the security and auditability required for blockchain applications.

Architecture

Components

1. Solana Program (programs/kasbah)

   • Core protocol implementation with treasury and commitment pools
   • Handles deposit and redemption operations

2. Zero-Knowledge Circuits (circuits/)

   • Implements KasbahCommitmentCircuit for ZK proofs
   • Uses Poseidon hash functions for commitments and Merkle tree verification

3. WebAssembly Module (wasm/)

   • Client-side ZK proof generation
   • Handles format conversions for proofs

4. Verifier (verifier/)

   • On-chain verification of Groth16 proofs
   • Adapted from Lightprotocol's implementation

How it Works

1. Deposit Flow:

   • User deposits tokens, creating a commitment
   • Commitment is added to an on-chain commitment pool
   • User generates a receipt with recipient information

2. Redemption Flow:

   • Recipient uses the receipt to generate a zero-knowledge proof
   • Proof is submitted to the Kasbah program
   • System verifies the proof and sends tokens to recipient
   • Nullifiers prevent double-spending

Technology Stack

• Blockchain: Solana
• Programming Languages: Rust, TypeScript
• Smart Contract Framework: Anchor
• Zero-Knowledge Proofs: Groth16 proofs
• ZK Circuit Language: Circom
• Client-Side Proof Generation: WebAssembly (WASM)

Getting Started

Prerequisites

• Rust (1.70.0+)
• Solana CLI (1.16.0+)
• Anchor (0.28.0+)
• Node.js (16+)
• Circom (2.0.0+)

Installation

1. Clone the repository:

   git clone https://github.com/yourusername/kasbah-capstone.git
   cd kasbah-capstone

2. Install dependencies:

   npm install

3. Build the project:

   anchor build

4. Build the WASM module:

   cd wasm
   cargo build --release
   cd ..

Testing

Run the test suite to verify the installation:

anchor test

Development

Building Circuits

To rebuild the circuits:

cd circuits
circom ksb.circom --r1cs --wasm

Generating TypeScript Clients

npm run generate-clients

Security

This project implements several security measures:

• Zero-Knowledge Proofs: For privacy-preserving verification
• Nullifiers: To prevent double-spending
• Commitment Pools: To organize and secure deposit data
• On-chain Verification: Using Solana's bn254 verification syscall

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the project
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Adapted verifier from Lightprotocol's implementation
• Built on Solana blockchain
• Uses Anchor framework for Solana development