Obscura

Obscura is a decentralized privacy mixer that enables anonymous ETH transfers on Ethereum using ZK-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge).

Unlike traditional mixers that rely on trust, Obscura provides mathematical privacy guarantees through cryptography. Users can deposit ETH with a cryptographic commitment and later withdraw to any address using a zero-knowledge proof that proves ownership without revealing the deposit transaction.

Key Features:

• Cryptographic Privacy: ZK proofs ensure deposits and withdrawals are mathematically unlinkable
• Merkle Tree Architecture: Supports up to 1,048,576 deposits with efficient proof generation
• Non-Custodial: Users maintain full control of funds throughout the process
• Gas-Optimized: Assembly-level Poseidon hash implementation for minimal transaction costs

The system works by:

1. User deposits ETH with a commitment hash (Poseidon(secret, nullifier, amount))
2. Contract stores commitment in a Merkle tree
3. User generates ZK proof proving knowledge of a valid deposit
4. User withdraws to any address with the proof

This provides the same privacy benefits as Tornado Cash but with improved efficiency and a clear path to censorship resistance through the planned Hydra Protocol evolution.

Obscura is built using cutting-edge zero-knowledge cryptography and modern Ethereum development tools.

Core Technologies:

• ZK-SNARKs: Groth16 proving system with custom Circom circuits
• Smart Contracts: Solidity with OpenZeppelin security libraries
• Circuit Development: Circom 2.0 for arithmetic circuit design
• Hash Function: Optimized Poseidon hash (t=3) for ZK-friendliness
• Testing Framework: Hardhat with comprehensive E2E test suites

Architecture:

1. ZK Circuits (Circom): Custom circuits handle privacy transfer logic with 11,826 constraints
2. Trusted Setup: Multi-round Powers-of-Tau ceremony with beacon finalization
3. Smart Contracts: Gas-optimized contracts with reentrancy protection and emergency pause functionality
4. Merkle Tree: 20-level incremental Merkle tree for efficient proof generation
5. Testing: Local Hardhat network testing + Sepolia testnet integration

Key Technical Achievements:

• Circuit Optimization: Reduced constraints through efficient range proofs and Merkle verification
• Gas Optimization: Assembly-level Poseidon implementation saves ~30% gas vs Solidity
• Security: Multi-layer protection with nullifier spending prevention and root rollback resistance
• Scalability: Merkle tree design supports millions of deposits

The project demonstrates advanced understanding of ZK cryptography, Ethereum development best practices, and privacy-preserving system design. All code is open-source and thoroughly tested.