Obscura

Problem Statement

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 unlinkableMerkle Tree Architecture: Supports up to 1,048,576 deposits with efficient proof generationNon-Custodial: Users maintain full control of funds throughout the processGas-Optimized: Assembly-level Poseidon hash implementation for minimal transaction costsThe system works by:User deposits ETH with a commitment hash (Poseidon(secret, nullifier, amount))Contract stores commitment in a Merkle treeUser generates ZK proof proving knowledge of a valid depositUser withdraws to any address with the proofThis 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.

Solution

Obscura is built using cutting-edge zero-knowledge cryptography and modern Ethereum development tools.Core Technologies:ZK-SNARKs: Groth16 proving system with custom Circom circuitsSmart Contracts: Solidity with OpenZeppelin security librariesCircuit Development: Circom 2.0 for arithmetic circuit designHash Function: Optimized Poseidon hash (t=3) for ZK-friendlinessTesting Framework: Hardhat with comprehensive E2E test suitesArchitecture:ZK Circuits (Circom): Custom circuits handle privacy transfer logic with 11,826 constraintsTrusted Setup: Multi-round Powers-of-Tau ceremony with beacon finalizationSmart Contracts: Gas-optimized contracts with reentrancy protection and emergency pause functionalityMerkle Tree: 20-level incremental Merkle tree for efficient proof generationTesting: Local Hardhat network testing + Sepolia testnet integrationKey Technical Achievements:Circuit Optimization: Reduced constraints through efficient range proofs and Merkle verificationGas Optimization: Assembly-level Poseidon implementation saves ~30% gas vs SoliditySecurity: Multi-layer protection with nullifier spending prevention and root rollback resistanceScalability: Merkle tree design supports millions of depositsThe project demonstrates advanced understanding of ZK cryptography, Ethereum development best practices, and privacy-preserving system design. All code is open-source and thoroughly tested.