WIP Add DAO voting example with private ballot implementation

dao-voting/Nargo.toml

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+[package]
+name = "dao_voting"
+type = "contract"
+authors = [""]
+compiler_version = ">=1.0.0"
+
+[dependencies]
+aztec = { git = "https://github.com/AztecProtocol/aztec-packages/", tag = "v3.0.0-devnet.20251212", directory = "noir-projects/aztec-nr/aztec" }
+
+# eth-proofs dependencies for Ethereum storage proof verification
+# These enable L1 balance verification but require version compatibility work
+#
+# Correct import paths (verified from https://github.com/noir-lang/eth-proofs):
+# ethereum = { git = "https://github.com/noir-lang/eth-proofs", tag = "main", directory = "ethereum/circuits/lib" }
+# token = { git = "https://github.com/noir-lang/eth-proofs", tag = "main", directory = "vlayer/ethereum/circuits/lib" }
+#
+# Usage in Noir:
+#   use dep::ethereum::misc::types::Address;
+#   use dep::token::token::ERC20;
+#   use dep::token::token_list::mainnet::USDC;
+#
+# Example from is_dao_worthy:
+#   let balance: u128 = USDC.get_balance(wallet, block_no, false);
+#
+# NOTE: Currently incompatible with Aztec v3 due to Serde trait issues.
+# Track progress at: https://github.com/noir-lang/eth-proofs

dao-voting/README.md

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+# DAO Voting with Tiered Voting Power
+
+A private DAO voting contract for Aztec that uses Ethereum storage proofs to verify token holdings while preserving voter privacy through tiered voting power.
+
+## Overview
+
+This contract enables private voting on proposals where voting power is determined by ERC20 token balances on Ethereum L1. Instead of using exact token balances (which could de-anonymize voters), the contract uses **tiered voting power** - voters prove they belong to a tier (e.g., "1,000-10,000 tokens") without revealing their exact balance.
+
+## Privacy Model
+
+| Data | Privacy Level | Notes |
+|------|--------------|-------|
+| Vote choice | **Private** | Hidden in VoteNote |
+| Exact L1 balance | **Private** | Only tier is verified |
+| Voter's tier | Semi-private | Provides k-anonymity |
+| Voter Aztec identity | **Private** | Not linked to tally |
+| L1 ↔ Aztec linkage | **Protected** | Harder to correlate |
+| Proposal details | Public | Times, snapshot block |
+| Vote tallies | Public | Aggregate per choice |
+
+## Tiered Voting Power
+
+### Tier Configuration
+
+| Tier | Balance Range | Voting Power |
+|------|---------------|--------------|
+| 0 | 0 (no tokens) | 0 (cannot vote) |
+| 1 | 1 - 999 | 1 |
+| 2 | 1,000 - 9,999 | 5 |
+| 3 | 10,000 - 99,999 | 25 |
+| 4 | 100,000+ | 100 |
+
+### Why Tiers?
+
+1. **Privacy**: Exact balance hidden, only tier revealed
+2. **k-Anonymity**: Users in same tier are indistinguishable
+3. **Anti-plutocracy**: Whale influence capped at tier 4
+4. **Correlation resistance**: Harder to link L1 wallet to Aztec identity
+
+## Prerequisites
+
+```bash
+# Install Aztec tools
+bash -i <(curl -s https://install.aztec.network)
+aztec-up 3.0.0-devnet.20251212
+
+# Install nargo for Noir compilation (if not using aztec compile)
+noirup -v 1.0.0-beta.15
+```
+
+## Building
+
+```bash
+# Compile the contract
+aztec compile
+
+# Generate TypeScript bindings
+aztec codegen target -o artifacts
+
+# Or use the combined command
+npm run compile
+```
+
+## Testing
+
+### Unit Tests (Noir)
+
+```bash
+# Start TXE (Testing Execution Environment)
+aztec start --txe --port=8081
+
+# Run Noir tests
+aztec test
+```
+
+### Integration Tests (TypeScript)
+
+```bash
+# Install dependencies
+npm install
+
+# Start local Aztec network (in separate terminal)
+aztec start --local-network
+
+# Run tests
+npm test
+```
+
+## Contract Interface
+
+### Initialization
+
+```noir
+fn constructor(
+    admin: AztecAddress,           // Who can create proposals
+    eth_token_address: [u8; 20],   // ERC20 token on Ethereum
+    eth_balance_slot: Field,       // Storage slot for balances
+    eth_chain_id: u32,             // Chain ID (1 for mainnet)
+)
+```
+
+### Creating Proposals
+
+```noir
+fn create_proposal(
+    description_hash: Field,  // Hash of off-chain description
+    snapshot_block: u64,      // Ethereum block for balance snapshot
+    voting_start: u64,        // Unix timestamp
+    voting_end: u64,          // Unix timestamp
+    num_choices: u8,          // 2-8 choices
+) -> Field  // Returns proposal_id
+```
+
+### Casting Votes
+
+```noir
+fn cast_vote(
+    proposal_id: Field,
+    choice: u8,               // 0 to num_choices-1
+    eth_address: [u8; 20],    // Voter's Ethereum address
+    claimed_tier: u8,         // Tier voter claims to be in (1-4)
+)
+```
+
+### View Functions
+
+- `get_proposal(proposal_id)` - Get proposal details
+- `get_vote_count(proposal_id, choice)` - Get votes for a choice
+- `get_results(proposal_id)` - Get full results
+- `get_tier_info(tier)` - Get tier configuration
+- `get_all_tiers()` - Get all tier configurations
+
+## Architecture
+
+```
+┌─────────────────────────────────────────────────────────┐
+│                    Ethereum L1                          │
+│  ┌─────────────────────────────────────────────────┐   │
+│  │  ERC20 Token Contract                           │   │
+│  │  - balances[address] = amount                   │   │
+│  └─────────────────────────────────────────────────┘   │
+└─────────────────────────────────────────────────────────┘
+                          │
+                          │ eth-proofs (storage proofs)
+                          ▼
+┌─────────────────────────────────────────────────────────┐
+│                    Aztec L2                             │
+│  ┌─────────────────────────────────────────────────┐   │
+│  │  DaoVoting Contract                             │   │
+│  │                                                 │   │
+│  │  Private:                                       │   │
+│  │  - cast_vote() verifies tier, creates nullifier│   │
+│  │  - Vote choice hidden in VoteNote              │   │
+│  │                                                 │   │
+│  │  Public:                                        │   │
+│  │  - Proposals stored publicly                   │   │
+│  │  - Vote tallies aggregated per choice          │   │
+│  │  - _update_tally() validates and updates       │   │
+│  └─────────────────────────────────────────────────┘   │
+└─────────────────────────────────────────────────────────┘
+```
+
+## eth-proofs Integration
+
+**Note**: The eth-proofs integration is currently stubbed out due to version compatibility issues with Aztec v3.
+
+### Correct Import Paths
+
+When compatibility is resolved, add to `Nargo.toml`:
+
+```toml
+# Core Ethereum types and proof verification
+ethereum = { git = "https://github.com/noir-lang/eth-proofs", tag = "main", directory = "ethereum/circuits/lib" }
+
+# ERC20 token support (get_balance, token_list)
+token = { git = "https://github.com/noir-lang/eth-proofs", tag = "main", directory = "vlayer/ethereum/circuits/lib" }
+```
+
+### Usage in Noir
+
+```noir
+use dep::ethereum::misc::types::Address;
+use dep::token::token::ERC20;
+use dep::token::token_list::mainnet::USDC;
+
+// Option 1: Use predefined token (USDC)
+let balance: u128 = USDC.get_balance(wallet_address, block_number, false);
+
+// Option 2: Custom token
+let token = ERC20 {
+    address: token_address,
+    balances_slot: 9,  // varies by token
+    allowances_slot: 0,
+    chain_id: 1,  // mainnet
+};
+let balance: u128 = token.get_balance(wallet_address, block_number, false);
+```
+
+### Enabling Full Integration
+
+1. Uncomment eth-proofs dependencies in `Nargo.toml`
+2. Uncomment imports in `src/main.nr`
+3. Uncomment balance verification code in `cast_vote` function
+4. Run eth-proofs oracle server with Ethereum RPC access
+
+Track compatibility progress at: https://github.com/noir-lang/eth-proofs
+
+## Security Considerations
+
+1. **Tier Enforcement**: Users must claim the correct tier - they cannot claim lower to hide wealth or higher without sufficient balance
+
+2. **Nullifier Strategy**: `nullifier = hash(proposal_id, eth_address)` prevents:
+   - Same ETH address voting twice on same proposal
+   - Vote splitting across multiple Aztec accounts
+
+3. **Time Validation**: Voting period is validated in the public function at execution time
+
+4. **Admin Controls**: Only admin can create/cancel proposals
+
+## Limitations
+
+- Requires eth-proofs oracle for L1 balance verification
+- Balance snapshot is at specific block, not real-time
+- Tier boundaries are public (attackers know the ranges)
+- Users at tier boundaries may be slightly less anonymous
+
+## License
+
+MIT