Riser is a Sepolia FHEVM web application for ERC-7984 confidential tokens

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Riser

Riser is a Sepolia FHEVM web application for ERC-7984 confidential tokens: shield public ERC-20 via wrappers (wrap), move balances privately (send), and unshield (unwrap). The UI is a React + Vite frontend; smart contracts use Hardhat, Zama FHEVM, and OpenZeppelin Confidential Contracts (ERC7984ERC20Wrapper).

Table of contents

  1. Live deployment
  2. Features
  3. Tech stack
  4. Repository layout
  5. Prerequisites
  6. Installation
  7. Environment variables
  8. Smart contracts
  9. Frontend
  10. Deploying contracts
  11. Troubleshooting
  12. License

Live deployment

The production build is hosted at https://riser-eth.vercel.app (Sepolia Zama FHEVM — connect a wallet on chain ID 11155111).

Features

  • Wallet connection on Ethereum Sepolia (11155111) with MetaMask (or any EIP-1193 wallet).
  • Confidential balances for cETH and cUSDT via the Zama SDK (decryption after authorization).
  • Send: confidential transfers between addresses using wrapped tokens.
  • Swap (wrap / unwrap): deposit public ERC-20 into FHEVM wrappers or unwrap back to public tokens; gas-aware approvals and wraps.
  • History: combines indexed confidential transfers and public ERC-20 activity relevant to your address.
  • Footer: optional Add cTokens to wallet (EIP-747) for the confidential token contracts.

Tech stack

Area Technology
Smart contracts Solidity 0.8.x, Hardhat, @fhevm/hardhat-plugin, OpenZeppelin + Confidential Contracts
Frontend React 19, TypeScript, Vite 6, Tailwind CSS 4
Chain / wallet Viem, @zama-fhe/sdk, Sepolia

Repository layout

riser/
├── contracts/           # Solidity sources (wrappers, mocks, experiments)
├── scripts/             # Hardhat deployment scripts (e.g. deploy.ts)
├── test/                # Hardhat tests
├── frontend/            # Vite React app (src/, index.html)
├── hardhat.config.ts    # Networks: hardhat, local, sepolia
├── package.json         # Root: Hardhat + shared deps
├── .env.example         # Template for PRIVATE_KEY / RPC (copy to .env)
└── README.md

The root package.json drives Hardhat. The frontend has its own package.json for Vite (frontend/).

Prerequisites

  • Node.js 18+ (LTS recommended).
  • npm (or compatible client) for installs.
  • A wallet with Sepolia ETH for transactions.
  • For deployment: a funded account whose private key you load via .env (see below).

Installation

From the repository root:

npm install

Install frontend dependencies:

cd frontend && npm install && cd ..

Environment variables

Create a .env file at the repository root (same level as hardhat.config.ts). Do not commit it; it is listed in .gitignore.

Variable Required Description
PRIVATE_KEY For sepolia / local funded deploys Hex private key of the deployer (no 0x prefix is common for Hardhat; follow your tooling’s expectation).
SEPOLIA_RPC_URL Optional JSON-RPC URL for Sepolia. If omitted, hardhat.config.ts falls back to a public endpoint.

Copy from the template:

cp .env.example .env
# Edit .env and set PRIVATE_KEY (and optionally SEPOLIA_RPC_URL).

Smart contracts

Commands are run from the repository root.

Command Description
npm run compile Compile Solidity (hardhat compile).
npm test Run Hardhat tests.
npm run node Start a local Hardhat node (hardhat node).

Compiled output goes to artifacts/ and cache/ (ignored by git). TypeChain types go to typechain-types/ (ignored).

Frontend

All commands below assume frontend/ as the working directory.

Command Description
npm run dev Start Vite dev server (hot reload).
npm run build Typecheck + production build → frontend/dist/.
npm run preview Preview the production build locally.

Configure contract addresses in frontend/src/App.tsx (ETH_CONTRACT_ADDRESS, USDT_CONTRACT_ADDRESS) to match the confidential wrapper contracts you use on Sepolia (or values produced by your deploy script).

Deploying contracts

The script scripts/deploy.ts deploys mock public ERC-20 tokens and ERC7984ERC20WrapperExample instances, then rewrites frontend/src/App.tsx wrapper addresses to match the new deployment.

Example (Sepolia):

npx hardhat run scripts/deploy.ts --network sepolia

Requirements:

  • Valid PRIVATE_KEY in .env with Sepolia ETH.
  • Successful compile (npm run compile).

After deployment, review App.tsx and commit address updates if you version-control them.

Troubleshooting

  • “No accounts found” / deploy fails — Ensure .env exists at the repo root and PRIVATE_KEY is set for the chosen network.
  • Frontend cannot reach RPC — Set SEPOLIA_RPC_URL to a reliable provider; public RPCs can rate-limit.
  • Wrap / unwrap errors — Confirm wrapper addresses match Sepolia; underlying token decimals must match what the UI reads on-chain; ensure sufficient public balance before wrap and private balance before unwrap.
  • Large git checkout — Ensure node_modules/, artifacts/, cache/, frontend/dist/, and .env are not committed (see .gitignore).