🏦 Sealed Bid Auction Smart Contract Tutorial

This repository provides the source code for the Sealed Bid Auction Smart Contract Tutorial which is a step-by-step Solidity guide for implementing a timelock encryption-based sealed-bid auction on the Filecoin Calibration Testnet. In a sealed bid auction, bidders submit their bids privately (encrypted bids are submitted on-chain), and only after the bidding phase ends is the winner revealed (encrypted bids are automatically decrypted on-chain at the end of the bidding phase).

📌 Features

• Private Bidding: Utilizes timelock encryption to keep bids confidential until the reveal phase.
• Phased Auction Process: Structured into encryption, bidding, revealing, and settlement phases.
• On-Chain Decryption: Employs smart contracts to automatically decrypt and reveal bids at the designated block.
• Fair Competition: Prevents last-minute bid sniping and promotes genuine valuation-based bidding.

📂 Repository Structure

📦 sealed-bid-auction
├── src/   # Solidity smart contracts
├── scripts/     # Deployment scripts
├── test/        # Unit tests for the contract
├── utils/       # Smart contract interaction scripts
└── README.md    # Project guide

🚀 Getting Started

Prerequisites

• Node.js and Yarn installed. Verify installations with:

  node --version
  yarn --version
  

Install Dependencies

yarn install

Compile the Contract

forge build

Run Tests

forge test

Deploying the Contract to the Filecoin Calibration Testnet

forge script script/SealedBidAuction.s.sol --rpc-url $CALIBRATION_TESTNET_RPC_URL --private-key $CALIBRATION_TESTNET_PRIVATE_KEY --broadcast

📜 How It Works

1. Encrypting Your Bid (Off-Chain): Bidders encrypt their bid amounts off-chain, generating ciphertexts for submission.
2. Submitting Your Bid (On-Chain): Encrypted bids are submitted to the smart contract along with a reserve price deposit.
3. Revealing the Bids (On-Chain): At a predefined block number, an off-chain oracle provides decryption keys to the contract, which then decrypts each bid on-chain.
4. Picking the Winner & Settling Payments (On-Chain): The contract identifies the highest bid. The winner pays the difference between their bid and the reserve price, while other bidders receive refunds.

🔒 Security Considerations

• Ensures bidders cannot manipulate their bids after submission.
• Prevents frontrunning attacks by placing encrypted bids only decrypted at the end of the bidding period.

📖 Tutorial & Documentation

Check out the detailed tutorial on our blog.

Licensing

This source code is licensed under the MIT License which can be accessed here.