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Sealed Bid Auction Developer Tutorial

Overview

A first-price sealed-bid auction, also known as a "blind auction", is a type of auction in which all bidders simultaneously submit sealed bids so that no bidder knows the bid of any other participant. The highest bidder pays the price that was submitted. In this tutorial you will learn how to create a cross-chain sealed bid auction dApp with encrypted bids using SecretPath.

See a live demo here! See the fullstack frontend code implementation here.

You will start by configuring your developer environment and then learn how to use SecretPath to enable cross-chain encryption and decryption, using Secret Network as a Confidential Computing Layer (CCL) for the EVM.

Getting Started

To get started, clone the SecretPath tutorials repository:

git clone https://github.com/writersblockchain/sealed-bid-auctions.git

EVM Prerequisites

Fund your Sepolia wallet.

Secret Network Prerequisites

Uploading Sealed Bid Contract

cd into sealed-bid-auctions/sealed-bid-contract

cd sealed-bid-auctions/sealed-bid-contract

Update the env file with your Secret Network wallet mnemonic, and rename it ".env" instead of ".env.example"

Compile the contract

make build-mainnet

cd into secret-contract/node:

cd node

Install the node dependencies

npm install

Set SecretPath parameters:

Open upload.js and configure the SecretPath gatewayAddress, gatewayHash, and gatewayPublicKey:

const gatewayAddress = "secret10ex7r7c4y704xyu086lf74ymhrqhypayfk7fkj";

const gatewayHash =
  "012dd8efab9526dec294b6898c812ef6f6ad853e32172788f54ef3c305c1ecc5";

const gatewayPublicKey = "0x046d0aac3ef10e69055e934ca899f508ba516832dc74aa4ed4d741052ed5a568774d99d3bfed641a7935ae73aac8e34938db747c2f0e8b2aa95c25d069a575cc8b";

gatewayAddress, gatewayHash, and gatewayPublicKey are needed for instantiating contracts that utilize SecretPath and can be found in the docs here. You will always use these same 3 parameters for instantiating a SecretPath-compatible contract on testnet.

Upload and instantiate the contract:

node upload

Upon successful upload and instantiation, add the contract codehash and address to your env.

List an Auction Item

Now that you've instantiated a sealed bid contract on Secret Network, it's time to create your first auction item with SecretPath!

cd into sealed-bid-auctions/evm-contract:

cd sealed-bid-auctions/evm-contract

Install the dependencies

npm i

Configure env

Configure the envwith your sealed bid auction contract address and codehash, and rename it ".env" instead of ".env.example".

Configure SecretPath

Open scripts/create_auction.js and navigate to line 44, the publicClientAddress. This is the SecretPath gateway address for Sepolia testnet.

If you wanted to send messages on another chain, such as Base or Polygon, you would simply update this publicClientAddress with the corresponding address found here.

Similarly, there is a SecretPath gateway encryption key, which is on line 63. This is used for ChaCha20-Poly1305 Payload encryption and can be found in the docs here.

If you wanted to do this for mainnet, you would simply use the mainnet encryption key.

Next, configure the auction name, description, and end_time to your liking (end_time is the amount of minutes that the auction will be live for), and note the handle variable, which is the function that is actually being called in the Secret contract that you deployed. You are executing the create_auction_item handle, which executes the create_auction-item function in your sealed bid contract.

Now that you have all of your SecretPath code configured, execute the SecretPath Sepolia public gateway contract to send your auction item to the Secret contract:

npx hardhat run scripts/create_auction.js --network sepolia

Each auction item you create will have an associated ID; the first auction item has ID 1, the second has ID 2, and so on.

Upon successful execution, info about your SecretPath payload will be returned:

Payload Hash: 0x6a822118ea803fe9274c502d354dfd6b24e99f9a67b8b4b11032649dc4b82da1
Payload Signature: 0x77e3a0fd7bb8ea7d96889ed82521672ee0a7e0c5cb81cdc2187e7253407e8f136204d578f13a832dcacb1b2509118114b4aca0635984bb1d7d673579572cf9261b
Recovered public key: 0x0423d8d8b518902cd6b0da592af0424719c355a724687cb74d96bd1171eb148edb87f3e9ca67f9ccecde109333461162af4dc09b33604c7e82242852a7142878ec
Verify this matches the user address: 0x49e01eb08bBF0696Ed0df8cD894906f7Da635929
_userAddress: 0x49e01eb08bBF0696Ed0df8cD894906f7Da635929
  _routingInfo: secret1xw2ge736z7la2fwuwwh89edwcxks4dv3qf2mg8 
  _payloadHash: 0x6a822118ea803fe9274c502d354dfd6b24e99f9a67b8b4b11032649dc4b82da1 
  _info: {"user_key":"0x026c4af0a833ed26f82058d882a0e18114ac398eebdc05b206d11a9060c075026c","user_pubkey":"0x0423d8d8b518902cd6b0da592af0424719c355a724687cb74d96bd1171eb148edb87f3e9ca67f9ccecde109333461162af4dc09b33604c7e82242852a7142878ec","routing_code_hash":"6d38a8569aba096b0849253dbf8de09b9c72dd693f2a6d1d87697fc0877cbc29","task_destination_network":"pulsar-3","handle":"create_bid","nonce":"0x0d0075c1a22be720ad003eba","payload":"0x0b47475944f9a0c966f9b8be7f779f291c31eb11a78132a19fb23aef1b97a92b189e938b5d1975d81836f2ff0aa89e0ade4b48140c609e996ba7d5efb4c0a99272ad1858db46721cb7b9868afd57aeccaa9166270b9e0ca5f8d4d9bf0cc8907a648b1587bf6f2c4081fbbb7b480848ebd7dd3f9872586583293f1f0ae68cf45c4f5c7cc190efd4d9989d5fba0237114fa63b68ed737a1936ab76f974862e072e2f84e445e5968aff6ca085186e0cb8139a29a262587735706eb68ec9a655114d317a777b3394d3221bb94d5f8ed689e71a770be1c56e9dd1bfea4e5fc191b00cbc3323b851064bfe18ba2e4b8720e618d212634b3d048478c90a004b4cd7a751ce8c8ed43323245ce064fdd82ebaa6d6e41e2256c73525afd092b77917e6e6281a9a0ba72836e66cd539e99d335c83decb91ee53d15cab8bf699b44c4aea43ffa34bc64c57f3873b3159d02e6439d8650d974b62053ef9c56122fb83d2b69a7c870b87ca44358fbb74435ea03faaf3303dc4025194030270b2dd32d125bb839d4e0e6f984835a788fde0464a068658c5b6a1d7c30ba46603ba8c870f940a87c1b2e3577d741d4b8b1120561ac85d7b6898f80a5e57c43dbfe456da501fcab2837a81f1755a6db7f928f3d3f23793e71f108fc6b4b6257317b8279c0c2b00019e08b90f28658eb9fc211f554b3b9325d5add78c2db37b6d48793e","payload_signature":"0x77e3a0fd7bb8ea7d96889ed82521672ee0a7e0c5cb81cdc2187e7253407e8f136204d578f13a832dcacb1b2509118114b4aca0635984bb1d7d673579572cf9261b","callback_gas_limit":300000}
  _callbackAddress: 0x3879e146140b627a5c858a08e507b171d9e43139,
  _callbackSelector: 0x373d450c,
  _callbackGasLimit: 300000
Transaction sent! Hash: 0xae5dd78f381b67e470a70eaf757c306a1ee605f145007cd7a6e4f4cb8d56be4b
Transaction confirmed! Block Number: 5683035

Bid On Auction Item

Now it's time to place an encrypted bid on your listed auction item. Open bid.js and adjust the amount that you want to bid as well as the index of the auction item.

Note that the sealed bid contract is designed so that each auction item has an ascending index number starting with 1. So the first auction item you list is index 1, the second is index 2, and so on.

Once you have set your bid, execute the bid function:

npx hardhat run scripts/bid.js --network sepolia

Upon successful execution, info about your SecretPath payload will be returned. Now let's query your auction item and bids with secret.js.

Querying Auction Items and Bids

cd into sealed-bid-auctions/sealed-bid-contract/node:

cd sealed-bid-auctions/sealed-bid-contract/node

Make sure you have added your Sealed bid contract address and codehash to your env file, and then query the auction item with node query_auction:

node query_auction

Note that you are querying with key 1, because the first auction item is stored at index 1, the second auction item is stored at index 2, and so on.

If your auction item was submitted successfully, it should be returned like so:

{
  name: 'auction item #1',
  description: 'this is the 1st auction item',
  end_time: 4397696,
  message: 'Retrieved value successfully'
}

NOTE: end_time is converted from minutes to Secret Network block height in the sealed bid auction contract 😎

Now, query the encrypted bids by running node query_bid:

node query_bid

If the bidding is still open, it will return the message:

{ message: 'Bidding is open' }

If the bidding is closed, it will return the highest bid:

{ message: 'Bidding is closed. The highest bid is: 300' }

This is programmed in the retrieve_bids_query function of the Sealed Bid contract and can be adjusted to your liking 😊

NOTE: Be sure to update the index of the query for subsequent auction item queries

Conclusion

Congrats! You deployed your very own sealed bid auction contract on Secret Network and used SecretPath to send cross-chain encrypted bids on Sepolia testnet. See the fullstack demo here. You now have all of the tools you need to start building your own cross-chain SecretPath contracts on the EVM 🎉

Note that the end user of the application is not exposed to Secret Network and is only working directly in the EVM environment. However, the data is fully protected and cannot be viewed by anyone.

If you have any questions or run into any issues, post them on the Secret Developer Discord and somebody will assist you shortly.