Phrase Trade EIP712

Overview

The PhraseTradeEIP712 contract implements the EIP-712 standard, providing a structured and secure way to sign typed data on-chain. It is a key component of the Phrase.Trade protocol, enabling efficient off-chain signing for operations like minting NFTs, reducing gas costs, and enhancing security.

Purpose

This contract is responsible for creating the EIP-712 domain separator and struct hash for secure and typed data signing. It allows for off-chain message signing that can be verified on-chain, ensuring gas efficiency and security.

Key Features

• Implements EIP-712 domain separator.

• Provides the ability to hash custom structs for signing.

• Facilitates the secure signing of off-chain data, which can then be submitted on-chain for verification.

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Contract Details

1. State Variables

• domainSeparator (bytes32): The EIP-712 domain separator that is used for message hashing and signature verification.

• name (string): The name of the contract, used in the domain separator.

• version (string): The version of the contract, also used in the domain separator.

• chainId (uint256): The chain ID for the blockchain network, included in the domain separator to ensure security across different networks.

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2. Constructor

constructor(string memory _name, string memory _version)

Parameters:

• _name (string): The name of the EIP-712 domain.

• _version (string): The version of the EIP-712 domain.

Functionality:

The constructor initializes the contract by setting the name, version, and chainId of the EIP-712 domain. It also calculates the domainSeparator using the keccak256 hash of the domain details (name, version, chainId, and contract address). This separator is used for all message signing within the contract.

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3. getStructHash

function getStructHash(
    string memory tokenURI,
    uint256 tillTimestamp,
    address creator
) public pure returns (bytes32)

Parameters:

• tokenURI (string): The URI of the token to be minted.

• tillTimestamp (uint256): The timestamp until the trade is valid.

• creator (address): The address of the token creator.

Functionality:

This function returns the hash of a struct, which includes the token URI, a validity timestamp, and the creator’s address. It uses keccak256 to create a unique identifier for the specific minting operation.

Example:

For a minting operation with a specific token URI, this function provides the struct hash, which can then be used to generate a message hash.

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4. getMessageHash

function getMessageHash(bytes32 structHash) public view returns (bytes32)

Parameters:

• structHash (bytes32): The hash of the struct that is to be signed.

Functionality:

This function returns the message hash, which is a combination of the domain separator and the struct hash. The message hash is what is signed by the user and can later be verified on-chain.

The encoding format used for the message is:

keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash))

This ensures that the message being signed adheres to the EIP-712 standard and that the struct data is securely encoded with the domain information.

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Summary

The PhraseTradeEIP712 contract serves as a core component for off-chain message signing and on-chain verification within the Phrase.Trade ecosystem. By implementing the EIP-712 standard, it ensures that data signing is efficient and secure, reducing gas costs for repetitive operations such as minting new phrase NFTs. The contract provides:

• Domain separation to ensure signatures are valid only within the Phrase.Trade ecosystem.

• The ability to hash custom structs for specific operations.

• A secure way to create message hashes that can be signed off-chain and verified on-chain.