ERC20 Token Contract

This is a comprehensive implementation of the ERC20 token standard in Solidity with advanced ownership management, mint/burn functionality, and enhanced security features.

Overview

• Author: Alireza Kiakojouri (@AlirezaEthDev)
• License: MIT
• Solidity Version: ^0.8.27
• Owner: The contract owner has exclusive minting privileges and uses a secure two-step ownership transfer pattern
• Name: Customizable token name set during deployment
• Symbol: Customizable token symbol set during deployment
• Decimals: Customizable decimal places for token precision
• Total Supply: Dynamic total supply that changes with mint/burn operations (starts at zero)

Features

• Full ERC20 Compliance: Implements all standard ERC20 functions and events
• ERC20Metadata Support: Includes name, symbol, and decimals functionality
• ERC165 Interface Detection: Supports interface identification standard
• Two-Step Ownership Transfer: Secure ownership management with pending owner mechanism
• Mint/Burn Functionality: Owner can mint tokens, users can burn their own tokens
• Advanced Security: Comprehensive input validation and custom error handling
• Zero Address Protection: Prevents transfers to/from zero addresses
• Balance & Allowance Checks: Built-in validation for sufficient balances and allowances
• Gas Optimized: Uses unchecked arithmetic where safe for gas efficiency

Contract Architecture

State Variables

• owner: Current contract owner with minting privileges
• pendingOwner: Address nominated for ownership transfer
• _name_, _symbol_, _decimals_: Token metadata
• _totalSupply_: Current total token supply
• balanceList: Mapping of address balances
• approveList: Nested mapping for token allowances
• whoIsApprovedBy: Tracking mapping for approval relationships

Events

Ownership Events:

• NewPendingOwnerSet(address _pendingOwner): Emitted when a new pending owner is nominated
• OwnerChanged(address _newOwner, address _pendingOwner): Emitted when ownership transfer completes

Token Supply Events:

• Mint(uint256 _mintValue, uint256 _supplyValue): Emitted when tokens are minted
• Burn(uint256 _burnValue, uint256 _supplyValue): Emitted when tokens are burned

Standard ERC20 Events:

• Transfer(address indexed _from, address indexed _to, uint256 _value): Token transfers
• Approval(address indexed _owner, address indexed _spender, uint256 _value): Token approvals

Custom Errors

• OnlyOwner(address _owner, address _sender): Unauthorized owner function access
• ZerpPendingOwner(address _setAddr): Invalid zero address for pending owner
• OnlyPendingPwner(address _pendingOwner, address _yourAddress): Unauthorized ownership claim
• Plus standard ERC6093 errors for transfers, approvals, and balance validations

Security Modifiers

• onlyOwner(): Restricts access to contract owner only
• balanceCheck(uint256 _requestValue): Validates sufficient balance for operations
• senderCheck(): Prevents zero address as sender
• receiptCheck(address _to): Prevents zero address as recipient
• approverCheck(): Validates approver is not zero address
• spenderCheck(address _spender): Validates spender is not zero address

Core Functions

ERC20 Standard Functions

• balanceOf(address _owner): Returns token balance of specified address
• transfer(address _to, uint256 _value): Transfers tokens from caller to recipient
• transferFrom(address _from, address _to, uint256 _value): Transfers tokens using allowance mechanism
• approve(address _spender, uint256 _value): Approves spender to transfer tokens on behalf of caller
• allowance(address _owner, address _spender): Returns approved allowance amount
• totalSupply(): Returns current total supply of tokens

ERC20Metadata Functions

• name(): Returns human-readable token name
• symbol(): Returns token symbol/ticker
• decimals(): Returns number of decimal places

Ownership Management

• setPendingOwner(address _pendingOwner): Nominates new owner (step 1 of transfer)
• changeOwner(): Completes ownership transfer (step 2 of transfer)

Mint/Burn Functions

• mint(address _to, uint256 _value): Creates new tokens (owner only)
• burn(uint256 _value): Destroys tokens from caller's balance

Interface Support

• supportsInterface(bytes4 interfaceID): ERC165 interface detection

Usage

Deployment

// Deploy with custom token parameters
ERC20 token = new ERC20("My Token", "MTK", 18);

Basic Operations

// Mint initial supply (owner only)
token.mint(recipient, 1000 * 10**18);

// Transfer tokens
token.transfer(recipient, amount);

// Approve spending
token.approve(spender, amount);

// Transfer from allowance
token.transferFrom(owner, recipient, amount);

// Burn tokens
token.burn(amount);

Ownership Transfer

// Step 1: Current owner nominates new owner
token.setPendingOwner(newOwnerAddress);

// Step 2: New owner claims ownership
token.changeOwner(); // Called by pending owner

Security Considerations

• Two-Step Ownership Transfer: Prevents accidental ownership loss
• Zero Address Protection: Comprehensive validation against zero addresses
• Balance Validation: All operations check for sufficient balances
• Custom Errors: Gas-efficient error handling with detailed information
• Allowance Security: Proper validation of spending permissions
• Overflow Protection: Uses Solidity 0.8+ built-in overflow protection

Dependencies

• IERC20.sol: ERC20 interface
• IERC165.sol: ERC165 interface
• IERC20Metadata.sol: ERC20Metadata interface
• IERC6093.sol: ERC20 error definitions
• Context.sol: Context utilities for meta-transactions

License

This project is licensed under the MIT License.