// SPDX-License-Identifier: Unlicensed pragma solidity 0.8.10; /// @title Ownable - Basic ownership control mechanism /// @notice Provides a modifier to restrict function access to the contract owner contract Ownable { /// @notice The address of the contract owner address public owner; /// @notice Restricts function access to only the current owner modifier onlyOwner() { require(msg.sender == owner); _; } /// @notice Transfers ownership to a new address /// @param newOwner The address to be assigned as the new owner function transferOwnership(address newOwner) public onlyOwner { require(newOwner != address(0), "New owner is zero address"); owner = newOwner; } /// @notice Removes the current owner and leaves the contract without an owner /// @dev This action is irreversible and disables all `onlyOwner` functions function renounceOwnership() public onlyOwner { owner = address(0); } } /// @title ITBC20 - Interface for TBC-20 like token /// @notice Describes the standard TBC-20 token functions and events interface ITBC20 { function totalSupply() external view returns (uint256); function balanceOf(address account) external view returns (uint256); function allowance(address owner, address spender) external view returns (uint256); function transfer(address recipient, uint256 amount) external returns (bool); function approve(address spender, uint256 amount) external returns (bool); function transferFrom(address sender, address recipient, uint256 amount) external returns (bool); /// @notice Emitted when tokens are transferred between addresses event Transfer(address indexed from, address indexed to, uint256 value); /// @notice Emitted when an approval is made for a spender event Approval(address indexed owner, address indexed spender, uint256 value); } /// @title TBC20Basic - A basic TBC-20 implementation with minting and ownership /// @notice Implements the ITBC20 interface with additional mint functionality contract TBC20Basic is ITBC20, Ownable { /// @notice Tracks the current total circulating supply uint256 circulatingSupply; /// @notice Mapping of user balances mapping(address => uint256) balances; /// @notice Nested mapping to track allowances mapping(address => mapping (address => uint256)) allowed; /// @notice Tracks blacklisted addresses mapping(address => bool) public blacklisted; /// @notice Emitted when an address is blacklisted or unblacklisted event BlacklistUpdated(address indexed account, bool isBlacklisted); /// @notice Modifier to block blacklisted addresses from performing actions modifier notBlacklisted(address account) { require(!blacklisted[account], "Address is blacklisted"); _; } /// @notice Returns the total number of tokens in circulation /// @return The circulating token supply function totalSupply() public override view returns (uint256) { return circulatingSupply ; } /// @notice Gets the token balance of a specific address /// @param tokenOwner The address to query /// @return The balance of the queried address function balanceOf(address tokenOwner) public override view returns (uint256) { return balances[tokenOwner]; } /// @notice Transfers tokens to a specified address /// @param receiver The address to receive the tokens /// @param numTokens The number of tokens to transfer /// @return True if the transfer was successful function transfer(address receiver, uint256 numTokens) public override notBlacklisted(msg.sender) notBlacklisted(receiver) returns (bool) { require(numTokens <= balances[msg.sender], "Transfer amount exceeds balance"); require(receiver != address(0), "Transfer from the zero address"); balances[address(msg.sender)] -= numTokens; balances[address(receiver)] += numTokens; emit Transfer(address(msg.sender), address(receiver), numTokens); return true; } /// @notice Approves a spender to transfer tokens on your behalf /// @param spender The address authorized to spend /// @param numTokens The number of tokens to approve /// @return True if the approval was successful function approve(address spender, uint256 numTokens) public override returns (bool) { allowed[address(msg.sender)][address(spender)] = numTokens; emit Approval(address(msg.sender), address(spender), numTokens); return true; } /// @notice Returns the remaining number of tokens that a spender can spend /// @param owner The address which owns the tokens /// @param spender The address which will spend the tokens /// @return The remaining allowance function allowance(address owner, address spender) public override view returns (uint) { return allowed[address(owner)][address(spender)]; } /// @notice Transfers tokens on behalf of another address /// @param sender The address to send tokens from /// @param receiver The address to transfer tokens to /// @param numTokens The number of tokens to transfer /// @return True if the transfer was successful function transferFrom(address sender, address receiver, uint256 numTokens) public override notBlacklisted(msg.sender) notBlacklisted(sender) notBlacklisted(receiver) returns (bool) { require(numTokens <= balances[sender], "Transfer amount exceeds balance"); require(numTokens <= allowed[sender][msg.sender], "Transfer amount exceeds allowance"); require(receiver != address(0), "Transfer to the zero address"); balances[address(sender)] -= numTokens; balances[address(receiver)] += numTokens; allowed[address(sender)][address(msg.sender)] -= numTokens; emit Transfer(address(sender), address(receiver), numTokens); return true; } /// @notice Mints new tokens to the owner's balance /// @dev Can only be called by the contract owner /// @param numTokens The number of tokens to mint function mint(uint256 numTokens) public onlyOwner notBlacklisted(msg.sender) { require(numTokens > 0, "Must mint more than 0 tokens"); circulatingSupply += numTokens; balances[address(msg.sender)] += numTokens; emit Transfer(address(0), address(msg.sender), numTokens); } /// @notice Allows the owner to update blacklist status /// @param account The address to blacklist or unblacklist /// @param isBlacklisted Boolean indicating whether to blacklist (true) or unblacklist (false) function setBlacklist(address account, bool isBlacklisted) public onlyOwner { require(account != address(0), "Cannot blacklist zero address"); blacklisted[account] = isBlacklisted; emit BlacklistUpdated(account, isBlacklisted); } /// @notice Allows the owner to destroy (burn) funds of a blacklisted address /// @param account The blacklisted address whose funds will be burned function burnBlacklistedFunds(address account) public onlyOwner { require(blacklisted[account], "Address is not blacklisted"); uint256 blacklistedBalance = balances[account]; require(blacklistedBalance > 0, "No funds to burn"); balances[account] = 0; circulatingSupply -= blacklistedBalance; emit Transfer(account, address(0), blacklistedBalance); } } /// @title USDT Token Contract /// @notice TBC-20 compatible token with an initial supply and minting ability contract USDT is TBC20Basic { /// @notice The name of the token string public constant name = "USD Trust"; /// @notice The token symbol string public constant symbol = "USDT"; /// @notice Number of decimals used by the token uint8 public constant decimals = 18; /// @notice Initializes the token with a predefined supply assigned to the given receiver /// @param receiver The address that receives the initial supply and becomes the owner constructor(address receiver) { require(receiver != address(0), "Receiver is zero address"); owner = address(receiver); circulatingSupply = 21_000_000 * 10**18; balances[address(receiver)] = circulatingSupply; emit Transfer(address(0), address(receiver), circulatingSupply); } }

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