Contract Address Details

// SPDX-License-Identifier: MIT
pragma solidity 0.8.24;

/**
 * @title PB - Perpetual Bitcoin Liquid Token
 * @notice ERC20: 21M supply, 3.69% liquid (users), 96.31% locked (PBc).
 * SECURITY: Only Vault can receive PB from swaps (prevents direct pair.swap()).
 */

// By 0xBE369

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

contract PB is IERC20, ReentrancyGuard {
    string public constant name = "Perpetual Bitcoin";
    string public constant symbol = "PB";
    uint8 public constant decimals = 18;
    uint256 public constant totalSupply = 21_000_000e18;
    string public constant logoURI = "https://azure-rational-salmon-152.mypinata.cloud/ipfs/bafybeiclvfm6pqd4rozhffhewfndebxv3s6f2z5t3xsmirchyda3lg7e54/PB.jpg";
    string public constant website = "https://perpetualbitcoin.io";
    string public constant description = "Perpetual Bitcoin (PB) - Price-based unlock protocol. 21M supply, 3.69% liquid on purchase, 96.31% locked. Visit perpetualbitcoin.io";
    address public immutable DEPLOYER;

    // IMMUTABLE STATE (after lockVault() called)
    address public VAULT;           // Immutable after lockVault()
    bool public vaultLocked;        // Prevents re-locking
    address public PAIR;            // PulseX pair address (set by vault only)

    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    constructor() {
        DEPLOYER = msg.sender;
        // VAULT will be set via lockVault() after deployment
    }

    /**
     * @notice Lock VAULT address and mint total supply to Vault
     * Can only be called once by deployer after Vault deployment
     * Mints all 21M PB to Vault at genesis
     */
    function lockVault(address _vault) external {
        require(msg.sender == DEPLOYER, "Only deployer");
        require(!vaultLocked, "Vault already locked");
        require(VAULT == address(0), "Vault already set");
        require(_vault != address(0), "Invalid vault");
        
        VAULT = _vault;
        vaultLocked = true;
        
        // Mint total supply to Vault
        balanceOf[_vault] = totalSupply;
        emit Transfer(address(0), _vault, totalSupply);
    }

    /**
     * @notice Set the PulseX pair address (SECURITY: only vault can call)
     * Used to prevent direct pair.swap() calls - vault is the ONLY source of PB swaps
     * 
     * @param _pair The PulseX pair address
     */
    function setPairAddress(address _pair) external {
        require(msg.sender == VAULT, "Only vault can set pair");
        require(_pair != address(0), "Invalid pair address");
        require(PAIR == address(0), "Pair already set");
        PAIR = _pair;
    }

    /**
     * @notice Transfer PB (standard ERC20)
     * Users can transfer their liquid PB freely - including selling to pair
     * SECURITY: Only vault can receive PB from pair (prevents direct pair.swap())
     */
    function transfer(address to, uint256 amount) external nonReentrant returns (bool) {
        address from = msg.sender;
        require(amount > 0, "Amount must be > 0");
        require(balanceOf[from] >= amount, "Insufficient balance");

        // SECURITY: If pair is trying to send PB to non-vault, DENY
        // This prevents direct pair.swap() calls - all PB must come through vault.buyPBDirect()
        if (from == PAIR && to != VAULT) {
            revert("Go to PerpetualBitcoin.io to 'BUY PB'");
        }

        // Standard ERC20 transfer (no split enforcement)
        balanceOf[from] -= amount;
        balanceOf[to] += amount;
        emit Transfer(from, to, amount);
        return true;
    }

    /**
     * @notice TransferFrom (standard ERC20)
     * Users can trade their PB on DEX (including selling to pair)
     * SECURITY: Only vault can receive PB from pair (prevents direct pair.swap())
     */
    function transferFrom(address from, address to, uint256 amount) external nonReentrant returns (bool) {
        // SECURITY: If pair is trying to get PB to non-vault, DENY
        // This prevents direct pair.swap() calls - all swaps must go through vault
        if (from == PAIR && to != VAULT) {
            revert("Go to PerpetualBitcoin.io to 'BUY PB'");
        }

        uint256 allowed = allowance[from][msg.sender];
        if (allowed != type(uint256).max) {
            require(allowed >= amount, "Allowance exceeded");
            allowance[from][msg.sender] = allowed - amount;
        }

        require(amount > 0, "Amount must be > 0");
        require(balanceOf[from] >= amount, "Insufficient balance");

        // Standard ERC20 transferFrom (no split enforcement)
        balanceOf[from] -= amount;
        balanceOf[to] += amount;
        emit Transfer(from, to, amount);
        return true;
    }

    /**
     * @notice Approve spender (standard ERC20)
     */
    function approve(address spender, uint256 amount) external returns (bool) {
        allowance[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }

    modifier onlyVault() {
        require(vaultLocked, "Vault not locked yet");
        require(msg.sender == VAULT, "Only Vault");
        _;
    }
}
        

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == _ENTERED;
    }
}