Cryo Explorer Ethereum Mainnet

// SPDX-License-Identifier: MIT

pragma solidity 0.7.5;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/math/SafeMath.sol";

contract Ctx {
  /// @notice EIP-20 token name for this token
  string public constant name = "Cryptex";

  /// @notice EIP-20 token symbol for this token
  string public constant symbol = "CTX";

  /// @notice EIP-20 token decimals for this token
  uint8 public constant decimals = 18;

  /// @notice Total number of tokens in circulation
  uint256 public totalSupply = 10000000e18; // 10 million CTX

  /// @notice Address which may mint new tokens
  address public minter;

  /// @notice The timestamp after which minting may occur
  uint256 public mintingAllowedAfter;

  /// @notice Minimum time between mints
  uint32 public constant minimumTimeBetweenMints = 1 days * 365;

  /// @notice Cap on the percentage of totalSupply that can be minted at each mint
  uint8 public constant mintCap = 2;

  /// @dev Allowance amounts on behalf of others
  mapping(address => mapping(address => uint96)) internal allowances;

  /// @dev Official record of token balances for each account
  mapping(address => uint96) internal balances;

  /// @notice A record of each accounts delegate
  mapping(address => address) public delegates;

  /// @notice A checkpoint for marking number of votes from a given block
  struct Checkpoint {
    uint32 fromBlock;
    uint96 votes;
  }

  /// @notice A record of votes checkpoints for each account, by index
  mapping(address => mapping(uint32 => Checkpoint)) public checkpoints;

  /// @notice The number of checkpoints for each account
  mapping(address => uint32) public numCheckpoints;

  /// @notice The EIP-712 typehash for the contract's domain
  bytes32 public constant DOMAIN_TYPEHASH =
    keccak256(
      "EIP712Domain(string name,uint256 chainId,address verifyingContract)"
    );

  /// @notice The EIP-712 typehash for the delegation struct used by the contract
  bytes32 public constant DELEGATION_TYPEHASH =
    keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");

  /// @notice The EIP-712 typehash for the permit struct used by the contract
  bytes32 public constant PERMIT_TYPEHASH =
    keccak256(
      "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
    );

  /// @notice A record of states for signing / validating signatures
  mapping(address => uint256) public nonces;

  /// @notice An event thats emitted when the minter address is changed
  event MinterChanged(address minter, address newMinter);

  /// @notice An event thats emitted when an account changes its delegate
  event DelegateChanged(
    address indexed delegator,
    address indexed fromDelegate,
    address indexed toDelegate
  );

  /// @notice An event thats emitted when a delegate account's vote balance changes
  event DelegateVotesChanged(
    address indexed delegate,
    uint256 previousBalance,
    uint256 newBalance
  );

  /// @notice The standard EIP-20 transfer event
  event Transfer(address indexed from, address indexed to, uint256 amount);

  /// @notice The standard EIP-20 approval event
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 amount
  );

  /**
   * @notice Construct a new Ctx token
   * @param account The initial account to grant all the tokens
   * @param minter_ The account with minting ability
   * @param mintingAllowedAfter_ The timestamp after which minting may occur
   */
  constructor(
    address account,
    address minter_,
    uint256 mintingAllowedAfter_
  ) {
    require(
      mintingAllowedAfter_ >= block.timestamp,
      "Ctx::constructor: minting can only begin after deployment"
    );

    balances[account] = uint96(totalSupply);
    emit Transfer(address(0), account, totalSupply);
    minter = minter_;
    emit MinterChanged(address(0), minter);
    mintingAllowedAfter = mintingAllowedAfter_;
  }

  /**
   * @notice Change the minter address
   * @param minter_ The address of the new minter
   */
  function setMinter(address minter_) external {
    require(
      msg.sender == minter,
      "Ctx::setMinter: only the minter can change the minter address"
    );
    emit MinterChanged(minter, minter_);
    minter = minter_;
  }

  /**
   * @notice Mint new tokens
   * @param dst The address of the destination account
   * @param rawAmount The number of tokens to be minted
   */
  function mint(address dst, uint256 rawAmount) external {
    require(msg.sender == minter, "Ctx::mint: only the minter can mint");
    require(
      block.timestamp >= mintingAllowedAfter,
      "Ctx::mint: minting not allowed yet"
    );
    require(
      dst != address(0),
      "Ctx::mint: cannot transfer to the zero address"
    );
    require(
      dst != address(this),
      "Ctx::mint: cannot transfer to the Ctx address"
    );

    // record the mint
    mintingAllowedAfter = SafeMath.add(
      block.timestamp,
      minimumTimeBetweenMints
    );

    // mint the amount
    uint96 amount = safe96(rawAmount, "Ctx::mint: amount exceeds 96 bits");
    require(
      amount <= SafeMath.div(SafeMath.mul(totalSupply, mintCap), 100),
      "Ctx::mint: exceeded mint cap"
    );
    totalSupply = safe96(
      SafeMath.add(totalSupply, amount),
      "Ctx::mint: totalSupply exceeds 96 bits"
    );

    // transfer the amount to the recipient
    balances[dst] = add96(
      balances[dst],
      amount,
      "Ctx::mint: transfer amount overflows"
    );
    emit Transfer(address(0), dst, amount);

    // move delegates
    _moveDelegates(address(0), delegates[dst], amount);
  }

  /**
   * @notice Get the number of tokens `spender` is approved to spend on behalf of `account`
   * @param account The address of the account holding the funds
   * @param spender The address of the account spending the funds
   * @return The number of tokens approved
   */
  function allowance(address account, address spender)
    external
    view
    returns (uint256)
  {
    return allowances[account][spender];
  }

  /**
   * @notice Sets `amount` as the allowance of `spender` over the `owner` s tokens.
   * @param owner The address of the caller.
   * @param spender The address of the account which may transfer tokens
   * @param amount The number of tokens that are approved
   * @dev This internal function is equivalent to `approve`, and can be used to
   * e.g. set automatic allowances for certain subsystems, etc.
   * @dev Emits an Approval event.
   * @dev owner cannot be the zero address.
   * @dev spender cannot be the zero address.
   */
  function _approve(
    address owner,
    address spender,
    uint96 amount
  ) internal virtual {
    require(
      owner != address(0),
      "Ctx::_approve: approve from the zero address"
    );
    require(
      spender != address(0),
      "Ctx::_approve: approve to the zero address"
    );

    allowances[owner][spender] = amount;
    emit Approval(owner, spender, amount);
  }

  /**
   * @notice Approve `spender` to transfer up to `amount` from `src`
   * @param spender The address of the account which may transfer tokens
   * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
   * @dev This will overwrite the approval amount for `spender`
   *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
   * @return Whether or not the approval succeeded
   */
  function approve(address spender, uint256 rawAmount) external returns (bool) {
    uint96 amount;
    if (rawAmount == uint256(-1)) {
      amount = uint96(-1);
    } else {
      amount = safe96(rawAmount, "Ctx::approve: amount exceeds 96 bits");
    }
    _approve(msg.sender, spender, amount);
    return true;
  }

  /**
   * @notice Atomically increases the allowance granted to `spender` by the caller.
   * @param spender address
   * @param addedValue uint256 raw
   * @dev This is an alternative to {approve} that can be used as a mitigation for
   * problems of Allowance Double-Spend Exploit.
   * @dev Emits Approval event indicating the updated allowance.
   * @dev spender cannot be the zero address.
   */
  function increaseAllowance(address spender, uint256 addedValue)
    public
    virtual
    returns (bool)
  {
    uint96 amount;
    if (addedValue == uint256(-1)) {
      amount = uint96(-1);
    } else {
      amount = safe96(
        addedValue,
        "Ctx::increaseAllowance: amount exceeds 96 bits"
      );
    }
    _approve(
      msg.sender,
      spender,
      add96(
        allowances[msg.sender][spender],
        amount,
        "Ctx::increaseAllowance: transfer amount overflows"
      )
    );
    return true;
  }

  /**
   * @notice Atomically decreases the allowance granted to `spender` by the caller.
   * @param spender address
   * @param subtractedValue uint256 raw
   * @dev This is an alternative to {approve} that can be used as a mitigation for
   * problems of Allowance Double-Spend Exploit.
   * @dev Emits an Approval event indicating the updated allowance.
   * @dev spender cannot be the sero address
   * @dev spender must have allowance for the caller of at least subtractedValue
   */
  function decreaseAllowance(address spender, uint256 subtractedValue)
    public
    virtual
    returns (bool)
  {
    uint96 amount;
    if (subtractedValue == uint256(-1)) {
      amount = uint96(-1);
    } else {
      amount = safe96(
        subtractedValue,
        "Ctx::decreaseAllowance: amount exceeds 96 bits"
      );
    }

    _approve(
      msg.sender,
      spender,
      sub96(
        allowances[msg.sender][spender],
        amount,
        "Ctx::decreaseAllowance: decreased allowance below zero"
      )
    );
    return true;
  }

  /**
   * @notice Triggers an approval from owner to spends
   * @param owner The address to approve from
   * @param spender The address to be approved
   * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
   * @param deadline The time at which to expire the signature
   * @param v The recovery byte of the signature
   * @param r Half of the ECDSA signature pair
   * @param s Half of the ECDSA signature pair
   */
  function permit(
    address owner,
    address spender,
    uint256 rawAmount,
    uint256 deadline,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external {
    uint96 amount;
    if (rawAmount == uint256(-1)) {
      amount = uint96(-1);
    } else {
      amount = safe96(rawAmount, "Ctx::permit: amount exceeds 96 bits");
    }

    bytes32 domainSeparator =
      keccak256(
        abi.encode(
          DOMAIN_TYPEHASH,
          keccak256(bytes(name)),
          getChainId(),
          address(this)
        )
      );
    bytes32 structHash =
      keccak256(
        abi.encode(
          PERMIT_TYPEHASH,
          owner,
          spender,
          rawAmount,
          nonces[owner]++,
          deadline
        )
      );
    bytes32 digest =
      keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    address signatory = ecrecover(digest, v, r, s);
    require(signatory != address(0), "Ctx::permit: invalid signature");
    require(signatory == owner, "Ctx::permit: unauthorized");
    require(block.timestamp <= deadline, "Ctx::permit: signature expired");

    allowances[owner][spender] = amount;

    emit Approval(owner, spender, amount);
  }

  /**
   * @notice Get the number of tokens held by the `account`
   * @param account The address of the account to get the balance of
   * @return The number of tokens held
   */
  function balanceOf(address account) external view returns (uint256) {
    return balances[account];
  }

  /**
   * @notice Transfer `amount` tokens from `msg.sender` to `dst`
   * @param dst The address of the destination account
   * @param rawAmount The number of tokens to transfer
   * @return Whether or not the transfer succeeded
   */
  function transfer(address dst, uint256 rawAmount) external returns (bool) {
    uint96 amount = safe96(rawAmount, "Ctx::transfer: amount exceeds 96 bits");
    _transferTokens(msg.sender, dst, amount);
    return true;
  }

  /**
   * @notice Transfer `amount` tokens from `src` to `dst`
   * @param src The address of the source account
   * @param dst The address of the destination account
   * @param rawAmount The number of tokens to transfer
   * @return Whether or not the transfer succeeded
   */
  function transferFrom(
    address src,
    address dst,
    uint256 rawAmount
  ) external returns (bool) {
    address spender = msg.sender;
    uint96 spenderAllowance = allowances[src][spender];
    uint96 amount = safe96(rawAmount, "Ctx::approve: amount exceeds 96 bits");

    if (spender != src && spenderAllowance != uint96(-1)) {
      uint96 newAllowance =
        sub96(
          spenderAllowance,
          amount,
          "Ctx::transferFrom: transfer amount exceeds spender allowance"
        );
      allowances[src][spender] = newAllowance;

      emit Approval(src, spender, newAllowance);
    }

    _transferTokens(src, dst, amount);
    return true;
  }

  /**
   * @notice Delegate votes from `msg.sender` to `delegatee`
   * @param delegatee The address to delegate votes to
   */
  function delegate(address delegatee) public {
    return _delegate(msg.sender, delegatee);
  }

  /**
   * @notice Delegates votes from signatory to `delegatee`
   * @param delegatee The address to delegate votes to
   * @param nonce The contract state required to match the signature
   * @param expiry The time at which to expire the signature
   * @param v The recovery byte of the signature
   * @param r Half of the ECDSA signature pair
   * @param s Half of the ECDSA signature pair
   */
  function delegateBySig(
    address delegatee,
    uint256 nonce,
    uint256 expiry,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public {
    bytes32 domainSeparator =
      keccak256(
        abi.encode(
          DOMAIN_TYPEHASH,
          keccak256(bytes(name)),
          getChainId(),
          address(this)
        )
      );
    bytes32 structHash =
      keccak256(abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry));
    bytes32 digest =
      keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    address signatory = ecrecover(digest, v, r, s);
    require(signatory != address(0), "Ctx::delegateBySig: invalid signature");
    require(nonce == nonces[signatory]++, "Ctx::delegateBySig: invalid nonce");
    require(block.timestamp <= expiry, "Ctx::delegateBySig: signature expired");
    return _delegate(signatory, delegatee);
  }

  /**
   * @notice Gets the current votes balance for `account`
   * @param account The address to get votes balance
   * @return The number of current votes for `account`
   */
  function getCurrentVotes(address account) external view returns (uint96) {
    uint32 nCheckpoints = numCheckpoints[account];
    return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
  }

  /**
   * @notice Determine the prior number of votes for an account as of a block number
   * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
   * @param account The address of the account to check
   * @param blockNumber The block number to get the vote balance at
   * @return The number of votes the account had as of the given block
   */
  function getPriorVotes(address account, uint256 blockNumber)
    public
    view
    returns (uint96)
  {
    require(
      blockNumber < block.number,
      "Ctx::getPriorVotes: not yet determined"
    );

    uint32 nCheckpoints = numCheckpoints[account];
    if (nCheckpoints == 0) {
      return 0;
    }

    // First check most recent balance
    if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
      return checkpoints[account][nCheckpoints - 1].votes;
    }

    // Next check implicit zero balance
    if (checkpoints[account][0].fromBlock > blockNumber) {
      return 0;
    }

    uint32 lower = 0;
    uint32 upper = nCheckpoints - 1;
    while (upper > lower) {
      uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
      Checkpoint memory cp = checkpoints[account][center];
      if (cp.fromBlock == blockNumber) {
        return cp.votes;
      } else if (cp.fromBlock < blockNumber) {
        lower = center;
      } else {
        upper = center - 1;
      }
    }
    return checkpoints[account][lower].votes;
  }

  function _delegate(address delegator, address delegatee) internal {
    address currentDelegate = delegates[delegator];
    uint96 delegatorBalance = balances[delegator];
    delegates[delegator] = delegatee;

    emit DelegateChanged(delegator, currentDelegate, delegatee);

    _moveDelegates(currentDelegate, delegatee, delegatorBalance);
  }

  function _transferTokens(
    address src,
    address dst,
    uint96 amount
  ) internal {
    require(
      src != address(0),
      "Ctx::_transferTokens: cannot transfer from the zero address"
    );
    require(
      dst != address(0),
      "Ctx::_transferTokens: cannot transfer to the zero address"
    );
    require(
      dst != address(this),
      "Ctx::_transferTokens: cannot transfer to the Ctx address"
    );

    balances[src] = sub96(
      balances[src],
      amount,
      "Ctx::_transferTokens: transfer amount exceeds balance"
    );
    balances[dst] = add96(
      balances[dst],
      amount,
      "Ctx::_transferTokens: transfer amount overflows"
    );
    emit Transfer(src, dst, amount);

    _moveDelegates(delegates[src], delegates[dst], amount);
  }

  function _moveDelegates(
    address srcRep,
    address dstRep,
    uint96 amount
  ) internal {
    if (srcRep != dstRep && amount > 0) {
      if (srcRep != address(0)) {
        uint32 srcRepNum = numCheckpoints[srcRep];
        uint96 srcRepOld =
          srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0;
        uint96 srcRepNew =
          sub96(srcRepOld, amount, "Ctx::_moveVotes: vote amount underflows");
        _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
      }

      if (dstRep != address(0)) {
        uint32 dstRepNum = numCheckpoints[dstRep];
        uint96 dstRepOld =
          dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0;
        uint96 dstRepNew =
          add96(dstRepOld, amount, "Ctx::_moveVotes: vote amount overflows");
        _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
      }
    }
  }

  function _writeCheckpoint(
    address delegatee,
    uint32 nCheckpoints,
    uint96 oldVotes,
    uint96 newVotes
  ) internal {
    uint32 blockNumber =
      safe32(
        block.number,
        "Ctx::_writeCheckpoint: block number exceeds 32 bits"
      );

    if (
      nCheckpoints > 0 &&
      checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber
    ) {
      checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
    } else {
      checkpoints[delegatee][nCheckpoints] = Checkpoint(blockNumber, newVotes);
      numCheckpoints[delegatee] = nCheckpoints + 1;
    }

    emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
  }

  function safe32(uint256 n, string memory errorMessage)
    internal
    pure
    returns (uint32)
  {
    require(n < 2**32, errorMessage);
    return uint32(n);
  }

  function safe96(uint256 n, string memory errorMessage)
    internal
    pure
    returns (uint96)
  {
    require(n < 2**96, errorMessage);
    return uint96(n);
  }

  function add96(
    uint96 a,
    uint96 b,
    string memory errorMessage
  ) internal pure returns (uint96) {
    uint96 c = a + b;
    require(c >= a, errorMessage);
    return c;
  }

  function sub96(
    uint96 a,
    uint96 b,
    string memory errorMessage
  ) internal pure returns (uint96) {
    require(b <= a, errorMessage);
    return a - b;
  }

  function getChainId() internal pure returns (uint256) {
    uint256 chainId;
    assembly {
      chainId := chainid()
    }
    return chainId;
  }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}