Security Utilities

/**
 * @dev Contract module that helps prevent reentrant calls
 */
abstract contract ReentrancyGuardUpgradeable {
    function __ReentrancyGuard_init() internal onlyInitializing;
    
    /**
     * @dev Prevents a contract from calling itself, directly or indirectly
     */
    modifier nonReentrant();
}

/**
 * @dev Variant using transient storage (EIP-1153)
 */
abstract contract ReentrancyGuardTransientUpgradeable {
    function __ReentrancyGuardTransient_init() internal onlyInitializing;
    
    /**
     * @dev Prevents reentrancy using transient storage
     */
    modifier nonReentrant();
}

/**
 * @dev Contract module which allows children to implement an emergency stop mechanism
 */
abstract contract PausableUpgradeable {
    function __Pausable_init() internal onlyInitializing;
    
    /**
     * @dev Returns true if the contract is paused
     */
    function paused() external view returns (bool);
    
    /**
     * @dev Modifier to make a function callable only when the contract is not paused
     */
    modifier whenNotPaused();
    
    /**
     * @dev Modifier to make a function callable only when the contract is paused
     */
    modifier whenPaused();
    
    /**
     * @dev Triggers stopped state (internal function)
     */
    function _pause() internal;
    
    /**
     * @dev Returns to normal state (internal function)
     */
    function _unpause() internal;
}

// Events
event Paused(address account);
event Unpaused(address account);

/**
 * @dev Provides a function to batch together multiple calls
 */
abstract contract MulticallUpgradeable {
    function __Multicall_init() internal onlyInitializing;
    
    /**
     * @dev Receives and executes a batch of function calls on this contract
     */
    function multicall(bytes[] calldata data) external returns (bytes[] memory results);
}

/**
 * @dev Provides tracking nonces for addresses
 */
abstract contract NoncesUpgradeable {
    function __Nonces_init() internal onlyInitializing;
    
    /**
     * @dev Returns the current nonce for owner
     */
    function nonces(address owner) external view returns (uint256);
    
    /**
     * @dev Consumes a nonce and returns the current value
     */
    function _useNonce(address owner) internal returns (uint256);
    
    /**
     * @dev Consumes a specific nonce
     */
    function _useCheckedNonce(address owner, uint256 nonce) internal;
}

/**
 * @dev Variant that supports keyed nonces
 */
abstract contract NoncesKeyedUpgradeable {
    function __NoncesKeyed_init() internal onlyInitializing;
    
    /**
     * @dev Returns the nonce for owner and key
     */
    function nonces(address owner, bytes32 key) external view returns (uint256);
    
    /**
     * @dev Consumes a keyed nonce
     */
    function _useNonce(address owner, bytes32 key) internal returns (uint256);
    
    /**
     * @dev Consumes a specific keyed nonce
     */
    function _useCheckedNonce(address owner, bytes32 key, uint256 nonce) internal;
}

/**
 * @dev Implementation of EIP-712 domain separator and typed data hashing
 */
abstract contract EIP712Upgradeable {
    function __EIP712_init(string memory name, string memory version) internal onlyInitializing;
    
    /**
     * @dev Returns the domain separator for the current chain
     */
    function _domainSeparatorV4() internal view returns (bytes32);
    
    /**
     * @dev Hash typed data according to EIP-712
     */
    function _hashTypedDataV4(bytes32 structHash) internal view returns (bytes32);
    
    /**
     * @dev Returns the fields and values that describe the domain separator
     */
    function eip712Domain() external view returns (
        bytes1 fields,
        string memory name,
        string memory version,
        uint256 chainId,
        address verifyingContract,
        bytes32 salt,
        uint256[] memory extensions
    );
}

/**
 * @dev Implementation of the ERC-165 standard for interface detection
 */
abstract contract ERC165Upgradeable {
    function __ERC165_init() internal onlyInitializing;
    
    /**
     * @dev Returns true if this contract implements the interface defined by interfaceId
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

/**
 * @dev ECDSA signature verification utilities
 */
library ECDSAUpgradeable {
    /**
     * @dev Recovers the signer of the hash using ECDSA
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address);
    
    /**
     * @dev Recovers signer from hash and signature components
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address);
    
    /**
     * @dev Returns an Ethereum Signed Message, created from a hash
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32);
    
    /**
     * @dev Returns an Ethereum Signed Message, created from a string
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32);
}

/**
 * @dev P256 (secp256r1) signature verification
 */
library P256Upgradeable {
    /**
     * @dev Verifies a P256 signature
     */
    function verify(bytes32 hash, bytes32 r, bytes32 s, bytes32 x, bytes32 y) internal view returns (bool);
}

/**
 * @dev RSA signature verification utilities
 */
library RSAUpgradeable {
    /**
     * @dev Verifies an RSA signature using PKCS1 v1.5 padding
     */
    function pkcs1Sha256(bytes memory message, bytes memory signature, bytes memory modulus, bytes memory exponent) internal view returns (bool);
}

/**
 * @dev ECDSA signature verification signer for account abstraction
 */
abstract contract SignerECDSAUpgradeable {
    function __SignerECDSA_init(address signerAddr) internal onlyInitializing;
    
    /**
     * @dev Sets the signer address
     */
    function _setSigner(address signerAddr) internal;
    
    /**
     * @dev Validates an ECDSA signature
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev P256 (secp256r1) signature verification signer
 */
abstract contract SignerP256Upgradeable {
    function __SignerP256_init(bytes32 qx, bytes32 qy) internal onlyInitializing;
    
    /**
     * @dev Sets the P256 public key
     */
    function _setSigner(bytes32 qx, bytes32 qy) internal;
    
    /**
     * @dev Validates a P256 signature
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev RSA signature verification signer
 */
abstract contract SignerRSAUpgradeable {
    function __SignerRSA_init(bytes memory e, bytes memory n) internal onlyInitializing;
    
    /**
     * @dev Sets the RSA public key (exponent and modulus)
     */
    function _setSigner(bytes memory e, bytes memory n) internal;
    
    /**
     * @dev Validates an RSA signature
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev ERC-7913 standard signature verification signer
 */
abstract contract SignerERC7913Upgradeable {
    function __SignerERC7913_init(bytes memory data) internal onlyInitializing;
    
    /**
     * @dev Sets the ERC-7913 signer data
     */
    function _setSigner(bytes memory data) internal;
    
    /**
     * @dev Validates an ERC-7913 signature
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev Multi-signature verification using ERC-7913
 */
abstract contract MultiSignerERC7913Upgradeable {
    function __MultiSignerERC7913_init(bytes[] memory signers) internal onlyInitializing;
    
    /**
     * @dev Sets multiple ERC-7913 signers
     */
    function _setSigners(bytes[] memory signers) internal;
    
    /**
     * @dev Validates multiple signatures
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev Weighted multi-signature verification using ERC-7913
 */
abstract contract MultiSignerERC7913WeightedUpgradeable {
    function __MultiSignerERC7913Weighted_init(bytes[] memory signers, uint256[] memory weights, uint256 threshold) internal onlyInitializing;
    
    /**
     * @dev Sets weighted signers and threshold
     */
    function _setSigners(bytes[] memory signers, uint256[] memory weights, uint256 threshold) internal;
    
    /**
     * @dev Validates weighted signatures against threshold
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev Draft ERC-7739 implementation for advanced signature schemes
 */
abstract contract ERC7739Upgradeable {
    function __ERC7739_init(bytes memory config) internal onlyInitializing;
    
    /**
     * @dev Validates ERC-7739 signatures
     */
    function _validateSignature(bytes32 hash, bytes calldata signature) internal view returns (bool);
}

/**
 * @dev Provides information about the current execution context
 */
abstract contract ContextUpgradeable {
    function __Context_init() internal onlyInitializing;
    
    /**
     * @dev Returns the sender of the transaction
     */
    function _msgSender() internal view returns (address);
    
    /**
     * @dev Returns the call data
     */
    function _msgData() internal view returns (bytes calldata);
    
    /**
     * @dev Returns the length of the context suffix
     */
    function _contextSuffixLength() internal view returns (uint256);
}

import {ERC20Upgradeable} from "@openzeppelin/contracts-upgradeable/token/ERC20/ERC20Upgradeable.sol";
import {PausableUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/PausableUpgradeable.sol";
import {ReentrancyGuardUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/ReentrancyGuardUpgradeable.sol";
import {OwnableUpgradeable} from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";

contract SecureToken is ERC20Upgradeable, PausableUpgradeable, ReentrancyGuardUpgradeable, OwnableUpgradeable {
    function initialize(address initialOwner) initializer public {
        __ERC20_init("SecureToken", "STK");
        __Pausable_init();
        __ReentrancyGuard_init();
        __Ownable_init(initialOwner);
    }
    
    function mint(address to, uint256 amount) public onlyOwner whenNotPaused {
        _mint(to, amount);
    }
    
    function transfer(address to, uint256 amount) public override whenNotPaused nonReentrant returns (bool) {
        return super.transfer(to, amount);
    }
    
    function pause() public onlyOwner {
        _pause();
    }
    
    function unpause() public onlyOwner {
        _unpause();
    }
}

import {MulticallUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/MulticallUpgradeable.sol";

contract BatchOperations is MulticallUpgradeable, OwnableUpgradeable {
    function initialize(address initialOwner) initializer public {
        __Multicall_init();
        __Ownable_init(initialOwner);
    }
    
    function setValues(uint256[] calldata ids, uint256[] calldata values) external onlyOwner {
        require(ids.length == values.length, "Length mismatch");
        for (uint256 i = 0; i < ids.length; i++) {
            // Set values
        }
    }
    
    // Users can batch multiple setValues calls in one transaction using multicall
}

import {EIP712Upgradeable} from "@openzeppelin/contracts-upgradeable/utils/cryptography/EIP712Upgradeable.sol";
import {ECDSAUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/cryptography/ECDSAUpgradeable.sol";
import {NoncesUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/NoncesUpgradeable.sol";

contract SignatureVerifier is EIP712Upgradeable, NoncesUpgradeable {
    bytes32 private constant PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    
    function initialize() initializer public {
        __EIP712_init("SignatureVerifier", "1");
        __Nonces_init();
    }
    
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        require(block.timestamp <= deadline, "Permit expired");
        
        bytes32 structHash = keccak256(abi.encode(
            PERMIT_TYPEHASH,
            owner,
            spender,
            value,
            _useNonce(owner),
            deadline
        ));
        
        bytes32 hash = _hashTypedDataV4(structHash);
        address signer = ECDSAUpgradeable.recover(hash, v, r, s);
        require(signer == owner, "Invalid signature");
        
        // Process permit
    }
}