ETAAcademy Web3.0 Security Audit Knowledge System Deep

// Example of complex interaction vulnerability that traditional audits might miss
contract VulnerableProtocol {
    mapping(address => uint256) public balances;
    mapping(address => bool) public hasWithdrawn;
    
    // Seemingly secure withdrawal function
    function withdraw() external {
        require(!hasWithdrawn[msg.sender], "Already withdrawn");
        uint256 amount = balances[msg.sender];
        require(amount > 0, "No balance");
        
        hasWithdrawn[msg.sender] = true;
        balances[msg.sender] = 0;
        
        // Potential cross-contract call risk
        (bool success, ) = msg.sender.call{value: amount}("");
        require(success, "Transfer failed");
    }
    
    // Hidden risks when interacting with other protocols
    function interactWithExternal(address protocol) external {
        // Complex cross-protocol interaction logic
        // Traditional audits struggle to cover all edge cases
    }
}

// Safe mathematical operation implementation example
library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }
    
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        uint256 c = a - b;
        return c;
    }
    
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }
    
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        uint256 c = a / b;
        return c;
    }
}

// EVM layer security considerations example
contract EVMSecurity {
    // Gas optimization and security balance
    uint256[] public largeArray;
    
    // Avoid DoS from infinite loops
    function processArray(uint256 limit) external {
        uint256 length = largeArray.length;
        require(limit <= length, "Invalid limit");
        
        for (uint256 i = 0; i < limit; i++) {
            // Processing logic
            // Ensure single operation gas consumption is controllable
            if (gasleft() < 50000) {
                break; // Prevent gas exhaustion
            }
        }
    }
    
    // Properly handle low-level calls
    function safeCall(address target, bytes memory data) 
        external 
        returns (bool, bytes memory) 
    {
        // Limit gas to prevent attacks
        (bool success, bytes memory result) = target.call{gas: 100000}(data);
        return (success, result);
    }
}

// Gas optimization best practices
contract GasOptimized {
    // Use packed struct to reduce storage overhead
    struct PackedData {
        uint128 amount;
        uint64 timestamp;
        uint64 nonce;
    }
    
    // Batch operations to reduce transaction count
    function batchTransfer(
        address[] calldata recipients,
        uint256[] calldata amounts
    ) external {
        require(recipients.length == amounts.length, "Length mismatch");
        
        for (uint256 i = 0; i < recipients.length; i++) {
            // Use assembly to optimize critical paths
            assembly {
                let recipient := calldataload(add(recipients.offset, mul(i, 0x20)))
                let amount := calldataload(add(amounts.offset, mul(i, 0x20)))
                
                // Execute transfer logic
                // ...
            }
        }
    }
}

// DoS protection implementation
contract AntiDoS {
    mapping(address => uint256) public lastAction;
    uint256 constant COOLDOWN = 1 minutes;
    
    modifier rateLimited() {
        require(
            block.timestamp >= lastAction[msg.sender] + COOLDOWN,
            "Rate limit exceeded"
        );
        lastAction[msg.sender] = block.timestamp;
        _;
    }
    
    // Prevent storage bloat attacks
    mapping(address => uint256) public userCount;
    uint256 constant MAX_USERS = 10000;
    
    function register() external rateLimited {
        require(userCount[msg.sender] < MAX_USERS, "User limit reached");
        userCount[msg.sender]++;
        // Registration logic
    }
}

// Context security checks
contract ContextSecurity {
    address private _owner;
    mapping(address => bool) private _authorized;
    
    modifier onlyOwner() {
        require(msg.sender == _owner, "Not owner");
        _;
    }
    
    modifier onlyAuthorized() {
        require(_authorized[msg.sender] || msg.sender == _owner, "Not authorized");
        _;
    }
    
    // Prevent privilege escalation attacks
    function delegateCall(address target, bytes memory data) 
        external 
        onlyOwner 
        returns (bytes memory) 
    {
        // Verify target contract
        require(isContractSafe(target), "Unsafe contract");
        
        (bool success, bytes memory result) = target.delegatecall(data);
        require(success, "Delegatecall failed");
        
        return result;
    }
    
    function isContractSafe(address target) private view returns (bool) {
        // Implement contract safety check logic
        // Check if on whitelist
        // Verify contract code hash, etc.
        return true;
    }
}

// Secure governance implementation
contract SecureGovernance {
    struct Proposal {
        uint256 id;
        address proposer;
        uint256 forVotes;
        uint256 againstVotes;
        uint256 startTime;
        uint256 endTime;
        bool executed;
        bytes callData;
    }
    
    mapping(uint256 => Proposal) public proposals;
    mapping(address => uint256) public votingPower;
    mapping(uint256 => mapping(address => bool)) public hasVoted;
    
    uint256 constant VOTING_PERIOD = 3 days;
    uint256 constant EXECUTION_DELAY = 2 days;
    uint256 constant QUORUM = 1000000 * 10**18; // Minimum votes required
    
    function createProposal(bytes memory callData) external returns (uint256) {
        require(votingPower[msg.sender] >= 10000 * 10**18, "Insufficient voting power");
        
        uint256 proposalId = uint256(keccak256(abi.encodePacked(block.timestamp, msg.sender, callData)));
        
        proposals[proposalId] = Proposal({
            id: proposalId,
            proposer: msg.sender,
            forVotes: 0,
            againstVotes: 0,
            startTime: block.timestamp,
            endTime: block.timestamp + VOTING_PERIOD,
            executed: false,
            callData: callData
        });
        
        return proposalId;
    }
    
    function vote(uint256 proposalId, bool support) external {
        Proposal storage proposal = proposals[proposalId];
        require(block.timestamp <= proposal.endTime, "Voting ended");
        require(!hasVoted[proposalId][msg.sender], "Already voted");
        
        uint256 votes = votingPower[msg.sender];
        require(votes > 0, "No voting power");
        
        hasVoted[proposalId][msg.sender] = true;
        
        if (support) {
            proposal.forVotes += votes;
        } else {
            proposal.againstVotes += votes;
        }
    }
    
    function executeProposal(uint256 proposalId) external {
        Proposal storage proposal = proposals[proposalId];
        require(!proposal.executed, "Already executed");
        require(block.timestamp > proposal.endTime + EXECUTION_DELAY, "Execution delay not met");
        require(proposal.forVotes >= QUORUM, "Quorum not reached");
        require(proposal.forVotes > proposal.againstVotes, "Proposal rejected");
        
        proposal.executed = true;
        
        // Execute proposal
        (bool success, ) = address(this).call(proposal.callData);
        require(success, "Execution failed");
    }
}

// DeFi security practice example
contract SecureDeFiProtocol {
    using SafeMath for uint256;
    
    // Prevent flash loan attacks
    modifier noFlashLoan() {
        uint256 initialBalance = address(this).balance;
        _;
        require(address(this).balance >= initialBalance, "Flash loan detected");
    }
    
    // Price oracle security
    address public priceOracle;
    uint256 public constant PRICE_FRESHNESS = 5 minutes;
    
    struct PriceData {
        uint256 price;
        uint256 timestamp;
    }
    
    mapping(address => PriceData) public prices;
    
    function updatePrice(address token, uint256 newPrice) external {
        require(msg.sender == priceOracle, "Only oracle");
        
        // Price change limitation
        uint256 currentPrice = prices[token].price;
        if (currentPrice > 0) {
            uint256 change = newPrice > currentPrice ? 
                newPrice.sub(currentPrice).mul(100).div(currentPrice) :
                currentPrice.sub(newPrice).mul(100).div(currentPrice);
            
            require(change <= 10, "Price change too large"); // Limit 10% change
        }
        
        prices[token] = PriceData({
            price: newPrice,
            timestamp: block.timestamp
        });
    }
    
    function getPrice(address token) public view returns (uint256) {
        PriceData memory data = prices[token];
        require(data.timestamp.add(PRICE_FRESHNESS) >= block.timestamp, "Price stale");
        return data.price;
    }
    
    // Liquidity pool protection
    uint256 public constant MAX_SLIPPAGE = 300; // 3%
    
    function swap(
        address tokenIn,
        address tokenOut,
        uint256 amountIn,
        uint256 minAmountOut
    ) external noFlashLoan {
        // Calculate expected output
        uint256 expectedOut = calculateSwapAmount(tokenIn, tokenOut, amountIn);
        
        // Slippage protection
        uint256 slippage = expectedOut.sub(minAmountOut).mul(10000).div(expectedOut);
        require(slippage <= MAX_SLIPPAGE, "Slippage too high");
        
        // Execute swap
        // ...
    }
    
    function calculateSwapAmount(
        address tokenIn,
        address tokenOut,
        uint256 amountIn
    ) public view returns (uint256) {
        // Implement AMM calculation logic
        // x * y = k
        // ...
        return 0; // placeholder
    }
}

// Secure library usage practices
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/Pausable.sol";

contract SecureWithLibraries is ReentrancyGuard, Ownable, Pausable {
    using Address for address;
    using SafeERC20 for IERC20;
    
    // Version locking
    string public constant VERSION = "1.0.0";
    bytes32 public constant DOMAIN_SEPARATOR = keccak256("SecureProtocol");
    
    // Dependency version check
    modifier checkVersion(address target) {
        require(
            IVersioned(target).version() == VERSION,
            "Version mismatch"
        );
        _;
    }
    
    // Secure external calls
    function safeExternalCall(
        address target,
        bytes memory data
    ) external onlyOwner whenNotPaused nonReentrant returns (bytes memory) {
        require(target.isContract(), "Target not a contract");
        
        (bool success, bytes memory result) = target.call(data);
        require(success, "External call failed");
        
        return result;
    }
}

interface IVersioned {
    function version() external view returns (string memory);
}

// Go implementation of smart contract static analyzer example
package analyzer

import (
    "fmt"
    "go/ast"
    "go/parser"
    "go/token"
)

type VulnerabilityScanner struct {
    Issues []SecurityIssue
}

type SecurityIssue struct {
    Severity string
    Location token.Position
    Message  string
    Category string
}

func (s *VulnerabilityScanner) ScanContract(code string) error {
    fset := token.NewFileSet()
    node, err := parser.ParseFile(fset, "", code, parser.AllErrors)
    if err != nil {
        return err
    }
    
    ast.Inspect(node, func(n ast.Node) bool {
        switch x := n.(type) {
        case *ast.CallExpr:
            s.checkDangerousCalls(x, fset)
        case *ast.IfStmt:
            s.checkAccessControl(x, fset)
        }
        return true
    })
    
    return nil
}

func (s *VulnerabilityScanner) checkDangerousCalls(call *ast.CallExpr, fset *token.FileSet) {
    // Check for dangerous function calls
    if ident, ok := call.Fun.(*ast.Ident); ok {
        if ident.Name == "delegatecall" || ident.Name == "call" {
            s.Issues = append(s.Issues, SecurityIssue{
                Severity: "HIGH",
                Location: fset.Position(call.Pos()),
                Message:  "Dangerous low-level call detected",
                Category: "External Call",
            })
        }
    }
}

// Rust implementation of vulnerability detection engine
use std::collections::HashMap;

#[derive(Debug, Clone)]
pub struct AuditEngine {
    rules: Vec<AuditRule>,
    results: Vec<AuditResult>,
}

#[derive(Debug, Clone)]
pub struct AuditRule {
    pub id: String,
    pub severity: Severity,
    pub pattern: String,
    pub description: String,
}

#[derive(Debug, Clone)]
pub enum Severity {
    Critical,
    High,
    Medium,
    Low,
    Info,
}

#[derive(Debug, Clone)]
pub struct AuditResult {
    pub rule_id: String,
    pub severity: Severity,
    pub location: Location,
    pub message: String,
}

#[derive(Debug, Clone)]
pub struct Location {
    pub file: String,
    pub line: usize,
    pub column: usize,
}

impl AuditEngine {
    pub fn new() -> Self {
        Self {
            rules: Vec::new(),
            results: Vec::new(),
        }
    }
    
    pub fn add_rule(&mut self, rule: AuditRule) {
        self.rules.push(rule);
    }
    
    pub fn scan(&mut self, contract_code: &str) -> Result<Vec<AuditResult>, String> {
        let mut results = Vec::new();
        
        for rule in &self.rules {
            if let Some(matches) = self.find_pattern(&rule.pattern, contract_code) {
                for (line_num, line) in matches {
                    results.push(AuditResult {
                        rule_id: rule.id.clone(),
                        severity: rule.severity.clone(),
                        location: Location {
                            file: "contract.sol".to_string(),
                            line: line_num,
                            column: 0,
                        },
                        message: format!("{}: {}", rule.description, line),
                    });
                }
            }
        }
        
        self.results = results.clone();
        Ok(results)
    }
    
    fn find_pattern(&self, pattern: &str, code: &str) -> Option<Vec<(usize, String)>> {
        let mut matches = Vec::new();
        
        for (line_num, line) in code.lines().enumerate() {
            if line.contains(pattern) {
                matches.push((line_num + 1, line.to_string()));
            }
        }
        
        if matches.is_empty() {
            None
        } else {
            Some(matches)
        }
    }
    
    pub fn generate_report(&self) -> String {
        let mut report = String::from("# Security Audit Report\n\n");
        
        let mut by_severity: HashMap<String, Vec<&AuditResult>> = HashMap::new();
        
        for result in &self.results {
            let severity_key = format!("{:?}", result.severity);
            by_severity.entry(severity_key).or_insert(Vec::new()).push(result);
        }
        
        for (severity, issues) in by_severity {
            report.push_str(&format!("## {} Issues\n\n", severity));
            for issue in issues {
                report.push_str(&format!("- **{}** (Line {}): {}\n", 
                    issue.rule_id, 
                    issue.location.line, 
                    issue.message
                ));
            }
            report.push_str("\n");
        }
        
        report
    }
}

// TypeScript implementation of audit report generator
interface AuditReport {
    projectName: string;
    auditDate: Date;
    auditors: string[];
    findings: Finding[];
    summary: Summary;
}

interface Finding {
    id: string;
    title: string;
    severity: 'Critical' | 'High' | 'Medium' | 'Low' | 'Info';
    category: string;
    description: string;
    recommendation: string;
    status: 'Open' | 'Resolved' | 'Acknowledged';
    affectedFiles: string[];
    lineNumbers: number[];
}

interface Summary {
    totalFindings: number;
    criticalCount: number;
    highCount: number;
    mediumCount: number;
    lowCount: number;
    resolvedCount: number;
}

class AuditReportGenerator {
    private report: AuditReport;
    
    constructor(projectName: string, auditors: string[]) {
        this.report = {
            projectName,
            auditDate: new Date(),
            auditors,
            findings: [],
            summary: {
                totalFindings: 0,
                criticalCount: 0,
                highCount: 0,
                mediumCount: 0,
                lowCount: 0,
                resolvedCount: 0,
            },
        };
    }
    
    addFinding(finding: Finding): void {
        this.report.findings.push(finding);
        this.updateSummary();
    }
    
    private updateSummary(): void {
        const summary = this.report.summary;
        summary.totalFindings = this.report.findings.length;
        
        summary.criticalCount = this.countBySeverity('Critical');
        summary.highCount = this.countBySeverity('High');
        summary.mediumCount = this.countBySeverity('Medium');
        summary.lowCount = this.countBySeverity('Low');
        summary.resolvedCount = this.report.findings
            .filter(f => f.status === 'Resolved').length;
    }
    
    private countBySeverity(severity: string): number {
        return this.report.findings
            .filter(f => f.severity === severity).length;
    }
    
    generateHTML(): string {
        const html = `
<!DOCTYPE html>
<html>
<head>
    <title>Security Audit Report - ${this.report.projectName}</title>
    <style>
        body { font-family: Arial, sans-serif; margin: 20px; }
        .critical { color: #d32f2f; }
        .high { color: #f57c00; }
        .medium { color: #fbc02d; }
        .low { color: #388e3c; }
        .info { color: #1976d2; }
        .summary { 
            background: #f5f5f5; 
            padding: 15px; 
            border-radius: 5px; 
            margin: 20px 0;
        }
        .finding {
            border: 1px solid #ddd;
            padding: 15px;
            margin: 10px 0;
            border-radius: 5px;
        }
    </style>
</head>
<body>
    <h1>Security Audit Report</h1>
    <h2>${this.report.projectName}</h2>
    <p>Date: ${this.report.auditDate.toLocaleDateString()}</p>
    <p>Auditors: ${this.report.auditors.join(', ')}</p>
    
    <div class="summary">
        <h3>Summary</h3>
        <p>Total Findings: ${this.report.summary.totalFindings}</p>
        <p class="critical">Critical: ${this.report.summary.criticalCount}</p>
        <p class="high">High: ${this.report.summary.highCount}</p>
        <p class="medium">Medium: ${this.report.summary.mediumCount}</p>
        <p class="low">Low: ${this.report.summary.lowCount}</p>
        <p>Resolved: ${this.report.summary.resolvedCount}</p>
    </div>
    
    <h3>Findings</h3>
    ${this.report.findings.map(f => this.renderFinding(f)).join('')}
</body>
</html>`;
        return html;
    }
    
    private renderFinding(finding: Finding): string {
        return `
<div class="finding">
    <h4 class="${finding.severity.toLowerCase()}">[${finding.severity}] ${finding.title}</h4>
    <p><strong>Category:</strong> ${finding.category}</p>
    <p><strong>Status:</strong> ${finding.status}</p>
    <p><strong>Description:</strong> ${finding.description}</p>
    <p><strong>Recommendation:</strong> ${finding.recommendation}</p>
    <p><strong>Affected Files:</strong> ${finding.affectedFiles.join(', ')}</p>
</div>`;
    }
}

# Audit configuration file example
audit_config:
  project: "DeFi Protocol X"
  version: "1.0.0"
  scope:
    contracts:
      - path: "contracts/core/*.sol"
      - path: "contracts/governance/*.sol"
    excluded:
      - "contracts/test/*.sol"
      - "contracts/mock/*.sol"
  
  focus_areas:
    - reentrancy
    - access_control
    - integer_overflow
    - price_manipulation
    - flash_loan_attacks
  
  tools:
    static_analysis:
      - slither
      - mythril
      - securify
    fuzzing:
      - echidna
      - medusa
    formal_verification:
      - certora
      - k_framework

# Python implementation of automated audit pipeline
import subprocess
import json
import os
from typing import List, Dict, Any

class AutomatedAuditPipeline:
    def __init__(self, project_path: str, config_path: str):
        self.project_path = project_path
        self.config = self.load_config(config_path)
        self.results = {
            'static_analysis': {},
            'fuzzing': {},
            'manual_review': []
        }
    
    def load_config(self, config_path: str) -> Dict:
        with open(config_path, 'r') as f:
            return json.load(f)
    
    def run_static_analysis(self) -> None:
        """Run static analysis tools"""
        tools = self.config['tools']['static_analysis']
        
        for tool in tools:
            print(f"Running {tool}...")
            if tool == 'slither':
                self.run_slither()
            elif tool == 'mythril':
                self.run_mythril()
            elif tool == 'securify':
                self.run_securify()
    
    def run_slither(self) -> None:
        """Run Slither analysis"""
        cmd = f"slither {self.project_path} --json slither_output.json"
        result = subprocess.run(cmd, shell=True, capture_output=True, text=True)
        
        if os.path.exists('slither_output.json'):
            with open('slither_output.json', 'r') as f:
                self.results['static_analysis']['slither'] = json.load(f)
    
    def run_mythril(self) -> None:
        """Run Mythril analysis"""
        contracts = self.get_contract_files()
        
        for contract in contracts:
            cmd = f"myth analyze {contract} -o json"
            result = subprocess.run(cmd, shell=True, capture_output=True, text=True)
            
            if result.stdout:
                contract_name = os.path.basename(contract)
                self.results['static_analysis'][f'mythril_{contract_name}'] = json.loads(result.stdout)
    
    def run_fuzzing(self) -> None:
        """Run fuzzing tests"""
        print("Starting fuzzing tests...")
        
        # Echidna configuration
        echidna_config = """
testLimit: 100000
testMode: assertion
corpusDir: corpus
coverageFormats: ["html", "lcov"]
        """
        
        with open('echidna.yaml', 'w') as f:
            f.write(echidna_config)
        
        cmd = f"echidna-test {self.project_path} --config echidna.yaml"
        result = subprocess.run(cmd, shell=True, capture_output=True, text=True)
        
        self.results['fuzzing']['echidna'] = {
            'output': result.stdout,
            'errors': result.stderr
        }
    
    def get_contract_files(self) -> List[str]:
        """Get all contract files"""
        contracts = []
        for root, dirs, files in os.walk(self.project_path):
            for file in files:
                if file.endswith('.sol'):
                    contracts.append(os.path.join(root, file))
        return contracts
    
    def analyze_results(self) -> Dict[str, Any]:
        """Analyze results from all tools"""
        issues = {
            'critical': [],
            'high': [],
            'medium': [],
            'low': [],
            'info': []
        }
        
        # Analyze Slither results
        if 'slither' in self.results['static_analysis']:
            slither_results = self.results['static_analysis']['slither']
            if 'results' in slither_results:
                for detector in slither_results['results']['detectors']:
                    severity = detector.get('impact', 'info').lower()
                    if severity in issues:
                        issues[severity].append({
                            'tool': 'slither',
                            'check': detector.get('check', 'unknown'),
                            'description': detector.get('description', ''),
                            'elements': detector.get('elements', [])
                        })
        
        return issues
    
    def generate_report(self) -> str:
        """Generate audit report"""
        issues = self.analyze_results()
        
        report = f"""
# Automated Audit Report
## Project: {self.config.get('project', 'Unknown')}
## Date: {datetime.now().strftime('%Y-%m-%d')}

### Executive Summary
- Critical Issues: {len(issues['critical'])}
- High Issues: {len(issues['high'])}
- Medium Issues: {len(issues['medium'])}
- Low Issues: {len(issues['low'])}
- Informational: {len(issues['info'])}

### Detailed Findings
"""
        
        for severity in ['critical', 'high', 'medium', 'low', 'info']:
            if issues[severity]:
                report += f"\n#### {severity.capitalize()} Severity Issues\n"
                for idx, issue in enumerate(issues[severity], 1):
                    report += f"\n**Issue #{idx}**: {issue['check']}\n"
                    report += f"- Tool: {issue['tool']}\n"
                    report += f"- Description: {issue['description']}\n"
        
        return report
    
    def run_full_audit(self) -> None:
        """Run full audit pipeline"""
        print("Starting automated audit pipeline...")
        
        # Static analysis
        self.run_static_analysis()
        
        # Fuzzing tests
        self.run_fuzzing()
        
        # Generate report
        report = self.generate_report()
        
        with open('audit_report.md', 'w') as f:
            f.write(report)
        
        print("Audit completed. Report saved to audit_report.md")

# Usage example
if __name__ == "__main__":
    from datetime import datetime
    
    pipeline = AutomatedAuditPipeline(
        project_path="./contracts",
        config_path="./audit_config.json"
    )
    pipeline.run_full_audit()

// Vulnerable code example
contract VulnerableBridge {
    mapping(address => uint256) public balances;
    mapping(bytes32 => bool) public processedTransfers;
    
    // Vulnerable function - no reentrancy protection
    function withdrawToL1(uint256 amount, bytes32 transferId) external {
        require(!processedTransfers[transferId], "Already processed");
        require(balances[msg.sender] >= amount, "Insufficient balance");
        
        // Mark as processed - wrong position!
        processedTransfers[transferId] = true;
        
        // External call - may trigger reentrancy
        ICallback(msg.sender).onWithdraw(amount);
        
        // State update - too late!
        balances[msg.sender] -= amount;
    }
}

// Attack contract
contract Attacker {
    VulnerableBridge bridge;
    bytes32 currentTransferId;
    uint256 attackCount;
    
    function attack() external {
        currentTransferId = keccak256(abi.encodePacked(block.timestamp));
        bridge.withdrawToL1(100 ether, currentTransferId);
    }
    
    function onWithdraw(uint256 amount) external {
        if (attackCount < 10) {
            attackCount++;
            // Reentrancy attack
            bytes32 newId = keccak256(abi.encodePacked(currentTransferId, attackCount));
            bridge.withdrawToL1(100 ether, newId);
        }
    }
}

// Fixed code
contract SecureBridge {
    using ReentrancyGuard for uint256;
    
    mapping(address => uint256) public balances;
    mapping(bytes32 => bool) public processedTransfers;
    uint256 private _guardCounter = 1;
    
    modifier nonReentrant() {
        _guardCounter++;
        uint256 localCounter = _guardCounter;
        _;
        require(localCounter == _guardCounter, "Reentrant call");
    }
    
    function withdrawToL1(uint256 amount, bytes32 transferId) external nonReentrant {
        require(!processedTransfers[transferId], "Already processed");
        require(balances[msg.sender] >= amount, "Insufficient balance");
        
        // Update state first
        processedTransfers[transferId] = true;
        balances[msg.sender] -= amount;
        
        // External call last
        ICallback(msg.sender).onWithdraw(amount);
    }
}

// Vulnerable code
contract VulnerableLending {
    IPriceOracle public oracle;
    
    function liquidate(address user, address collateral) external {
        uint256 debt = getUserDebt(user);
        uint256 collateralValue = getCollateralValue(user, collateral);
        
        // Simple price fetching - easily manipulated
        uint256 price = oracle.getPrice(collateral);
        uint256 healthFactor = (collateralValue * price) / debt;
        
        require(healthFactor < 1e18, "Cannot liquidate healthy position");
        
        // Execute liquidation...
    }
}

// Fix: Use Time-Weighted Average Price (TWAP)
contract SecureLending {
    IPriceOracle public oracle;
    uint256 constant TWAP_PERIOD = 30 minutes;
    
    struct PricePoint {
        uint256 price;
        uint256 timestamp;
    }
    
    mapping(address => PricePoint[]) public priceHistory;
    
    function updatePrice(address token) external {
        uint256 currentPrice = oracle.getPrice(token);
        priceHistory[token].push(PricePoint({
            price: currentPrice,
            timestamp: block.timestamp
        }));
        
        // Clean old data
        cleanOldPrices(token);
    }
    
    function getTWAPPrice(address token) public view returns (uint256) {
        PricePoint[] memory history = priceHistory[token];
        require(history.length > 0, "No price history");
        
        uint256 weightedSum = 0;
        uint256 totalWeight = 0;
        uint256 cutoffTime = block.timestamp - TWAP_PERIOD;
        
        for (uint i = 0; i < history.length; i++) {
            if (history[i].timestamp >= cutoffTime) {
                uint256 weight = history[i].timestamp - cutoffTime;
                weightedSum += history[i].price * weight;
                totalWeight += weight;
            }
        }
        
        require(totalWeight > 0, "Insufficient price data");
        return weightedSum / totalWeight;
    }
    
    function liquidate(address user, address collateral) external {
        uint256 debt = getUserDebt(user);
        uint256 collateralValue = getCollateralValue(user, collateral);
        
        // Use TWAP price, resistant to instant price manipulation
        uint256 price = getTWAPPrice(collateral);
        uint256 healthFactor = (collateralValue * price) / debt;
        
        require(healthFactor < 1e18, "Cannot liquidate healthy position");
        
        // Execute liquidation...
    }
    
    function cleanOldPrices(address token) private {
        // Implement cleanup logic
    }
    
    function getUserDebt(address user) private view returns (uint256) {
        // Implement get user debt logic
        return 0;
    }
    
    function getCollateralValue(address user, address collateral) private view returns (uint256) {
        // Implement get collateral value logic
        return 0;
    }
}

// Comprehensive defense strategy implementation
contract DefenseInDepth {
    // Layer 1: Access Control
    mapping(address => bool) public authorized;
    address public admin;
    
    modifier onlyAuthorized() {
        require(authorized[msg.sender] || msg.sender == admin, "Unauthorized");
        _;
    }
    
    // Layer 2: Reentrancy Protection
    uint256 private _status;
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;
    
    modifier nonReentrant() {
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
        _status = _ENTERED;
        _;
        _status = _NOT_ENTERED;
    }
    
    // Layer 3: Pause Mechanism
    bool public paused;
    
    modifier whenNotPaused() {
        require(!paused, "Contract is paused");
        _;
    }
    
    // Layer 4: Rate Limiting
    mapping(address => uint256) public lastAction;
    uint256 public cooldownPeriod = 1 hours;
    
    modifier rateLimited() {
        require(
            block.timestamp >= lastAction[msg.sender] + cooldownPeriod,
            "Rate limit exceeded"
        );
        lastAction[msg.sender] = block.timestamp;
        _;
    }
    
    // Layer 5: Amount Limiting
    uint256 public maxTransactionAmount = 1000 ether;
    
    modifier amountLimited(uint256 amount) {
        require(amount <= maxTransactionAmount, "Amount exceeds limit");
        _;
    }
    
    // Critical function with comprehensive protection
    function criticalOperation(uint256 amount) 
        external 
        onlyAuthorized
        nonReentrant
        whenNotPaused
        rateLimited
        amountLimited(amount)
    {
        // Execute critical operation
    }
}

# Formal verification using Z3 solver
from z3 import *

class FormalVerification:
    def __init__(self):
        self.solver = Solver()
    
    def verify_no_overflow(self):
        """Verify arithmetic operations won't overflow"""
        # Define variables
        a = BitVec('a', 256)
        b = BitVec('b', 256)
        
        # Define constraints
        # Conditions for no addition overflow
        add_no_overflow = And(
            a >= 0,
            b >= 0,
            a + b >= a,
            a + b >= b
        )
        
        # Conditions for no multiplication overflow
        mul_no_overflow = Implies(
            a != 0,
            (a * b) / a == b
        )
        
        # Add constraints to solver
        self.solver.add(Not(add_no_overflow))
        
        # Check if satisfiable (if overflow exists)
        if self.solver.check() == sat:
            print("Potential overflow found:")
            model = self.solver.model()
            print(f"a = {model[a]}")
            print(f"b = {model[b]}")
            return False
        else:
            print("No overflow risk")
            return True
    
    def verify_access_control(self):
        """Verify access control logic"""
        # Define roles and permissions
        Admin = Bool('Admin')
        User = Bool('User')
        Authorized = Bool('Authorized')
        
        # Define access control rules
        can_execute = Or(Admin, And(User, Authorized))
        
        # Verify only authorized users can execute
        self.solver.push()
        self.solver.add(can_execute)
        self.solver.add(Not(Admin))
        self.solver.add(Not(Authorized))
        
        if self.solver.check() == sat:
            print("Access control vulnerability exists")
            return False
        else:
            print("Access control is secure")
            return True
        
        self.solver.pop()
    
    def verify_invariants(self, contract_state):
        """Verify contract invariants"""
        # Define state variables
        total_supply = Int('total_supply')
        sum_balances = Int('sum_balances')
        
        # Invariant: total supply equals sum of all balances
        invariant = (total_supply == sum_balances)
        
        # Add contract state
        self.solver.add(total_supply >= 0)
        self.solver.add(sum_balances >= 0)
        
        # Verify invariant
        self.solver.add(Not(invariant))
        
        if self.solver.check() == unsat:
            print("Invariant always holds")
            return True
        else:
            print("Invariant may be violated")
            model = self.solver.model()
            print(f"Counterexample: total_supply = {model[total_supply]}, sum_balances = {model[sum_balances]}")
            return False

# Usage example
verifier = FormalVerification()
verifier.verify_no_overflow()
verifier.verify_access_control()
verifier.verify_invariants({})

security_team:
  leadership:
    - role: "Chief Security Officer"
      responsibilities:
        - strategy_planning
        - risk_management
        - compliance_oversight
    
    - role: "Lead Auditor"
      responsibilities:
        - audit_methodology
        - quality_assurance
        - team_coordination
  
  technical_roles:
    - role: "Smart Contract Auditor"
      skills:
        - solidity_expertise
        - formal_verification
        - vulnerability_research
      count: 3-5
    
    - role: "Blockchain Security Engineer"
      skills:
        - consensus_mechanisms
        - cryptography
        - network_security
      count: 2-3
    
    - role: "DeFi Specialist"
      skills:
        - defi_protocols
        - economic_modeling
        - flash_loan_analysis
      count: 2-3
    
    - role: "Security Researcher"
      skills:
        - zero_day_research
        - exploit_development
        - threat_intelligence
      count: 2-3
  
  support_roles:
    - role: "DevOps Engineer"
      responsibilities:
        - ci_cd_integration
        - tool_automation
        - infrastructure_management
    
    - role: "Technical Writer"
      responsibilities:
        - report_generation
        - documentation
        - client_communication

# Skill assessment and learning planning system
class SkillDevelopmentPlan:
    def __init__(self):
        self.skill_levels = {
            'beginner': 1,
            'intermediate': 2,
            'advanced': 3,
            'expert': 4
        }
        
        self.learning_paths = {
            'smart_contract_security': [
                {
                    'level': 'beginner',
                    'topics': [
                        'Solidity basics',
                        'Common vulnerabilities',
                        'Basic testing'
                    ],
                    'duration': '2 weeks',
                    'resources': [
                        'ETAAcademy Math Module',
                        'Ethereum Yellow Paper',
                        'OpenZeppelin Contracts'
                    ]
                },
                {
                    'level': 'intermediate',
                    'topics': [
                        'Advanced patterns',
                        'Gas optimization',
                        'Formal verification basics'
                    ],
                    'duration': '4 weeks',
                    'resources': [
                        'ETAAcademy EVM Module',
                        'Trail of Bits guides',
                        'Consensys best practices'
                    ]
                },
                {
                    'level': 'advanced',
                    'topics': [
                        'Complex DeFi protocols',
                        'Cross-chain security',
                        'MEV analysis'
                    ],
                    'duration': '8 weeks',
                    'resources': [
                        'ETAAcademy DeFi Module',
                        'Research papers',
                        'Real audit reports'
                    ]
                },
                {
                    'level': 'expert',
                    'topics': [
                        'Zero-day research',
                        'Novel attack vectors',
                        'Protocol design'
                    ],
                    'duration': 'Ongoing',
                    'resources': [
                        'Original research',
                        'Bug bounty programs',
                        'Conference presentations'
                    ]
                }
            ]
        }
    
    def assess_skill_level(self, auditor_profile):
        """Assess auditor skill level"""
        score = 0
        
        # Score based on experience
        if auditor_profile['audits_completed'] > 50:
            score += 3
        elif auditor_profile['audits_completed'] > 20:
            score += 2
        elif auditor_profile['audits_completed'] > 5:
            score += 1
        
        # Score based on findings
        if auditor_profile['critical_findings'] > 10:
            score += 2
        elif auditor_profile['critical_findings'] > 3:
            score += 1
        
        # Score based on certifications
        if 'certified_auditor' in auditor_profile['certifications']:
            score += 1
        
        # Determine skill level
        if score >= 6:
            return 'expert'
        elif score >= 4:
            return 'advanced'
        elif score >= 2:
            return 'intermediate'
        else:
            return 'beginner'
    
    def generate_learning_plan(self, current_level, target_level):
        """Generate personalized learning plan"""
        plan = {
            'current_level': current_level,
            'target_level': target_level,
            'steps': [],
            'estimated_duration': 0
        }
        
        current_idx = self.skill_levels[current_level]
        target_idx = self.skill_levels[target_level]
        
        for level_idx in range(current_idx, target_idx):
            for level_name, level_value in self.skill_levels.items():
                if level_value == level_idx + 1:
                    path = self.learning_paths['smart_contract_security'][level_idx]
                    plan['steps'].append(path)
                    
                    # Calculate total duration
                    if 'weeks' in path['duration']:
                        weeks = int(path['duration'].split()[0])
                        plan['estimated_duration'] += weeks
        
        return plan
    
    def track_progress(self, auditor_id, completed_topics):
        """Track learning progress"""
        progress = {
            'auditor_id': auditor_id,
            'completed': completed_topics,
            'completion_rate': 0,
            'next_topics': []
        }
        
        # Calculate completion rate and recommend next steps
        # Implement progress tracking logic
        
        return progress

# Usage example
sdp = SkillDevelopmentPlan()
auditor = {
    'audits_completed': 15,
    'critical_findings': 5,
    'certifications': ['certified_auditor']
}

current_level = sdp.assess_skill_level(auditor)
learning_plan = sdp.generate_learning_plan(current_level, 'expert')
print(f"Current Level: {current_level}")
print(f"Learning Plan: {learning_plan}")

#!/bin/bash
# Complete audit toolchain integration script

# Configure environment variables
export AUDIT_HOME="/opt/audit-tools"
export PATH="$AUDIT_HOME/bin:$PATH"

# Install core tools
install_audit_tools() {
    echo "Installing audit tools..."
    
    # Slither
    pip install slither-analyzer
    
    # Mythril
    pip install mythril
    
    # Echidna
    wget https://github.com/crytic/echidna/releases/latest/download/echidna-test-linux
    chmod +x echidna-test-linux
    mv echidna-test-linux $AUDIT_HOME/bin/echidna
    
    # Medusa
    go install github.com/crytic/medusa@latest
    
    # Certora Prover
    pip install certora-cli
    
    echo "Tools installed successfully"
}

# Run comprehensive audit process
run_comprehensive_audit() {
    PROJECT_PATH=$1
    OUTPUT_DIR=$2
    
    mkdir -p $OUTPUT_DIR
    
    echo "Starting comprehensive audit of $PROJECT_PATH"
    
    # Static analysis
    echo "Running static analysis..."
    slither $PROJECT_PATH --json $OUTPUT_DIR/slither.json
    myth analyze $PROJECT_PATH/*.sol -o json > $OUTPUT_DIR/mythril.json
    
    # Fuzzing
    echo "Running fuzzing..."
    echidna-test $PROJECT_PATH --config echidna.yaml --corpus-dir $OUTPUT_DIR/corpus
    
    # Formal verification
    echo "Running formal verification..."
    certoraRun $PROJECT_PATH/certora.conf --output $OUTPUT_DIR/certora
    
    # Generate comprehensive report
    python generate_report.py \
        --slither $OUTPUT_DIR/slither.json \
        --mythril $OUTPUT_DIR/mythril.json \
        --echidna $OUTPUT_DIR/echidna.txt \
        --certora $OUTPUT_DIR/certora \
        --output $OUTPUT_DIR/final_report.html
    
    echo "Audit completed. Report available at $OUTPUT_DIR/final_report.html"
}

# Continuous monitoring setup
setup_continuous_monitoring() {
    # Configure GitHub Actions
    cat > .github/workflows/security-audit.yml << EOF
name: Security Audit

on:
  push:
    branches: [ main, develop ]
  pull_request:
    branches: [ main ]

jobs:
  audit:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v2
    
    - name: Set up Python
      uses: actions/setup-python@v2
      with:
        python-version: '3.9'
    
    - name: Install dependencies
      run: |
        pip install slither-analyzer mythril
        npm install -g @ethereum-security/toolkit
    
    - name: Run Slither
      run: slither . --json slither-report.json
      continue-on-error: true
    
    - name: Run Mythril
      run: myth analyze contracts/*.sol -o json > mythril-report.json
      continue-on-error: true
    
    - name: Upload reports
      uses: actions/upload-artifact@v2
      with:
        name: audit-reports
        path: |
          slither-report.json
          mythril-report.json
    
    - name: Comment PR
      if: github.event_name == 'pull_request'
      uses: actions/github-script@v6
      with:
        script: |
          const fs = require('fs');
          const slither = JSON.parse(fs.readFileSync('slither-report.json', 'utf8'));
          
          let comment = '## Security Audit Results\\n\\n';
          comment += \`Found \${slither.results.detectors.length} potential issues\\n\`;
          
          github.rest.issues.createComment({
            issue_number: context.issue.number,
            owner: context.repo.owner,
            repo: context.repo.repo,
            body: comment
          });
EOF
}

# Main function
main() {
    case "$1" in
        install)
            install_audit_tools
            ;;
        audit)
            run_comprehensive_audit $2 $3
            ;;
        monitor)
            setup_continuous_monitoring
            ;;
        *)
            echo "Usage: $0 {install|audit|monitor} [args]"
            exit 1
            ;;
    esac
}

main "$@"

# AI-driven vulnerability detection system
import torch
import torch.nn as nn
import numpy as np
from transformers import AutoTokenizer, AutoModel

class AIVulnerabilityDetector:
    def __init__(self, model_path='ethereum-security-bert'):
        self.tokenizer = AutoTokenizer.from_pretrained(model_path)
        self.model = AutoModel.from_pretrained(model_path)
        self.classifier = VulnerabilityClassifier()
        
    def analyze_contract(self, contract_code):
        """Analyze contract code using AI"""
        # Code preprocessing
        tokens = self.tokenizer(
            contract_code,
            return_tensors='pt',
            max_length=512,
            truncation=True,
            padding=True
        )
        
        # Feature extraction
        with torch.no_grad():
            outputs = self.model(**tokens)
            features = outputs.last_hidden_state.mean(dim=1)
        
        # Vulnerability classification
        predictions = self.classifier(features)
        
        return self.interpret_predictions(predictions)
    
    def interpret_predictions(self, predictions):
        """Interpret AI predictions"""
        vulnerability_types = [
            'Reentrancy',
            'Integer Overflow',
            'Access Control',
            'Uninitialized Storage',
            'Denial of Service'
        ]
        
        results = []
        for i, prob in enumerate(predictions[0]):
            if prob > 0.7:  # High confidence threshold
                results.append({
                    'type': vulnerability_types[i],
                    'confidence': float(prob),
                    'severity': self.calculate_severity(vulnerability_types[i], float(prob))
                })
        
        return results
    
    def calculate_severity(self, vuln_type, confidence):
        """Calculate vulnerability severity"""
        severity_map = {
            'Reentrancy': 'Critical',
            'Integer Overflow': 'High',
            'Access Control': 'Critical',
            'Uninitialized Storage': 'Medium',
            'Denial of Service': 'High'
        }
        
        base_severity = severity_map.get(vuln_type, 'Low')
        
        # Adjust based on confidence
        if confidence < 0.8:
            if base_severity == 'Critical':
                return 'High'
            elif base_severity == 'High':
                return 'Medium'
        
        return base_severity

class VulnerabilityClassifier(nn.Module):
    def __init__(self, input_dim=768, num_classes=5):
        super().__init__()
        self.fc1 = nn.Linear(input_dim, 256)
        self.dropout = nn.Dropout(0.3)
        self.fc2 = nn.Linear(256, 128)
        self.fc3 = nn.Linear(128, num_classes)
        self.sigmoid = nn.Sigmoid()
        
    def forward(self, x):
        x = torch.relu(self.fc1(x))
        x = self.dropout(x)
        x = torch.relu(self.fc2(x))
        x = self.fc3(x)
        return self.sigmoid(x)

// Zero-knowledge audit verification contract
contract ZKAuditVerifier {
    using Pairing for *;
    
    struct VerifyingKey {
        Pairing.G1Point alpha;
        Pairing.G2Point beta;
        Pairing.G2Point gamma;
        Pairing.G2Point delta;
        Pairing.G1Point[] gamma_abc;
    }
    
    struct Proof {
        Pairing.G1Point a;
        Pairing.G2Point b;
        Pairing.G1Point c;
    }
    
    VerifyingKey verifyingKey;
    
    event AuditVerified(address indexed contract_, bool passed);
    
    function verifyAudit(
        uint[2] memory a,
        uint[2][2] memory b,
        uint[2] memory c,
        uint[2] memory input
    ) public view returns (bool) {
        Proof memory proof;
        proof.a = Pairing.G1Point(a[0], a[1]);
        proof.b = Pairing.G2Point([b[0][0], b[0][1]], [b[1][0], b[1][1]]);
        proof.c = Pairing.G1Point(c[0], c[1]);
        
        uint[] memory inputValues = new uint[](input.length);
        for(uint i = 0; i < input.length; i++){
            inputValues[i] = input[i];
        }
        
        return verify(inputValues, proof);
    }
    
    function verify(uint[] memory input, Proof memory proof) internal view returns (bool) {
        uint256 snark_scalar_field = 21888242871839275222246405745257275088548364400416034343698204186575808495617;
        VerifyingKey memory vk = verifyingKey;
        require(input.length + 1 == vk.gamma_abc.length);
        
        // Compute VK * input
        Pairing.G1Point memory vk_x = Pairing.G1Point(0, 0);
        for (uint i = 0; i < input.length; i++) {
            require(input[i] < snark_scalar_field);
            vk_x = Pairing.addition(vk_x, Pairing.scalar_mul(vk.gamma_abc[i + 1], input[i]));
        }
        vk_x = Pairing.addition(vk_x, vk.gamma_abc[0]);
        
        return Pairing.pairing(
            Pairing.negate(proof.a),
            proof.b,
            vk.alpha,
            vk.beta,
            vk_x,
            vk.gamma,
            proof.c,
            vk.delta
        );
    }
}

# Post-quantum cryptography implementation example
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2
import numpy as np

class PostQuantumSecurity:
    def __init__(self):
        self.lattice_dimension = 256
        self.modulus = 2**32 - 5
        
    def generate_lattice_keys(self):
        """Generate lattice-based key pairs"""
        # Private key: short vector
        private_key = np.random.randint(-2, 3, size=(self.lattice_dimension,))
        
        # Public key: A * s + e
        A = np.random.randint(0, self.modulus, 
                             size=(self.lattice_dimension, self.lattice_dimension))
        e = np.random.randint(-2, 3, size=(self.lattice_dimension,))
        
        public_key = (A @ private_key + e) % self.modulus
        
        return private_key, (A, public_key)
    
    def hash_based_signature(self, message, private_key):
        """Implement hash-based signature (quantum-resistant)"""
        # Lamport signature scheme
        message_hash = hashes.Hash(hashes.SHA3_256())
        message_hash.update(message.encode())
        digest = message_hash.finalize()
        
        signature = []
        for bit in format(int.from_bytes(digest, 'big'), '0256b'):
            if bit == '0':
                signature.append(private_key[0])
            else:
                signature.append(private_key[1])
        
        return signature
    
    def verify_quantum_safe_signature(self, message, signature, public_key):
        """Verify quantum-safe signature"""
        message_hash = hashes.Hash(hashes.SHA3_256())
        message_hash.update(message.encode())
        digest = message_hash.finalize()
        
        for i, bit in enumerate(format(int.from_bytes(digest, 'big'), '0256b')):
            expected = public_key[0][i] if bit == '0' else public_key[1][i]
            if signature[i] != expected:
                return False
        
        return True