# Security Implementation Guide

This document outlines the security improvements implemented and setup instructions.

## Files Modified/Created

### New Files Created:
- `.env.example` - Environment variables template
- `includes/file_handler.php` - Secure file upload handler
- `includes/security.php` - Security manager and rate limiting
- `security_update.sql` - Database schema updates
- `uploads/.htaccess` - Prevents script execution in uploads

### Modified Files:
- `config/database.php` - Environment variable support, secure error handling
- `config/config.php` - Integrated security components, fixed directory permissions
- `auth/login.php` - Removed hardcoded credentials, added rate limiting

## Setup Instructions

### 1. Environment Configuration
1. Copy `.env.example` to `.env`
2. Update database credentials in `.env`:
   ```
   DB_PASS=your_secure_database_password
   ```
3. Set a strong database password for the MySQL root user

### 2. Database Updates
Run the security update SQL:
```sql
SOURCE security_update.sql;
```

### 3. File Permissions
Ensure proper permissions are set:
```bash
chmod 755 uploads/
chmod 644 uploads/.htaccess
chmod 600 .env
```

### 4. Web Server Configuration (Apache)
Add to your virtual host or .htaccess in document root:
```apache
# Hide sensitive files
<Files ~ "^\.env$">
    Order allow,deny
    Deny from all
</Files>

<Files ~ "^\..*">
    Order allow,deny
    Deny from all
</Files>
```

## Security Features Implemented

### 1. Database Security ✅
- Environment variable configuration
- Secure error handling (no information disclosure)
- Connection with proper PDO settings

### 2. Session Security ✅
- Secure session configuration (HttpOnly, Secure, SameSite)
- Session timeout (30 minutes default)
- Session ID regeneration
- Automatic cleanup

### 3. File Upload Security ✅
- File type validation (extension + MIME type)
- File size limits
- Secure filename generation
- Directory traversal prevention
- Script execution prevention in upload directories
- Secure file permissions (644)

### 4. Authentication Security ✅
- Rate limiting (5 attempts per 15 minutes)
- Secure password hashing
- Session regeneration on login
- No credential disclosure

### 5. CSRF Protection ✅
- Token generation with expiry
- Secure token validation
- Time-based token refresh

### 6. Security Headers ✅
- Content Security Policy
- X-Frame-Options
- X-Content-Type-Options
- XSS Protection
- Referrer Policy
- HSTS (when HTTPS is used)

### 7. Input Validation ✅
- HTML entity encoding
- Tag stripping
- Prepared statements for SQL
- Password complexity requirements

## Testing Security Measures

### Test Rate Limiting:
1. Attempt login with wrong credentials 6 times
2. Verify lockout message appears
3. Wait 15 minutes or clear `rate_limits` table

### Test File Upload:
1. Try uploading PHP file - should be rejected
2. Upload legitimate PDF/image - should succeed
3. Check file permissions are 644

### Test Session Security:
1. Login and wait 30 minutes
2. Try to access protected page - should redirect to login
3. Check session cookies in browser dev tools

## Production Checklist

- [ ] Set strong database password
- [ ] Configure HTTPS and update SITE_URL
- [ ] Set restrictive file permissions
- [ ] Configure proper Apache/Nginx security headers
- [ ] Hide .env file from web access
- [ ] Test all security measures
- [ ] Set up monitoring for failed login attempts
- [ ] Configure proper backup procedures

## Monitoring

Monitor these log files for security events:
- PHP error logs for database connection issues
- Rate limiting table for brute force attempts
- Web server access logs for unusual patterns

## Additional Recommendations

1. **Regular Updates**: Keep PHP and database software updated
2. **SSL Certificate**: Implement HTTPS in production
3. **Backup Strategy**: Regular encrypted backups
4. **Monitoring**: Log analysis and intrusion detection
5. **Penetration Testing**: Regular security assessments

## Support

For security questions or issues, review the implemented code in:
- `includes/security.php` - Core security functions
- `includes/file_handler.php` - File upload security
- `config/` directory - Configuration security