Security Architecture for Multi-Tenant AI Platforms

Multi-tenant AI platforms present unique security challenges that go beyond traditional software-as-a-service applications. These systems must protect sensitive data across multiple tenants while enabling AI models to learn and adapt, manage shared computational resources without cross-tenant information leakage, and maintain performance while implementing comprehensive security controls. The stakes are particularly high when dealing with enterprise customers who require strict data isolation, compliance with regulations like GDPR and HIPAA, and protection against sophisticated attack vectors targeting AI systems.

This comprehensive guide explores the security architecture patterns, implementation strategies, and operational practices necessary for building secure multi-tenant AI platforms that meet enterprise security requirements while maintaining the flexibility and performance that make AI systems valuable.

Multi-Tenant AI Security Threat Model

Understanding the unique threat landscape for multi-tenant AI platforms is crucial for designing effective security measures:

Multi-Tenant AI Platform Threat Model:

Data Layer Threats:
┌─────────────────────────────────────────────────────────────┐
│ Tenant A Data                                               │
├─────────────────────────────────────────────────────────────┤
│ • Training Data                                             │
│ • Model Parameters    ◄──── Data Leakage Attacks           │
│ • User Inputs                                               │
│ • Inference Results   ◄──── Model Inversion Attacks        │
└─────────────────────────────────────────────────────────────┘
                            │
                            ▼ Cross-Tenant Access
┌─────────────────────────────────────────────────────────────┐
│ Shared AI Infrastructure                                    │
├─────────────────────────────────────────────────────────────┤
│ • GPU Memory          ◄──── Memory Residue Attacks         │
│ • Model Cache         ◄──── Cache Poisoning Attacks        │
│ • Shared Embeddings   ◄──── Embedding Space Attacks        │
│ • Inference Pipeline  ◄──── Adversarial Attacks            │
└─────────────────────────────────────────────────────────────┘
                            │
                            ▼ Privilege Escalation
┌─────────────────────────────────────────────────────────────┐
│ Tenant B Data                                               │
├─────────────────────────────────────────────────────────────┤
│ • Confidential Data   ◄──── Unauthorized Access            │
│ • Proprietary Models  ◄──── Model Extraction Attacks       │
│ • Business Logic      ◄──── Logic Inference Attacks        │
│ • Performance Data    ◄──── Timing Side-Channel Attacks    │
└─────────────────────────────────────────────────────────────┘

Attack Vectors:
┌─────────────────────────────────────────────────────────────┐
│ External Threats                                            │
├─────────────────────────────────────────────────────────────┤
│ • Malicious Tenants                                         │
│ • Compromised Accounts                                      │
│ • Advanced Persistent Threats                               │
│ • Nation-State Actors                                       │
│                                                             │
│ Internal Threats                                            │
│ • Insider Threats                                           │
│ • Misconfigured Systems                                     │
│ • Administrative Errors                                     │
│ • Supply Chain Attacks                                      │
│                                                             │
│ AI-Specific Threats                                         │
│ • Model Poisoning                                           │
│ • Membership Inference                                      │
│ • Property Inference                                        │
│ • Backdoor Attacks                                          │
└─────────────────────────────────────────────────────────────┘

Comprehensive Security Architecture

Here’s a multi-layered security architecture designed for multi-tenant AI platforms:

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import asyncio
import hashlib
import hmac
import json
import logging
import time
import uuid
from typing import Dict, List, Optional, Any, Union, Tuple, Set
from dataclasses import dataclass, field
from enum import Enum
from datetime import datetime, timedelta
import cryptography
from cryptography.fernet import Fernet
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
import jwt
import bcrypt
from abc import ABC, abstractmethod

class SecurityLevel(Enum):
    PUBLIC = "public"
    INTERNAL = "internal"
    CONFIDENTIAL = "confidential"
    RESTRICTED = "restricted"
    TOP_SECRET = "top_secret"

class TenantIsolationLevel(Enum):
    SHARED = "shared"
    PARTITIONED = "partitioned"
    ISOLATED = "isolated"
    DEDICATED = "dedicated"

class AccessControlModel(Enum):
    RBAC = "role_based"
    ABAC = "attribute_based"
    MAC = "mandatory"
    DAC = "discretionary"

@dataclass
class SecurityContext:
    """Security context for operations"""
    tenant_id: str
    user_id: str
    roles: List[str]
    permissions: Set[str]
    security_level: SecurityLevel
    session_id: str
    timestamp: datetime
    source_ip: str
    device_fingerprint: Optional[str] = None
    mfa_verified: bool = False

@dataclass
class TenantSecurityPolicy:
    """Security policy for a tenant"""
    tenant_id: str
    isolation_level: TenantIsolationLevel
    access_control_model: AccessControlModel
    data_classification: SecurityLevel
    encryption_requirements: Dict[str, str]
    compliance_frameworks: List[str]
    audit_requirements: Dict[str, bool]
    retention_policies: Dict[str, timedelta]
    network_restrictions: Dict[str, Any]
    metadata: Dict[str, Any] = field(default_factory=dict)

class TenantIsolationManager:
    """Manages tenant isolation across all system layers"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.tenant_policies: Dict[str, TenantSecurityPolicy] = {}
        self.resource_mappings: Dict[str, Dict[str, str]] = {}
        
        # Encryption management
        self.encryption_manager = EncryptionManager(config.get('encryption', {}))
        
        # Network isolation
        self.network_isolator = NetworkIsolator(config.get('network', {}))
        
        # Compute isolation
        self.compute_isolator = ComputeIsolator(config.get('compute', {}))
        
    async def register_tenant(self, 
                            tenant_id: str,
                            security_policy: TenantSecurityPolicy) -> bool:
        """Register a new tenant with security policy"""
        
        try:
            # Validate security policy
            if not await self._validate_security_policy(security_policy):
                raise ValueError("Invalid security policy")
            
            # Store tenant policy
            self.tenant_policies[tenant_id] = security_policy
            
            # Initialize tenant-specific resources
            await self._initialize_tenant_resources(tenant_id, security_policy)
            
            # Setup isolation boundaries
            await self._setup_tenant_isolation(tenant_id, security_policy)
            
            logging.info(f"Tenant {tenant_id} registered with security policy")
            return True
            
        except Exception as e:
            logging.error(f"Failed to register tenant {tenant_id}: {e}")
            return False
    
    async def _initialize_tenant_resources(self, 
                                         tenant_id: str,
                                         policy: TenantSecurityPolicy):
        """Initialize tenant-specific security resources"""
        
        # Generate tenant-specific encryption keys
        tenant_keys = await self.encryption_manager.generate_tenant_keys(
            tenant_id, policy.encryption_requirements
        )
        
        # Setup network isolation
        if policy.isolation_level in [TenantIsolationLevel.ISOLATED, TenantIsolationLevel.DEDICATED]:
            await self.network_isolator.create_tenant_vpc(tenant_id)
        
        # Setup compute isolation
        await self.compute_isolator.allocate_tenant_resources(
            tenant_id, policy.isolation_level
        )
        
        # Initialize audit logging
        await self._initialize_tenant_audit_logging(tenant_id, policy)
    
    async def _setup_tenant_isolation(self, 
                                    tenant_id: str,
                                    policy: TenantSecurityPolicy):
        """Setup multi-layer tenant isolation"""
        
        isolation_config = {
            'data_isolation': await self._setup_data_isolation(tenant_id, policy),
            'compute_isolation': await self._setup_compute_isolation(tenant_id, policy),
            'network_isolation': await self._setup_network_isolation(tenant_id, policy),
            'model_isolation': await self._setup_model_isolation(tenant_id, policy)
        }
        
        self.resource_mappings[tenant_id] = isolation_config
    
    async def _setup_data_isolation(self, 
                                  tenant_id: str,
                                  policy: TenantSecurityPolicy) -> Dict[str, str]:
        """Setup data-layer isolation"""
        
        isolation_config = {}
        
        if policy.isolation_level == TenantIsolationLevel.SHARED:
            # Logical isolation with row-level security
            isolation_config['database_schema'] = f"tenant_{tenant_id}"
            isolation_config['table_prefix'] = f"{tenant_id}_"
            isolation_config['encryption_key'] = f"tenant_key_{tenant_id}"
            
        elif policy.isolation_level == TenantIsolationLevel.PARTITIONED:
            # Database partitioning
            isolation_config['database_partition'] = f"partition_{tenant_id}"
            isolation_config['dedicated_tables'] = True
            isolation_config['encryption_key'] = f"tenant_key_{tenant_id}"
            
        elif policy.isolation_level == TenantIsolationLevel.ISOLATED:
            # Separate database instance
            isolation_config['database_instance'] = f"db_instance_{tenant_id}"
            isolation_config['dedicated_storage'] = True
            isolation_config['encryption_key'] = f"tenant_key_{tenant_id}"
            
        elif policy.isolation_level == TenantIsolationLevel.DEDICATED:
            # Completely separate infrastructure
            isolation_config['dedicated_cluster'] = f"cluster_{tenant_id}"
            isolation_config['dedicated_storage'] = True
            isolation_config['hardware_isolation'] = True
            isolation_config['encryption_key'] = f"tenant_key_{tenant_id}"
        
        return isolation_config
    
    async def _setup_compute_isolation(self, 
                                     tenant_id: str,
                                     policy: TenantSecurityPolicy) -> Dict[str, str]:
        """Setup compute-layer isolation"""
        
        isolation_config = {}
        
        if policy.isolation_level == TenantIsolationLevel.SHARED:
            # Container-based isolation
            isolation_config['namespace'] = f"tenant-{tenant_id}"
            isolation_config['resource_quota'] = f"quota-{tenant_id}"
            isolation_config['security_context'] = f"secctx-{tenant_id}"
            
        elif policy.isolation_level == TenantIsolationLevel.PARTITIONED:
            # Node pools with taints/tolerations
            isolation_config['node_pool'] = f"nodepool-{tenant_id}"
            isolation_config['dedicated_nodes'] = True
            
        elif policy.isolation_level == TenantIsolationLevel.ISOLATED:
            # Separate clusters
            isolation_config['cluster'] = f"cluster-{tenant_id}"
            isolation_config['dedicated_control_plane'] = True
            
        elif policy.isolation_level == TenantIsolationLevel.DEDICATED:
            # Physical hardware isolation
            isolation_config['dedicated_hardware'] = f"hardware-{tenant_id}"
            isolation_config['bare_metal'] = True
        
        return isolation_config
    
    async def validate_tenant_access(self, 
                                   tenant_id: str,
                                   resource_id: str,
                                   operation: str,
                                   security_context: SecurityContext) -> bool:
        """Validate tenant access to resources"""
        
        try:
            # Verify tenant exists
            if tenant_id not in self.tenant_policies:
                logging.warning(f"Access denied: Unknown tenant {tenant_id}")
                return False
            
            # Verify security context matches tenant
            if security_context.tenant_id != tenant_id:
                logging.warning(f"Access denied: Security context mismatch")
                return False
            
            # Check isolation boundaries
            if not await self._check_isolation_boundaries(
                tenant_id, resource_id, operation, security_context
            ):
                return False
            
            # Apply access control model
            policy = self.tenant_policies[tenant_id]
            return await self._apply_access_control(
                policy, resource_id, operation, security_context
            )
            
        except Exception as e:
            logging.error(f"Access validation error: {e}")
            return False

class EncryptionManager:
    """Manages encryption keys and operations for multi-tenant environment"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.tenant_keys: Dict[str, Dict[str, bytes]] = {}
        self.key_rotation_intervals: Dict[str, timedelta] = {}
        
        # Initialize master key
        self.master_key = self._load_or_generate_master_key()
        
    async def generate_tenant_keys(self, 
                                 tenant_id: str,
                                 encryption_requirements: Dict[str, str]) -> Dict[str, bytes]:
        """Generate encryption keys for tenant"""
        
        tenant_keys = {}
        
        for key_type, algorithm in encryption_requirements.items():
            if algorithm == 'AES-256':
                key = Fernet.generate_key()
            elif algorithm == 'ChaCha20':
                key = secrets.token_bytes(32)  # 256-bit key
            elif algorithm == 'RSA-2048':
                private_key = rsa.generate_private_key(
                    public_exponent=65537,
                    key_size=2048
                )
                key = private_key.private_bytes(
                    encoding=serialization.Encoding.PEM,
                    format=serialization.PrivateFormat.PKCS8,
                    encryption_algorithm=serialization.NoEncryption()
                )
            else:
                raise ValueError(f"Unsupported encryption algorithm: {algorithm}")
            
            tenant_keys[key_type] = key
        
        # Store encrypted keys
        self.tenant_keys[tenant_id] = self._encrypt_keys_with_master(tenant_keys)
        
        # Setup key rotation
        self.key_rotation_intervals[tenant_id] = timedelta(
            days=self.config.get('key_rotation_days', 90)
        )
        
        return tenant_keys
    
    async def encrypt_data(self, 
                          tenant_id: str,
                          data: bytes,
                          key_type: str = 'data_encryption') -> bytes:
        """Encrypt data for specific tenant"""
        
        if tenant_id not in self.tenant_keys:
            raise ValueError(f"No keys found for tenant {tenant_id}")
        
        tenant_keys = self._decrypt_keys_with_master(self.tenant_keys[tenant_id])
        
        if key_type not in tenant_keys:
            raise ValueError(f"Key type {key_type} not found for tenant {tenant_id}")
        
        key = tenant_keys[key_type]
        
        # Use Fernet for symmetric encryption
        f = Fernet(key)
        encrypted_data = f.encrypt(data)
        
        return encrypted_data
    
    async def decrypt_data(self, 
                          tenant_id: str,
                          encrypted_data: bytes,
                          key_type: str = 'data_encryption') -> bytes:
        """Decrypt data for specific tenant"""
        
        if tenant_id not in self.tenant_keys:
            raise ValueError(f"No keys found for tenant {tenant_id}")
        
        tenant_keys = self._decrypt_keys_with_master(self.tenant_keys[tenant_id])
        
        if key_type not in tenant_keys:
            raise ValueError(f"Key type {key_type} not found for tenant {tenant_id}")
        
        key = tenant_keys[key_type]
        
        # Use Fernet for symmetric decryption
        f = Fernet(key)
        data = f.decrypt(encrypted_data)
        
        return data
    
    def _encrypt_keys_with_master(self, tenant_keys: Dict[str, bytes]) -> Dict[str, bytes]:
        """Encrypt tenant keys with master key"""
        
        encrypted_keys = {}
        master_fernet = Fernet(self.master_key)
        
        for key_type, key in tenant_keys.items():
            encrypted_keys[key_type] = master_fernet.encrypt(key)
        
        return encrypted_keys
    
    def _decrypt_keys_with_master(self, encrypted_keys: Dict[str, bytes]) -> Dict[str, bytes]:
        """Decrypt tenant keys with master key"""
        
        tenant_keys = {}
        master_fernet = Fernet(self.master_key)
        
        for key_type, encrypted_key in encrypted_keys.items():
            tenant_keys[key_type] = master_fernet.decrypt(encrypted_key)
        
        return tenant_keys
    
    def _load_or_generate_master_key(self) -> bytes:
        """Load existing master key or generate new one"""
        
        # In production, this would be loaded from HSM or key management service
        master_key_path = self.config.get('master_key_path', 'master.key')
        
        try:
            with open(master_key_path, 'rb') as f:
                return f.read()
        except FileNotFoundError:
            # Generate new master key
            master_key = Fernet.generate_key()
            with open(master_key_path, 'wb') as f:
                f.write(master_key)
            return master_key

class SecureModelManager:
    """Manages AI models with tenant isolation and security controls"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.tenant_models: Dict[str, Dict[str, Any]] = {}
        self.model_access_logs: List[Dict[str, Any]] = []
        
        # Security components
        self.encryption_manager = EncryptionManager(config.get('encryption', {}))
        self.access_validator = AccessValidator(config.get('access_control', {}))
        
        # Model isolation
        self.isolation_boundaries: Dict[str, Set[str]] = {}
        
    async def register_tenant_model(self, 
                                  tenant_id: str,
                                  model_id: str,
                                  model_config: Dict[str, Any],
                                  security_context: SecurityContext) -> bool:
        """Register a model for specific tenant"""
        
        try:
            # Validate access
            if not await self.access_validator.validate_model_registration(
                tenant_id, model_id, security_context
            ):
                return False
            
            # Initialize tenant model storage
            if tenant_id not in self.tenant_models:
                self.tenant_models[tenant_id] = {}
                self.isolation_boundaries[tenant_id] = set()
            
            # Encrypt model configuration
            encrypted_config = await self.encryption_manager.encrypt_data(
                tenant_id,
                json.dumps(model_config).encode(),
                'model_config'
            )
            
            # Store model with isolation metadata
            self.tenant_models[tenant_id][model_id] = {
                'config': encrypted_config,
                'created_at': datetime.now(),
                'created_by': security_context.user_id,
                'access_count': 0,
                'last_accessed': None,
                'isolation_tags': self._generate_isolation_tags(tenant_id, model_id)
            }
            
            # Update isolation boundaries
            self.isolation_boundaries[tenant_id].add(model_id)
            
            # Log model registration
            await self._log_model_operation(
                tenant_id, model_id, 'register', security_context
            )
            
            return True
            
        except Exception as e:
            logging.error(f"Failed to register model {model_id} for tenant {tenant_id}: {e}")
            return False
    
    async def load_tenant_model(self, 
                              tenant_id: str,
                              model_id: str,
                              security_context: SecurityContext) -> Optional[Dict[str, Any]]:
        """Load model for specific tenant with access validation"""
        
        try:
            # Validate tenant access
            if not await self._validate_tenant_model_access(
                tenant_id, model_id, 'load', security_context
            ):
                return None
            
            # Check isolation boundaries
            if not await self._check_model_isolation_boundaries(
                tenant_id, model_id, security_context
            ):
                return None
            
            # Decrypt and load model
            model_data = self.tenant_models[tenant_id][model_id]
            
            decrypted_config = await self.encryption_manager.decrypt_data(
                tenant_id,
                model_data['config'],
                'model_config'
            )
            
            model_config = json.loads(decrypted_config.decode())
            
            # Update access tracking
            model_data['access_count'] += 1
            model_data['last_accessed'] = datetime.now()
            
            # Log model access
            await self._log_model_operation(
                tenant_id, model_id, 'load', security_context
            )
            
            return model_config
            
        except Exception as e:
            logging.error(f"Failed to load model {model_id} for tenant {tenant_id}: {e}")
            return None
    
    async def execute_secure_inference(self, 
                                     tenant_id: str,
                                     model_id: str,
                                     input_data: Dict[str, Any],
                                     security_context: SecurityContext) -> Optional[Dict[str, Any]]:
        """Execute inference with tenant isolation and security controls"""
        
        try:
            # Validate access
            if not await self._validate_tenant_model_access(
                tenant_id, model_id, 'inference', security_context
            ):
                return None
            
            # Sanitize input data
            sanitized_input = await self._sanitize_input_data(
                tenant_id, input_data, security_context
            )
            
            # Execute inference in isolated environment
            inference_result = await self._execute_isolated_inference(
                tenant_id, model_id, sanitized_input, security_context
            )
            
            # Apply output filtering
            filtered_result = await self._filter_inference_output(
                tenant_id, inference_result, security_context
            )
            
            # Log inference operation
            await self._log_model_operation(
                tenant_id, model_id, 'inference', security_context,
                additional_data={
                    'input_size': len(str(input_data)),
                    'output_size': len(str(filtered_result)) if filtered_result else 0
                }
            )
            
            return filtered_result
            
        except Exception as e:
            logging.error(f"Secure inference failed for tenant {tenant_id}, model {model_id}: {e}")
            return None
    
    async def _execute_isolated_inference(self, 
                                        tenant_id: str,
                                        model_id: str,
                                        input_data: Dict[str, Any],
                                        security_context: SecurityContext) -> Dict[str, Any]:
        """Execute inference in tenant-isolated environment"""
        
        # Load model configuration
        model_config = await self.load_tenant_model(tenant_id, model_id, security_context)
        if not model_config:
            raise ValueError("Failed to load model configuration")
        
        # Create isolated execution context
        execution_context = await self._create_isolated_execution_context(
            tenant_id, model_id
        )
        
        try:
            # Execute inference within isolation boundary
            with execution_context:
                # Clear any residual memory/cache
                await self._clear_execution_environment()
                
                # Load model in isolated memory space
                model = await self._load_model_isolated(model_config, tenant_id)
                
                # Execute inference
                result = await model.predict(input_data)
                
                # Clear model from memory
                await self._clear_model_memory(model)
                
                return result
                
        except Exception as e:
            logging.error(f"Isolated inference execution failed: {e}")
            raise
        finally:
            # Ensure cleanup
            await self._cleanup_execution_context(execution_context)
    
    async def _sanitize_input_data(self, 
                                 tenant_id: str,
                                 input_data: Dict[str, Any],
                                 security_context: SecurityContext) -> Dict[str, Any]:
        """Sanitize input data to prevent attacks"""
        
        sanitized_data = {}
        
        for key, value in input_data.items():
            if isinstance(value, str):
                # Remove potentially malicious content
                sanitized_value = self._sanitize_string_input(value)
                sanitized_data[key] = sanitized_value
            elif isinstance(value, (int, float)):
                # Validate numeric ranges
                sanitized_data[key] = self._sanitize_numeric_input(value)
            elif isinstance(value, list):
                # Sanitize list elements
                sanitized_data[key] = [
                    self._sanitize_string_input(str(item)) if isinstance(item, str) else item
                    for item in value[:self.config.get('max_list_size', 1000)]
                ]
            else:
                # Convert other types to string and sanitize
                sanitized_data[key] = self._sanitize_string_input(str(value))
        
        return sanitized_data
    
    def _sanitize_string_input(self, text: str) -> str:
        """Sanitize string input"""
        
        # Remove potentially malicious patterns
        import re
        
        # Remove script tags
        text = re.sub(r'<script.*?</script>', '', text, flags=re.IGNORECASE | re.DOTALL)
        
        # Remove SQL injection patterns
        sql_patterns = [
            r'\b(SELECT|INSERT|UPDATE|DELETE|DROP|CREATE|ALTER|EXEC|EXECUTE)\b',
            r'[\'";]',
            r'--',
            r'/\*',
            r'\*/'
        ]
        
        for pattern in sql_patterns:
            text = re.sub(pattern, '', text, flags=re.IGNORECASE)
        
        # Limit length
        max_length = self.config.get('max_string_length', 10000)
        text = text[:max_length]
        
        return text.strip()

class AccessValidator:
    """Validates access control for multi-tenant AI operations"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.rbac_policies: Dict[str, Dict[str, Any]] = {}
        self.access_cache: Dict[str, Dict[str, Any]] = {}
        
    async def validate_model_registration(self, 
                                        tenant_id: str,
                                        model_id: str,
                                        security_context: SecurityContext) -> bool:
        """Validate model registration access"""
        
        # Check basic tenant access
        if security_context.tenant_id != tenant_id:
            logging.warning(f"Tenant mismatch: context={security_context.tenant_id}, requested={tenant_id}")
            return False
        
        # Check role permissions
        required_permissions = {'model:create', 'model:register'}
        if not required_permissions.issubset(security_context.permissions):
            logging.warning(f"Insufficient permissions for model registration")
            return False
        
        # Check tenant-specific policies
        tenant_policy = self.rbac_policies.get(tenant_id)
        if tenant_policy:
            if not tenant_policy.get('allow_model_registration', True):
                logging.warning(f"Model registration disabled for tenant {tenant_id}")
                return False
        
        return True
    
    async def validate_inference_access(self, 
                                      tenant_id: str,
                                      model_id: str,
                                      security_context: SecurityContext) -> bool:
        """Validate inference operation access"""
        
        # Check cache first
        cache_key = f"{tenant_id}:{model_id}:{security_context.user_id}:inference"
        cached_result = self.access_cache.get(cache_key)
        
        if cached_result and (datetime.now() - cached_result['timestamp']).seconds < 300:  # 5 min cache
            return cached_result['allowed']
        
        # Validate access
        allowed = await self._validate_access_detailed(
            tenant_id, model_id, 'inference', security_context
        )
        
        # Cache result
        self.access_cache[cache_key] = {
            'allowed': allowed,
            'timestamp': datetime.now()
        }
        
        return allowed
    
    async def _validate_access_detailed(self, 
                                      tenant_id: str,
                                      resource_id: str,
                                      operation: str,
                                      security_context: SecurityContext) -> bool:
        """Detailed access validation"""
        
        # Multi-factor validation
        validations = [
            await self._validate_tenant_membership(tenant_id, security_context),
            await self._validate_role_permissions(operation, security_context),
            await self._validate_resource_access(resource_id, security_context),
            await self._validate_time_restrictions(security_context),
            await self._validate_network_restrictions(security_context),
            await self._validate_mfa_requirements(security_context)
        ]
        
        return all(validations)
    
    async def _validate_mfa_requirements(self, security_context: SecurityContext) -> bool:
        """Validate multi-factor authentication requirements"""
        
        # For sensitive operations, require MFA
        if security_context.security_level in [SecurityLevel.CONFIDENTIAL, SecurityLevel.RESTRICTED]:
            return security_context.mfa_verified
        
        return True

class AuditManager:
    """Manages comprehensive audit logging for multi-tenant AI platform"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.audit_logs: List[Dict[str, Any]] = []
        self.tenant_audit_configs: Dict[str, Dict[str, Any]] = {}
        
    async def log_security_event(self, 
                                event_type: str,
                                tenant_id: str,
                                security_context: SecurityContext,
                                details: Dict[str, Any]):
        """Log security-related events"""
        
        audit_entry = {
            'timestamp': datetime.now().isoformat(),
            'event_type': event_type,
            'tenant_id': tenant_id,
            'user_id': security_context.user_id,
            'session_id': security_context.session_id,
            'source_ip': security_context.source_ip,
            'security_level': security_context.security_level.value,
            'details': details,
            'event_id': str(uuid.uuid4())
        }
        
        # Apply tenant-specific audit configuration
        tenant_config = self.tenant_audit_configs.get(tenant_id, {})
        if tenant_config.get('detailed_logging', False):
            audit_entry['detailed_context'] = {
                'roles': security_context.roles,
                'permissions': list(security_context.permissions),
                'device_fingerprint': security_context.device_fingerprint,
                'mfa_verified': security_context.mfa_verified
            }
        
        # Store audit entry
        self.audit_logs.append(audit_entry)
        
        # Forward to external audit systems if configured
        await self._forward_to_external_audit(audit_entry, tenant_id)
        
        # Check for suspicious patterns
        await self._analyze_audit_patterns(audit_entry, tenant_id)
    
    async def _analyze_audit_patterns(self, 
                                    audit_entry: Dict[str, Any],
                                    tenant_id: str):
        """Analyze audit patterns for suspicious activity"""
        
        # Get recent entries for this tenant and user
        recent_entries = [
            entry for entry in self.audit_logs[-1000:]  # Last 1000 entries
            if (entry['tenant_id'] == tenant_id and 
                entry['user_id'] == audit_entry['user_id'] and
                (datetime.now() - datetime.fromisoformat(entry['timestamp'])).seconds < 3600)  # Last hour
        ]
        
        # Check for suspicious patterns
        suspicious_patterns = []
        
        # Pattern 1: Unusual access frequency
        if len(recent_entries) > 100:  # More than 100 operations in an hour
            suspicious_patterns.append('high_frequency_access')
        
        # Pattern 2: Multiple failed access attempts
        failed_attempts = [e for e in recent_entries if e.get('details', {}).get('success') is False]
        if len(failed_attempts) > 10:
            suspicious_patterns.append('multiple_failed_attempts')
        
        # Pattern 3: Access from multiple IP addresses
        unique_ips = set(entry['source_ip'] for entry in recent_entries)
        if len(unique_ips) > 5:
            suspicious_patterns.append('multiple_ip_addresses')
        
        # Pattern 4: Unusual time access
        current_hour = datetime.now().hour
        if current_hour < 6 or current_hour > 22:  # Outside business hours
            business_hours_entries = [
                e for e in recent_entries
                if 6 <= datetime.fromisoformat(e['timestamp']).hour <= 22
            ]
            if len(business_hours_entries) < len(recent_entries) * 0.1:  # Less than 10% normal access
                suspicious_patterns.append('unusual_time_access')
        
        # Generate security alerts for suspicious patterns
        if suspicious_patterns:
            await self._generate_security_alert(
                tenant_id, audit_entry['user_id'], suspicious_patterns, recent_entries
            )

class ThreatDetectionEngine:
    """Detects and mitigates AI-specific threats in multi-tenant environment"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.threat_models: Dict[str, Any] = {}
        self.detection_history: List[Dict[str, Any]] = []
        
        # Initialize threat detection models
        self._initialize_threat_models()
    
    def _initialize_threat_models(self):
        """Initialize threat detection models"""
        
        self.threat_models = {
            'model_inversion': ModelInversionDetector(),
            'membership_inference': MembershipInferenceDetector(),
            'model_extraction': ModelExtractionDetector(),
            'adversarial_examples': AdversarialExampleDetector(),
            'data_poisoning': DataPoisoningDetector()
        }
    
    async def analyze_inference_request(self, 
                                      tenant_id: str,
                                      model_id: str,
                                      input_data: Dict[str, Any],
                                      security_context: SecurityContext) -> Dict[str, Any]:
        """Analyze inference request for potential threats"""
        
        threat_analysis = {
            'tenant_id': tenant_id,
            'model_id': model_id,
            'timestamp': datetime.now(),
            'threats_detected': [],
            'risk_score': 0.0,
            'recommended_actions': []
        }
        
        # Run threat detection models
        for threat_type, detector in self.threat_models.items():
            try:
                detection_result = await detector.analyze(
                    input_data, model_id, tenant_id, security_context
                )
                
                if detection_result['threat_detected']:
                    threat_analysis['threats_detected'].append({
                        'type': threat_type,
                        'confidence': detection_result['confidence'],
                        'indicators': detection_result['indicators']
                    })
                    
                    threat_analysis['risk_score'] = max(
                        threat_analysis['risk_score'],
                        detection_result['risk_score']
                    )
            
            except Exception as e:
                logging.error(f"Threat detection error for {threat_type}: {e}")
        
        # Generate recommendations
        if threat_analysis['risk_score'] > 0.8:
            threat_analysis['recommended_actions'].append('block_request')
        elif threat_analysis['risk_score'] > 0.6:
            threat_analysis['recommended_actions'].append('enhanced_monitoring')
        elif threat_analysis['risk_score'] > 0.4:
            threat_analysis['recommended_actions'].append('log_detailed_metrics')
        
        # Store analysis results
        self.detection_history.append(threat_analysis)
        
        return threat_analysis

class ModelInversionDetector:
    """Detects model inversion attacks"""
    
    async def analyze(self, 
                     input_data: Dict[str, Any],
                     model_id: str,
                     tenant_id: str,
                     security_context: SecurityContext) -> Dict[str, Any]:
        """Analyze for model inversion attack patterns"""
        
        risk_indicators = []
        risk_score = 0.0
        
        # Check for systematic probing patterns
        if self._detect_systematic_probing(input_data, security_context):
            risk_indicators.append('systematic_probing_detected')
            risk_score += 0.4
        
        # Check for gradient-based attack signatures
        if self._detect_gradient_attacks(input_data):
            risk_indicators.append('gradient_attack_signature')
            risk_score += 0.5
        
        # Check for unusual query patterns
        if await self._detect_unusual_query_patterns(input_data, tenant_id, security_context):
            risk_indicators.append('unusual_query_patterns')
            risk_score += 0.3
        
        return {
            'threat_detected': risk_score > 0.5,
            'confidence': min(risk_score, 1.0),
            'risk_score': min(risk_score, 1.0),
            'indicators': risk_indicators
        }
    
    def _detect_systematic_probing(self, 
                                 input_data: Dict[str, Any],
                                 security_context: SecurityContext) -> bool:
        """Detect systematic probing behavior"""
        
        # Look for patterns in input data that suggest systematic exploration
        # This is a simplified example - real implementation would be more sophisticated
        
        if isinstance(input_data, dict):
            # Check for incremental value patterns
            numeric_values = [v for v in input_data.values() if isinstance(v, (int, float))]
            if len(numeric_values) > 5:
                # Check if values are in arithmetic progression (systematic exploration)
                differences = [numeric_values[i+1] - numeric_values[i] for i in range(len(numeric_values)-1)]
                if len(set(differences)) <= 2:  # All differences are the same or alternate between two values
                    return True
        
        return False
    
    def _detect_gradient_attacks(self, input_data: Dict[str, Any]) -> bool:
        """Detect gradient-based attack signatures"""
        
        # Look for patterns that suggest gradient computation
        if isinstance(input_data, dict):
            for key, value in input_data.items():
                if isinstance(value, (list, tuple)):
                    # Check for small perturbations that might indicate gradient steps
                    if len(value) > 10:
                        differences = [abs(value[i+1] - value[i]) for i in range(len(value)-1)]
                        avg_diff = sum(differences) / len(differences)
                        
                        # Very small, consistent differences might indicate gradient-based exploration
                        if avg_diff < 0.001 and max(differences) < 0.01:
                            return True
        
        return False

class ComplianceManager:
    """Manages regulatory compliance for multi-tenant AI platform"""
    
    def __init__(self, config: Dict[str, Any]):
        self.config = config
        self.compliance_frameworks = {
            'GDPR': GDPRComplianceHandler(),
            'HIPAA': HIPAAComplianceHandler(),
            'SOX': SOXComplianceHandler(),
            'PCI_DSS': PCIDSSComplianceHandler()
        }
        self.tenant_compliance_requirements: Dict[str, List[str]] = {}
    
    async def validate_compliance(self, 
                                tenant_id: str,
                                operation: str,
                                data_classification: SecurityLevel,
                                security_context: SecurityContext) -> Dict[str, Any]:
        """Validate operation against compliance requirements"""
        
        compliance_result = {
            'compliant': True,
            'violations': [],
            'recommendations': [],
            'required_actions': []
        }
        
        # Get tenant compliance requirements
        requirements = self.tenant_compliance_requirements.get(tenant_id, [])
        
        # Check each applicable compliance framework
        for framework_name in requirements:
            if framework_name in self.compliance_frameworks:
                framework = self.compliance_frameworks[framework_name]
                
                result = await framework.validate_operation(
                    tenant_id, operation, data_classification, security_context
                )
                
                if not result['compliant']:
                    compliance_result['compliant'] = False
                    compliance_result['violations'].extend(result['violations'])
                    compliance_result['required_actions'].extend(result['required_actions'])
                
                compliance_result['recommendations'].extend(result.get('recommendations', []))
        
        return compliance_result

class GDPRComplianceHandler:
    """Handles GDPR compliance requirements"""
    
    async def validate_operation(self, 
                               tenant_id: str,
                               operation: str,
                               data_classification: SecurityLevel,
                               security_context: SecurityContext) -> Dict[str, Any]:
        """Validate operation against GDPR requirements"""
        
        result = {
            'compliant': True,
            'violations': [],
            'required_actions': [],
            'recommendations': []
        }
        
        # Check for personal data processing
        if operation in ['inference', 'training', 'model_update']:
            # Verify consent and legal basis
            if not await self._check_consent_and_legal_basis(tenant_id, security_context):
                result['compliant'] = False
                result['violations'].append('missing_consent_or_legal_basis')
                result['required_actions'].append('obtain_explicit_consent')
        
        # Check data minimization principle
        if operation == 'data_collection':
            if not await self._check_data_minimization(tenant_id, security_context):
                result['compliant'] = False
                result['violations'].append('data_minimization_violation')
                result['required_actions'].append('limit_data_collection')
        
        # Check right to be forgotten
        if operation == 'data_deletion':
            result['recommendations'].append('implement_right_to_be_forgotten')
        
        return result
    
    async def _check_consent_and_legal_basis(self, 
                                           tenant_id: str,
                                           security_context: SecurityContext) -> bool:
        """Check if consent and legal basis are present"""
        # Implementation would check actual consent records
        return True  # Simplified for example

class SecurityMonitoringDashboard:
    """Real-time security monitoring dashboard"""
    
    def __init__(self, security_components: Dict[str, Any]):
        self.security_components = security_components
        
    def generate_security_report(self, tenant_id: str) -> Dict[str, Any]:
        """Generate comprehensive security report for tenant"""
        
        report = {
            'tenant_id': tenant_id,
            'report_timestamp': datetime.now().isoformat(),
            'security_posture': {},
            'threat_landscape': {},
            'compliance_status': {},
            'recommendations': []
        }
        
        # Security posture analysis
        report['security_posture'] = {
            'isolation_level': self._assess_isolation_level(tenant_id),
            'encryption_coverage': self._assess_encryption_coverage(tenant_id),
            'access_control_maturity': self._assess_access_control_maturity(tenant_id),
            'audit_completeness': self._assess_audit_completeness(tenant_id)
        }
        
        # Threat landscape analysis
        report['threat_landscape'] = {
            'active_threats': self._get_active_threats(tenant_id),
            'risk_trends': self._analyze_risk_trends(tenant_id),
            'vulnerability_assessment': self._assess_vulnerabilities(tenant_id)
        }
        
        # Compliance status
        report['compliance_status'] = {
            'framework_compliance': self._assess_compliance_status(tenant_id),
            'gaps_identified': self._identify_compliance_gaps(tenant_id),
            'remediation_timeline': self._estimate_remediation_timeline(tenant_id)
        }
        
        # Security recommendations
        report['recommendations'] = self._generate_security_recommendations(report)
        
        return report

Conclusion

Building secure multi-tenant AI platforms requires a comprehensive approach that addresses threats at every layer of the system architecture. Key security principles include:

  1. Defense in Depth: Implement multiple layers of security controls from network to application level
  2. Zero Trust Architecture: Never trust, always verify - validate every access request and operation
  3. Data-Centric Security: Protect data throughout its lifecycle with encryption, access controls, and audit trails
  4. AI-Specific Threat Mitigation: Address unique threats like model inversion, membership inference, and adversarial attacks
  5. Continuous Monitoring: Implement real-time threat detection and response capabilities
  6. Compliance by Design: Build regulatory compliance requirements into the system architecture

The security architecture presented here provides a foundation for building enterprise-grade multi-tenant AI platforms that can protect sensitive data while enabling the innovation and efficiency that AI systems provide. As the threat landscape continues to evolve, maintaining strong security requires ongoing vigilance, continuous improvement, and adaptation to new attack vectors.

Organizations that invest in comprehensive security architecture for their AI platforms will be better positioned to serve enterprise customers, meet regulatory requirements, and maintain competitive advantage in an increasingly security-conscious market.