Secure Architecture Patterns for LLM Applications
This document outlines architectural patterns for developing secure LLM-based applications. These patterns address common security challenges and provide reusable approaches for implementing robust security controls throughout the application lifecycle.
Core Security Principles
Effective security architecture for LLM applications is built on these foundational principles:
Defense in Depth
Implement multiple, overlapping security controls at different layers of the architecture to ensure that a failure in any single control does not compromise the entire system.
Key Implementation Approaches:
- Multiple security layers with independent enforcement mechanisms
- Complementary controls addressing different attack vectors
- Segregated security domains with controlled interactions
- Independent validation at multiple processing stages
Least Privilege
Limit capabilities, data access, and system interactions to the minimum necessary for the intended functionality.
Key Implementation Approaches:
- Granular capability assignment based on specific requirements
- Contextual privilege scoping based on operational needs
- Progressive privilege disclosure tied to verification
- Just-in-time access provision with appropriate expiration
Secure Defaults
Ensure that the default configuration and behavior of all components prioritize security, requiring explicit action to enable less secure options.
Key Implementation Approaches:
- Conservative security posture by default
- Explicit activation requirements for sensitive capabilities
- Safe failure modes with secure fallback behaviors
- Progressive disclosure of capabilities based on verification
Segregation of Duties
Separate critical functions to ensure that no single component has complete control over security-sensitive operations.
Key Implementation Approaches:
- Distributed control over sensitive operations
- Independent verification of critical actions
- Separation between authorization and execution
- Multi-component approval for high-risk operations
Reference Architecture Overview
The following reference architecture illustrates a comprehensive security approach for LLM applications:
┌────────────────────────────────────────────────────────────────────┐
│ Client-Facing Interface │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ API Gateway │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │ Rate Limiting │ │ Input Validation │ │ Authentication │ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ Request Processing Layer │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │Session Management│ │Authorization Service│ │Context Management│ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ Security Gateway Layer │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │ Input Security │ │ Pattern Detection │ │ Intent Analysis│ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ LLM Interface Layer │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │System Instruction│ │ Context Assembly │ │Parameter Control│ │
│ │ Management │ │ │ │ │ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ Model Access Layer │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │ Model Selection │ │ Request Formatting │ │Capability Control│ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
▼
┌──────────────┐
│ LLM Model │
└──────┬───────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ Response Processing Layer │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │Output Validation│ │ Content Filtering │ │Sensitive Info │ │
│ │ │ │ │ │ Detection │ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ Integration Control Layer │
│ │
│ ┌─────────────────┐ ┌────────────────────┐ ┌────────────────┐ │
│ │Tool Use Security│ │ Action Validation │ │Output Formatting│ │
│ └─────────────────┘ └────────────────────┘ └────────────────┘ │
└─────────────────────────────────┬──────────────────────────────────┘
│
┌─────────────────────────────────▼──────────────────────────────────┐
│ Client Response │
└────────────────────────────────────────────────────────────────────┘
Architecture Component Patterns
Input Processing Security Patterns
1. Multi-Level Input Validation
Pattern Description:
Implement layered validation of user inputs, applying increasingly sophisticated validation at different architecture layers.
Key Components:
- Structural validation at the API gateway
- Semantic validation at the processing layer
- Intent analysis at the security gateway
- Context-specific validation at the LLM interface
Implementation Approach:
┌───────────────┐ ┌───────────────┐ ┌───────────────┐ ┌───────────────┐
│ Structural │ │ Semantic │ │ Intent │ │ Contextual │
│ Validation │─────►│ Validation │─────►│ Analysis │─────►│ Validation │
│ - Format │ │ - Content │ │ - Purpose │ │ - History │
│ - Schema │ │ - Meaning │ │ - Goal │ │ - Interaction │
└───────────────┘ └───────────────┘ └───────────────┘ └───────────────┘
Security Benefits:
- Prevents malformed inputs from reaching downstream components
- Enables targeted response to different validation failures
- Provides defense in depth against evasion techniques
- Allows context-aware validation decisions
2. Request Classification and Routing
Pattern Description:
Classify incoming requests by risk level, intent, and content type to route through appropriate security processing pipelines.
Key Components:
- Intent classification service
- Risk assessment engine
- Content categorization
- Dynamic routing rules
Implementation Approach:
┌───────────────┐
│ Classification │
│ Engine │
└───────┬───────┘
│
┌───────────────┴──────────────┐
│ │
┌────────▼─────────┐ ┌─────────▼────────┐
│ Low-Risk Path │ │ High-Risk Path │
│ - Basic Filtering│ │ - Deep Analysis │
│ - Fast Processing│ │ - Enhanced │
│ - Limited │ │ Monitoring │
│ Monitoring │ │ - Strict Controls│
└──────────────────┘ └──────────────────┘
Security Benefits:
- Concentrates security resources on higher-risk requests
- Enables specialized processing for different request types
- Maintains performance for low-risk interactions
- Supports differentiated monitoring and controls
3. Contextual Security State Management
Pattern Description:
Maintain security-relevant state across the conversation, enabling context-aware security decisions based on interaction history.
Key Components:
- Secure conversation state store
- Security context manager
- Historical pattern analyzer
- Risk evolution tracker
Implementation Approach:
┌─────────────────┐ ┌─────────────────┐ ┌────────────────┐
│ Conversation │ │ Security │ │ Pattern │
│ State Store │◄───►│ Context │◄───►│ Analysis │
└─────────────────┘ └─────────────────┘ └────────────────┘
▲
│
┌──────┴────────┐
│ Security │
│ Decision │
│ Engine │
└───────────────┘
Security Benefits:
- Enables detection of multi-turn exploitation attempts
- Provides historical context for security decisions
- Supports tracking of behavioral patterns over time
- Allows adaptive security based on interaction evolution
Instruction and Context Management Patterns
1. Secure Instruction Encapsulation
Pattern Description:
Encapsulate system instructions in a protected context that isolates them from user inputs and prevents unauthorized modification.
Key Components:
- Instruction registry with integrity protection
- Instruction application service
- Instruction verification mechanisms
- Immutable instruction references
Implementation Approach:
┌───────────────────┐ ┌────────────────────┐ ┌───────────────────┐
│ Protected │ │ Instruction │ │ Instruction │
│ Instruction │─────►│ Assembly │─────►│ Verification │
│ Repository │ │ Service │ │ Service │
└───────────────────┘ └────────────────────┘ └───────────────────┘
│
▼
┌────────────────┐
│ User Request │
└────────────────┘
│
▼
┌─────────────────┐
│ Model Request │
│ with Verified │
│ Instructions │
└─────────────────┘
Security Benefits:
- Prevents instruction manipulation attempts
- Ensures consistency of security constraints
- Provides auditability of instruction application
- Enables centralized instruction management
2. Context Window Segregation
Pattern Description:
Segment the context window into isolated zones with different security properties and controlled information flow between zones.
Key Components:
- Zoned context manager
- Cross-zone reference monitor
- Zone transition validator
- Zone integrity verification
Implementation Approach:
┌─────────────────────────────────────────────────────────────┐
│ Context Window │
│ │
│ ┌───────────────┐ ┌───────────────┐ ┌───────────────┐ │
│ │ System Zone │ │ Application │ │ User Input │ │
│ │ (Highest │ │ Zone │ │ Zone │ │
│ │ Privilege) │ │ (Controlled) │ │ (Untrusted) │ │
│ └───────┬───────┘ └───────┬───────┘ └───────┬───────┘ │
│ │ │ │ │
│ ▼ ▼ ▼ │
│ ┌───────────────────────────────────────────────────────┐ │
│ │ Zone Reference Monitor │ │
│ │ │ │
│ │ - Enforces information flow between zones