# 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