# Threat Model and Security Considerations

## Overview

Context-as-a-Service (CaaS) is designed with enterprise security and privacy as core principles. This document outlines the threat model, security considerations, and mitigation strategies implemented in the system.

## Trust Gateway Architecture

The Trust Gateway is the cornerstone of CaaS security, designed to prevent data leakage and enable deployment in sensitive environments.

### Key Security Properties

1. **Zero Data Leakage**: All processing can occur on-premises or in air-gapped environments
2. **No External Dependencies**: No required calls to third-party APIs for core functionality
3. **Local Processing**: All document analysis, context extraction, and routing occur locally
4. **Transparent Routing**: Heuristic-based routing provides deterministic, auditable decisions

## Threat Categories

### 1. Data Confidentiality Threats

#### Threat: Document Content Exposure
- **Description**: Sensitive documents could be exposed to unauthorized parties through API calls or third-party services
- **Likelihood**: High (if using external RAG services)
- **Impact**: Critical (confidential data breach)
- **Mitigation**:
  - Trust Gateway enables on-premises deployment
  - No external API calls required for document processing
  - Air-gapped deployment support
  - Local vector storage options
  - Encryption at rest and in transit

#### Threat: Context Window Leakage
- **Description**: Conversation context could be exposed through logging or external LLM calls
- **Likelihood**: Medium
- **Impact**: High (conversation privacy breach)
- **Mitigation**:
  - Sliding window management keeps only recent context
  - Configurable context retention policies
  - Local conversation storage
  - No automatic transmission to external services
  - Audit logging of context access

#### Threat: Metadata Exposure
- **Description**: Document metadata (structure, sources, timestamps) could reveal sensitive information
- **Likelihood**: Medium
- **Impact**: Medium (organizational intelligence)
- **Mitigation**:
  - Metadata stored locally
  - Access control on metadata endpoints
  - Configurable metadata retention
  - Option to anonymize source information

### 2. Data Integrity Threats

#### Threat: Document Tampering
- **Description**: Malicious actors could modify ingested documents
- **Likelihood**: Low (with proper access controls)
- **Impact**: High (poisoned context)
- **Mitigation**:
  - Document ingestion checksums
  - Immutable document storage option
  - Audit trail of all ingestion operations
  - Document verification before serving

#### Threat: Weight Manipulation
- **Description**: Auto-tuned weights could be manipulated to prioritize/deprioritize content
- **Likelihood**: Low
- **Impact**: Medium (biased context serving)
- **Mitigation**:
  - Weight calculation transparency
  - Audit logs of weight changes
  - Configurable weight bounds
  - Manual weight override capabilities

### 3. Availability Threats

#### Threat: Resource Exhaustion
- **Description**: Large document ingestion could exhaust system resources
- **Likelihood**: Medium
- **Impact**: Medium (service degradation)
- **Mitigation**:
  - Configurable resource limits
  - Rate limiting on ingestion endpoints
  - Async processing with queues
  - Monitoring and alerting

#### Threat: Adversarial Queries
- **Description**: Malicious queries designed to extract maximum context or cause slowdowns
- **Likelihood**: Medium
- **Impact**: Medium (performance degradation)
- **Mitigation**:
  - Query rate limiting
  - Maximum context token limits
  - Query complexity analysis
  - Request authentication

### 4. Privacy Threats

#### Threat: Source Attribution Linking
- **Description**: Source citations could reveal private information about document origins
- **Likelihood**: Medium
- **Impact**: Medium (privacy breach)
- **Mitigation**:
  - Configurable source anonymization
  - Source access controls
  - Option to disable source tracking
  - Redaction capabilities

#### Threat: Temporal Analysis
- **Description**: Time decay patterns could reveal when sensitive documents were created
- **Likelihood**: Low
- **Impact**: Low (temporal intelligence)
- **Mitigation**:
  - Configurable decay parameters
  - Option to disable time-based ranking
  - Timestamp anonymization options

## Deployment Models

### On-Premises Deployment (Recommended for Enterprise)
- **Security Level**: Maximum
- **Data Location**: Customer infrastructure
- **Network Requirements**: None (can be air-gapped)
- **Use Cases**: Financial services, healthcare, government, defense

### Private Cloud Deployment
- **Security Level**: High
- **Data Location**: Customer's private cloud (AWS VPC, Azure VNet, etc.)
- **Network Requirements**: Private network only
- **Use Cases**: Enterprise SaaS, medium-to-large businesses

### Hybrid Deployment
- **Security Level**: Medium-High
- **Data Location**: Sensitive data on-prem, non-sensitive in cloud
- **Network Requirements**: Secure tunnels for hybrid communication
- **Use Cases**: Organizations with mixed sensitivity requirements

### Public Cloud Deployment (Development/Testing Only)
- **Security Level**: Basic
- **Data Location**: Public cloud infrastructure
- **Network Requirements**: Internet accessible
- **Use Cases**: Development, testing, non-sensitive applications

## Security Best Practices

### 1. Authentication & Authorization
- Implement strong authentication for all API endpoints
- Use role-based access control (RBAC) for different operations
- Separate read/write permissions for documents and contexts
- Regular credential rotation

### 2. Network Security
- Deploy behind firewalls and VPNs in production
- Use HTTPS/TLS for all API communications
- Consider mTLS for service-to-service communication
- Network segmentation for different sensitivity levels

### 3. Data Protection
- Encrypt documents at rest using AES-256 or equivalent
- Encrypt all network traffic with TLS 1.3+
- Implement secure key management (KMS, HSM)
- Regular security audits of storage systems

### 4. Logging & Monitoring
- Comprehensive audit logging of all operations
- Monitor for anomalous access patterns
- Alert on suspicious activities
- Log retention policies aligned with compliance requirements

### 5. Secure Configuration
- Change all default credentials
- Disable unnecessary features and endpoints
- Use secure defaults for all configurations
- Regular security configuration reviews

## Compliance Considerations

### GDPR (General Data Protection Regulation)
- **Right to be forgotten**: Document deletion capabilities
- **Data minimization**: Configurable retention policies
- **Data portability**: Export capabilities
- **Consent management**: Explicit document ingestion tracking

### HIPAA (Health Insurance Portability and Accountability Act)
- **PHI Protection**: On-premises deployment option
- **Access Controls**: RBAC implementation
- **Audit Trails**: Comprehensive logging
- **Encryption**: At rest and in transit

### SOC 2 Type II
- **Security**: Trust Gateway architecture
- **Availability**: Resource management and monitoring
- **Confidentiality**: Encryption and access controls
- **Privacy**: Anonymization and retention policies

## Incident Response

### Security Incident Categories
1. **Data Breach**: Unauthorized access to documents or contexts
2. **Service Disruption**: DoS or resource exhaustion
3. **Configuration Error**: Misconfigurations exposing data
4. **Third-Party Compromise**: If external integrations are used

### Response Procedures
1. **Detection**: Monitoring alerts or user reports
2. **Containment**: Isolate affected components
3. **Eradication**: Remove the threat
4. **Recovery**: Restore normal operations
5. **Post-Incident**: Review and improve

## Known Limitations

### Current Version (0.1.0)
- No built-in authentication (must be added at infrastructure layer)
- No built-in encryption at rest (relies on filesystem/OS encryption)
- No built-in rate limiting (must be added at reverse proxy/API gateway)
- Limited audit logging (basic operation logs only)

### Planned Improvements
- Built-in authentication/authorization middleware
- Native encryption at rest options
- Advanced rate limiting and quota management
- Enhanced audit logging with correlation IDs
- Security scanning integration
- Automated security testing in CI/CD

## Security Reporting

If you discover a security vulnerability in Context-as-a-Service, please report it responsibly:

1. **Do not** open a public GitHub issue
2. Email security concerns to: [security@your-domain.com] (to be configured)
3. Include:
   - Description of the vulnerability
   - Steps to reproduce
   - Potential impact
   - Suggested fixes (if any)

We will respond within 48 hours and provide updates on the resolution timeline.

## References

- [OWASP Top 10](https://owasp.org/www-project-top-ten/)
- [NIST Cybersecurity Framework](https://www.nist.gov/cyberframework)
- [Cloud Security Alliance Guidelines](https://cloudsecurityalliance.org/)
- [Zero Trust Architecture](https://www.nist.gov/publications/zero-trust-architecture)
