Security Model

Comprehensive security architecture ensuring zero-trust, policy-driven protection for AI agents.

Table of contents

  1. Overview
    1. Security Principles
  2. Multi-Tier Sandboxing
    1. Tier 1: Docker Isolation
    2. Tier 2: gVisor Isolation
    3. Risk Assessment Algorithm
  3. Policy Engine
    1. Policy Architecture
    2. Policy Types
      1. Access Control Policies
      2. Data Flow Policies
      3. Resource Usage Policies
    3. Policy Evaluation Engine
    4. Performance Optimization
  4. Cryptographic Security
    1. Digital Signatures
    2. Key Management
    3. Encryption Standards
  5. Audit and Compliance
    1. Cryptographic Audit Trail
    2. Hash Chaining
    3. Compliance Features
  6. Tool Security with SchemaPin
    1. Tool Verification Process
    2. Trust-On-First-Use (TOFU)
    3. AI-Driven Tool Review
  7. Network Security
    1. Secure Communication
    2. Network Isolation
  8. Incident Response
    1. Security Event Detection
    2. Incident Response Workflow
    3. Recovery Procedures
  9. Security Best Practices
    1. Development Guidelines
    2. Deployment Security
    3. Operational Security
  10. Security Configuration
    1. Environment Variables
    2. Security Configuration File
  11. Security Metrics
    1. Key Performance Indicators
  12. Future Enhancements
    1. Advanced Cryptography
    2. AI-Enhanced Security
  13. Next Steps

Overview

Symbiont implements a security-first architecture designed for regulated and high-assurance environments. The security model is built on zero-trust principles with comprehensive policy enforcement, multi-tier sandboxing, and cryptographic auditability.

Security Principles

  • Zero Trust: All components and communications are verified
  • Defense in Depth: Multiple security layers with no single point of failure
  • Policy-Driven: Declarative security policies enforced at runtime
  • Complete Auditability: Every operation logged with cryptographic integrity
  • Least Privilege: Minimal permissions required for operation

Multi-Tier Sandboxing

The runtime implements two isolation tiers based on risk assessment:

graph TB
    A[Risk Assessment Engine] --> B{Risk Level}
    
    B -->|Low Risk| C[Tier 1: Docker]
    B -->|Medium/High Risk| D[Tier 2: gVisor]
    
    subgraph "Tier 1: Container Isolation"
        C1[Container Runtime]
        C2[Resource Limits]
        C3[Network Isolation]
        C4[Read-only Filesystem]
    end
    
    subgraph "Tier 2: User-space Kernel"
        D1[System Call Interception]
        D2[Memory Protection]
        D3[I/O Virtualization]
        D4[Enhanced Isolation]
    end
    
    C --> C1
    D --> D1

Note: Additional isolation tiers with hardware virtualization are available in Enterprise editions.

Tier 1: Docker Isolation

Use Cases:

  • Trusted development tasks
  • Low-sensitivity data processing
  • Internal tool operations

Security Features:

docker_security:
  memory_limit: "512MB"
  cpu_limit: "0.5"
  network_mode: "none"
  read_only_root: true
  security_opts:
    - "no-new-privileges:true"
    - "seccomp:default"
  capabilities:
    drop: ["ALL"]
    add: ["SETUID", "SETGID"]

Threat Protection:

  • Process isolation from host
  • Resource exhaustion prevention
  • Network access control
  • Filesystem protection

Tier 2: gVisor Isolation

Use Cases:

  • Standard production workloads
  • Sensitive data processing
  • External tool integration

Security Features:

  • User-space kernel implementation
  • System call filtering and translation
  • Memory protection boundaries
  • I/O request validation

Configuration:

gvisor_security:
  runtime: "runsc"
  platform: "ptrace"
  network: "sandbox"
  file_access: "exclusive"
  debug: false
  strace: false

Advanced Protection:

  • Kernel vulnerability isolation
  • System call interception
  • Memory corruption prevention
  • Side-channel attack mitigation

Enterprise Feature: Advanced isolation with hardware virtualization (Firecracker) is available in Enterprise editions for maximum security requirements.

Risk Assessment Algorithm 

pub struct RiskAssessment {
    data_sensitivity: f32,      // 0.0 = public, 1.0 = top secret
    code_trust_level: f32,      // 0.0 = untrusted, 1.0 = verified
    network_access: bool,       // Requires external network
    filesystem_access: bool,    // Requires filesystem write
    external_apis: bool,        // Uses external services
}

pub fn calculate_risk_score(assessment: RiskAssessment) -> f32 {
    let base_score = assessment.data_sensitivity * 0.4
        + (1.0 - assessment.code_trust_level) * 0.3;
    
    let access_penalty = if assessment.network_access { 0.1 } else { 0.0 }
        + if assessment.filesystem_access { 0.1 } else { 0.0 }
        + if assessment.external_apis { 0.1 } else { 0.0 };
    
    (base_score + access_penalty).min(1.0)
}

Policy Engine

Policy Architecture

The policy engine provides declarative security controls with runtime enforcement:

graph TB
    A[Policy Definition] --> B[Policy Parser]
    B --> C[Policy Store]
    C --> D[Policy Engine]
    D --> E[Enforcement Points]
    
    E --> F[Agent Creation]
    E --> G[Resource Access]
    E --> H[Message Routing]
    E --> I[Tool Invocation]
    E --> J[Data Operations]
    
    K[Audit Logger] --> L[Policy Violations]
    E --> K

Policy Types

Access Control Policies

Define who can access what resources under which conditions:

policy secure_data_access {
    allow: read(sensitive_data) if (
        user.clearance >= "secret" &&
        user.need_to_know.contains(data.classification) &&
        session.mfa_verified == true
    )
    
    deny: export(data) if data.contains_pii == true
    
    require: [
        user.background_check.current,
        session.secure_connection,
        audit_trail = "detailed"
    ]
}

Data Flow Policies

Control how data moves through the system:

policy data_flow_control {
    allow: transform(data) if (
        source.classification <= target.classification &&
        user.transform_permissions.contains(operation.type)
    )
    
    deny: aggregate(datasets) if (
        any(datasets, |d| d.privacy_level > operation.privacy_budget)
    )
    
    require: differential_privacy for statistical_operations
}

Resource Usage Policies

Manage computational resource allocation:

policy resource_governance {
    allow: allocate(resources) if (
        user.resource_quota.remaining >= resources.total &&
        operation.priority <= user.max_priority
    )
    
    deny: long_running_operations if system.maintenance_mode
    
    require: supervisor_approval for high_memory_operations
}

Policy Evaluation Engine 

pub trait PolicyEngine {
    async fn evaluate_policy(
        &self, 
        context: PolicyContext, 
        action: Action
    ) -> PolicyDecision;
    
    async fn register_policy(&self, policy: Policy) -> Result<PolicyId>;
    async fn update_policy(&self, policy_id: PolicyId, policy: Policy) -> Result<()>;
}

pub enum PolicyDecision {
    Allow,
    Deny { reason: String },
    AllowWithConditions { conditions: Vec<PolicyCondition> },
    RequireApproval { approver: String },
}

Performance Optimization

Policy Caching:

  • Compiled policy evaluation for performance
  • LRU cache for frequent decisions
  • Batch evaluation for bulk operations
  • Sub-millisecond evaluation times

Incremental Updates:

  • Real-time policy updates without restart
  • Versioned policy deployment
  • Rollback capabilities for policy errors

Cryptographic Security

Digital Signatures

All security-relevant operations are cryptographically signed:

Signature Algorithm: Ed25519 (RFC 8032)

  • Key Size: 256-bit private keys, 256-bit public keys
  • Signature Size: 512 bits (64 bytes)
  • Performance: 70,000+ signatures/second, 25,000+ verifications/second
pub struct CryptographicSignature {
    pub algorithm: SignatureAlgorithm::Ed25519,
    pub public_key: PublicKey,
    pub signature: [u8; 64],
    pub timestamp: SystemTime,
}

impl AuditEvent {
    pub fn sign(&mut self, private_key: &PrivateKey) -> Result<()> {
        let message = self.serialize_for_signing()?;
        self.signature = private_key.sign(&message);
        Ok(())
    }
    
    pub fn verify(&self, public_key: &PublicKey) -> bool {
        let message = self.serialize_for_signing().unwrap();
        public_key.verify(&message, &self.signature)
    }
}

Key Management

Key Storage:

  • Hardware Security Module (HSM) integration
  • Secure enclave support for key protection
  • Key rotation with configurable intervals
  • Distributed key backup and recovery

Key Hierarchy:

  • Root signing keys for system operations
  • Per-agent keys for operation signing
  • Ephemeral keys for session encryption
  • External keys for tool verification
pub struct KeyManager {
    hsm: HardwareSecurityModule,
    key_store: SecureKeyStore,
    rotation_policy: KeyRotationPolicy,
}

impl KeyManager {
    pub async fn generate_agent_keys(&self, agent_id: AgentId) -> Result<KeyPair>;
    pub async fn rotate_keys(&self, key_id: KeyId) -> Result<KeyPair>;
    pub async fn revoke_key(&self, key_id: KeyId) -> Result<()>;
}

Encryption Standards

Symmetric Encryption: AES-256-GCM

  • 256-bit keys with authenticated encryption
  • Unique nonces for each encryption operation
  • Associated data for context binding

Asymmetric Encryption: X25519 + ChaCha20-Poly1305

  • Elliptic curve key exchange
  • Stream cipher with authenticated encryption
  • Perfect forward secrecy

Message Encryption:

pub fn encrypt_message(
    plaintext: &[u8], 
    recipient_public_key: &PublicKey,
    sender_private_key: &PrivateKey
) -> Result<EncryptedMessage> {
    let shared_secret = sender_private_key.diffie_hellman(recipient_public_key);
    let nonce = generate_random_nonce();
    let ciphertext = ChaCha20Poly1305::new(&shared_secret)
        .encrypt(&nonce, plaintext)?;
    
    Ok(EncryptedMessage {
        nonce,
        ciphertext,
        sender_public_key: sender_private_key.public_key(),
    })
}

Audit and Compliance

Cryptographic Audit Trail

Every security-relevant operation generates an immutable audit event:

pub struct AuditEvent {
    pub event_id: Uuid,
    pub timestamp: SystemTime,
    pub agent_id: AgentId,
    pub event_type: AuditEventType,
    pub details: serde_json::Value,
    pub signature: Ed25519Signature,
    pub previous_hash: Hash,
    pub event_hash: Hash,
}

Audit Event Types:

  • Agent lifecycle events (creation, termination)
  • Policy evaluation decisions
  • Resource allocation and usage
  • Message sending and routing
  • External tool invocations
  • Security violations and alerts

Hash Chaining

Events are linked in an immutable chain:

impl AuditChain {
    pub fn append_event(&mut self, mut event: AuditEvent) -> Result<()> {
        event.previous_hash = self.last_hash;
        event.event_hash = self.calculate_event_hash(&event);
        event.sign(&self.signing_key)?;
        
        self.events.push(event.clone());
        self.last_hash = event.event_hash;
        
        self.verify_chain_integrity()?;
        Ok(())
    }
    
    pub fn verify_integrity(&self) -> Result<bool> {
        for (i, event) in self.events.iter().enumerate() {
            // Verify signature
            if !event.verify(&self.public_key) {
                return Ok(false);
            }
            
            // Verify hash chain
            if i > 0 && event.previous_hash != self.events[i-1].event_hash {
                return Ok(false);
            }
        }
        Ok(true)
    }
}

Compliance Features

Regulatory Support:

HIPAA (Healthcare):

  • PHI access logging with user identification
  • Data minimization enforcement
  • Breach detection and notification
  • Audit trail retention for 6 years

GDPR (Privacy):

  • Personal data processing logs
  • Consent verification tracking
  • Data subject rights enforcement
  • Data retention policy compliance

SOX (Financial):

  • Internal control documentation
  • Change management tracking
  • Access control verification
  • Financial data protection

Custom Compliance:

pub struct ComplianceFramework {
    pub name: String,
    pub audit_requirements: Vec<AuditRequirement>,
    pub retention_policy: RetentionPolicy,
    pub access_controls: Vec<AccessControl>,
    pub data_protection: DataProtectionRules,
}

impl ComplianceFramework {
    pub fn validate_compliance(&self, audit_trail: &AuditChain) -> ComplianceReport;
    pub fn generate_compliance_report(&self, period: TimePeriod) -> Report;
}

Tool Security with SchemaPin

Tool Verification Process

External tools are verified using cryptographic signatures:

sequenceDiagram
    participant Tool as Tool Provider
    participant SP as SchemaPin
    participant AI as AI Reviewer
    participant Runtime as Symbiont Runtime
    participant Agent as Agent
    
    Tool->>SP: Submit Tool Schema
    SP->>AI: Security Analysis
    AI-->>SP: Analysis Results
    SP->>SP: Human Review (if needed)
    SP->>SP: Sign Schema
    SP-->>Tool: Signed Schema
    
    Agent->>Runtime: Request Tool Use
    Runtime->>SP: Verify Tool Schema
    SP-->>Runtime: Verification Result
    Runtime-->>Agent: Allow/Deny Tool Use

Trust-On-First-Use (TOFU)

Key Pinning Process:

  1. First encounter with a tool provider
  2. Verify provider’s public key through external channels
  3. Pin the public key in local trust store
  4. Use pinned key for all future verifications
pub struct TOFUKeyStore {
    pinned_keys: HashMap<ProviderId, PinnedKey>,
    trust_policies: Vec<TrustPolicy>,
}

impl TOFUKeyStore {
    pub async fn pin_key(&mut self, provider: ProviderId, key: PublicKey) -> Result<()> {
        if self.pinned_keys.contains_key(&provider) {
            return Err("Key already pinned for provider");
        }
        
        self.pinned_keys.insert(provider, PinnedKey {
            public_key: key,
            pinned_at: SystemTime::now(),
            trust_level: TrustLevel::Unverified,
        });
        
        Ok(())
    }
    
    pub fn verify_tool(&self, tool: &MCPTool) -> VerificationResult {
        if let Some(pinned_key) = self.pinned_keys.get(&tool.provider_id) {
            if pinned_key.public_key.verify(&tool.schema_hash, &tool.signature) {
                VerificationResult::Trusted
            } else {
                VerificationResult::SignatureInvalid
            }
        } else {
            VerificationResult::UnknownProvider
        }
    }
}

AI-Driven Tool Review

Automated security analysis before tool approval:

Analysis Components:

  • Vulnerability Detection: Pattern matching against known vulnerability signatures
  • Malicious Code Detection: ML-based malicious behavior identification
  • Resource Usage Analysis: Assessment of computational resource requirements
  • Privacy Impact Assessment: Data handling and privacy implications
pub struct SecurityAnalyzer {
    vulnerability_patterns: VulnerabilityDatabase,
    ml_detector: MaliciousCodeDetector,
    resource_analyzer: ResourceAnalyzer,
    privacy_assessor: PrivacyAssessor,
}

impl SecurityAnalyzer {
    pub async fn analyze_tool(&self, tool: &MCPTool) -> SecurityAnalysis {
        let mut findings = Vec::new();
        
        // Vulnerability pattern matching
        findings.extend(self.vulnerability_patterns.scan(&tool.schema));
        
        // ML-based detection
        let ml_result = self.ml_detector.analyze(&tool.schema).await?;
        findings.extend(ml_result.findings);
        
        // Resource usage analysis
        let resource_risk = self.resource_analyzer.assess(&tool.schema);
        
        // Privacy impact assessment
        let privacy_impact = self.privacy_assessor.evaluate(&tool.schema);
        
        SecurityAnalysis {
            tool_id: tool.id.clone(),
            risk_score: calculate_risk_score(&findings),
            findings,
            resource_requirements: resource_risk,
            privacy_impact,
            recommendation: self.generate_recommendation(&findings),
        }
    }
}

Network Security

Secure Communication

Transport Layer Security:

  • TLS 1.3 for all external communications
  • Mutual TLS (mTLS) for service-to-service communication
  • Certificate pinning for known services
  • Perfect forward secrecy

Message-Level Security:

  • End-to-end encryption for agent messages
  • Message authentication codes (MAC)
  • Replay attack prevention with timestamps
  • Message ordering guarantees
pub struct SecureChannel {
    encryption_key: [u8; 32],
    mac_key: [u8; 32],
    send_counter: AtomicU64,
    recv_counter: AtomicU64,
}

impl SecureChannel {
    pub fn encrypt_message(&self, plaintext: &[u8]) -> Result<Vec<u8>> {
        let counter = self.send_counter.fetch_add(1, Ordering::SeqCst);
        let nonce = self.generate_nonce(counter);
        
        let ciphertext = ChaCha20Poly1305::new(&self.encryption_key)
            .encrypt(&nonce, plaintext)?;
        
        let mac = Hmac::<Sha256>::new_from_slice(&self.mac_key)?
            .chain_update(&ciphertext)
            .chain_update(&counter.to_le_bytes())
            .finalize()
            .into_bytes();
        
        Ok([ciphertext, mac.to_vec()].concat())
    }
}

Network Isolation

Sandbox Network Control:

  • No network access by default
  • Explicit allow-list for external connections
  • Traffic monitoring and anomaly detection
  • DNS filtering and validation

Network Policies:

network_policy:
  default_action: "deny"
  allowed_destinations:
    - domain: "api.openai.com"
      ports: [443]
      protocol: "https"
    - ip_range: "10.0.0.0/8"
      ports: [6333]  # Qdrant
      protocol: "http"
  
  monitoring:
    log_all_connections: true
    detect_anomalies: true
    rate_limiting: true

Incident Response

Security Event Detection

Automated Detection:

  • Policy violation monitoring
  • Anomalous behavior detection
  • Resource usage anomalies
  • Failed authentication tracking

Alert Classification:

pub enum SecurityEventSeverity {
    Info,       // Normal security events
    Low,        // Minor policy violations
    Medium,     // Suspicious behavior
    High,       // Confirmed security issues
    Critical,   // Active security breaches
}

pub struct SecurityEvent {
    pub id: Uuid,
    pub timestamp: SystemTime,
    pub severity: SecurityEventSeverity,
    pub category: SecurityEventCategory,
    pub description: String,
    pub affected_components: Vec<ComponentId>,
    pub recommended_actions: Vec<String>,
}

Incident Response Workflow 

graph TB
    A[Security Event] --> B[Event Classification]
    B --> C{Severity Level}
    
    C -->|Info/Low| D[Log Event]
    C -->|Medium| E[Alert Security Team]
    C -->|High| F[Automatic Mitigation]
    C -->|Critical| G[Emergency Response]
    
    F --> H[Isolate Affected Components]
    F --> I[Revoke Compromised Credentials]
    F --> J[Preserve Evidence]
    
    G --> H
    G --> K[Notify Leadership]
    G --> L[External Incident Response]

Recovery Procedures

Automated Recovery:

  • Agent restart with clean state
  • Key rotation for compromised credentials
  • Policy updates to prevent recurrence
  • System health verification

Manual Recovery:

  • Forensic analysis of security events
  • Root cause analysis and remediation
  • Security control updates
  • Incident documentation and lessons learned

Security Best Practices

Development Guidelines

  1. Secure by Default: All security features enabled by default
  2. Principle of Least Privilege: Minimal permissions for all operations
  3. Defense in Depth: Multiple security layers with redundancy
  4. Fail Securely: Security failures should deny access, not grant it
  5. Audit Everything: Complete logging of security-relevant operations

Deployment Security

Environment Hardening:

# Disable unnecessary services
systemctl disable cups bluetooth

# Kernel hardening
echo "kernel.dmesg_restrict=1" >> /etc/sysctl.conf
echo "kernel.kptr_restrict=2" >> /etc/sysctl.conf

# File system security
mount -o remount,nodev,nosuid,noexec /tmp

Container Security:

# Use minimal base image
FROM scratch
COPY --from=builder /app/symbiont /bin/symbiont

# Run as non-root user
USER 1000:1000

# Set security options
LABEL security.no-new-privileges=true

Operational Security

Monitoring Checklist:

  • Real-time security event monitoring
  • Policy violation tracking
  • Resource usage anomaly detection
  • Failed authentication monitoring
  • Certificate expiration tracking

Maintenance Procedures:

  • Regular security updates and patches
  • Key rotation on schedule
  • Policy review and updates
  • Security audit and penetration testing
  • Incident response plan testing

Security Configuration

Environment Variables 

# Cryptographic settings
export SYMBIONT_CRYPTO_PROVIDER=ring
export SYMBIONT_KEY_STORE_TYPE=hsm
export SYMBIONT_HSM_CONFIG_PATH=/etc/symbiont/hsm.conf

# Audit settings
export SYMBIONT_AUDIT_ENABLED=true
export SYMBIONT_AUDIT_STORAGE=/var/audit/symbiont
export SYMBIONT_AUDIT_RETENTION_DAYS=2555  # 7 years

# Security policies
export SYMBIONT_POLICY_ENFORCEMENT=strict
export SYMBIONT_DEFAULT_SANDBOX_TIER=gvisor
export SYMBIONT_TOFU_ENABLED=true

Security Configuration File 

[security]
# Cryptographic settings
crypto_provider = "ring"
signature_algorithm = "ed25519"
encryption_algorithm = "chacha20_poly1305"

# Key management
key_rotation_interval_days = 90
hsm_enabled = true
hsm_config_path = "/etc/symbiont/hsm.conf"

# Audit settings
audit_enabled = true
audit_storage_path = "/var/audit/symbiont"
audit_retention_days = 2555
audit_compression = true

# Sandbox security
default_sandbox_tier = "gvisor"
sandbox_escape_detection = true
resource_limit_enforcement = "strict"

# Network security
tls_min_version = "1.3"
certificate_pinning = true
network_isolation = true

# Policy enforcement
policy_enforcement_mode = "strict"
policy_violation_action = "deny_and_alert"
emergency_override_enabled = false

[tofu]
enabled = true
key_verification_required = true
trust_on_first_use_timeout_hours = 24
automatic_key_pinning = false

Security Metrics

Key Performance Indicators

Security Operations:

  • Policy evaluation latency: <1ms average
  • Audit event generation rate: 10,000+ events/second
  • Security incident response time: <5 minutes
  • Cryptographic operation throughput: 70,000+ ops/second

Compliance Metrics:

  • Policy compliance rate: >99.9%
  • Audit trail integrity: 100%
  • Security event false positive rate: <1%
  • Incident resolution time: <24 hours

Risk Assessment:

  • Vulnerability patching time: <48 hours
  • Security control effectiveness: >95%
  • Threat detection accuracy: >99%
  • Recovery time objective: <1 hour

Future Enhancements

Advanced Cryptography

Post-Quantum Cryptography:

  • NIST-approved post-quantum algorithms
  • Hybrid classical/post-quantum schemes
  • Migration planning for quantum threats

Homomorphic Encryption:

  • Privacy-preserving computation on encrypted data
  • CKKS scheme for approximate arithmetic
  • Integration with machine learning workflows

Zero-Knowledge Proofs:

  • zk-SNARKs for computation verification
  • Privacy-preserving authentication
  • Compliance proof generation

AI-Enhanced Security

Behavior Analysis:

  • Machine learning for anomaly detection
  • Predictive security analytics
  • Adaptive threat response

Automated Response:

  • Self-healing security controls
  • Dynamic policy generation
  • Intelligent incident classification

Next Steps

The Symbiont security model provides enterprise-grade protection suitable for regulated industries and high-assurance environments. Its layered approach ensures robust protection against evolving threats while maintaining operational efficiency.