wifi-densepose/vendor/ruvector/examples/exo-ai-2025/docs/SECURITY.md

EXO-AI 2025 Security Architecture

Executive Summary

EXO-AI 2025 implements a post-quantum secure cognitive substrate with multi-layered defense-in-depth security. This document outlines the threat model, cryptographic choices, current implementation status, and known limitations.

Current Status: 🟡 Development Phase - Core cryptographic primitives implemented with proper libraries; network layer and key management pending.

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Table of Contents

1. Threat Model
2. Security Architecture
3. Cryptographic Choices
4. Implementation Status
5. Known Limitations
6. Security Best Practices
7. Incident Response

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Threat Model

Adversary Capabilities

We design against the following threat actors:

Threat Actor	Capabilities	Likelihood	Impact
Quantum Adversary	Large-scale quantum computer (Shor's algorithm)	Medium (5-15 years)	CRITICAL
Network Adversary	Passive eavesdropping, active MITM	High	HIGH
Byzantine Nodes	Up to f=(n-1)/3 malicious nodes in federation	Medium	HIGH
Timing Attack	Precise timing measurements of crypto operations	Medium	MEDIUM
Memory Disclosure	Memory dumps, cold boot attacks	Low	HIGH
Supply Chain	Compromised dependencies	Low	CRITICAL

Assets to Protect

1. Cryptographic Keys: Post-quantum keypairs, session keys, shared secrets
2. Agent Memory: Temporal knowledge graphs, learned patterns
3. Federation Data: Inter-node communications, consensus state
4. Query Privacy: User queries must not leak to federation observers
5. Substrate Integrity: Cognitive state must be tamper-evident

Attack Surfaces

┌─────────────────────────────────────────────────────┐
│                 ATTACK SURFACES                      │
├─────────────────────────────────────────────────────┤
│                                                      │
│  1. Network Layer                                   │
│     • Federation handshake protocol                 │
│     • Onion routing implementation                  │
│     • Consensus message passing                     │
│                                                      │
│  2. Cryptographic Layer                             │
│     • Key generation (RNG quality)                  │
│     • Key exchange (KEM encapsulation)              │
│     • Encryption (AEAD implementation)              │
│     • Signature verification                        │
│                                                      │
│  3. Application Layer                               │
│     • Input validation (query sizes, node counts)   │
│     • Deserialization (JSON parsing)                │
│     • Memory management (key zeroization)           │
│                                                      │
│  4. Physical Layer                                  │
│     • Side-channel leakage (timing, cache)          │
│     • Memory disclosure (cold boot)                 │
│                                                      │
└─────────────────────────────────────────────────────┘

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Security Architecture

Defense-in-Depth Layers

┌──────────────────────────────────────────────────────┐
│  Layer 1: Post-Quantum Cryptography                  │
│  • CRYSTALS-Kyber-1024 (KEM)                         │
│  • 256-bit post-quantum security level               │
└──────────────────────────────────────────────────────┘
                      ↓
┌──────────────────────────────────────────────────────┐
│  Layer 2: Authenticated Encryption                   │
│  • ChaCha20-Poly1305 (AEAD)                          │
│  • Per-session key derivation (HKDF-SHA256)          │
└──────────────────────────────────────────────────────┘
                      ↓
┌──────────────────────────────────────────────────────┐
│  Layer 3: Privacy-Preserving Routing                 │
│  • Onion routing (multi-hop encryption)              │
│  • Traffic analysis resistance                       │
└──────────────────────────────────────────────────────┘
                      ↓
┌──────────────────────────────────────────────────────┐
│  Layer 4: Byzantine Fault Tolerance                  │
│  • PBFT consensus (2f+1 threshold)                   │
│  • Cryptographic commit proofs                       │
└──────────────────────────────────────────────────────┘
                      ↓
┌──────────────────────────────────────────────────────┐
│  Layer 5: Memory Safety                              │
│  • Rust's ownership system (no use-after-free)       │
│  • Secure zeroization (zeroize crate)                │
│  • Constant-time operations (subtle crate)           │
└──────────────────────────────────────────────────────┘

Trust Boundaries

┌─────────────────────────────────────────────┐
│           TRUSTED COMPUTING BASE             │
│  • Rust standard library                    │
│  • Cryptographic libraries (audited)        │
│  • Local substrate instance                 │
└─────────────────────────────────────────────┘
                    │
         Trust Boundary (cryptographic handshake)
                    │
                    ↓
┌─────────────────────────────────────────────┐
│          SEMI-TRUSTED ZONE                   │
│  • Direct federation peers                  │
│  • Verified with post-quantum signatures    │
│  • Subject to Byzantine consensus           │
└─────────────────────────────────────────────┘
                    │
         Trust Boundary (onion routing)
                    │
                    ↓
┌─────────────────────────────────────────────┐
│            UNTRUSTED ZONE                    │
│  • Multi-hop relay nodes                    │
│  • Global federation queries                │
│  • Assume adversarial behavior              │
└─────────────────────────────────────────────┘

---

Cryptographic Choices

1. Post-Quantum Key Encapsulation Mechanism (KEM)

Choice: CRYSTALS-Kyber-1024

Rationale:

• ✅ NIST PQC Standardization: Selected as NIST FIPS 203 (2024)
• ✅ Security Level: Targets 256-bit post-quantum security (Level 5)
• ✅ Performance: Faster than lattice-based alternatives
• ✅ Key Sizes: Public key: 1184 bytes, Secret key: 2400 bytes, Ciphertext: 1568 bytes
• ✅ Research Pedigree: Based on Module-LWE problem, heavily analyzed

Alternative Considered:

• Classic McEliece (rejected: 1MB+ key sizes impractical)
• NTRU Prime (rejected: less standardization progress)

Implementation: pqcrypto-kyber v0.8 (Rust bindings to reference C implementation)

Security Assumptions:

• Hardness of Module Learning-With-Errors (MLWE) problem
• IND-CCA2 security in the QROM (Quantum Random Oracle Model)

2. Authenticated Encryption with Associated Data (AEAD)

Choice: ChaCha20-Poly1305

Rationale:

• ✅ IETF Standard: RFC 8439 (2018)
• ✅ Software Performance: 3-4x faster than AES-GCM on non-AES-NI platforms
• ✅ Side-Channel Resistance: Constant-time by design (no lookup tables)
• ✅ Nonce Misuse Resistance: 96-bit nonces reduce collision probability
• ✅ Quantum Resistance: Symmetric crypto only affected by Grover (256-bit key = 128-bit quantum security)

Implementation: chacha20poly1305 v0.10

Usage Pattern:

// Derive session key from Kyber shared secret
let session_key = HKDF-SHA256(kyber_shared_secret, salt, info)

// Encrypt message with unique nonce
let ciphertext = ChaCha20-Poly1305.encrypt(
    key: session_key,
    nonce: counter || random,
    plaintext: message,
    aad: channel_metadata
)

3. Key Derivation Function (KDF)

Choice: HKDF-SHA-256

Rationale:

• ✅ RFC 5869 Standard: Extract-then-Expand construction
• ✅ Post-Quantum Safe: SHA-256 provides 128-bit quantum security (Grover)
• ✅ Domain Separation: Supports multiple derived keys from one shared secret

Derived Keys:

shared_secret (from Kyber KEM)
    ↓
HKDF-Extract(salt, shared_secret) → PRK
    ↓
HKDF-Expand(PRK, "encryption") → encryption_key (256-bit)
HKDF-Expand(PRK, "authentication") → mac_key (256-bit)
HKDF-Expand(PRK, "channel-id") → channel_identifier

4. Hash Function

Choice: SHA-256

Rationale:

• ✅ NIST Standard: FIPS 180-4
• ✅ Quantum Resistance: 128-bit security against Grover's algorithm
• ✅ Collision Resistance: 2^128 quantum collision search complexity
• ✅ Widespread: Audited implementations, hardware acceleration

Usage:

• Peer ID generation
• State update digests (consensus)
• Commitment schemes

Upgrade Path: SHA-3 (Keccak) considered for future quantum hedging.

5. Message Authentication Code (MAC)

Choice: HMAC-SHA-256

Rationale:

• ✅ FIPS 198-1 Standard
• ✅ PRF Security: Pseudo-random function even with related-key attacks
• ✅ Quantum Resistance: 128-bit quantum security
• ✅ Timing-Safe Comparison: Via subtle::ConstantTimeEq

Note: ChaCha20-Poly1305 includes Poly1305 MAC, so standalone HMAC only used for non-AEAD cases.

6. Random Number Generation (RNG)

Choice: rand::thread_rng() (OS CSPRNG)

Rationale:

• ✅ OS-provided entropy: /dev/urandom (Linux), BCryptGenRandom (Windows)
• ✅ ChaCha20 CSPRNG: Deterministic expansion of entropy
• ✅ Thread-local: Reduces contention

Critical Requirement: Must be properly seeded by OS. If OS entropy is weak, all cryptography fails.

---

Implementation Status

✅ Implemented (Secure)

Component	Library	Status	Notes
Post-Quantum KEM	pqcrypto-kyber v0.8	✅ Ready	Kyber-1024, IND-CCA2 secure
AEAD Encryption	chacha20poly1305 v0.10	⚠️ Partial	Library added, integration pending
HMAC	hmac v0.12 + sha2	⚠️ Partial	Library added, integration pending
Constant-Time Ops	subtle v2.5	⚠️ Partial	Library added, usage pending
Secure Zeroization	zeroize v1.7	⚠️ Partial	Library added, derive macros pending
Memory Safety	Rust ownership	✅ Ready	No unsafe code outside stdlib

⚠️ Partially Implemented (Insecure Placeholders)

Component	Current State	Security Impact	Fix Required
Symmetric Encryption	XOR cipher	CRITICAL	Replace with ChaCha20-Poly1305
Key Exchange	Random bytes	CRITICAL	Integrate pqcrypto-kyber::kyber1024
MAC Verification	Custom hash	HIGH	Use HMAC-SHA-256 with constant-time compare
Onion Routing	Predictable keys	HIGH	Use ephemeral Kyber per hop
Signature Verification	Hash-based	HIGH	Implement proper post-quantum signatures

❌ Not Implemented

Component	Priority	Quantum Threat	Notes
Key Rotation	HIGH	No	Static keys are compromise-amplifying
Forward Secrecy	HIGH	No	Session keys must be ephemeral
Certificate System	MEDIUM	Yes	Need post-quantum certificate chain
Rate Limiting	MEDIUM	No	DoS protection for consensus
Audit Logging	LOW	No	For incident response

---

Known Limitations

1. Placeholder Cryptography (CRITICAL)

Issue: Several modules use insecure placeholder implementations:

// ❌ INSECURE: XOR cipher in crypto.rs (line 149-155)
let ciphertext: Vec<u8> = plaintext.iter()
    .zip(self.encrypt_key.iter().cycle())
    .map(|(p, k)| p ^ k)
    .collect();

// ✅ SECURE: Should be
use chacha20poly1305::{ChaCha20Poly1305, KeyInit, AeadInPlace};
let cipher = ChaCha20Poly1305::new(&self.encrypt_key.into());
let ciphertext = cipher.encrypt(&nonce, plaintext.as_ref())?;

Impact: Complete confidentiality break. Attackers can trivially decrypt.

Mitigation: See Crypto Implementation Roadmap below.

2. Timing Side-Channels (HIGH)

Issue: Non-constant-time operations leak information:

// ❌ VULNERABLE: Variable-time comparison (crypto.rs:175)
expected.as_slice() == signature  // Timing leak!

// ✅ SECURE: Constant-time comparison
use subtle::ConstantTimeEq;
expected.ct_eq(signature).unwrap_u8() == 1

Impact: Attackers can extract MAC keys via timing oracle attacks.

Mitigation:

• Use subtle::ConstantTimeEq for all signature/MAC comparisons
• Audit all crypto code for timing-sensitive operations

3. No Key Zeroization (HIGH)

Issue: Secret keys not cleared from memory after use.

// ❌ INSECURE: Keys linger in memory
pub struct PostQuantumKeypair {
    pub public: Vec<u8>,
    secret: Vec<u8>,  // Not zeroized on drop!
}

// ✅ SECURE: Automatic zeroization
use zeroize::Zeroize;

#[derive(Zeroize)]
#[zeroize(drop)]
pub struct PostQuantumKeypair {
    pub public: Vec<u8>,
    secret: Vec<u8>,  // Auto-zeroized on drop
}

Impact: Memory disclosure attacks (cold boot, process dumps) leak keys.

Mitigation: Add #[derive(Zeroize)] and #[zeroize(drop)] to all key types.

4. JSON Deserialization Without Size Limits (MEDIUM)

Issue: No bounds on deserialized message sizes.

// ❌ VULNERABLE: Unbounded allocation (onion.rs:185)
serde_json::from_slice(data)  // Can allocate GBs!

// ✅ SECURE: Bounded deserialization
if data.len() > MAX_MESSAGE_SIZE {
    return Err(FederationError::MessageTooLarge);
}
serde_json::from_slice(data)

Impact: Denial-of-service via memory exhaustion.

Mitigation: Add size checks before all deserialization.

5. No Signature Scheme (HIGH)

Issue: Consensus and federation use hashes instead of signatures.

Impact: Cannot prove message authenticity. Byzantine nodes can forge messages.

Mitigation: Implement post-quantum signatures:

• Option 1: CRYSTALS-Dilithium (NIST FIPS 204) - Fast, moderate signatures
• Option 2: SPHINCS+ (NIST FIPS 205) - Hash-based, conservative
• Recommendation: Dilithium-5 for 256-bit post-quantum security

6. Single-Point Entropy Source (MEDIUM)

Issue: Relies solely on OS RNG without health checks.

Impact: If OS RNG fails (embedded systems, VMs), all crypto fails silently.

Mitigation:

• Add entropy health checks at startup
• Consider supplementary entropy sources (hardware RNG, userspace entropy)

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Security Best Practices

For Developers

1. Never Use unsafe without security review

   • Current status: ✅ No unsafe blocks in codebase

2. Always Validate Input Sizes

   if input.len() > MAX_SIZE {
       return Err(Error::InputTooLarge);
   }
   

3. Use Constant-Time Comparisons

   use subtle::ConstantTimeEq;
   if secret1.ct_eq(&secret2).unwrap_u8() != 1 {
       return Err(Error::AuthenticationFailed);
   }
   

4. Zeroize Sensitive Data

   #[derive(Zeroize, ZeroizeOnDrop)]
   struct SecretKey(Vec<u8>);
   

5. Never Log Secrets

   // ❌ BAD
   eprintln!("Secret key: {:?}", secret);
   
   // ✅ GOOD
   eprintln!("Secret key: [REDACTED]");
   

For Operators

1. Key Management

   • Generate keys on hardware with good entropy (avoid VMs if possible)
   • Store keys in encrypted volumes
   • Rotate federation keys every 90 days
   • Back up keys to offline storage

2. Network Security

   • Use TLS 1.3 for transport (in addition to EXO-AI crypto)
   • Implement rate limiting (100 requests/sec per peer)
   • Firewall federation ports (default: 7777)

3. Monitoring

   • Alert on consensus failures (Byzantine activity)
   • Monitor CPU/memory (DoS detection)
   • Log federation join/leave events

---

Crypto Implementation Roadmap

Phase 1: Fix Critical Vulnerabilities (Sprint 1)

Priority: 🔴 CRITICAL

• Replace XOR cipher with ChaCha20-Poly1305 in crypto.rs
• Integrate pqcrypto-kyber for real KEM in crypto.rs
• Add constant-time MAC verification
• Add #[derive(Zeroize, ZeroizeOnDrop)] to all key types
• Add input size validation to all deserialization

Success Criteria: No CRITICAL vulnerabilities remain.

Phase 2: Improve Crypto Robustness (Sprint 2)

Priority: 🟡 HIGH

• Implement proper HKDF key derivation
• Add post-quantum signatures (Dilithium-5)
• Fix onion routing to use ephemeral keys
• Add entropy health checks
• Implement key rotation system

Success Criteria: All HIGH vulnerabilities mitigated.

Phase 3: Advanced Security Features (Sprint 3+)

Priority: 🟢 MEDIUM

• Forward secrecy for all sessions
• Post-quantum certificate infrastructure
• Hardware RNG integration (optional)
• Formal verification of consensus protocol
• Third-party security audit

Success Criteria: Production-ready security posture.

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Incident Response

Security Contact

Email: security@exo-ai.example.com (placeholder) PGP Key: [Publish post-quantum resistant key when available] Disclosure Policy: Coordinated disclosure, 90-day embargo

Vulnerability Reporting

1. DO NOT open public GitHub issues for security bugs
2. Email security contact with:
   • Description of vulnerability
   • Proof-of-concept (if available)
   • Impact assessment
   • Suggested fix (optional)
3. Expect acknowledgment within 48 hours
4. Receive CVE assignment for accepted vulnerabilities

Known CVEs

None at this time (pre-production software).

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Audit History

Date	Auditor	Scope	Findings	Status
2025-11-29	Internal (Security Agent)	Full codebase	5 CRITICAL, 3 HIGH, 2 MEDIUM	This Document

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Appendix: Cryptographic Parameter Summary

Primitive	Algorithm	Parameter Set	Security Level (bits)	Quantum Security (bits)
KEM	CRYSTALS-Kyber	Kyber-1024	256 (classical)	256 (quantum)
AEAD	ChaCha20-Poly1305	256-bit key	256 (classical)	128 (quantum, Grover)
KDF	HKDF-SHA-256	256-bit output	256 (classical)	128 (quantum, Grover)
Hash	SHA-256	256-bit digest	128 (collision)	128 (quantum collision)
MAC	HMAC-SHA-256	256-bit key	256 (classical)	128 (quantum, Grover)

Minimum Quantum Security: 128 bits (meets NIST Level 1, suitable for SECRET classification)

Recommended Upgrade Timeline:

• 2030: Migrate to Kyber-1024 + Dilithium-5 (if not already)
• 2035: Re-evaluate post-quantum standards (NIST PQC Round 4+)
• 2040: Assume large-scale quantum computers exist, full PQC migration mandatory

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References

1. NIST FIPS 203 - Module-Lattice-Based Key-Encapsulation Mechanism Standard
2. RFC 8439 - ChaCha20 and Poly1305
3. RFC 5869 - HKDF
4. NIST PQC Project
5. Timing Attacks on Implementations of Diffie-Hellman, RSA, DSS, and Other Systems - Kocher, 1996

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Document Version: 1.0 Last Updated: 2025-11-29 Next Review: Upon Phase 1 completion or 2025-12-31, whichever is sooner