Section 3: Core Cryptographic Protocols

1. Overview & Scope

This document establishes the mandatory cryptographic baseline for all Aevum Zenth operations. The protocol suite is engineered for:

• Cross-divisional interoperability: Seamless secure communication between Energy, Aerospace, Healthcare, Finance, and all subsidiary networks.
• Post-quantum resilience: Hybrid classical/quantum-safe algorithms deployed ahead of NIST PQC standardization deadlines.
• Hardware-enforced trust: FIPS 140-3 Level 4 / CAVP certified HSM integration for all root key operations.
• Automated lifecycle management: Zero-touch key rotation, revocation, and audit logging at scale.

2. Core Protocol Suite

All systems must implement the following cryptographic primitives. Legacy algorithms (RSA-2048, SHA-1, AES-CBC) are deprecated as of Q1 2026.

3. Key Management Architecture

3.1 Hierarchical Key Structure

Aevum Zenth utilizes a sharded, threshold-protected key hierarchy to eliminate single points of compromise:

1. Root Key (RK): Generated offline in AZ-HSM-01 vaults. Split via Shamir's Secret Sharing (5/9 threshold). Never leaves secure enclaves.
2. Division Master Keys (DMK): Derived per subsidiary. Rotated every 90 days. Stored in FIPS 140-3 Level 3 HSMs.
3. Service Keys (SK): Application-level keys. Rotated automatically every 24 hours via AZ-KMS API.
4. Data Keys (DK): Ephemeral session keys. Never transmitted in plaintext. Encrypted with SK before storage.

3.2 Automated Rotation & Revocation

# Key Management Service Configuration
az_kms:
  rotation_policy:
    service_keys: 24h
    division_master: 90d
    grace_period: 15m
  threshold_cryptography:
    shamir_split: 9
    shamir_threshold: 5
    geographic_shards:
      - neo-geneva
      - new-york
      - london
      - tokyo
      - singapore
  quantum_backup:
    enabled: true
    algorithm: Kyber1024
    storage: cold-hsm-offsite

4. Implementation Guidelines

All development teams must utilize the official az-crypto-sdk (v4.x+). Direct cryptographic primitive usage is prohibited.

use az_crypto_sdk::prelude::*;
use az_crypto_sdk::kex::HybridKEM;
use az_crypto_sdk::enc::Aes256Gcm;

// Initialize hybrid key exchange (X25519-Kyber768)
let kex = HybridKEM::new(Algorithm::AZ_KEX_01);
let (shared_secret, ciphertext) = kex.encrypt(peer_pubkey).expect("KEX failed");

// Derive data encryption key via HKDF
let dek = Hkdf::derive(
    &shared_secret,
    ["azenth::data-key"].concat(),
    &context_info
);

// Encrypt payload with AES-256-GCM
let cipher = Aes256Gcm::encrypt(dek, plaintext, nonce).expect("Enc failed");
log::info("Secure payload generated. Tag: {:?}", cipher.tag);

5. Security Model & Threat Mitigation

The cryptographic suite is designed to withstand the following threat vectors:

• Quantum Decryption Attacks: Mitigated via hybrid X25519-Kyber768 and Dilithium3 signatures. Classical and quantum components must both be compromised for data exposure.
• Side-Channel Attacks: All SDK implementations use constant-time operations, masking, and hardware-level cache isolation. HSMs provide physical tamper resistance.
• Key Compromise: Threshold cryptography ensures no single node holds reconstructible root keys. Compromised shards trigger automatic revocation and re-distribution.
• Replay & MitM: Enforced via sequence number binding, channel IDs, and mutual TLS 1.3 with certificate pinning at the device level.

6. Compliance & Auditing

Implementation must align with the following regulatory and internal frameworks:

7. Appendix & References

Parameter Registry

• AZ-KEX-01: X25519 (RFC 7748) + Kyber768 (ML-KEM-768)
• AZ-SIG-01: Ed25519 (RFC 8032) + Dilithium3 (ML-DSA-65)
• AZ-ZKP-01: AZ-Plonk v2 optimized for BN254 curve, ~12k gate circuit limit
• AZ-HASH-01: SHA3-256 (FIPS 202) for compliance, Blake3 for performance-critical paths

Change Log