Multi-Layer Security — Defense in Depth at Every Layer

Nine Layers of Security

Each layer defends independently — an attacker must break all nine to compromise the system, and breaking even one is designed to be computationally infeasible

• Layer 1 — 90%+ Byzantine Tolerance: ARCH consensus tolerates over 90% malicious nodes, far exceeding the traditional 33% BFT threshold. Even if the vast majority of the network is compromised, the honest minority prevails. This is not a theoretical improvement — it is a fundamental redesign of consensus security.
• Layer 2 — Per-Field AES-256-GCM Encryption: data is not encrypted at the record or table level — it is encrypted at the individual field level. A medical record can have the patient name encrypted for doctors only, the billing code encrypted for insurers only, and the diagnosis encrypted for the patient only. Granularity that no other blockchain offers.
• Layer 3 — On-Chain Schema Validation: every transaction is validated against its schema before acceptance. Invalid data structures are rejected at the protocol level, not at the application level. This eliminates entire classes of injection attacks, malformed data exploits, and type confusion vulnerabilities.
• Layer 4 — Protocol-Level RBAC (16 Roles, 5 Effects): role-based access control is not a smart contract library — it is built into the protocol itself. 16 fine-grained roles with 5 permission effects (allow, deny, inherit, delegate, revoke) govern every operation. Unauthorized actions are rejected before they reach the execution layer.
• Layer 5 — Proof of Identity for Sybil Resistance: decentralized identity with crypto-biometric authentication (Face ID, fingerprint, hardware devices) ensures unique person identification, preventing a single attacker from creating multiple identities to game consensus, voting, or reputation systems. Self-sovereign identity — enforced cryptographically, no third-party dependency.
• Layer 6 — FHE Threshold Decryption: sensitive data encrypted with Fully Homomorphic Encryption can only be decrypted when a threshold of authorized parties cooperate. No single node, no single admin, no single government agency can unilaterally access encrypted data. Mathematically enforced separation of power.
• Layer 7 — Forward Secrecy (Auto Key Rotation): cryptographic keys are automatically rotated on a schedule. Compromising a current key does not reveal past communications — each session uses ephemeral keys derived from the rotation schedule. Yesterday's data remains safe even if today's key is stolen.
• Layer 8 — Post-Quantum (Falcon-512): Falcon-512 lattice-based signatures are resistant to quantum computer attacks. Combined with the next-key-hash disclosure mechanism, the network is quantum-safe today — not as a future upgrade, but as a current production feature.
• Layer 9 — Self-Healing Network: the network automatically detects and isolates compromised or malfunctioning nodes. Consensus continues without disruption, data is re-replicated to healthy nodes, and the compromised node is quarantined pending investigation. The network heals itself faster than an attacker can spread.