Security Model

Cryptographic Primitives

Primitive	Algorithm	Usage
Signatures	Ed25519 (ed25519-dalek)	Transaction signing, block signing
Block hashing	SHA-512	Block hash with domain tag "BLK"
Transaction hashing	SHA-256	Signing message hash
State hashing	BLAKE3	State root computation
Storage hashing	Keccak256	Contract storage slot derivation
Compression	snap, lz4	P2P message compression

Transport Security

P2P Layer

• Encryption: libp2p Noise protocol (authenticated encryption)
• Multiplexing: Yamux
• Identity: Ed25519 peer keys
• Max transmit size: 256KB per message

RPC Layer

• TLS: Not terminated by RPC server. Production deployments must use a TLS-terminating reverse proxy.
• CORS: Restricted to localhost origins. Configure allowed origins for production.
• Body limit: 1MB maximum request body.

Rate Limiting

Layer	Limit	Window
Global RPC	200 req/s	1 second sliding window
Per-IP RPC	50 req/s	1 second sliding window
Batch size	100 requests	Per HTTP request
Block hash scan	1000 blocks	Per chain_getBlockByHash call

Input Validation

RPC

• JSON-RPC version must be exactly "2.0"
• Error messages are sanitized before returning to clients
• Internal errors return generic messages (no stack traces or internal formats)
• Mempool rejection details are stripped from error responses

Mempool

• Nonce validation: Sequential nonces required (gap tolerance up to 5000 for burst recovery)
• Balance check: Sender must have sufficient balance for amount + fee
• Signature verification: Ed25519 signature verified before admission
• Quota system: Per-class limits (Financial: 50K, IoT: 100K, Global: 100K)
• Per-sender cap: Maximum 512 pending transactions per sender

Transaction Pipeline

Stateless guards (run first):

1. Signature format validation
2. Ed25519 signature verification
3. Public key → address derivation check

Stateful guards (run after stateless pass):

1. Nonce >= account nonce
2. Balance >= amount + fee
3. Account not blacklisted

Atomic commit: balance deduction and nonce increment happen atomically.

Consensus Security

BFT Quorum

• Quorum: 2f+1 (67%) of validators must sign Block Acceptance Certificate
• Byzantine tolerance: Up to f = (n-1)/3 byzantine nodes
• Certificate verification: Masternodes verify all attestation signatures

PoU Anti-Gaming

• Score smoothing: Exponential moving average prevents score manipulation via transient behavior
• Proposer rotation: After 50 blocks, proposer must step down (prevents monopoly)
• Minimum score threshold: Score < 300 disqualifies from rewards

Election Safety

• Deterministic group IDs: Based on epoch, not wall-clock time (prevents MN disagreement)
• Election deduplication: Only first result per round is committed
• Soft-reject unknown groups: Masternodes warn but continue processing for unknown group IDs

Key Management

SDK Wallet

• Zeroization: Private keys are zeroized on Drop (via zeroize crate)
• No persistence: SDK wallet does not save keys to disk
• HTTPS enforcement: Remote RPC endpoints require HTTPS by default

Faucet

• Round-robin keys: 10 keypairs rotated to prevent nonce contention
• Serialized claims: faucet_lock mutex prevents TOCTOU race conditions
• Claim limits: 5 SAVT per claim, 24-hour cooldown per address

Node Security

Peer Liveness

• Gossipsub keepalive: PoU score sharing publishes via gossipsub to refresh last_seen
• Inactivity timeout: 600 seconds (configurable) before peer removal
• SlowPeer disconnect: Nodes disconnected if gossipsub send queue is saturated

Resource Limits

• Connection handler queue: 50,000 messages (LN + MN)
• Gossipsub mesh: mesh_n=8, mesh_n_high=12, mesh_n_low=4
• Stack size: 8MB to prevent stack overflow
• Memory: Bounded mempool pools with backpressure

Responsible Disclosure

Report security vulnerabilities via the project's responsible disclosure process. Do not file public issues for security bugs.