QUANTUM_COLD_STORAGE

Quantum-safe extreme cold storage on MeshChain

Use case

1. User locks real BTC / SOL / stables in an internet vault (bridge contracts / multisig custodians).
2. Equivalent MESH claims are minted on the Meshtastic ledger.
3. User stores the mesh wallet offline — no Wi‑Fi, no 5G, no cellular modem — only LoRa mesh when they deliberately power a radio.
4. Spending mesh funds or redeeming to BTC/SOL requires physical presence on a mesh + explicit signed action (rare for true cold storage).

Goal: long-term custody where the authorization keys never sit on networks that are continuously reachable (internet / mobile).

Why classical-only is not enough

Algorithm	Quantum threat
ed25519 / secp256k1	Broken by Shor (large enough cryptographically relevant QC)
SHA-256 / BLAKE3	Needs larger outputs under Grover (usually 256-bit still OK with margin)
AES-256	Generally considered OK with PQ (Grover halves bits)

v1 used ed25519 for LoRa size. That is not long-term quantum-safe.
v2 crypto profile: ML-DSA-65 (FIPS 204) for mesh authorization; ed25519 optional hybrid only for transition.

Quantum-safe design (MeshChain v2 profile)

Identity & spend keys

• Primary: ML-DSA-65 keypair generated air-gapped on cold machine.
• Seed / secret never exported over mesh, BLE (except offline companion cable), MQTT, or phone cloud.
• Short id still SHA-256(pubkey)[0..8] (or hash of PQ pubkey) for compact addressing.

Signatures on LoRa

ML-DSA-65 signatures are ~3 KB — do not fit one Meshtastic packet (~200 B payload).

Mechanism	Role
FRAG frames	Split PQ signature (and large pubkeys) across N packets with session id + hash
Spend rarity	Cold storage expects minutes of airtime for one redeem — acceptable
Hybrid mode (optional)	ed25519 + ML-DSA both required until sunset date of classical

Robustness

Layer	Measure
Consensus	≥3 validators, ceil(2N/3) finality, disk persistence
Transport	Private Meshtastic channel; rate limits; dedupe; session reassembly timeouts
Bridge	Unique deposit seq / burn_txid; multi-relayer attestation (M-of-N) before vault release
Cold ops	Paper/metal backup of PQ seed; dual-control for large redeems; vault pause switch
Supply	1:1 or oracle-pegged claims; no silent inflation without mint auth
RF	No dependence on 5G/Wi‑Fi for holding; radio powered only when needed

Extreme cold workflow

[Air-gapped PQ wallet]  --(optional USB)--  [Meshtastic radio ON only for session]
        ^                                              |
        |                                              | LoRa mesh (private)
        |                                              v
   keys never leave                          [Validators / gateway]
   internet-connected phone                          |
                                                     | when redeeming only
                                                     v
                                            [Bridge → BTC/SOL vault unlock]

Holding: radio can stay off for months. Balance is on the ledger; keys are offline.
Receive: someone else sends MESH, or bridge mints after vault deposit — user later syncs headers when they briefly radio-on.
Redeem to internet crypto: burn MESH + multi-packet PQ sig → relayers release vault BTC/SOL to a fresh address.

BTC + SOL vaulting

Asset	Internet side	Mesh side
SOL / SPL stables	Solana mesh_bridge vault program	Mint/Burn MESH
BTC	Multisig / DLCs / federation vault (Liquid optional later)	Same MESH units or asset-tagged claims

MESH can be multi-asset later (asset_id on Mint/Burn). v1 single MESH; cold storage policy maps 1 USDC↔1 MESH or 1 sat claim units.

What “quantum safe” does not mean

• Mesh RF is not invisible; metadata can leak.
• Validators can still censor if compromised.
• Bridge vault smart contracts on Solana/BTC still use classical chain crypto until those L1s migrate — vault long-term should use multisig + watchtowers + eventual PQ migration of custody scripts.
• True “store forever against nation-state QC” requires operational discipline, not only algorithms.

Migration path

1. Now: ed25519 mesh + vault bridge (works, not PQ).
2. v2: ML-DSA-65 mesh spends + FRAG transport; hybrid dual-sign optional.
3. v3: deprecate ed25519; asset-tagged BTC/SOL claims; M-of-N relayers.
4. Parallel: keep vault cold policies (time-locks, multisig) even while L1s are classical.