Lifeboat and snapshots

After Q-day, an Ed25519 signature no longer proves who owns a wallet. The Lifeboat gives each holder a second proof that never depended on Ed25519.

The pieces

Piece	Where it lives	What it holds
Lifeboat key	Offline, in the holder’s key file	LM-OTS secret seed, id and public key
Lifeboat account	On-chain, one per wallet	sha256("QARK-LIFEBOAT-v1" ‖ id ‖ public key) and the slot it was set
Snapshot	On-chain, one per coin per epoch	Merkle root of every holder’s wallet, Lifeboat fingerprint and balance

Timeline

1. BoardHolder registers a hash of their Lifeboat key.
2. SnapshotMerkle root of every wallet, fingerprint and balance.
3. Q-dayCanary trips. Boarding and snapshots freeze.
4. RecoverProve the leaf, sign with the Lifeboat key, get reissued.Not built

The last snapshot before Q-day is the record a recovery will be proven against.

1. Before Q-day. Holders board. The fingerprint is a hash, so nothing on-chain helps an attacker.
2. Snapshots. QuantArk posts a Merkle root per coin. Each leaf is sha256(wallet ‖ fingerprint ‖ balance). Wallets without a Lifeboat get an all-zero fingerprint and still appear with their balance.
3. Q-day. The canary trips. Boarding and snapshots freeze, so nothing posted after the break can be trusted or forged into the record.
4. Recovery. A holder proves their leaf against the last snapshot and signs with the Lifeboat key. The balance is reissued on a quantum-safe program or chain.

Step 4 is not built

The recovery claim does not exist yet. Today the Lifeboat records fingerprints and snapshots record balances. The claim, and where balances are reissued, are open design work tracked in Known limits.

Snapshots

• Posted by the QuantArk admin with post_snapshot, one account per coin and epoch.
• The root is computed by an indexer that reads every token account of the coin. The program stores the root, holder count and total.
• Each snapshot must cover every holder. A holder missing from a snapshot would have nothing to prove, so snapshots never use partial holder lists.
• Anyone can rebuild the tree from chain data and check the root. Format in Formats and hashing.

Lifeboat coverage

Each coin page shows how many of its holders have boarded. Higher coverage means more of the coin’s holders can prove ownership after Q-day.