Tier System

Overview

LockBox gates advanced features behind four service tiers. The active tier is set in the node configuration and applies globally to all assets managed by that service instance.

Capability Matrix

Shard Copies

Higher tiers store multiple encrypted copies of each real shard, each encrypted under a different HKDF-derived key. This provides redundancy against storage corruption. In the current implementation, copies are stored locally with distinct key contexts; geographic distribution across separate storage backends is planned but not yet implemented.

Decoy Shards

The decoy ratio determines how many fake shards are mixed in per real shard. A ratio of 1.0 means one decoy per real shard; 2.0 means two decoys per real shard. See Shard Indistinguishability for the full model.

Multi-Sig

Premium and Elite tiers allow a lock to be co-signed by multiple addresses. The MultiSigAddresses field on a LockedAsset lists the co-signer addresses; MinSignatures sets the threshold. At unlock time, the service verifies that at least MinSignatures valid Ed25519 signatures over the asset ID are present in the unlock request.

CreateMultiSig (the gRPC endpoint for establishing a multi-sig group independently of a lock) is not yet implemented and returns codes.Unimplemented.

Emergency Unlock

Available on Premium and Elite. Emergency unlock bypasses LockScript evaluation and proceeds directly to shard recovery after verifying the Groth16 ownership proof. It is rate-limited per tier and intended for loss-of-key recovery scenarios.

Checking Tier Capabilities in Code

caps := service.GetCapabilities(config.Tier)
 
if caps.MultiSigSupported {
    // validate multi-sig
}
 
if caps.EmergencyUnlock {
    // allow emergency path
}
 
for copy := 0; copy < caps.ShardCopies; copy++ {
    storeShardCopy(shard, copy)
}