High level Architecture

The DeRec architecture defines a threshold-based recovery system coordinated through explicit protocol flows between an Owner and a set of Helpers. The design separates secret protection, key material distribution, and recovery orchestration into clearly defined responsibilities.

Protection Phase

During protection, the Owner prepares the Secret for recoverability without exposing it to any Helper. The process is local to the Owner environment.

1. The Owner splits the Secret into n shares using a threshold secret-sharing scheme.

2. Each share is transmitted to a different Helper using protocol-defined secure communication.

Helpers receive and store one share per secret version. The Secret itself is never transmitted to any Helper.

Recovery Phase

Recovery is an explicit protocol-driven process initiated by the Owner. The Owner requests shares from Helpers and reconstructs the Secret once the threshold condition is satisfied.

1. The Owner initiates a recovery session.

2. The Owner requests shares from Helpers.

3. Helpers validate the request according to protocol rules.

4. Helpers return their stored share.

5. Once at least t valid shares are obtained, the Owner reconstructs the Secret locally.

Recovery succeeds only if the number of valid shares retrieved is greater than or equal to the configured threshold.

Threshold Model

Let n be the total number of Helpers and t the recovery threshold. The protocol guarantees that any set of at least t shares can reconstruct the Secret, while any set of fewer than t shares provides no usable information about it. The threshold is defined by the Owner's configuration and determines the balance between availability and resistance to collusion.

Role Separation

The architecture enforces logical separation between roles. The Owner is responsible for share generation, distribution, and Secret reconstruction. Helpers are responsible only for storing and returning their assigned share in accordance with the protocol. No Helper reconstructs the Secret, and no share alone reveals it.

Trust and Security Boundaries

Owner's environment is assumed to be trusted during protection and recovery. Helpers are assumed to operate independently. The security guarantee relies on the threshold model: compromise of fewer than t Helpers does not compromise the Secret. The protocol defines message flows and validation rules to ensure deterministic and interoperable behavior across implementations.

Multi-device extension: Replicas

The architecture extends to multi-device deployments through the replica feature. An Owner identity can be backed by more than one device, with each additional device holding a synchronized copy of the Secret.

• Every paired replica receives every Secret version, kept in sync as the Secret changes.

• From a Helper's perspective, every device in the Owner identity is the same Owner — they all hold the same per-Helper keys delivered inside the Secret.

• Replica devices share the Owner's trust boundary. The protocol does not separate them cryptographically; any replica is operationally equivalent to the Owner.

See the Replicas section in the Concepts chapter for the pair handshake, the synchronization mechanics, and the security implications of treating all replicas as equivalent.