Concepts

MPC mental model

Blockchain Kit uses a multi-party computation model: a usable signing key is never stored as a single recoverable secret on one device.

At a high level:

1. Key material is split across participants.
2. Participants cooperate for signing operations.
3. The final signature is produced without recombining a full private key in one place.

This improves resilience against single-device compromise and accidental key export.

Unlock vs signing

Two separate concerns are easy to confuse:

• Unlock strategy (Passkey, PIN, Password) controls local protection and user authentication.
• MPC signing protocol controls distributed signing and threshold participation.

Changing unlock method does not change the core MPC security model.

Backup model

Backups are wrapper-based and intended for controlled recovery, not key export. Treat recovery artifacts as highly sensitive operational assets and enforce strict access control, auditability, and rotation.