MPC Threshold-Signature Custody

A signing request fanned across t-of-n key-share holders — no party ever holds a whole key

MPC Threshold-Signature Custody A signing request fanned across t-of-n key-share holders — no party ever holds a whole key Requester · wallet / app · Architecture component Requester wallet / app MPC Coordinator · holds no key · Architecture component MPC Coordinator holds no key Policy Engine · quorum + limits · Architecture component · 2-of-3 Policy Engine quorum + limits 2-of-3 Signer A · share 1/3 · Architecture component Signer A share 1/3 Signer B · share 2/3 · Architecture component Signer B share 2/3 Signer C · share 3/3 · Architecture component Signer C share 3/3 Signature Assembly · combine partials · Architecture component Signature Assembly combine partials Chain RPC · broadcast tx · Architecture component Chain RPC broadcast tx signed tx Legend External Backend Security

Security

  • • Full private key is never assembled
  • • 2-of-3 shares produce a valid signature
  • • One compromised share cannot sign alone

Operations

  • • Coordinator orchestrates, holds no key material
  • • Policy quorum and limits gate every request
  • • Shares run in separate trust domains