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Version: 0.14 (unstable)

Miden Guardian

Miden Guardian is a system built by OpenZeppelin that allows Miden accounts to back up and sync their private state securely without trust assumptions about other participants or the server operator.

The problem​

Miden's execution model requires clients to manage their own private state — accounts, notes, storage — locally on-device. While this provides strong privacy and scalability, it introduces real challenges:

  • Solo-account users risk losing access if local state is not backed up. Losing any part of the account state means losing access to the account itself.
  • Shared-account users risk having stale state due to a faulty or malicious participant withholding updates.
  • Multi-device users need all devices to see the same account state, but there is no public ledger to read from.

On a public chain, the ledger is a universally readable source of truth — every device and every signer can independently observe the latest state. In Miden's private account model, the canonical state is defined by the on-chain commitment, but it isn't readable in a way that keeps devices and signers automatically up to date. The coordination surface moves off-chain.

What Guardian provides​

Guardian addresses these challenges by acting as an off-chain coordination layer:

  • Backup and recovery — Account state is stored on Guardian, recoverable even if a device is lost.
  • Multi-device sync — Multiple devices push and pull state through Guardian, staying in sync with the latest canonical state.
  • Multi-party coordination — Shared accounts use delta proposals to coordinate threshold signing across participants.
  • Integrity verification — Every state change is validated against the Miden network and acknowledged with a cryptographic signature.

Guardian is non-custodial. The provider cannot move funds unilaterally — it stores state and coordinates changes, but users retain cryptographic control over their accounts at all times.

Learn more​

📄️ Architecture

How Guardian fits between clients and the Miden network.

📄️ Data Structures

State, deltas, commitments, and delta proposals.

📄️ Components

API, authentication, storage, and other server components.

📄️ Security

Trust model, integrity guarantees, and edge cases.

📄️ Operator Guide

How to run, deploy, and troubleshoot a Guardian server.

📄️ Private Multisig

Multi-party threshold signature workflows powered by Guardian.

Repository​