Miden Multisig Client

High-level Rust SDK built on top of miden-client for private multisignature workflows on Miden. The crate wraps the on-chain multisig contracts plus Guardian coordination so you can:

• create multisig accounts, register them with a GUARDIAN, and keep state off-chain,
• propose, sign, and execute transactions with threshold enforcement,
• fall back to offline SwitchGuardian workflows when connectivity is limited,
• export/import proposals as files for sharing using side channels,

How Private Multisigs & GUARDIAN Work

Miden multisig accounts store their authentication logic on-chain, but their state (signers, metadata, proposals) is kept private. GUARDIAN acts as a coordination server:

1. A proposer pushes a delta (transaction plan) to Guardian. GUARDIAN tracks who signed and emits an ack signature once the threshold is met.
2. Cosigners fetch pending deltas, verify details locally, sign the transaction summary, and push signatures back to GUARDIAN.
3. Once ready, any cosigner builds the final transaction using all cosigner signatures + the GUARDIAN ack, executes it on-chain.

Installation

Add the crate to your workspace (already available in this repo). From another project:

[dependencies]
miden-multisig-client = { git = "https://github.com/OpenZeppelin/guardian", package = "miden-multisig-client" }

Quick Start

use miden_client::rpc::Endpoint;
use miden_multisig_client::{MultisigClient, TransactionType};
use miden_objects::{Word, account::AccountId};

# async fn example() -> anyhow::Result<()> {
let signer1: Word = /* your RPO Falcon commitment */ Word::default();
let signer2: Word = Word::default();

let mut client = MultisigClient::builder()
    .miden_endpoint(Endpoint::new("http://localhost:57291"))
    .guardian_endpoint("http://localhost:50051")
    // Directory where the underlying miden-client SQLite store will live
    .account_dir("/tmp/multisig")
    // Generate a new Falcon keypair for GUARDIAN authentication (builder can also accept your own key)
    .generate_key()
    .build()
    .await?;

let account = client.create_account(2, vec![signer1, signer2]).await?;
println!("Account registered on GUARDIAN endpoint: {}", client.guardian_endpoint());
# Ok(())
# }

Core Workflow Examples

Propose ➜ Sign ➜ Execute

use miden_multisig_client::TransactionType;
use miden_objects::account::AccountId;

let recipient = AccountId::from_hex("0x7bfb0f38b0fafa103f86a805594170")?;
let faucet = AccountId::from_hex("0x7bfb0f38b0fafa103f86a805594171")?;
let tx = TransactionType::transfer(recipient, faucet, 1_000);

// Proposer creates the delta on GUARDIAN
let proposal = client.propose_transaction(tx).await?;

// Second cosigner lists available proposals and signs the matching one
let proposals = client.list_proposals().await?;
let to_sign = proposals
    .iter()
    .find(|p| p.id == proposal.id)
    .expect("proposal not found");
client.sign_proposal(&to_sign.id).await?;

// Once threshold is met, any cosigner can execute
client.execute_proposal(&proposal.id).await?;

Fallback to Offline (if GUARDIAN unavailable)

If the GUARDIAN endpoint can’t be reached, the SDK can produce an offline proposal only for SwitchGuardian transactions:

use miden_multisig_client::{ProposalResult, TransactionType};

let tx = TransactionType::switch_guardian("https://new-guardian.example.com", new_guardian_commitment);
match client.propose_with_fallback(tx).await? {
    ProposalResult::Online(p) => {
        println!("Proposal {} is live on GUARDIAN", p.id);
    }
    ProposalResult::Offline(exported) => {
        let path = "proposal_offline.json";
        std::fs::write(path, exported.to_json()?)?;
        println!("GUARDIAN unavailable. Share {} with cosigners, collect signatures, then run `execute_imported_proposal` once ready.", path);
    }
}

Fully Offline Signing and Execution

use miden_multisig_client::TransactionType;

let tx = TransactionType::switch_guardian("https://guardian.example.com", new_guardian_commitment);
let mut exported = client.create_proposal_offline(tx).await?;

// Cosigner signs locally
client.sign_imported_proposal(&mut exported).await?;
std::fs::write("proposal_signed.json", exported.to_json()?)?;

// Once enough signatures are collected offline:
client.execute_imported_proposal(&exported).await?;

Listing Notes

List all notes that are currently consumable by the loaded account:

let notes = client.list_consumable_notes().await?;
for note in notes {
    println!("Note {} has {} assets", note.id.to_hex(), note.assets.len());
}

List notes from a specific faucet with a minimum amount filter:

use miden_multisig_client::NoteFilter;

let faucet = AccountId::from_hex("0x7bfb0f38b0fafa103f86a805594170")?;
let filter = NoteFilter::by_faucet_min_amount(faucet, 5_000);
let spendable = client.list_consumable_notes_filtered(filter).await?;

Demo CLI

Run the Terminal UI demo in examples/demo, which exercises the same APIs for account management, note listing, proposal signing, and offline export/import.

Contributions and bug reports are welcome!