MultiSig Connect

MultiSig Connect is the browser extension component of MultiSig — a non-custodial Sui blockchain multisig console built by the SuiSec team (@suisecurity).

The extension presents Sui multisig wallets as standard Wallet Standard accounts to any dApp, letting multisig teams use DEXes, NFT platforms, governance portals, and any other Sui dApp without requiring the dApp to add special multisig support. Transactions initiated in a dApp are captured and routed to the MultiSig web app for threshold approval.

Holds no keys. Never signs. Every signing request from a dApp is captured and parked for multisig approval — the extension itself has zero signing ability and zero private-key material.

Key properties

• Zero signing capability. The extension holds no private keys and cannot sign anything. A fully compromised extension gives an attacker nothing to exploit — there is no signing material to steal.
• No network access. The extension has no host_permissions and makes zero independent network requests. All multisig data flows in from the trusted MultiSig web app via origin-validated postMessage → chrome.storage. It cannot exfiltrate data and cannot be used as a network pivot.
• Works with any Sui dApp — no dApp changes required. MultiSig Connect presents each multisig as a standard Wallet Standard account. DEXes, lending protocols, NFT platforms, governance portals — if a Sui dApp supports wallets, it works with multisig without modification.
• Every captured transaction is security-analysed before signing. In the companion MultiSig web app, each co-signer independently decodes the raw transaction bytes and runs a local dry-run simulation against live Sui chain state before committing a signature. No blind approvals, no relay-provided descriptions taken on trust.
• Free and requires no registration. Install the extension, connect your Sui wallet at multisig.suisec.app, and go.

Why this extension exists

A Sui multisig address is a valid on-chain account, but signing for it requires multiple members to coordinate partial signatures — something no ordinary browser wallet can do inline. Without this extension, a multisig team has to manually copy transaction bytes out of a dApp and into a coordination tool. MultiSig Connect eliminates that step: it injects the multisig as a wallet the dApp recognises, intercepts the signing request, and parks it as a pending proposal in the MultiSig web app for members to review and threshold-sign.

This means any Sui multisig can interact with the full Sui ecosystem — swaps, lending, staking, governance — without the dApp needing to know it is a multisig.

How it works

• Injects a Wallet Standard wallet into every dApp page, exposing each multisig the connected wallet belongs to as a ReadonlyWalletAccount.
• When a dApp asks the "wallet" to sign, the request is intercepted and forwarded (via postMessage) to the companion web app, where multisig members approve it with their own wallets. The dApp sees the request as parked, not signed here.
• Multisig data is pushed in by the web app (postMessage → chrome.storage). The extension never contacts any backend/relay on its own — it has no host_permissions and makes no network requests.

Security model

• No keys, no signing in the extension.
• No backend access: zero relay/API host permissions; data flows only from the trusted web app via origin-checked postMessage.
• The companion web app's origin is validated (event.origin) before any data is accepted into storage.
• Even if the extension were fully compromised, there are no keys and no signing capability to exploit.

Part of the MultiSig product

This extension is one component of the MultiSig product by SuiSec:

Component	Purpose
Web app	Create multisig wallets, propose and sign transactions, publish and verify Move packages
Browser extension (this repo)	Present multisig wallets to any Sui dApp; capture and park signing requests
Relay (api.suisec.app)	Non-custodial coordination: stores proposals and partial signatures, never holds keys

MultiSig is free to use and requires no account registration — connect your wallet and go.

Configuration

lib/config.ts holds the defaults:

• webAppUrl — the companion web app that performs approval and pushes data in.
• network — mainnet | testnet.

Development

Requires Bun and Node ≥ 20.12 (the build toolchain uses node:util styleText). Building with Bun's runtime avoids the Node version requirement:

bun install
bun run --bun build      # production build → output/chrome-mv3
bun run --bun zip        # packaged zip for the Chrome Web Store
bun run dev              # live-reload development

Load the unpacked extension from output/chrome-mv3 in chrome://extensions (Developer mode → Load unpacked).

Install manually (from a Release)

While the Chrome Web Store listing is in review, you can install the extension from a GitHub Release:

1. Download the .zip from the latest Release.
2. Unzip it — you'll get a folder containing manifest.json.
3. Open chrome://extensions, enable Developer mode (top right).
4. Click Load unpacked and select the unzipped folder.

Manually loaded extensions get a random extension ID and do not auto-update. Once the Web Store listing is live, prefer installing from there.

License

Apache-2.0