blobviem

Need a self custodial, embedded wallet that gives TPM security and requires no backend setup?

blobviem gives you an ETH wallet that is stored inside of a passkey, and can be locked/unlocked during your app!

Support is mostly limited to Safari now, but largeBlob passkeys are in Chrome experimentally, and are gaining popularity.

Changelog

1.10.0:

• Introduced sessionType of passkey or session. (see Quick Start)

  • passkey session: will prompt the user upon all signatures. Does not store the private key in browser storage, only in-memory during signatures.

  • session session: stores the key in sessionStorage, and does not prompt for future signatures.

  NOTE: Both session types persist data in localStorage, and will require your user to log back in if localStorage is cleared.

Quick Start

npm install blobviem

At your index.js / top level component, wrap everything in the provider:

    return 
        <PasskeyContextProvider sessionType='passkey'>
            <App />
        </PasskeyContextProvider>

Next,

In your component, just usePasskey()

    const {account, login, logout, register, generateWallet} = usePasskey();

    return <>
        <h1>{account?.address}</h1> {/* if you're logged in, `account` is a viem account. */}
        <button onClick={() => {
          login();
        }}>Log in</button> {/* shows a passkey login prompt */}

        <button onClick={() => {
          register({appName: "Example"});
        }}>Register</button> {/* shows a new passkey prompt */}

        <button onClick={() => {
          generateWallet();
        }}>Create new wallet</button>  {/* shows a passkey login prompt, specifically for the one made in register() */}
    </>

login

• Login() will prompt an already set-up user to use their existing passkey.

register

• For registration, you should:
  • call register for your user, as the result of some user interaction (button press), and wait for it to finish.
  • after registration completes, call generateWallet from some other user interaction.

Embedded wallets

Embedded wallets are mostly going two routes today: - MPC, with some keyshare carefully stored in the browser, or - AA, with a throwaway EOA held in-browser for signing user operations (relayed to a bundler).

One of the big value-drivers for AA wallets is the support of EIP-7212, a precompile that allows for cheap validation of signatures produced by passkeys.

What if you could provide a passkey wallet without AA?

largeBlob

Authenticators are now starting to support largeBlob storage.

LargeBlob grants a small data-store that can be associated with a passkey. Under the webauthn APIs, the data is guarded by the strongest means available -- on iOS/Mac the secure enclave, on Windows a motherboard TPM, etc.

largeBlob references

• The glitch demo is often linked to as an authoritative demo of the API.
• A specification exists, though most out-of-the-box installations of TypeScript (at time of writing) do not support the types required to interface with largeBlob. This is likely because largeBlob storage support is pretty fragmented.

Supported Platforms

• This stuff works best on Webkit right now.
  • Safari 17+
  • Mobile Safari / iOS 17+
• Experimental support is available via a special launch flag for Chrome.

Caveats

• Support: There is no way to tell, staticaly / ahead-of-time, that a platform doesn't support largeBlob. While we can limit certain browsers that we know don't support this, you really have to perform a runtime credential request to tell authoritatively.

• 2 step registration: generateWallet and register cannot be the same step today, because:

  • You cannot update a largeBlob passkey while creating the passkey, and
  • You cannot show two sequential passkey interactions without two explicit userInteractions.

• Data loss: If you call generateWallet on an existing wallet (i.e sometime after your registration), you will lose the wallet. Only call this one time per wallet, ever.