eth-ledger-bridge-keyring

An implementation of MetaMask's Keyring interface, that uses a Ledger hardware wallet for all cryptographic operations.

In most regards, it works in the same way as eth-hd-keyring, but using a Ledger device. However there are a number of differences:

• Because the keys are stored in the device, operations that rely on the device will fail if there is no Ledger device attached, or a different Ledger device is attached.

• It does not support the signMessage, signTypedData or exportAccount methods, because Ledger devices do not support these operations.

• Because extensions have limited access to browser features, there's no easy way to interact wth the Ledger Hardware wallet from the MetaMask extension. This library implements a workaround to those restrictions by injecting (on demand) an iframe to the background page of the extension, (which is hosted here.

The iframe is allowed to interact with the Ledger device (since U2F requires SSL and the iframe is hosted under https) using the libraries from LedgerJS hw-app-eth and hw-transport-u2f and establishes a two-way communication channel with the extension via postMessage.

The iframe code it's hosted in the same repo under the branch gh-pages and it's being served via github pages. In the future we might move it under the metamask.io domain.

Usage

In addition to all the known methods from the Keyring class protocol, there are a few others:

• isUnlocked : Returns true if we have the public key in memory, which allows to generate the list of accounts at any time

• unlock : Connects to the Ledger device and exports the extended public key, which is later used to read the available ethereum addresses inside the Ledger account.

• setAccountToUnlock : the index of the account that you want to unlock in order to use with the signTransaction and signPersonalMessage methods

• getFirstPage : returns the first ordered set of accounts from the Ledger account

• getNextPage : returns the next ordered set of accounts from the Ledger account based on the current page

• getPreviousPage : returns the previous ordered set of accounts from the Ledger account based on the current page

• forgetDevice : removes all the device info from memory so the next interaction with the keyring will prompt the user to connect the Ledger device and export the account information

Testing

Run the following command:

npm test

Attributions

This code was inspired by eth-ledger-keyring and eth-hd-keyring