How to add a signature using Ledger Nano

Question

I'm trying to add a signature using a Ledger Nano HW wallet but I could not find a question about it. I'm going to research the topic and post a working solution for that.

Answer 1

I managed to do it with the following TypeScript code:

import { Transaction, Keypair, xdr, Network } from 'stellar-sdk'

// import Transport from "@ledgerhq/hw-transport-node-hid"
import Transport from '@ledgerhq/hw-transport-u2f'
import Str from '@ledgerhq/hw-app-str'

export class StellarUtils {
  constructor() {
    Network.use(new Network(environment.stellar.stellarPassphrase))
  }

  async getStrPublicKey(): Promise<string> {
    const isSupported = await this.isSupported()
    if (isSupported) {
      const transport = await Transport.create()
      const str = new Str(transport)
      const result = await str.getPublicKey('44\'/148\'/0\'')
      transport.close()
      return result.publicKey
    } else { throw new Error('Not supported') }
  }

  async signTransaction(transactionXDR: string) {
    const isSupported = await this.isSupported()
    if (isSupported) {
      const transport = await Transport.create()
      const str = new Str(transport)
      const tx = new Transaction(transactionXDR)
      const result = await str.signTransaction('44\'/148\'/0\'', tx.signatureBase())
      const keyPair = Keypair.fromPublicKey(await this.getStrPublicKey())
      const hint = (keyPair as any).signatureHint()
      const decorated = new (xdr as any).DecoratedSignature({ hint: hint, signature: result.signature });
      (tx as any).signatures.push(decorated)
      return tx
    } else { throw new Error('Not supported') }
  }
}