Tuvali - A library to send vc/vp using BLE.

This is the module for the OpenID for Verifiable Presentations over BLE implementation to support sending vc/vp using Bluetooth Low Energy local channel.

Usage as a Swift library (for native ios)

• Add the github link as a spm package dependency in swift project.
• Select the appropriate branch/version.

API documentation

Firstly, for establishing the secured connection over BLE the Verifier's URI needs to be exchanged between two devices. The exchange of URI can be accomplished, but is not limited to, by using a QR code.

For example use QR code generator to visually display URI and QR code scanner to read. A mobile app that displays a QR code can act as an Verifier by including its URI as data in the QR code and another device can act as Wallet which scans the QR code, it can extract the URI and initiate a BLE connection with the advertising device.

URI Exchange and Establishing Connection

Verifier

The Verifier device generates a URI using the startAdvertisement() method and displays it as a QR code. Once the advertisement starts, the Verifier continuously advertises with a payload derived from the URI.

URI contains:

OPENID4VP://connect?name=STADONENTRY&key=8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a

URI structure can be found in the spec. Currently the library doesnot support iOS as a verifier.But it can act as a wallet for android verifier.

Wallet

Start Connection

The Wallet device scans the QR code, extracts the URI, and starts scanning using the startConnection method.

class Wallet:WalletProtocol {
  
 
  func startConnection(_ uri: String) {
    // Implementation for starting the connection
  }

End Connection

The device on which app is running can destroy the connection by calling disconnect method:

 func disconnect() {
   // Implementation for disconnecting
 }

Share Data

Once the connection is established, Wallet can send the data by:

  func sendData(_ payload: String) {
    // Implementation for sending data
  }
}

Wallet will start sending data in a secured way to the Verifier. Note: At this moment, we currently support data transfer from Wallet to Verifier only.

Usage:

Start Connection

import ios_tuvali_library

var wallet=Wallet()
wallet.startConnection(uri, resolver: { result in
  print("Connection started: \(result)")
}, rejecter: { code, message, error in
  print("Error starting connection: \(message)")
})

Disconnect

import ios_tuvali_library

var wallet=Wallet()
wallet.disconnect(resolver: { result in
  print("Disconnected: \(result)")
}, rejecter: { code, message, error in
  print("Error disconnecting: \(message)")
})

Send Data

import ios_tuvali_library

let payload = "your-data-here"
var wallet=Wallet()
wallet.sendData(payload, resolver: { result in
  print("Data sent: \(result)")
}, rejecter: { code, message, error in
  print("Error sending data: \(message)")
})

Events

Tuvali sends multiple events to propagate connection status, received data etc. These events can be subscribed to by calling:

Wallet Events

WalletModule.handleDataEvents { 
// implementation
}

Common Events

Events which are emitted by both Wallet and Verifier

1. ConnectedEvent
   • on BLE connection getting established between Wallet and Verifier
2. SecureChannelEstablishedEvent
   • on completion of key exchange between Wallet and Verifier
3. ErrorEvent
   • on any error in Wallet or Verifier
4. DisconnectedEvent
   • on BLE disconnection between Wallet and Verifier

Note

Currently, data transfer is supported from Wallet to Verifier only. Verifier functionalities are not available for iOS at the moment.