Workflow customization

Workflow in Inji is achieved by finite-state machine components. State machines are written using a library called xstate. All the state machines are available in the machines folder of the Inji codebase. There are few machines under the screens folder but these are too specific to those features.

Here is a list of state machines and their responsibilities. The developers can choose to use the existing state machine components and customize the workflow as per their needs.

app.ts

This is the root state machine for the application. On initialisation, it starts other state machines from:

• store.ts

• auth.ts

• vc.ts

• settings.ts

• activityLog.ts

• requestMachine.ts

• scanMachine.ts

• revoke.ts

store.ts

This state machine takes care of actions related to storing and retrieving data on the mobile phone. It exposes the wrapper to all the other state machines to work with data stored on the device.

It also performs the custom encryption and decryption required for saving and retrieving data from the underlying store.

As of now, the store state machine uses following two libraries which abstracts how the data is stored between iOS and Android:

• react-native-mmkv-storage - stores all the meta information and references of the encrypted VC.

• react-native-fs - stores the encrypted VC as a separate file,

auth.ts

This state machine helps to set up authentication for the application. It allows users to choose between biometric and passcode-based authentication on the first launch. It also updates the app state as authorized or unauthorized based on user action on first launch.

On first launch, once the user selects language preference, and goes through intro sliders, user has been asked to choose the unlock method.

After selecting the unlock method as passcode or biometric, the user is navigated to Home screen Once user is on home screen, app state is considered as authorized. Once a user logs out from settings, the state is considered as unauthorized.

vc.ts

This state machine takes care of the VC received in Inji as a Wallet or Verifier. When Inji is being used as a Wallet, all the user-downloaded VCs are displayed on the Home screen.

It also keeps track of sharing VC over BLE. When Inji is being used as a Verifier, all received VCs are displayed under the Received Card option in Settings.

ExistingMosipVCItemMAchine.ts

This state machine takes care of VC downloaded via UIN/VID. This contains all the activities/state related to VC like:

• downloading VC

• sending the event to the store machine to store the VC

• activate VC

• uses the events from vc.ts

• verifies the credentials once received

After a request is made to download a new VC, an event will be sent to this state machine. It will internally check if VC is "ISSUED" successfully, then initiate VC download. It also takes care of retrying in case there is any issue during the download.

Any new feature for a VC is to be added to this state machine.

EsignetMosipVCItemMachine.ts

This state machine takes care of VC downloaded via eSignet. This contains all the activities/state related to VC like:

• downloading VC

• sending the event to the store machine to store the VC

• activate VC

• uses the events from vc.ts

issuersMachine.ts

This state machine manages the entire OpenID4VCI flow. The issuer state machine calls the endpoints /issuers and /issuers/<issuer_name> to display the list of issuers in the user interface, as well as downloads and caches the issuer's configuration. It also performs the following actions:

• OIDC authorization using react-native-app-auth library

• generating key-pairs for OpenID4VCI flow

• download credential

• verify the verifiable credential

• store the verifiable credential

settings.ts

This state machine helps to show contents and interactions on the settings screen of the application. This facilitates options like language switch, enable/disable biometric unlock etc.

activityLog

This state machine helps to view the audit log of the different activities on the application and shows it on a separate screen. Some of the activities that are shown are VC download, VC receive, VC sent events etc.

requestMachine.ts

This state machine is instantiated when the user launches the verification section which displays the QR code. This QR is generated with content from a low-level offline VC-sharing component. The content of the QR code is scanned by a wallet Inji application to establish connection with verifier and share the VC credential. Once the VC is received on the Verifier side, the state machine allows seeing the received VC details as well for Verification.

scanMachine.ts

This state machine is instantiated when the user launches the scanner section which opens up the camera to scan the QR code presented by the Verifier. The scanned data is fed into the underlying offline VC sharing component to allow the discovery of the Verifier device and establish a connection to it. Once the connection is established, the user is allowed to select the downloaded VCs that can be shared with Verifier. The state machine also allows selfie/face verification before sharing VC.

revoke.ts

Note: This feature is currently disabled in Inji but underlying support for code is available.

A unique ID can be revoked using Inji. For example, if the resident has used a VID to generate VCs and no longer wishes to use the VID, then it can be disabled. This state machine will communicate with the backend service to disable the VC.

QrLoginMachine.ts

This state machine facilitates flow for Login with QR code through Open ID connect from various portals. This is launched when the user opens up the scanner and scans a QR code from a website that supports login with Inji. Once the scan is performed, the user can review the required claims and select voluntary claims to be submitted. Once the submission is done successfully, the portal will be able to redirect automatically and logs the user in.

pinInput.ts

This is a utility state machine which is used to facilitate PIN/OTP login wherever required in the application.

faceSanner.ts

This is a state machine which facilitates the interactions to face scanning. It is used to support face authentication in Login with a QR code, sharing with selfies flow.

biometrics.ts

This state machine facilitates toggling biometric unlock on/off settings screen. This also allows setting up and using biometric unlock for the application.