Relying Party ID (rpId) Setup for Android

Set up the relying party ID (rpId) for passkey authentication in your Android app.

Overview

This guide explains how to set up the relying party ID (rpId) for passkey authentication in your Android app.

1. Create or locate your debug keystore

   Most Android development environments automatically create a debug keystore for you. It is typically located at:

    ~/.android/debug.keystore
   

2. Extract the SHA-256 fingerprint from your debug keystore

   Use the following command to extract the SHA-256 fingerprint:

   keytool -list -v \
       -keystore ~/.android/debug.keystore \
       -alias androiddebugkey \
       -storepass android \
       -keypass android
   

   Look for the line that starts with SHA256: and copy the fingerprint.

3. Create the assetlinks.json file

   Create a file named assetlinks.json with the following content, replacing <YOUR_SHA256_FINGERPRINT> with the fingerprint you extracted in the previous step and <YOUR_PACKAGE_NAME> with your app’s package name:

   [
     {
       "relation": [
           "delegate_permission/common.handle_all_urls",
           "delegate_permission/common.get_login_creds"
       ],
       "target": {
         "namespace": "android_app",
         "package_name": "android.package.name",
         "sha256_cert_fingerprints": [
           "<YOUR_SHA256_FINGERPRINT>"
         ]
       }
     }
   ]
   

   Replace:

   • android.package.name with your actual package name.
   • <YOUR_SHA256_FINGERPRINT> with the SHA-256 fingerprint you obtained earlier.
4. Host the assetlinks.json file

   Host the assetlinks.json file at the following URL on your domain:

   https://<your-domain>/.well-known/assetlinks.json
   

   Ensure that the file is publicly accessible.

   The simplest way to deploy your Digital Asset Links file for local development is to set up a simple static file server and use a tunneling service like ngrok and LiveServer to expose it over HTTPS. For production, you can deploy the file on a platform like Vercel, Netlify, or any static file hosting service that supports HTTPS.

5. Verify the setup

   You can verify that your assetlinks.json file is correctly set up by visiting the following URL in your browser:

   https://<your-domain>/.well-known/assetlinks.json
   

   You should see the contents of your assetlinks.json file. Additionally, you can use online tools to validate your Digital Asset Links setup.

6. Link your app to the domain

   Once the file is publicly available, Android will verify your app’s association with the domain by matching your app’s package name and certificate fingerprint to the values listed in the assetlinks.json file.

   The domain in https://<domain> is your relying party ID (rpId). Ensure that this domain matches the rpId you set in your Turnkey SDK config.