Add Passage

Add Passage to your Android project

Prerequisites

• A recent version of Android Studio

• Make sure that your project meets these requirements:

  • Targets API level 33 or higher

  • Uses Android 13 or higher

• A device or emulator that meets passkey requirements

• A Passage account (register for free if you haven’t already)

• A Passage app (if you don't have one, learn how to create one here)

If you don't already have an Android project and just want to try out Passage, you can clone our Android Example App.

Step 1: Publish Digital Asset Links file

Google's Digital Asset Links protocol enables an app or website to make public, verifiable statements about other apps or websites.Your website must declare that it is associated with your specific Android app, and declare that it wants to share user credentials in order for passkey authentication to work.

Generate signing certificate fingerprint

To securely associate your website with your Android app, Google requires your Digital Asset Links JSON file to contain the SHA256 fingerprint of your app’s signing certificate.

To get your signing certificate fingerprint, copy and paste this code in your terminal, replacing the placeholder all caps values:

keytool -list -v -keystore PATH_TO_KEYSTORE -alias KEYSTORE_ALIAS -storepass STORE_PASSWORD -keypass KEY_PASSWORD

The output should include something like this:

SHA256: 5C:A2:55:53:25:86:7B:5A:21:82:EE:14:5A:3B:9C:99...

Need help with finding or using your certificate? Learn more here.

Create asset links JSON file

Create a new assetlinks.json file like this one, replacing the YOUR_WEBSITE, YOUR_ANDROID_PACKAGE_NAME, and YOUR_CERT_FINGERPRINT values:

[
 {
    "relation" : [
      "delegate_permission/common.handle_all_urls",
      "delegate_permission/common.get_login_creds"
    ],
    "target" : {
      "namespace" : "web",
      "site" : "https://YOUR_WEBSITE"
    }
  },
 {
    "relation": [
      "delegate_permission/common.handle_all_urls",
      "delegate_permission/common.get_login_creds"
    ],
    "target": {
      "namespace": "android_app",
      "package_name": "YOUR_ANDROID_PACKAGE_NAME",
      "sha256_cert_fingerprints": ["YOUR_CERT_FINGERPRINT"]
    }
  }
]

Note that YOUR_WEBSITE must match your Passage app's auth origin

Publish asset links JSON file

Publish this file to your site’s .well-known/ directory.

Step 2: Register your Android app with Passage

For passkeys to work in any Android app, Google requires the app's "APK key hash" to be set as the relying party's auth origin.

Generate your key hash

To get the key hash from your signing certificate, simply copy and paste this code in your terminal, replacing YOUR_SHA256_FINGERPRINT with the SHA256 fingerprint generated from the previous step:

echo "android:apk-key-hash:$(echo -n YOUR_SHA256_FINGERPRINT | xxd -r -p | base64 | tr -- '+/' '-_' | tr -d '=')"

Which should produce something like:

android:apk-key-hash:eiV7fQqjB85Hdtf2IpIV0ZsldECmDJRX9ajDxafpr

Submit key hash in Passage Console

In Passage Console, you’ll need to submit your android apk key hash in Settings -> General -> Android SDK.

Add your APK key hash in your app's Passage console.

Step 3: Add Passage SDK to your Android app

In your module (app-level) Gradle file (usually <project>/<app-module>/build.gradle), add the Passage dependency like this, and then sync your Android project with Gradle files:

dependencies {
  // ...
  implementation 'id.passage.android:passage:1.0.0'
}

Then in your app’s strings.xml file, copy and past the following, replacing YOUR_APP_ID and YOUR_AUTH_ORIGIN:

<resources>
    //..

    <!-- Required Passage app settings -->
    <string name="passage_app_id">YOUR_APP_ID</string>
    <string name="passage_auth_origin">YOUR_AUTH_ORIGIN</string>
    <string name="asset_statements">
      [{
        \\"include\\": \\"https://@string/passage_auth_origin/.well-known/assetlinks.json\\"
      }]
    </string>

    <!-- Optional Passage app settings -->
    <string name="passage_language">en</string><!-- defaults to en -->
    <string name="use_passage_store">true</string><!-- defaults to true -->

</resources>

Finally, paste the following meta-data into your app’s AndroidManifest.xml:

<manifest ...>
    <application ...>

        <meta-data
          android:name="asset_statements"
          android:resource="@string/asset_statements" />

    </application>
</manifest>

You did it! 🎉

The hard part is over! It's time to Get Started using Passage.