> ## Documentation Index
> Fetch the complete documentation index at: https://docs.turnkey.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Passkey authentication

> Set up and implement passkey authentication using Turnkey's Kotlin SDK.

## Overview

This guide shows how to implement passkey authentication using the Turnkey Kotlin SDK.
You'll add the necessary platform configuration, set up the provider with a proper `rpId`, and call `loginWithPasskey` and `signUpWithPasskey` from your UI.

## Passkey setup

To enable passkeys, you must configure your app's relying party ID (`rpId`) correctly.
For Android, you must configure a Digital Asset Links by setting up an `assetlinks.json` file. Refer to [our relying party setup guide](/sdks/kotlin/authentication/rp-id-setup) and [Google's Documentation](https://developer.android.com/training/app-links/verify-android-applinks).

### 1. Ensure `rpId` is set correctly in your Turnkey SDK initialization

Set the `rpId` to the domain you've associated (for example, `yourdomain.com`). This should match the domain configured in Digital Asset Links.

```kotlin theme={"system"}
package com.example.test_app

import android.app.Application
import com.turnkey.core.TurnkeyContext
import com.turnkey.models.AuthConfig
import com.turnkey.models.TurnkeyConfig

class App : Application() {
    override fun onCreate() {
        super.onCreate()

        TurnkeyContext.init(
            app = this,
            config = TurnkeyConfig(
                // other config params...
                authConfig = AuthConfig(
                    rpId = "<your-rp-id>",
                )
            )
        )
    }
}
```

## Usage

You can now call `loginWithPasskey` and `signUpWithPasskey` from your UI to handle passkey authentication.

### Sign up with passkey

```kotlin theme={"system"}
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.lifecycleScope
import com.turnkey.core.TurnkeyContext
import kotlinx.coroutines.launch

class MainActivity : AppCompatActivity() {
    private val activity = this // Reference to the activity for use in passkey flows

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val button = findViewById<Button>(R.id.button)
        button.setOnClickListener {
            lifecycleScope.launch {
                try {
                    TurnkeyContext.signUpWithPasskey(activity = activity)
                } catch (t: Throwable) {
                    println(t)
                }
            }
        }
    }
}
```

### Log in with passkey

```kotlin theme={"system"}
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.lifecycleScope
import com.turnkey.core.TurnkeyContext
import kotlinx.coroutines.launch

class MainActivity : AppCompatActivity() {
    private val activity = this // Reference to the activity for use in passkey flows

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val button = findViewById<Button>(R.id.button)
        button.setOnClickListener {
            lifecycleScope.launch {
                try {
                    TurnkeyContext.loginWithPasskey(activity = activity)
                } catch (t: Throwable) {
                    println(t)
                }
            }
        }
    }
}
```

## Tips

* Ensure your `rpId` matches the domain configured in your Digital Asset Links otherwise authentication may fail.
* For local testing, the simplest way to deploy a valid Digital Asset Links file is to set up a simple static file server and use a tunneling service like [ngrok](https://ngrok.com/) and [LiveServer](https://marketplace.visualstudio.com/items?itemName=ritwickdey.LiveServer) to expose it over HTTPS.
* For use in `Fragments` you use `requireActivity()` to get the activity reference.

```kotlin theme={"system"}
import android.os.Bundle
import android.view.View
import android.widget.Button
import androidx.fragment.app.Fragment
import androidx.lifecycle.lifecycleScope
import com.example.kotlin_demo_wallet.R
import com.turnkey.core.TurnkeyContext
import kotlinx.coroutines.launch

class MyFragment : Fragment(R.layout.fragment_main) {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {

        val button = view.findViewById<Button>(R.id.button)
        button.setOnClickListener {
            lifecycleScope.launch {
                try {
                    TurnkeyContext.loginWithPasskey(activity = requireActivity())
                } catch (t: Throwable) {
                    println(t)
                }
            }
        }
    }
}
```