# Sign In with Device
> **Concepts:** Learn about how [**Sign in with Device**](/features/passwordless-login.md) works.
{% hint style="warning" %}
There are major updates planned for this feature. [Contact us in Slack](https://join.slack.com/t/askcotter/shared_invite/zt-dxzf311g-5Mp3~odZNB2DwYaxIJ1dJA) so we can help you prepare for it.
{% endhint %}
### What you're building
### Import Cotter as a dependency
Add Cotter to your `pubspec.yaml` , then run `flutter pub get`.
```yaml
dependencies:
cotter:
```
Check the latest releases in [pub.dev](https://pub.dev/packages/cotter#-installing-tab-). You may need to restart your flutter for it to run pod install (stop flutter run and re run it).
**For Android**: Update `minSdkVersion` to `18` [following the installation instructions](/sdk-reference/flutter.md).
### Step 1: Import and Initialize Cotter
Import Cotter in your `lib/main.dart`, then initialize it inside `HomePageState`.
```dart
import 'package:cotter/cotter.dart'; // Import Cotter
class HomePageState extends State {
...
// 1️⃣ Initialize Cotter
Cotter cotter = new Cotter(apiKeyID: API_KEY_ID); // 👈 Specify your API KEY ID here
// 2️⃣ TODO: Make Sign Up Function
// 3️⃣ TODO: Make Login Function
@override
Widget build(BuildContext context) { ... }
}
```
You can [create a free account at Cotter](https://dev.cotter.app) to get your `API_KEY_ID`.
{% hint style="info" %}
**Make sure you allow Trusted Devices Method in the** [**dashboard**](https://dev.cotter.app)**.**
{% endhint %}
### Step 2: Make a Sign Up Function
To sign up, call `cotter.signUpWithDevice` and input the user's email. This will create a new user in Cotter and trust the current device to allow logins. This function returns the [User object](/api-reference/user-api/user-object.md).
```dart
// 2️⃣ Make Sign Up Function
void signUp(BuildContext context) async {
try {
// 🚀 One-line Sign Up
// Create a new user in Cotter and trust the current device
var user = await cotter.signUpWithDevice(identifier: inputController.text);
print(user);
} catch (e) {
print(e);
}
}
```
#### (Optional) You can also verify the user's email or phone number at this step
To verify the user's email or phone number, follow this guide **after you've finished this one**.
{% content-ref url="/pages/-MAYBXzMAs8ZfSEUGux-" %}
[Add Email/Phone Verification](/sdk-reference/flutter/sign-in-with-device/add-email-phone-verification.md)
{% endcontent-ref %}
### Step 3: Make a Login Function
To sign in, call `cotter.signInWithDevice` . If the user is logging-in from a device that they trust, they'll automatically be approved. This function returns the [Event object](/api-reference/event-object.md).
```dart
// 3️⃣ Make Login Function
void login(BuildContext context) async {
try {
// 🚀 One-line Login
var event = await cotter.signInWithDevice(identifier: inputController.text, context: context);
print(event);
} catch (e) {
print(e);
}
}
```
#### To get the Logged-in User Info and Access Token, follow this section:
{% content-ref url="/pages/-M9axG8HPu6f\_at6wCcT" %}
[Getting OAuth Tokens](/sdk-reference/flutter/getting-oauth-tokens.md)
{% endcontent-ref %}
{% content-ref url="/pages/-M9awQf5uqyq2X9ZO4JM" %}
[Getting the Logged-in User](/sdk-reference/flutter/getting-the-logged-in-user.md)
{% endcontent-ref %}
#### Logging-in From a Trusted Device
If the user logged-in from a trusted device, their login request will automatically be approved.
#### Logging-in From a Non-Trusted Device
If the user logged-in from a different device that is not trusted, they will be presented with a prompt asking them to approve the login from their trusted phone inside your app. We'll cover this in the next guide.
## Validating Cotter's Access Token
Checkout how to verify the OAuth Tokens from Cotter here:
{% content-ref url="/pages/-M4HZPVawEx2QN3qLmnv" %}
[Verifying JWT Tokens](/getting-access-token/verifying-jwt-tokens.md)
{% endcontent-ref %}
## 🎉 You're done!
### Add Email/Phone Verification
You can also verify your user's email or phone number during the sign up process.
{% content-ref url="/pages/-MAYBXzMAs8ZfSEUGux-" %}
[Add Email/Phone Verification](/sdk-reference/flutter/sign-in-with-device/add-email-phone-verification.md)
{% endcontent-ref %}
### Getting the Logged-in User
Cotter's SDK automatically saves the logged-in user in your device's secure storage. Check out how to get the user information:
{% content-ref url="/pages/-M9awQf5uqyq2X9ZO4JM" %}
[Getting the Logged-in User](/sdk-reference/flutter/getting-the-logged-in-user.md)
{% endcontent-ref %}
### Getting OAuth Tokens
Cotter also automatically generates an `access_token`, `id_token` , and `refresh_token` that is securely stored in the device's secure storage. Check how to get these tokens:
{% content-ref url="/pages/-M9axG8HPu6f\_at6wCcT" %}
[Getting OAuth Tokens](/sdk-reference/flutter/getting-oauth-tokens.md)
{% endcontent-ref %}
---
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```
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