# Authentication

The Sudo Platform allows users to sign in from client apps using various mechanisms. Once signed in, a user obtains authentication tokens (OpenID Connect ID and access tokens) that can be used to access other services within the platform.

## OIDC Federated Sign In

{% hint style="danger" %}
In order to use federated sign in, you must have completed the federated sign in setup for your project by contacting <support@sudoplatform.com>.
{% endhint %}

If you are using an external identity provider that supports [OpenID Connect (OIDC)](https://openid.net/specs/openid-connect-core-1_0.html) standard then Sudo Platform access can be granted via federated sign in. When the user signs into your identity provider they will be federated and authenticated into Sudo Platform via OpenID Connect web flow. The user is not required to sign into your identity provider again until the refresh token expires. The refresh token lifetime can be configured by contacting <support@sudoplatform.com>.

The federated sign in requires the app to be configured with a URL scheme so that the authentication tokens from your identity provider can be passed into your app when the user performs federated sign in via a web view launched by the app. The URL scheme that you set up for your app must match one of the callback and logout URLs configured in the federated sign in configuration. To setup these URLs, contact <support@sudoplatform.com>.

{% hint style="info" %}
If you have more than one URL scheme configured for callback and logout URLs then make sure you edit "sudoplatformconfig.json" file to keep only the URL scheme that's relevant for your app for "signInRedirectUri" and "signOutRedirectUri".
{% endhint %}

> Setting up a URL scheme for iOS app:

{% embed url="<https://developer.apple.com/documentation/uikit/inter-process:communication/allowing:apps:and:websites:to:link:to:your:content/defining:a:custom:url:scheme:for:your:app>" %}

For example, add the following entry in Info.plist file of your app.

```markup
    <key>CFBundleURLTypes</key>
    <array>
        <dict>
            <key>CFBundleURLSchemes</key>
            <array>
                <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
            </array>
        </dict>
    </array>
```

> Setting up a URL scheme for Android app:

{% embed url="<https://developer.android.com/training/app-links/deep-linking>" %}

For example, add the following to your app manifest in the main activity section:

```markup
<intent-filter>
    <action android:name="android.intent.action.VIEW" />
    <category android:name="android.intent.category.DEFAULT" />
    <category android:name="android.intent.category.BROWSABLE" />
    <data android:scheme="com.mycompany.myapp"/>
</intent-filter>
```

> Signing in via federated sign in.

{% tabs %}
{% tab title="Swift" %}

```swift
do {
    let tokens = try await client.presentFederatedSignInUI(presentationAnchor: window)
    // "tokens.idToken" can be used to initialize other service specific clients to authenticate to the backend API.
    // ID token and access token will expire after number of seconds specified in "lifetime".  The tokens will be
    // refreshed automatically or can be manually refreshed by calling the "refreshTokens" API.
} catch {
    // Handle error. An error may be thrown if the backend is unable to perform
    // requested operation due to availability or security issues.
    // An error might be also be thrown for unrecoverable circumstances arising
    // from programmatic error or configuration error. For example, if the keychain
    // access entitlement is not set up correctly or basic system resources are
    // unavailable.
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
// Your main activity must pass the authentication tokens from your
// identity provider into SudoUserClient when the activity is resumed
// via the URL scheme.
override fun onResume() {
    super.onResume()

    val data = this.intent.data
    if (data != null) {
        client.processFederatedSignInTokens(data)
    }
}

// Present the federated sign in UI assuming it's being called from
// an activity.
client.presentFederatedSignInUI(this) { result ->
    when (result) {
        is ApiResult.Success -> {
            // User registered and signed in successfully.        
        }
        is ApiResult.Failure -> {
            // Handle error. A failure result may be returned if the backend is unable
            // perform the registration due to availability or security issues.
        }
    }
}
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
try {
  client.presentFederatedSignInUI()
  // User registered and signed in successfully.
catch (err) {
  // Handle error. A failure result may be returned if the backend is unable
  // perform the registration due to availability or security issues.
}

// In addition to the above, you will need to add code to process the redirect url.
processRedirectUrl = async () => {
  const redirectUrl = window.location.href
  await client.processFederatedSignInTokens(redirectUrl)
}
```

{% endtab %}
{% endtabs %}

{% hint style="success" %}
**See it in action.** Be sure to take a look at the [iOS](https://github.com/sudoplatform/samples-ios) and [Android](https://github.com/sudoplatform/samples-android) sample apps on GitHub, which demonstrate how to use federated sign in.
{% endhint %}

## Custom Federated Sign In

{% hint style="danger" %}
In order to use custom federated sign in, you must have completed the custom federated sign in setup described in the [Registration](https://docs.sudoplatform.com/guides/registration#custom-federated-sign-in) section.
{% endhint %}

In order to sign in using a custom authentication provider, you must invoke `signInWithAuthenticationProvider` API of `SudoUserClient` with your `AuthenticationProvider` implementation as an input similar to how `registerWithAuthenticationProvider` was invoked to register a new Sudo Platform user. For details of `AuthenticationProvider` implementation, please refer to the [Registration](https://docs.sudoplatform.com/guides/registration#custom-federated-sign-in) section and [API Reference](https://docs.sudoplatform.com/guides/users/api-reference).

## Sign In via Private Key

If a user was registered using [Sign in Key Registration](https://docs.sudoplatform.com/guides/registration#registration-via-private-key), they can use the private key from the public/private key pair generated at registration time to digitally sign an authentication token to sign-in.

> To sign-in using private key based authentication:

{% tabs %}
{% tab title="Swift" %}

```swift
do {
    let tokens = try await client.signInWithKey()
    // "tokens.idToken" can be used to initialize other service specific clients to authenticate to the backend API.
    // ID token and access token will expire after number of seconds specified in "lifetime" so use "refreshToken"
    // to refresh these tokens via "refreshTokens" API.
} catch {
    // Handle error. An error may be thrown if the backend is unable to perform
    // requested operation due to availability or security issues.
    // An error might be also be thrown for unrecoverable circumstances arising
    // from programmatic error or configuration error. For example, if the keychain
    // access entitlement is not set up correctly or basic system resources are
    // unavailable.
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
CoroutineScope(Dispatchers.IO).launch {
    try {
        val result = client.signInWithKey()
        // "idToken" can be used to initialize other service specific clients to authenticate to the backend API.
        // ID token and access token will expire after number of seconds specified in "lifetime" so use "refreshToken"
        // to refresh these tokens via "refreshTokens" API.
        println("idToken: ${result.idToken}, accessToken: ${result.accessToken}, refreshToken: ${result.refreshToken}")
    } catch (e: AuthenticationException) {
        // Handle error. A failure result may be returned if the backend is unable
        // to perform the sign in due to availability or security issues.
        println("${e.localizedMessage}")
    }
}
```

{% endtab %}
{% endtabs %}

## Refreshing ID and Access Tokens

Authentication tokens will expire after 1 hour so in order to avoid needing to sign in periodically you should refresh those tokens.

{% hint style="info" %}
Each Sudo Platform client such as Telephony client will automatically refresh ID and access tokens as needed but this will incur a delay in the API call so it is recommended to refresh the tokens at a scheduled interval or on app launch.
{% endhint %}

> To refresh ID and access tokens:

{% tabs %}
{% tab title="Swift" %}

```swift
do {
    let tokens = try await client.refreshTokens(refreshToken: refreshToken)
    // "tokens.idToken" can be used to initialize other service specific clients to authenticate to the backend API.
    // ID token and access token will expire after number of seconds specified in "lifetime" so use "refreshToken"
    // to refresh these tokens via "refreshTokens" API.
} catch {
    // Handle error. An error may be thrown if the backend is unable to perform
    // requested operation due to availability or security issues.
    // An error might be also be thrown for unrecoverable circumstances arising
    // from programmatic error or configuration error. For example, if the keychain
    // access entitlement is not set up correctly or basic system resources are
    // unavailable.
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
CoroutineScope(Dispatchers.IO).launch {
    try {
        val result = client.refreshTokens(refreshToken)
        // "idToken" can be used to initialize other service specific clients to authenticate to the backend API.
        // ID token and access token will expire after number of seconds specified in "lifetime" so use "refreshToken"
        // to refresh these tokens via "refreshTokens" API.
        println("idToken: ${result.idToken}, accessToken: ${result.accessToken}, refreshToken: ${result.refreshToken}")
    } catch (e: AuthenticationException) {
        // Handle error. A failure result may be returned if the backend is unable
        // to perform the sign in due to availability or security issues.
        println("${e.localizedMessage}")
    }
}
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
try {
  const result = await client.refreshTokens(refreshToken)
  // "idToken" can be used to initialize other service specific clients to authenticate to the backend API.
  // ID token and access token will expire at the time indicated in tokenExpiry so use "refreshToken"
  // to refresh these tokens via the "refreshTokens" API.
} catch (err) {
  // Handle error. A failure result may be returned if the backend is unable
  // to perform the sign in due to availability or security issues.
}
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
It is not necessary to perform the sign in again until the refresh token expires as long as the ID token is getting refreshed via the mechanisms mentioned above. It is the consumer's responsibility to perform the sign in at a fixed interval or reactively when `notAuthorized` error is returned from a platform service client API call. The default expiry for refresh token is 30 days.
{% endhint %}

## Sign Out

> To sign out a user:

{% tabs %}
{% tab title="Swift" %}

```swift
do {
    try await client.globalSignOut()
} catch {
    // Handle error. An error may be thrown if the backend is unable to perform
    // requested operation due to availability or security issues.
    // An error might be also be thrown for unrecoverable circumstances arising
    // from programmatic error or configuration error. For example, if the keychain
    // access entitlement is not set up correctly or basic system resources are
    // unavailable.
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
CoroutineScope(Dispatchers.IO).launch {
    try {
        client.globalSignOut()
        // Sign out successful.
    } catch (e: SignOutException) {
        // Handle error. A failure result may be returned if the backend is unable
        // perform the sign out due to availability or security issues.
        println("${e.localizedMessage}")
    }
}
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
try {
  await client.globalSignOut()
  // Sign out successful.  
} catch (err) {
  // Handle error. A failure result may be returned if the backend is unable
  // to perform the sign out due to availability or security issues.     
}
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
Sign out will invalidate authentication tokens from all devices regardless of the sign in method used. For the current device, all tokens will be invalidated immediately but on other devices the API access will still be granted to up to the lifetime of ID token. The ID token lifetime is 1 hour by default but this can be changed by submitting a support request.
{% endhint %}

> To invalidate authentication tokens for a single device.

{% tabs %}
{% tab title="Swift" %}

```swift
do {
    try client.signOut()
} catch {
    // Handle error. An error might be thrown for unrecoverable circumstances arising
    // from programmatic error or configuration error. For example, if the keychain
    // access entitlement is not set up correctly, the client is not signed in,
    // or basic system resources are unavailable.
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
client.clearAuthTokens()
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
client.clearAuthenticationTokens()
```

{% endtab %}
{% endtabs %}

> Sign out from hosted UI for OIDC federated sign in.

{% tabs %}
{% tab title="Swift" %}

```swift
do {
    try await client.presentFederatedSignOutUI(presentationAnchor: window)
} catch {
    // Handle error. An error may be thrown if the backend is unable to perform
    // requested operation due to availability or security issues.
    // An error might be also be thrown for unrecoverable circumstances arising
    // from programmatic error or configuration error. For example, if the keychain
    // access entitlement is not set up correctly or basic system resources are
    // unavailable.
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
client.presentFederatedSignOutUI { result ->
    when (result) {
        is ApiResult.Success -> {
            // User signed out successfully.        
        }
        is ApiResult.Failure -> {
            // Handle error. A failure result may be returned if the backend is unable
            // perform the sign out due to availability or security issues.
        }
    }
}
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
client.presentSignOutUI()
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
This will invalidated any cached information from the web session used to contact Sudo Platform but does not invalidate any authentication tokens. You can call `clearAuthTokens` or `globalSignOut` subsequently to either invalidate authentication tokens from the current device or sign out the user from all devices.
{% endhint %}