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For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the SAML sign-in experience (user authentication) with Android (Kotlin / Java) and Logto.

Prerequisites

Create an application in Logto​

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Native app application, simply follow these steps:

  1. Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button. Get started
  2. In the opening modal, click the "Native app" section or filter all the available "Native app" frameworks using the quick filter checkboxes on the left. Click the "Android (Kotlin)" / "Android (Java)" framework card to start creating your application. Frameworks
  3. Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Android (Kotlin) / Android (Java) SDK​

tip:

Installation​

note:

The minimum supported Android API level of Logto Android SDK is level 24.

Before you install Logto Android SDK, ensure mavenCentral() is added to your repository configuration in the Gradle project build file:

settings.gradle.kts
dependencyResolutionManagement {
  repositories {
    mavenCentral()
  }
}

Add Logto Android SDK to your dependencies:

build.gradle.kts
dependencies {
  implementation("io.logto.sdk:android:1.1.3")
}

Since the SDK needs internet access, you need to add the following permission to your AndroidManifest.xml file:

AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools">

  <!-- add internet permission -->
  <uses-permission android:name="android.permission.INTERNET" />

  <!-- other configurations... -->
</manifest>

Init LogtoClient​

Create a LogtoViewModel.kt and init LogtoClient in this view model:

LogtoViewModel.kt
//...with other imports
import io.logto.sdk.android.LogtoClient
import io.logto.sdk.android.type.LogtoConfig

class LogtoViewModel(application: Application) : AndroidViewModel(application) {
    private val logtoConfig = LogtoConfig(
          endpoint = "<your-logto-endpoint>",
          appId = "<your-app-id>",
          scopes = null,
          resources = null,
          usingPersistStorage = true,
    )

    private val logtoClient = LogtoClient(logtoConfig, application)

    companion object {
        val Factory: ViewModelProvider.Factory = object : ViewModelProvider.Factory {
            @Suppress("UNCHECKED_CAST")
            override fun <T : ViewModel> create(
                modelClass: Class<T>,
                extras: CreationExtras
            ): T {
                // Get the Application object from extras
                val application = checkNotNull(extras[APPLICATION_KEY])
                return LogtoViewModel(application) as T
            }
        }
    }
}

then, create a LogtoViewModel for your MainActivity.kt:

MainActivity.kt
//...with other imports
class MainActivity : AppCompatActivity() {
    private val logtoViewModel: LogtoViewModel by viewModels { LogtoViewModel.Factory }
    //...other codes
}

Configure redirect URI​

Let's switch to the Application details page of Logto Console. Add a Redirect URI io.logto.android://io.logto.sample/callback and click "Save changes".

Redirect URI in Logto Console

Implement sign-in and sign-out​

note:

Before calling logtoClient.signIn, make sure you have correctly configured Redirect URI in Admin Console.

You can use logtoClient.signIn to sign in the user and logtoClient.signOut to sign out the user.

For example, in an Android app:

LogtoModelView.kt
//...with other imports
class LogtoViewModel(application: Application) : AndroidViewModel(application) {
    // ...other codes

    // Add a live data to observe the authentication status
    private val _authenticated = MutableLiveData(logtoClient.isAuthenticated)
    val authenticated: LiveData<Boolean>
        get() = _authenticated

    fun signIn(context: Activity) {
        logtoClient.signIn(context, "io.logto.android://io.logto.sample/callback") { logtoException ->
            logtoException?.let { println(it) }
            // Update the live data
            _authenticated.postValue(logtoClient.isAuthenticated)
        }
    }

    fun signOut() {
        logtoClient.signOut { logtoException ->
            logtoException?.let { println(it) }
            // Update the live data
            _authenticated.postValue(logtoClient.isAuthenticated)
        }
    }
}

Then call the signIn and signOut methods in your activity:

MainActivity.kt
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        //...other codes

        // Assume you have a button with id "sign_in_button" in your layout
        val signInButton = findViewById<Button>(R.id.sign_in_button)
        signInButton.setOnClickListener {
            logtoViewModel.signIn(this)
        }

        // Assume you have a button with id "sign_out_button" in your layout
        val signOutButton = findViewById<Button>(R.id.sign_out_button)
        signOutButton.setOnClickListener {
            if (logtoViewModel.authenticated) { // Check if the user is authenticated
                logtoViewModel.signOut()
            }
        }

        // Observe the authentication status to update the UI
        logtoViewModel.authenticated.observe(this) { authenticated ->
            if (authenticated) {
                // The user is authenticated
                signInButton.visibility = View.GONE
                signOutButton.visibility = View.VISIBLE
            } else {
                // The user is not authenticated
                signInButton.visibility = View.VISIBLE
                signOutButton.visibility = View.GONE
            }
        }

    }
}

Checkpoint: Test your application​

Now, you can test your application:

  1. Run your application, you will see the sign-in button.
  2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
  3. After you signed in, you will be redirected back to your application and see the sign-out button.
  4. Click the sign-out button to clear token storage and sign out.

Add SAML connector​

To enable quick sign-in and improve user conversion, connect with Android (Kotlin) / Android (Java) as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

  1. Navigate to Console > Connectors > Social Connectors.
  2. Click "Add social connector" and select "SAML".
  3. Follow the README guide and complete required fields and customize settings.

Connector tab

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up Standard SAML app​

Create social IdP's account and register SAML application (IdP)​

Let's go through configurations of SAML connector.

Before we kicking off, you can go to a social identity provider which supports SAML protocol and create your own account. Okta, OneLogin, Salesforce and some other platforms support authentication based on SAML protocol.

If your IdP mandate the encryption of SAML assertion and receiving of signed authentication requests, you should generate your private key and corresponding certificate using RSA algorithm. Keep the private key for your SP use and upload the certificate to IdP.

You also need to configure the ACS (Assertion Consumer Service) URL as ${your_logto_origin}/api/authn/saml/${connector_id} to handle IdP's SAML assertion. Where you can find your connectorId at SAML connector's details page in Logto's Admin Console.

note:

Per current Logto's design, we only support Redirect-binding for sending authentication request and POST-binding for receiving SAML assertion. Although this sounds not cool, but we believe that the current design can handle most of your use cases. If you have any problems, feel free to reach out!

Configure SAML connector (SP)​

In this section, we will introduce each attribute in detail.

entityID Required​

entityID (i.e. issuer) is Entity identifier. It is used to identify your entity (SAML SP entity), and match the equivalence in each SAML request/response.

signInEndpoint Required​

The IdP's endpoint that you send SAML authentication requests to. Usually, you can find this value in IdP details page (i.e. IdP's SSO URL or Login URL).

x509Certificate Required​

The x509 certificate generated from IdPs private key, IdP is expected to have this value available.

The content of the certificate comes with -----BEGIN CERTIFICATE----- header and -----END CERTIFICATE----- tail.

idpMetadataXml Required​

The field is used to place contents from your IdP metadata XML file.

note:

The XML parser we are using does not support customized namespace. If the IdP metadata comes with namespace, you should manually remove them. For namespace of XML file, see reference.

assertionConsumerServiceUrl Required​

The assertion consumer service (ACS) URL is the SP's endpoint to receive IdP's SAML Assertion POST requests. As we mentioned in previous part, it is usually configured at IdP settings but some IdP get this value from SAML authentication requests, we hence also add this value as a REQUIRED field. It's value should look like ${your_logto_origin}/api/authn/saml/${connector_id}.

signAuthnRequest​

The boolean value that controls whether SAML authentication request should be signed, whose default value is false.

encryptAssertion​

encryptAssertion is a boolean value that indicates if IdP will encrypt SAML assertion, with default value false.

note:

The signAuthnRequest and encryptAssertion attributes should align with corresponding parameters of IdP setting, otherwise error will be thrown to show that configuration does not match. All SAML responses need to be signed.

requestSignatureAlgorithm​

This should be aligned with the signature algorithms of IdP so that Logto can verify the signature of the SAML assertion. Its value should be either http://www.w3.org/2000/09/xmldsig#rsa-sha1, http://www.w3.org/2001/04/xmldsig-more#rsa-sha256 or http://www.w3.org/2001/04/xmldsig-more#rsa-sha512 and the default value is http://www.w3.org/2001/04/xmldsig-more#rsa-sha256.

messageSigningOrder​

messageSigningOrder indicates the signing and encrypting order of IdP, it's value should be either sign-then-encrypt or encrypt-then-sign and the default value is sign-then-encrypt.

privateKey and privateKeyPass​

privateKey is an OPTIONAL value and is required when signAuthnRequest is true.

privateKeyPass is the password you've set when creating privateKey, required when necessary.

If signAuthnRequest is true, the corresponding certificate generated from privateKey is required by IdP for checking the signature.

encPrivateKey and encPrivateKeyPass​

encPrivateKey is an OPTIONAL value and is required when encryptAssertion is true.

encPrivateKeyPass is the password you've set when creating encPrivateKey, required when necessary.

If encryptAssertion is true, the corresponding certificate generated from encPrivateKey is required by IdP for encrypting SAML assertion.

note:

For keys and certificates generation, openssl is a wonderful tool. Here is sample command line that might be helpful:

openssl genrsa -passout pass:${privateKeyPassword} -out ${encryptPrivateKeyFilename}.pem 4096
openssl req -new -x509 -key ${encryptPrivateKeyFilename}.pem -out ${encryptionCertificateFilename}.cer -days 3650

privateKey and encPrivateKey files are enforced to be encoded in pkcs1 scheme as pem string, which means the private key files should start with -----BEGIN RSA PRIVATE KEY----- and end with -----END RSA PRIVATE KEY-----.

nameIDFormat​

nameIDFormat is an OPTIONAL attribute that declares the name id format that would respond. The value can be among urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified, urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress, urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName, urn:oasis:names:tc:SAML:2.0:nameid-format:persistent and urn:oasis:names:tc:SAML:2.0:nameid-format:transient, and the default value is urn:oasis:names:tc:SAML:2.0:nameid-format:unspecified.

timeout​

timeout is the time tolerance for time validation, since the time between your SP entity and IdP entity could be different and network connection may also bring some delay. The unit is in millisecond, and the default value is 5000 (i.e. 5s).

profileMap​

Logto also provide a profileMap field that users can customize the mapping from the social vendors' profiles which are usually not standard. Each profileMap keys is Logto's standard user profile field name and corresponding value should be social profiles field name. In current stage, Logto only concern 'id', 'name', 'avatar', 'email' and 'phone' from social profile, only 'id' is REQUIRED and others are optional fields.

Config types​

NameTypeRequiredDefault Value
signInEndpointstringtrue
x509certificatestringtrue
idpMetadataXmlstringtrue
entityIDstringtrue
assertionConsumerServiceUrlstringtrue
messageSigningOrderencrypt-then-sign | sign-then-encryptfalsesign-then-encrypt
requestSignatureAlgorithmhttp://www.w3.org/2000/09/xmldsig#rsa-sha1 | http://www.w3.org/2001/04/xmldsig-more#rsa-sha256 | http://www.w3.org/2001/04/xmldsig-more#rsa-sha512falsehttp://www.w3.org/2001/04/xmldsig-more#rsa-sha256
signAuthnRequestbooleanfalsefalse
encryptAssertionbooleanfalsefalse
privateKeystringfalse
privateKeyPassstringfalse
nameIDFormaturn:oasis:names:tc:SAML:1.1:nameid-format:unspecified | urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress | urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName | urn:oasis:names:tc:SAML:2.0:nameid-format:persistent | urn:oasis:names:tc:SAML:2.0:nameid-format:transientfalseurn:oasis:names:tc:SAML:1.1:nameid-format:unspecified
timeoutnumberfalse5000
profileMapProfileMapfalse
ProfileMap fieldsTypeRequiredDefault value
idstringfalseid
namestringfalsename
avatarstringfalseavatar
emailstringfalseemail
phonestringfalsephone

Reference​

Save your configuration​

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the SAML connector should be available now.

Enable SAML connector in Sign-in Experience​

Once you create a social connector successfully, you can enable it as a "Continue with SAML" button in Sign-in Experience.

  1. Navigate to Console > Sign-in experience > Sign-up and sign-in.
  2. (Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
  3. Add configured SAML connector to the "Social sign-in" section.

Sign-in Experience tab

Testing and Validation​

Return to your Android (Kotlin / Java) app. You should now be able to sign in with SAML. Enjoy!

Further readings​

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.