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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 iOS (Swift) 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 "iOS (Swift)" framework card to start creating your application. Frameworks
  3. Enter the application name, e.g., "Bookstore," and click "Create application".

πŸŽ‰ 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 iOS (Swift) SDK​

Add Logto SDK as a dependency​

Use the following URL to add Logto SDK as a dependency in Swift Package Manager.

https://github.com/logto-io/swift.git

Since Xcode 11, you can directly import a Swift package w/o any additional tool.

We do not support Carthage and CocoaPods at the time due to some technical issues.

Carthage​

Carthage needs a xcodeproj file to build, but swift package generate-xcodeproj will report a failure since we are using binary targets for native social plugins. We will try to find a workaround later.

CocoaPods​

CocoaPods does not support local dependency and monorepo, thus it's hard to create a .podspec for this repo.

Init LogtoClient​

Initialize the client by creating a LogtoClient instance with a LogtoConfig object.

ContentView.swift
import Logto
import LogtoClient

let config = try? LogtoConfig(
endpoint: "<your-logto-endpoint>", // E.g. http://localhost:3001
appId: "<your-app-id>"
)
let client = LogtoClient(useConfig: config)
info:

By default, we store credentials like ID Token and Refresh Token in the Keychain. Thus the user doesn't need to sign in again when he returns.

To turn off this behavior, set usingPersistStorage to false:

let config = try? LogtoConfig(
// ...
usingPersistStorage: false
)

Sign in​

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

  1. Your app invokes the sign-in method.
  2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
  3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in​

  1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
  2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.


Configure redirect URI​

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

Redirect URI in Logto Console
info:

The Redirect URI in iOS SDK is only for internal use. There's NO NEED to add a Custom URL Scheme until a connector asks.

Sign-in and sign-out​

note:

Before calling .signInWithBrowser(redirectUri:), make sure you have correctly configured Redirect URI in Admin Console.

You can use client.signInWithBrowser(redirectUri:) to sign in the user and client.signOut() to sign out the user.

For example, in a SwiftUI app:

ContentView.swift
struct ContentView: View {
@State var isAuthenticated: Bool

init() {
isAuthenticated = client.isAuthenticated
}

var body: some View {
VStack {
if isAuthenticated {
Button("Sign Out") {
Task { [self] in
await client.signOut()
isAuthenticated = false
}
}
} else {
Button("Sign In") {
Task { [self] in
do {
try await client.signInWithBrowser(redirectUri: "${
props.redirectUris[0] ?? 'io.logto://callback'
}")
isAuthenticated = true
} catch let error as LogtoClientErrors.SignIn {
// error occured during sign in
} catch {
// other errors
}
}
}
}
}
}
}

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 iOS (Swift) 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 iOS (Swift) 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.