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Differences between ADAL.NET and MSAL.NET apps

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Migrating your applications from using ADAL to using MSAL comes with security and resiliency benefits. This article outlines differences between MSAL.NET and ADAL.NET. All new applications should use MSAL.NET and the Microsoft identity platform, which is the latest generation of Microsoft Authentication Libraries. Using MSAL.NET, you acquire tokens for users signing-in to your application with Microsoft Entra ID (work and school accounts), Microsoft (personal) accounts (MSA), or Azure AD B2C. If you have an existing application that is using ADAL.NET, migrate it to MSAL.NET.

You still need to use ADAL.NET if your application needs to sign in users with earlier versions of Active Directory Federation Services (ADFS). For more information, see ADFS support.

Prerequisites

Go through MSAL overview to learn more about MSAL.

Differences

ADAL NET MSAL NET
NuGet packages and Namespaces ADAL was consumed from the Microsoft.IdentityModel.Clients.ActiveDirectory NuGet package. The namespace was Microsoft.IdentityModel.Clients.ActiveDirectory. Add the Microsoft.Identity.Client NuGet package, and use the Microsoft.Identity.Client namespace. If you're building a confidential client application, check out Microsoft.Identity.Web.
Scopes and resources ADAL.NET acquires tokens for resources. MSAL.NET acquires tokens for scopes. Several MSAL.NET AcquireTokenXXX overrides require a parameter called scopes(IEnumerable<string> scopes). This parameter is a simple list of strings that declare the permissions and resources that are requested. Well-known scopes are the Microsoft Graph's scopes. You can also access v1.0 resources using MSAL.NET.
Core classes ADAL.NET used AuthenticationContext as the representation of your connection to the Security Token Service (STS) or authorization server, through an Authority. MSAL.NET is designed around client applications. It defines IPublicClientApplication interfaces for public client applications and IConfidentialClientApplication for confidential client applications, as well as a base interface IClientApplicationBase for the contract common to both types of applications.
Token acquisition In public clients, ADAL uses AcquireTokenAsync and AcquireTokenSilentAsync for authentication calls. In public clients, MSAL uses AcquireTokenInteractive and AcquireTokenSilent for the same authentication calls. The parameters are different from the ADAL ones.

In Confidential client applications, there are token acquisition methods with an explicit name depending on the scenario. Another difference is that, in MSAL.NET, you no longer have to pass in the ClientID of your application in every AcquireTokenXX call. The ClientID is set only once when building IPublicClientApplication or IConfidentialClientApplication.
IAccount and IUser ADAL defines the notion of user through the IUser interface. However, a user is a human or a software agent. As such, a user can own one or more accounts in the Microsoft identity platform (several Microsoft Entra accounts, Azure AD B2C, Microsoft personal accounts). The user can also be responsible for one or more Microsoft identity platform accounts. MSAL.NET defines the concept of account (through the IAccount interface). The IAccount interface represents information about a single account. The user can have several accounts in different tenants. MSAL.NET provides better information in guest scenarios, as home account information is provided. You can read more about the differences between IUser and IAccount.
Cache persistence ADAL.NET allows you to extend the TokenCache class to implement the desired persistence functionality on platforms without a secure storage (.NET Framework and .NET core) by using the BeforeAccess, and BeforeWrite methods. For details, see token cache serialization in ADAL.NET. MSAL.NET makes the token cache a sealed class, removing the ability to extend it. As such, your implementation of token cache persistence must be in the form of a helper class that interacts with the sealed token cache. This interaction is described in token cache serialization in MSAL.NET article. The serialization for a public client application (See token cache for a public client application), is different from that of for a confidential client application (See token cache for a web app or web API).
Common authority ADAL uses Azure AD v1.0. https://login.microsoftonline.com/common authority in Azure AD v1.0 (which ADAL uses) allows users to sign in using any Microsoft Entra organization (work or school) account. Azure AD v1.0 doesn't allow sign in with Microsoft personal accounts. For more information, see authority validation in ADAL.NET. MSAL uses Azure AD v2.0. https://login.microsoftonline.com/common authority in Azure AD v2.0 (which MSAL uses) allows users to sign in with any Microsoft Entra organization (work or school) account or with a Microsoft personal account. To restrict sign in using only organization accounts (work or school account) in MSAL, you'll need to use the https://login.microsoftonline.com/organizations endpoint. For details, see the authority parameter in public client application.

Supported grants

Below is a summary comparing MSAL.NET and ADAL.NET supported grants for both public and confidential client applications.

Public client applications

The following image summarizes some of the differences between ADAL.NET and MSAL.NET for a public client application.

Screenshot showing some of the differences between ADAL.NET and MSAL.NET for a public client application.

Here are the grants supported in ADAL.NET and MSAL.NET for Desktop and Mobile applications.

Grant MSAL.NET ADAL.NET
Interactive Acquiring tokens interactively in MSAL.NET Interactive Auth
Integrated Windows authentication Integrated Windows authentication Integrated authentication on Windows (Kerberos)
Username / Password Username-password authentication Acquiring tokens with username and password
Device code flow Device code flow Device profile for devices without web browsers

Confidential client applications

The following image summarizes some of the differences between ADAL.NET and MSAL.NET for a confidential client application.

Screenshot showing some of the differences between ADAL.NET and MSAL.NET for a confidential client application.

Here are the grants supported in ADAL.NET, MSAL.NET, and Microsoft.Identity.Web for web applications, web APIs, and daemon applications.

Type of App Grant MSAL.NET ADAL.NET
Web app, web API, daemon Client Credentials Client credential flows in MSAL.NET Client credential flows in ADAL.NET
Web API On behalf of On behalf of in MSAL.NET Service to service calls on behalf of the user with ADAL.NET
Web app Auth Code Acquiring tokens with authorization codes on web apps with A MSAL.NET Acquiring tokens with authorization codes on web apps with ADAL.NET

Migrating from ADAL 2.x with refresh tokens

In ADAL.NET v2.X, the refresh tokens were exposed allowing you to develop solutions around the use of these tokens by caching them and using the AcquireTokenByRefreshToken methods provided by ADAL 2.x.

Some of those solutions were used in scenarios such as:

  • Long running services that do actions including refreshing dashboards for the users when the users are no longer connected / signed-in to the app.
  • WebFarm scenarios for enabling the client to bring the refresh token to the web service (caching is done client side, encrypted cookie, and not server side).

MSAL.NET doesn't expose refresh tokens for security reasons. MSAL handles refreshing tokens for you.

Fortunately, MSAL.NET has an API that allows you to migrate your previous refresh tokens (acquired with ADAL) into the IConfidentialClientApplication:

/// <summary>
/// Acquires an access token from an existing refresh token and stores it and the refresh token into
/// the application user token cache, where it will be available for further AcquireTokenSilent calls.
/// This method can be used in migration to MSAL from ADAL v2 and in various integration
/// scenarios where you have a RefreshToken available.
/// (see https://aka.ms/msal-net-migration-adal2-msal2)
/// </summary>
/// <param name="scopes">Scope to request from the token endpoint.
/// Setting this to null or empty will request an access token, refresh token and ID token with default scopes</param>
/// <param name="refreshToken">The refresh token from ADAL 2.x</param>
IByRefreshToken.AcquireTokenByRefreshToken(IEnumerable<string> scopes, string refreshToken);

With this method, you can provide the previously used refresh token along with any scopes (resources) you want. The refresh token will be exchanged for a new one and cached into your application.

As this method is intended for scenarios that aren't typical, it isn't readily accessible with the IConfidentialClientApplication without first casting it to IByRefreshToken.

The code snippet below shows some migration code in a confidential client application.

TokenCache userCache = GetTokenCacheForSignedInUser();
string rt = GetCachedRefreshTokenForSignedInUser();

IConfidentialClientApplication app;
app = ConfidentialClientApplicationBuilder.Create(clientId)
 .WithAuthority(Authority)
 .WithRedirectUri(RedirectUri)
 .WithClientSecret(ClientSecret)
 .Build();
IByRefreshToken appRt = app as IByRefreshToken;

AuthenticationResult result = await appRt.AcquireTokenByRefreshToken(null, rt)
                                         .ExecuteAsync()
                                         .ConfigureAwait(false);

GetCachedRefreshTokenForSignedInUser retrieves the refresh token that was stored in some storage by a previous version of the application that used to use ADAL 2.x. GetTokenCacheForSignedInUser deserializes a cache for the signed-in user (as confidential client applications should have one cache per user).

An access token and an ID token are returned in the AuthenticationResult value while the new refresh token is stored in the cache. You can also use this method for various integration scenarios where you have a refresh token available.

v1.0 and v2.0 tokens

There are two versions of tokens: v1.0 tokens and v2.0 tokens. The v1.0 endpoint (used by ADAL) emits v1.0 ID tokens while the v2.0 endpoint (used by MSAL) emits v2.0 ID tokens. However, both endpoints emit access tokens of the version of the token that the web API accepts. A property of the application manifest of the web API enables developers to choose which version of token is accepted. See accessTokenAcceptedVersion in the application manifest reference documentation.

For more information about v1.0 and v2.0 access tokens, see Microsoft Entra access tokens.

Exceptions

Interaction required exceptions

Using MSAL.NET, you catch MsalUiRequiredException as described in AcquireTokenSilent

catch(MsalUiRequiredException exception)
{
 try {"try to authenticate interactively"}
}

For details, see Handle errors and exceptions in MSAL.NET

ADAL.NET had less explicit exceptions. For example, when silent authentication failed in ADAL the procedure was to catch the exception and look for the user_interaction_required error code:

catch(AdalException exception)
{
 if (exception.ErrorCode == "user_interaction_required")
 {
  try
  {“try to authenticate interactively”}}
 }
}

For details, see the recommended pattern to acquire a token in public client applications with ADAL.NET.

Prompt behavior

Prompt behavior in MSAL.NET is equivalent to prompt behavior in ADAL.NET:

ADAL.NET MSAL.NET Description
PromptBehavior.Auto NoPrompt Microsoft Entra ID chooses the best behavior (signing in users silently if they are signed in with only one account, or displaying the account selector if they are signed in with several accounts).
PromptBehavior.Always ForceLogin Resets the sign-in box and forces the user to reenter their credentials.
PromptBehavior.RefreshSession Consent Forces the user to consent again to all permissions.
PromptBehavior.Never Never Don't use; instead, use the recommended pattern for public client apps.
PromptBehavior.SelectAccount SelectAccount Displays the account selector and forces the user to select an account.

Handling claim challenge exceptions

At times when acquiring a token, Microsoft Entra ID throws an exception in case a resource requires more claims from the user (for instance two-factor authentication).

In MSAL.NET, claim challenge exceptions are handled in the following way:

  • The Claims are surfaced in the MsalServiceException.
  • There's a WithClaims(String) method that can apply to the AcquireTokenXXX builders.

For details see Handling MsalUiRequiredException.

In ADAL.NET, claim challenge exceptions were handled in the following way:

  • AdalClaimChallengeException is an exception (deriving from AdalServiceException). The Claims member contains some JSON fragment with the claims, which are expected.
  • The public client application receiving this exception needed to call the AcquireTokenInteractive override having a claims parameter. This override of AcquireTokenInteractive doesn't even try to hit the cache as it isn't necessary. The reason is that the token in the cache doesn't have the right claims (otherwise an AdalClaimChallengeException wouldn't have been thrown). As such, there's no need to look at the cache. The ClaimChallengeException can be received in a WebAPI doing OBO, but the AcquireTokenInteractive needs to be called in a public client application calling this web API.

For details, including samples see handling AdalClaimChallengeException.

Scopes

ADAL uses the concept of resources with resourceId string, MSAL.NET, however, uses scopes. The logic used by Microsoft Entra ID is as follows:

  • For ADAL (v1.0) endpoint with a v1.0 access token (the only possible), aud=resource.
  • For MSAL (v2.0 endpoint) asking an access token for a resource accepting v2.0 tokens, aud=resource.AppId.
  • For MSAL (v2.0 endpoint) asking an access token for a resource accepting a v1.0 access token, Microsoft Entra ID parses the desired audience from the requested scope. This is done by taking everything before the last slash and using it as the resource identifier. As such, if https://database.windows.net expects an audience of https://database.windows.net/, you'll need to request a scope of https://database.windows.net//.default (notice the double slash before ./default). This is illustrated by examples 1 and 2 below.

Example 1

If you want to acquire tokens for an application accepting v1.0 tokens (for instance the Microsoft Graph API, which is https://graph.microsoft.com), you'd need to create scopes by concatenating a desired resource identifier with a desired OAuth2 permission for that resource.

For instance, to access the name of the user via a v1.0 web API whose App ID URI is ResourceId, you'd want to use:

var scopes = new [] { ResourceId+"/user_impersonation" };

If you want to read and write with MSAL.NET Microsoft Entra ID using the Microsoft Graph API (https://graph.microsoft.com/), you'd create a list of scopes like in the code snippet below:

string ResourceId = "https://graph.microsoft.com/"; 
string[] scopes = { ResourceId + "Directory.Read", ResourceId + "Directory.Write" }

Example 2

If resourceId ends with a '/', you'll need to have a double '/' when writing the scope value. For example, if you want to write the scope corresponding to the Azure Resource Manager API (https://management.core.windows.net/), request the following scope (note the two slashes).

var resource = "https://management.core.windows.net/"
var scopes = new[] {"https://management.core.windows.net//user_impersonation"};
var result = await app.AcquireTokenInteractive(scopes).ExecuteAsync();

// then call the API: https://management.azure.com/subscriptions?api-version=2016-09-01

This is because the Resource Manager API expects a slash in its audience claim (aud), and then there's a slash to separate the API name from the scope.

If you want to acquire a token for all the static scopes of a v1.0 application, you'd create your scopes list as shown in the code snippet below:

ResourceId = "someAppIDURI";
var scopes = new [] { ResourceId+"/.default" };

For a client credential flow, the scope to pass would also be /.default. This scope tells to Microsoft Entra ID: "all the app-level permissions that the admin has consented to in the application registration.

Next steps

Migrate your apps from ADAL to MSAL Migrate your ADAL.NET confidential client apps to use MSAL.NET