Username Password Authentication
In your desktop application, you can use the Username/Password flow to acquire a token silently. No UI is required when using the application.
This flow is not recommended because your application asking a user for their password is not secure. For more information about this problem, see this article. The preferred flow for acquiring a token silently on Windows domain joined machines is Integrated Windows Authentication.
If you want to use Username/password, you should really think about how to move away from it. By using username/password you are giving-up a number of things:
- core tenants of modern identity: password gets fished, replayed. Because we have this concept of a share secret that can be intercepted. This is incompatible with passwordless.
- users who need to do MFA won't be able to sign-in (as there is no interaction)
- Users won't be able to do single sign-on
Apart from the Integrated Windows Authentication constraints, the following constraints also apply:
- Available starting with MSAL 2.1.0
- The Username/Password flow is not compatible with conditional access and multi-factor authentication: As a consequence, if your app runs in an Azure AD tenant where the tenant admin requires multi-factor authentication, you cannot use this flow. Many organizations do that.
- It works only for Work and school accounts (not MSA)
- The flow is available on .net desktop and .net core, but not on UWP
More information on using ROPC with B2C.
PublicClientApplicationcontains the method AcquireTokenByUsernamePasswordAsync
The following sample presents a simplified case
static async Task GetATokenForGraph()
{
string authority = "https://login.microsoftonline.com/contoso.com";
string[] scopes = new string[] { "user.read" };
PublicClientApplication app = new PublicClientApplication(clientId, authority);
var accounts = await app.GetAccountsAsync();
AuthenticationResult result = null;
if (accounts.Any())
{
result = await app.AcquireTokenSilentAsync(scopes, accounts.FirstOrDefault());
}
else
{
try
{
var securePassword = new SecureString();
foreach (char c in "dummy") // you should fetch the password
securePassword.AppendChar(c); // keystroke by keystroke
result = await app.AcquireTokenByUsernamePasswordAsync(scopes, "[email protected]",
securePassword);
}
catch(MsalException)
{
// See details below
}
}
Console.WriteLine(result.Account.Username);
}The following sample presents the most current case, with explanations of the kind of exceptions you can get, and their mitigations
static async Task GetATokenForGraph()
{
string authority = "https://login.microsoftonline.com/contoso.com";
string[] scopes = new string[] { "user.read" };
PublicClientApplication app = new PublicClientApplication(clientId, authority);
var accounts = await app.GetAccountsAsync();
AuthenticationResult result = null;
if (accounts.Any())
{
result = await app.AcquireTokenSilentAsync(scopes, accounts.FirstOrDefault());
}
else
{
try
{
var securePassword = new SecureString();
foreach (char c in "dummy") // you should fetch the password keystroke
securePassword.AppendChar(c); // by keystroke
result = await app.AcquireTokenByUsernamePasswordAsync(scopes, "[email protected]",
securePassword);
}
catch (MsalUiRequiredException ex) when (ex.Message.Contains("AADSTS65001"))
{
// Here are the kind of error messages you could have, and possible mitigations
// ------------------------------------------------------------------------
// MsalUiRequiredException: AADSTS65001: The user or administrator has not consented to use the application
// with ID '{appId}' named '{appName}'. Send an interactive authorization request for this user and resource.
// Mitigation: you need to get user consent first. This can be done either statically (through the portal), or dynamically (but this
// requires an interaction with Azure AD, which is not possible with the username/password flow)
// Statically: in the portal by doing the following in the "API permissions" tab of the application registration:
// 1. Click "Add a permission" and add all the delegated permissions corresponding to the scopes you want (for instance
// User.Read and User.ReadBasic.All)
// 2. Click "Grant/revoke admin consent for <tenant>") and click "yes".
// Dynamically, if you are not using .NET Core (which does not have any Web UI) by calling (once only) AcquireTokenAsync interactive.
// remember that Username/password is for public client applications that is desktop/mobile applications.
// If you are using .NET core or don't want to call AcquireTokenAsync, you might want to:
// - use device code flow (See https://aka.ms/msal-net-device-code-flow)
// - or suggest the user to navigate to a URL to consent: https://login.microsoftonline.com/common/oauth2/v2.0/authorize?client_id={clientId}&response_type=code&scope=user.read
// ------------------------------------------------------------------------
// ------------------------------------------------------------------------
// ErrorCode: invalid_grant
// SubError: basic_action
// MsalUiRequiredException: AADSTS50079: The user is required to use multi-factor authentication.
// The tenant admin for your organization has chosen to oblige users to perform multi-factor authentication.
// Mitigation: none for this flow
// Your application cannot use the Username/Password grant.
// Like in the previous case, you might want to use an interactive flow (AcquireTokenAsync()), or Device Code Flow instead.
// Note this is one of the reason why using username/password is not recommended;
// ------------------------------------------------------------------------
// ------------------------------------------------------------------------
// ex.ErrorCode: invalid_grant
// subError: null
// Message = "AADSTS70002: Error validating credentials.
// AADSTS50126: Invalid username or password
// In the case of a managed user (user from an Azure AD tenant opposed to a
// federated user, which would be owned
// in another IdP through ADFS), the user has entered the wrong password
// Mitigation: ask the user to re-enter the password
// ------------------------------------------------------------------------
// ------------------------------------------------------------------------
// ex.ErrorCode: invalid_grant
// subError: null
// MsalServiceException: ADSTS50034: To sign into this application the account must be added to the {domainName} directory.
// or The user account does not exist in the {domainName} directory. To sign into this application, the account must be added to the directory.
// The user was not found in the directory
// Explanation: wrong username
// Mitigation: ask the user to re-enter the username.
// ------------------------------------------------------------------------
}
catch (MsalServiceException ex) when (ex.ErrorCode == "invalid_request")
{
// ------------------------------------------------------------------------
// AADSTS90010: The grant type is not supported over the /common or /consumers endpoints. Please use the /organizations or tenant-specific endpoint.
// you used common.
// Mitigation: as explained in the message from Azure AD, the authority you use in the application needs to be tenanted or otherwise "organizations". change the
// "Tenant": property in the appsettings.json to be a GUID (tenant Id), or domain name (contoso.com) if such a domain is registered with your tenant
// or "organizations", if you want this application to sign-in users in any Work and School accounts.
// ------------------------------------------------------------------------
}
catch (MsalServiceException ex) when (ex.ErrorCode == "unauthorized_client")
{
// ------------------------------------------------------------------------
// AADSTS700016: Application with identifier '{clientId}' was not found in the directory '{domain}'.
// This can happen if the application has not been installed by the administrator of the tenant or consented to by any user in the tenant.
// You may have sent your authentication request to the wrong tenant
// Cause: The clientId in the appsettings.json might be wrong
// Mitigation: check the clientId and the app registration
// ------------------------------------------------------------------------
}
catch (MsalServiceException ex) when (ex.ErrorCode == "invalid_client")
{
// ------------------------------------------------------------------------
// AADSTS70002: The request body must contain the following parameter: 'client_secret or client_assertion'.
// Explanation: this can happen if your application was not registered as a public client application in Azure AD
// Mitigation: in the Azure portal, edit the manifest for your application and set the `allowPublicClient` to `true`
// ------------------------------------------------------------------------
}
catch (MsalServiceException)
{
throw;
}
catch (MsalClientException ex) when (ex.ErrorCode == "unknown_user_type")
{
// Message = "Unsupported User Type 'Unknown'. Please see https://aka.ms/msal-net-up"
// The user is not recognized as a managed user, or a federated user. Azure AD was not
// able to identify the IdP that needs to process the user
throw new ArgumentException("U/P: Wrong username", ex);
}
catch (MsalClientException ex) when (ex.ErrorCode == "user_realm_discovery_failed")
{
// The user is not recognized as a managed user, or a federated user. Azure AD was not
// able to identify the IdP that needs to process the user. That's for instance the case
// if you use a phone number
throw new ArgumentException("U/P: Wrong username", ex);
}
catch (MsalClientException ex) when (ex.ErrorCode == "unknown_user")
{
// the username was probably empty
// ex.Message = "Could not identify the user logged into the OS. See http://aka.ms/msal-net-iwa for details."
throw new ArgumentException("U/P: Wrong username", ex);
}
catch (MsalClientException ex) when (ex.ErrorCode == "parsing_wstrust_response_failed")
{
// ------------------------------------------------------------------------
// In the case of a Federated user (that is owned by a federated IdP, as opposed to a managed user owned in an Azure AD tenant)
// ID3242: The security token could not be authenticated or authorized.
// The user does not exist or has entered the wrong password
// ------------------------------------------------------------------------
}
}
Console.WriteLine(result.Account.Username);
}See Azure Active Directory v2.0 and the OAuth 2.0 resource owner password credential to learn more about the underlying protocol
| Sample | Platform | Description |
|---|---|---|
| active-directory-dotnetcore-console-up-v2 | Console (.NET Core) | .NET Core console application letting a user signed-in with the Azure AD v2.0 endpoint using username/password to acquire a token for the Microsoft Graph 
|
Vanity URL: https://aka.ms/msal-net-up