What is adal in office 365?

Modern authentication in Exchange Online enables authentication features like multi-factor authentication (MFA), smart cards, certificate-based authentication (CBA), and third-party SAML identity providers. Modern authentication is based on the Active Directory Authentication Library (ADAL) and OAuth 2.0.

When you enable modern authentication in Exchange Online, Windows-based Outlook clients that support modern authentication (Outlook 2013 or later) use modern authentication to connect to Exchange Online mailboxes. For more information, see How modern authentication works for Office client apps.

When you disable modern authentication in Exchange Online, Windows-based Outlook clients that support modern authentication use basic authentication to connect to Exchange Online mailboxes. They don't use modern authentication.

Notes:

In the Microsoft 365 admin center, go to Settings > Org Settings > Modern Authentication. In the Modern authentication flyout that appears, click to enable or disable Turn on modern authentication for Outlook 2013 for Windows and later (recommended).

This article introduces Modern Authentication (which is based on the Active Directory Authentication Library (ADAL) and OAuth 2.0) that can be found in the March 2016 Cumulative Update for Skype for Business for Skype for Business Server 2015, or from initial release for Skype for Business Server 2019.

ADAL is the acronym for the 'Active Directory Authentication Library', and, along with OAuth 2.0, it is an underpinning of Modern Authentication. This code library is designed to make secured resources in your directory available to client applications (like Skype for Business) via security tokens. ADAL works with OAuth 2.0 to enable more authentication and authorization scenarios, like Multi-factor Authentication (MFA), and more forms of SAML Auth.

A variety of apps that act as clients can leverage Modern Authentication for help in getting to secured resources. In Skype for Business Server, this technology is used between on-premises clients and on-premises servers in order to give users a proper level of authorization to resources.

Modern Authentication conversations (which are based on ADAL and OAuth 2.0) have some elements in common.

In Skype for Business Server Modern Authentication (ADAL) conversations, Skype for Business Server communicates through ADFS (ADFS 3.0 in Windows Server 2012 R2). The authentication may happen using some other Identity Provider (IdP), but Skype for Business server needs to be configured to communicate with ADFS, directly. If you haven't configured ADFS to work with Skype for Business Server please complete the ADFS installation.

ADAL is included in the March 2016 Cumulative Update for Skype for Business Server 2015, and the March 2016 Cumulative Update for Skype for Business must be installed and is needed for successful configuration. For Skype for Business Server 2019, it is available from initial release of the product.

A PowerShell package including .ps1 files with the commands used by ADAL must be downloaded for successful configuration.

ADAL enables sign-in features such as Multi-Factor Authentication (MFA), smart card, and certificate-based authentication for Office client apps across different platforms. Furthermore, on Windows devices, some of the security-related features are available exclusively via WAM and are otherwise not possible.

• Open the Regedit application as the client.
• Go to “Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity.”
• Verify if there is a DWORD value named “EnableADAL” that is set to 0.
• Update the DWORD value for “EnableADAL” to 1.
• Select OK.