Microsoft announced today that it has added a preview version of multi-factor authentication capabilities to Windows Azure, helping secure access to Office 365, Windows Azure, Windows Intune, Dynamics CRM Online and any other solutions that integrate with Windows Azure Active Directory (WAAD). The capability comes via a new Azure service called Active Authentication.

According to Microsoft, Active Authentication works by adding an extra step to the sign in process. After a user enters their username and password, they are required to also authenticate with the Active Authentication app on their mobile device or via an automated phone call or text message.  This helps prevent unauthorized access to data and applications in the cloud – reducing the risk of a breach and enabling regulatory compliance.

If you’re familiar with the two-step authentication feature Microsoft added to its Microsoft account this year, you get the idea. (If not, please read Enable and Use Two-Step Authentication with Your Microsoft Account for more information.)

Of course, as a service for businesses, Active Authentication is tailored for the specific needs of that market. It offers the following capabilities:

Rapid set up. To enable multi-factor authentication, add the Active Authentication service to your Windows Azure AD tenant and turn it on for your users. (You can also add the service to your custom applications using just a few lines of code.)

Automated enrollment. WAAD users enroll their own phone numbers and set authentication preferences during the standard sign in process. There are no tokens to provision and ship, Microsoft says, so you can quickly enable the service for users around the globe.

Scalable. Active Authentication is “reliable and scalable and supports high-volume, mission critical applications and large-scale employee, partner, and customer deployments,” according to Microsoft.

It’s also not free. Active Authentication $1.00 per user per month or $1.00 for every 10 authentications during the current preview time period. Prices at launch will be $1.50 per user per month or $1.50 for every 10 authentications.

For more technical information about Active Authentication, check out Windows Azure Active Authentication: Multi-Factor for Security and Compliance at the Active Directory Team Blog.