Authorization and Authentication
Applies to: SharePoint Foundation 2010
Microsoft SharePoint Foundation supports security for user access at the Web site, list, list or library folder, and item levels. Security management is role-based at all levels, providing coherent security management across the SharePoint Foundation platform with a consistent role-based user interface and object model for assigning permissions on objects. As a result, list-level, folder-level, or item-level security implements the same user model as Web site–level security, making it easier to manage user rights and group rights throughout a Web site. SharePoint Foundation also supports unique permissions on the folders and items contained within lists and document libraries.
Authorization refers to the process by which SharePoint Foundation provides security for Web sites, lists, folders, or items by determining which users can perform specific actions on a given object. The authorization process assumes that the user has already been authenticated, which refers to the process by which SharePoint Foundation identifies the current user. SharePoint Foundation does not implement its own system for authentication or identity management, but instead relies solely on external systems, whether Windows authentication or non-Windows authentication.
SharePoint Foundation supports the following types of authentication:
Windows: All Microsoft Internet Information Services (IIS) and Windows authentication integration options, including Basic, Digest, Certificates, Windows NT LAN Manager (NTLM), and Kerberos. Windows authentication allows IIS to perform the authentication for SharePoint Foundation.
For information about signing in to SharePoint by using Windows claims mode, see Incoming Claims: Signing into SharePoint.
Important
For information about suspending impersonation, see Avoiding Suspending Impersonation of the Calling User.
ASP.NET Forms: A non-Windows identity management system that uses the pluggable Microsoft ASP.NET forms-based authentication system. This mode enables SharePoint Foundation to work with a variety of identity management systems, including externally defined groups or roles such as Lightweight Directory Access Protocol (LDAP) and light-weight database identity management systems. Forms authentication allows ASP.NET to perform the authentication for SharePoint Foundation, often involving a redirect to a log-on page. In SharePoint Foundation, ASP.NET forms are supported only under claims authentication. A forms provider must be registered within a Web application that is configured for claims. For information about signing in to SharePoint by using ASP.NET membership and role passive sign-in, see Incoming Claims: Signing into SharePoint.
Note
SharePoint Foundation does not support working with a case-sensitive membership provider. It uses case-insensitive SQL storage for all users in the database, regardless of the membership provider.
Claims-Based Identity and Authentication
The claims-based identity is an identity model in SharePoint Foundation and Microsoft SharePoint Server 2010 that includes features such as authentication across users of Windows-based systems and systems that are not Windows-based, multiple authentication types, stronger real-time authentication, a wider set of principal types, and delegation of user identity between applications.
When a user signs in to SharePoint Foundation and SharePoint Server 2010, the user's token is validated and then used to sign in to SharePoint. The user's token is a security token issued by a claims provider. There are five supported sign-in or access modes in SharePoint Foundation and SharePoint Server 2010:
Windows Classic–Mode Sign-In
Windows Claims–Mode Sign-In
SAML Passive Sign-in Mode
ASP.NET Membership and Role Passive Sign-In
Anonymous Access
Note
For more information about signing into SharePoint and the different sign-in modes, see Incoming Claims: Signing into SharePoint.
When you build claims-aware applications, the user presents an identity to your application as a set of claims. One claim could be the user’s name, another might be an e-mail address. The idea here is that an external identity system is configured to give your application all the information that it needs about the user with each request, along with cryptographic assurance that the identity data received by your application comes from a trusted source.
Under this model, single sign-on is much easier to achieve, and your application is no longer responsible for the following:
Authenticating users
Storing user accounts and passwords
Calling to enterprise directories to look up user identity details
Integrating with identity systems from other platforms or companies
Under this model, your application makes identity-related decisions based on claims supplied by the user. This could be anything from simple application personalization with the user’s first name, to authorizing the user to access higher-value features and resources in your application.
Note
For more information about claims-based identity and claims providers, see Claims-Based Identity Overview and Concepts and Claims Provider.
Forms-Based Authentication
Forms-based authentication provides custom identity management in SharePoint Foundation by implementing a membership provider, which defines interfaces for identifying and authenticating individual users, and a role manager, which defines interfaces for grouping individual users into logical groups or roles. In SharePoint Foundation, a membership provider must implement the required System.Web.Security.Membership.ValidateUser method. Given a user name, the role provider system returns a list of roles to which the user belongs.
The membership provider is responsible for validating the credential information by using the System.Web.Security.Membership.ValidateUser method (required now in SharePoint Foundation). However, the actual user token is created by the security token service (STS). The STS creates the user token from the user name validated by the membership provider and from the set of group memberships associated with the user name that are provided by the membership provider.
Note
For more information about STS, see Claims-Based Identity Overview and Concepts.
The role manager is optional. If a custom authentication system does not support groups, a role manager is not necessary. SharePoint Foundation supports one membership provider and one role manager per URL zone (SPUrlZone). The ASP.NET forms roles have no inherent rights associated with them. Instead, SharePoint Foundation assigns rights to the forms roles through its policies and authorization. In SharePoint Foundation, the forms-based authentication is integrated with the claims-based identity model. If you need additional augmentation to bypass the limit of having one role provider per URL Zone, you can rely on claims providers.
Note
For more information about claims-based identity and claims providers, see Claims-Based Identity Overview and Concepts and Claims Provider.
In ASP.NET membership and role passive sign-in, the sign-in happens by redirecting the client to a Web page where the ASP.NET log-in controls are hosted. After the identity object that represents a user identity is created, SharePoint Foundation 2010 converts it to a ClaimsIdentity object (which represents a claims-based representation of a user).
Note
For more information about signing into SharePoint, see Incoming Claims: Signing into SharePoint.
SharePoint Foundation consumes the standard ASP.NET 2.0 role provider interface to gather group information about the current user. For authentication purposes, roles and groups are the same thing: a way of grouping users into logical sets for authorization. Each ASP.NET role is treated as a domain group by SharePoint Foundation.
For information about the pluggable authentication framework provided by ASP.NET, see New Security Features in ASP.NET 2.0.
Note
For more information about forms-based authentication, see Forms Authentication in SharePoint Products and Technologies (Part 1): Introduction.