The class provides additional context about the underlying transport layer.
Assembly: System (in System.dll)
The class is used with classes in the System.Security.Authentication.ExtendedProtection namespace to provide support for authentication using extended protection for applications.
The design of integrated Windows authentication allows for some credential challenge responses to be universal, meaning they can be re-used or forwarded. If this particular design feature is not needed then the challenge responses should be constructed with, at minimum, target specific information and, at best, also some channel specific information. Services can then provide extended protection to ensure that credential challenge responses contain service specific information (a Service Provider Name or SPN) and, if necessary, channel specific information (a channel binding token or CBT). With this information in the credential exchanges, services are able to better protect against malicious use of credential challenge responses that might have been improperly obtained.
HttpWebRequest is the only class derived from WebRequest class that can potentially use IWA. The FtpWebRequest class does only FTP clear text authentication. The FileWebRequest class doesn't perform any authentication.
There are several ways an application may get a instance. An application that uses SslStream can get the using the TransportContext property. An application that uses HttpWebRequest can get a using the GetRequestStream or EndGetRequestStream methods.
Windows 7, Windows Server 2008 R2
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.