BeginAuthenticateAsServer Method (X509Certificate, Boolean, SslProtocols, Boolean, AsyncCallback, Object)

SslStream.BeginAuthenticateAsServer Method (X509Certificate, Boolean, SslProtocols, Boolean, AsyncCallback, Object)

Called by servers to begin an asynchronous operation to authenticate the server and optionally the client using the specified certificates, requirements and security protocol.

Namespace:  System.Net.Security
Assembly:  System (in System.dll)

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public virtual IAsyncResult BeginAuthenticateAsServer(
	X509Certificate serverCertificate,
	bool clientCertificateRequired,
	SslProtocols enabledSslProtocols,
	bool checkCertificateRevocation,
	AsyncCallback asyncCallback,
	Object asyncState


Type: System.Security.Cryptography.X509Certificates.X509Certificate

The X509Certificate used to authenticate the server.

Type: System.Boolean

A Boolean value that specifies whether the client must supply a certificate for authentication.

Type: System.Security.Authentication.SslProtocols

The SslProtocols value that represents the protocol used for authentication.

Type: System.Boolean

A Boolean value that specifies whether the certificate revocation list is checked during authentication.

Type: System.AsyncCallback

An AsyncCallback delegate that references the method to invoke when the authentication is complete.

Type: System.Object

A user-defined object that contains information about the operation. This object is passed to the asyncCallback delegate when the operation completes.

Return Value

Type: System.IAsyncResult
An IAsyncResult object that indicates the status of the asynchronous operation.


serverCertificate is null.


enabledSslProtocols is not a valid SslProtocols value.


The authentication failed and left this object in an unusable state.


Authentication has already occurred.


Server authentication using this SslStream was tried previously.


Authentication is already in progress.


This object has been closed.


The BeginAuthenticateAsServer method is not supported on Windows 95, Windows 98, or Windows Millennium.


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The asynchronous authentication operation must be completed by calling the EndAuthenticateAsServer method. Typically, the method is invoked by the asyncCallback delegate.

This method does not block while the operation completes. To block until the operation completes, use one of the AuthenticateAsServer method overloads.

For detailed information about using the asynchronous programming model, see Calling Synchronous Methods Asynchronously

If you receive a AuthenticationException, this SslStream is no longer useable. You should close this object and remove all references to it so that it can be collected by the garbage collector.

Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition Platform Note: The BeginAuthenticateAsServer method is not supported.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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.

.NET Framework

Supported in: 3.5, 3.0, 2.0

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