This documentation is archived and is not being maintained.

HttpWebRequest::ClientCertificates Property

Gets or sets the collection of security certificates that are associated with this request.

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

property X509CertificateCollection^ ClientCertificates {
	X509CertificateCollection^ get ();
	void set (X509CertificateCollection^ value);

Property Value

Type: System.Security.Cryptography.X509Certificates::X509CertificateCollection
The X509CertificateCollection that contains the security certificates associated with this request.


The value specified for a set operation is nullptr.

An application can add a certificate to a collection, but might not have access rights to it. To use a certificate contained in the collection, the application must have the same access rights as the entity that issued the certificate.


The Framework caches SSL sessions as they are created and attempts to reuse a cached session for a new request, if possible. When attempting to reuse an SSL session, the Framework uses the first element of ClientCertificates (if there is one), or tries to reuse an anonymous sessions if ClientCertificates is empty.


For performance reasons, you shouldn't add a client certificate to a HttpWebRequest unless you know the server will ask for it.

For a code example illustrating how to enumerate the certificates in the client certificate store, see the X509Certificate2Collection class.

Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition Platform Note: The Framework attempts to reuse an SSL session only if a client certificate is not required.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.