X509Chain Class

X509Chain Class


Represents a chain-building engine for X509Certificate2 certificates.

Namespace:   System.Security.Cryptography.X509Certificates
Assembly:  System (in System.dll)


public class X509Chain : IDisposable


Initializes a new instance of the X509Chain class.


Initializes a new instance of the X509Chain class specifying a value that indicates whether the machine context should be used.


Initializes a new instance of the X509Chain class using an IntPtr handle to an X.509 chain.


Gets a handle to an X.509 chain.


Gets a collection of X509ChainElement objects.


Gets or sets the X509ChainPolicy to use when building an X.509 certificate chain.


Gets the status of each element in an X509Chain object.


Gets a safe handle for this X509Chain instance.


Builds an X.509 chain using the policy specified in X509ChainPolicy.


Creates an X509Chain object after querying for the mapping defined in the CryptoConfig file, and maps the chain to that mapping.


Releases all of the resources used by this X509Chain.


Releases the unmanaged resources used by this X509Chain, and optionally releases the managed resources.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Clears the current X509Chain object.


Returns a string that represents the current object.(Inherited from Object.)

The X509Chain object has a global error status called ChainStatus that should be used for certificate validation. The rules governing certificate validation are complex, and it is easy to oversimplify the validation logic by ignoring the error status of one or more of the elements involved. The global error status takes into consideration the status of each element in the chain.


Starting with the .NET Framework 4.6, this type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the “Using an Object that Implements IDisposable” section in the IDisposable interface topic.

For apps that target the .NET Framework 4.5.2 and earlier versions, the X509Chain class does not implement the IDisposable interface and therefore does not have a Dispose method.

The following code example opens the current user's personal certificate store, allows you to select a certificate, then writes certificate and certificate chain information to the console. The output depends on the certificate you select.

using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.IO;

class TestX509Chain
	static void Main(string[] args)
		//Create new X509 store from local certificate store.
		X509Store store = new X509Store("MY", StoreLocation.CurrentUser);
		store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadWrite);

		//Output store information.
		Console.WriteLine ("Store Information");
		Console.WriteLine ("Number of certificates in the store: {0}", store.Certificates.Count);
		Console.WriteLine ("Store location: {0}", store.Location);
		Console.WriteLine ("Store name: {0} {1}", store.Name, Environment.NewLine);

		//Put certificates from the store into a collection so user can select one.
		X509Certificate2Collection fcollection = (X509Certificate2Collection)store.Certificates;
		X509Certificate2Collection collection = X509Certificate2UI.SelectFromCollection(fcollection, "Select an X509 Certificate", "Choose a certificate to examine.", X509SelectionFlag.SingleSelection);
		X509Certificate2 certificate = collection[0];
		//Output chain information of the selected certificate.
		X509Chain ch = new X509Chain();
		ch.Build (certificate);
		Console.WriteLine ("Chain Information");
		ch.ChainPolicy.RevocationMode = X509RevocationMode.Online;
		Console.WriteLine ("Chain revocation flag: {0}", ch.ChainPolicy.RevocationFlag);
		Console.WriteLine ("Chain revocation mode: {0}", ch.ChainPolicy.RevocationMode);
		Console.WriteLine ("Chain verification flag: {0}", ch.ChainPolicy.VerificationFlags);
		Console.WriteLine ("Chain verification time: {0}", ch.ChainPolicy.VerificationTime);
		Console.WriteLine ("Chain status length: {0}", ch.ChainStatus.Length);
		Console.WriteLine ("Chain application policy count: {0}", ch.ChainPolicy.ApplicationPolicy.Count);
		Console.WriteLine ("Chain certificate policy count: {0} {1}", ch.ChainPolicy.CertificatePolicy.Count, Environment.NewLine);
		//Output chain element information.
		Console.WriteLine ("Chain Element Information");
		Console.WriteLine ("Number of chain elements: {0}", ch.ChainElements.Count);
		Console.WriteLine ("Chain elements synchronized? {0} {1}", ch.ChainElements.IsSynchronized, Environment.NewLine);

		foreach (X509ChainElement element in ch.ChainElements)
			Console.WriteLine ("Element issuer name: {0}", element.Certificate.Issuer);
			Console.WriteLine ("Element certificate valid until: {0}", element.Certificate.NotAfter);
			Console.WriteLine ("Element certificate is valid: {0}", element.Certificate.Verify ());
			Console.WriteLine ("Element error status length: {0}", element.ChainElementStatus.Length);
			Console.WriteLine ("Element information: {0}", element.Information);
			Console.WriteLine ("Number of element extensions: {0}{1}", element.Certificate.Extensions.Count, Environment.NewLine);

			if (ch.ChainStatus.Length > 1)
				for (int index = 0; index < element.ChainElementStatus.Length; index++)
					Console.WriteLine (element.ChainElementStatus[index].Status);
					Console.WriteLine (element.ChainElementStatus[index].StatusInformation);

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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