X500DistinguishedName Class

X500DistinguishedName Class

Note: This class is new in the .NET Framework version 2.0.

Represents the distinguished name of an X509 certificate. This class cannot be inherited.

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

public sealed class X500DistinguishedName : AsnEncodedData
public final class X500DistinguishedName extends AsnEncodedData
public final class X500DistinguishedName extends AsnEncodedData

This class is like an extension to the SubjectName or IssuerName property, which is the name of the person or entity that the certificate is being issued to. X.500 is an international standard for distributed directory services. The distinguished name uses the following format:


The following field length limits apply:


Length Limit


2 characters


Up to 64 characters


Up to 32 characters


Up to 64 characters

The following guidelines apply:

  • Field values can be uppercase or lowercase.

  • Delimiters are slash marks (/) and must appear before the first value and between subsequent values.

  • Delimiters can be followed by a space.

The following is an example of a correctly formatted name: [X500:/ C=US/ O=Microsoft/ OU=WGA/ CN=TedSt]

The following code example shows how to use the X500DistinguishedName class.

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

class X500Sample
	static void Main()
			X509Store store = new X509Store("MY", StoreLocation.CurrentUser);
			store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);
			X509Certificate2Collection collection = (X509Certificate2Collection)store.Certificates;
			X509Certificate2Collection fcollection = (X509Certificate2Collection)collection.Find(X509FindType.FindByTimeValid, DateTime.Now, false);
			X509Certificate2Collection scollection = X509Certificate2UI.SelectFromCollection(fcollection, "Test Certificate Select", "Select a certificate from the following list to get information on that certificate", X509SelectionFlag.MultiSelection);
			Console.WriteLine("Number of certificates: {0}{1}", scollection.Count, Environment.NewLine);
			foreach (X509Certificate2 x509 in scollection)
				X500DistinguishedName dname = new X500DistinguishedName(x509.SubjectName);
				Console.WriteLine("X500DistinguishedName: {0}{1}", dname.Name, Environment.NewLine);
		catch (CryptographicException)
			Console.WriteLine("Information could not be written out for this certificate.");



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

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

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

.NET Framework

Supported in: 2.0

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