X509Extension.Critical Property

Definition

Namespace:

System.Security.Cryptography.X509Certificates

Assemblies:

netstandard.dll, System.Security.Cryptography.dll

Source:

X509Extension.cs

Gets a Boolean value indicating whether the extension is critical.

C#

public bool Critical { get; set; }

Property Value

Boolean

true if the extension is critical; otherwise, false.

Examples

The following code example demonstrates using the X509Extension class.

C#

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

public class CertSelect
{
    public static void Main()
    {
        try
        {
            X509Store store = new X509Store("MY", StoreLocation.CurrentUser);
            store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);

            X509Certificate2Collection collection = (X509Certificate2Collection)store.Certificates;
            for (int i = 0; i < collection.Count; i++)
            {
                foreach (X509Extension extension in collection[i].Extensions)
                {
                    Console.WriteLine(extension.Oid.FriendlyName + "(" + extension.Oid.Value + ")");

                    if (extension.Oid.FriendlyName == "Key Usage")
                    {
                        X509KeyUsageExtension ext = (X509KeyUsageExtension)extension;
                        Console.WriteLine(ext.KeyUsages);
                    }

                    if (extension.Oid.FriendlyName == "Basic Constraints")
                    {
                        X509BasicConstraintsExtension ext = (X509BasicConstraintsExtension)extension;
                        Console.WriteLine(ext.CertificateAuthority);
                        Console.WriteLine(ext.HasPathLengthConstraint);
                        Console.WriteLine(ext.PathLengthConstraint);
                    }

                    if (extension.Oid.FriendlyName == "Subject Key Identifier")
                    {
                        X509SubjectKeyIdentifierExtension ext = (X509SubjectKeyIdentifierExtension)extension;
                        Console.WriteLine(ext.SubjectKeyIdentifier);
                    }

                    if (extension.Oid.FriendlyName == "Enhanced Key Usage")
                    {
                        X509EnhancedKeyUsageExtension ext = (X509EnhancedKeyUsageExtension)extension;
                        OidCollection oids = ext.EnhancedKeyUsages;
                        foreach (Oid oid in oids)
                        {
                            Console.WriteLine(oid.FriendlyName + "(" + oid.Value + ")");
                        }
                    }
                }
            }
            store.Close();
        }
        catch (CryptographicException)
        {
            Console.WriteLine("Information could not be written out for this certificate.");
        }
    }
}

Remarks

Use this property to designate whether an extension is critical.

Applies to