X509EnhancedKeyUsageExtension Class

Definition

Namespace:

System.Security.Cryptography.X509Certificates

Assemblies:

netstandard.dll, System.Security.Cryptography.dll

Source:

X509EnhancedKeyUsageExtension.cs

Defines the collection of object identifiers (OIDs) that indicates the applications that use the key. This class cannot be inherited.

C#

public sealed class X509EnhancedKeyUsageExtension : System.Security.Cryptography.X509Certificates.X509Extension

Inheritance

Object

AsnEncodedData

X509Extension

X509EnhancedKeyUsageExtension

Examples

The following code example demonstrates how to open a user's personal certificate store and display information about each certificate in the store. This example uses the X509EnhancedKeyUsageExtension class to display the information.

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

An enhanced key usage (EKU) extension is a collection of object identifiers (OIDs) that indicate the applications that use the key.

Constructors

X509EnhancedKeyUsageExtension()	Initializes a new instance of the X509EnhancedKeyUsageExtension class.
X509EnhancedKeyUsageExtension(AsnEncodedData, Boolean)	Initializes a new instance of the X509EnhancedKeyUsageExtension class using an AsnEncodedData object and a value that identifies whether the extension is critical.
X509EnhancedKeyUsageExtension(OidCollection, Boolean)	Initializes a new instance of the X509EnhancedKeyUsageExtension class using an OidCollection and a value that identifies whether the extension is critical.

Properties

Critical	Gets a Boolean value indicating whether the extension is critical. (Inherited from X509Extension)
EnhancedKeyUsages	Gets the collection of object identifiers (OIDs) that indicate the applications that use the key.
Oid	Gets or sets the Oid value for an AsnEncodedData object. (Inherited from AsnEncodedData)
RawData	Gets or sets the Abstract Syntax Notation One (ASN.1)-encoded data represented in a byte array. (Inherited from AsnEncodedData)

Methods

CopyFrom(AsnEncodedData)	Initializes a new instance of the X509EnhancedKeyUsageExtension class using an AsnEncodedData object.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Format(Boolean)	Returns a formatted version of the Abstract Syntax Notation One (ASN.1)-encoded data as a string. (Inherited from AsnEncodedData)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

Applies to