X509EnhancedKeyUsageExtension Class

 

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

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

System.Object
  System.Security.Cryptography.AsnEncodedData
    System.Security.Cryptography.X509Certificates.X509Extension
      System.Security.Cryptography.X509Certificates.X509EnhancedKeyUsageExtension

Public NotInheritable Class X509EnhancedKeyUsageExtension
	Inherits X509Extension

NameDescription
System_CAPS_pubmethodX509EnhancedKeyUsageExtension()

Initializes a new instance of the X509EnhancedKeyUsageExtension class.

System_CAPS_pubmethodX509EnhancedKeyUsageExtension(AsnEncodedData, Boolean)

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

System_CAPS_pubmethodX509EnhancedKeyUsageExtension(OidCollection, Boolean)

Initializes a new instance of the X509EnhancedKeyUsageExtension class using an OidCollection and a value that identifies whether the extension is critical.

NameDescription
System_CAPS_pubpropertyCritical

Gets a Boolean value indicating whether the extension is critical.(Inherited from X509Extension.)

System_CAPS_pubpropertyEnhancedKeyUsages

Gets the collection of object identifiers (OIDs) that indicate the applications that use the key.

System_CAPS_pubpropertyOid

Gets or sets the Oid value for an AsnEncodedData object.(Inherited from AsnEncodedData.)

System_CAPS_pubpropertyRawData

Gets or sets the Abstract Syntax Notation One (ASN.1)-encoded data represented in a byte array.(Inherited from AsnEncodedData.)

NameDescription
System_CAPS_pubmethodCopyFrom(AsnEncodedData)

Initializes a new instance of the X509EnhancedKeyUsageExtension class using an AsnEncodedData object.(Overrides X509Extension.CopyFrom(AsnEncodedData).)

System_CAPS_pubmethodEquals(Object)

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

System_CAPS_pubmethodFormat(Boolean)

Returns a formatted version of the Abstract Syntax Notation One (ASN.1)-encoded data as a string.(Inherited from AsnEncodedData.)

System_CAPS_pubmethodGetHashCode()

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

System_CAPS_pubmethodGetType()

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

System_CAPS_pubmethodToString()

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

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

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.

Imports System
Imports System.Security.Cryptography
Imports System.Security.Cryptography.X509Certificates



Module CertSelect

    Sub Main()
        Try
            Dim store As New X509Store("MY", StoreLocation.CurrentUser)
            store.Open(OpenFlags.ReadOnly Or OpenFlags.OpenExistingOnly)

            Dim collection As X509Certificate2Collection = CType(store.Certificates, X509Certificate2Collection)
            Dim i As Integer
            For i = 0 To collection.Count
                Dim extension As X509Extension
                For Each extension In collection(i).Extensions
                    Console.WriteLine(extension.Oid.FriendlyName + "(" + extension.Oid.Value + ")")


                    If extension.Oid.FriendlyName = "Key Usage" Then
                        Dim ext As X509KeyUsageExtension = CType(extension, X509KeyUsageExtension)
                        Console.WriteLine(ext.KeyUsages)
                    End If

                    If extension.Oid.FriendlyName = "Basic Constraints" Then
                        Dim ext As X509BasicConstraintsExtension = CType(extension, X509BasicConstraintsExtension)
                        Console.WriteLine(ext.CertificateAuthority)
                        Console.WriteLine(ext.HasPathLengthConstraint)
                        Console.WriteLine(ext.PathLengthConstraint)
                    End If

                    If extension.Oid.FriendlyName = "Subject Key Identifier" Then
                        Dim ext As X509SubjectKeyIdentifierExtension = CType(extension, X509SubjectKeyIdentifierExtension)
                        Console.WriteLine(ext.SubjectKeyIdentifier)
                    End If

                    If extension.Oid.FriendlyName = "Enhanced Key Usage" Then
                        Dim ext As X509EnhancedKeyUsageExtension = CType(extension, X509EnhancedKeyUsageExtension)
                        Dim oids As OidCollection = ext.EnhancedKeyUsages
                        Dim oid As Oid
                        For Each oid In oids
                            Console.WriteLine(oid.FriendlyName + "(" + oid.Value + ")")
                        Next oid
                    End If
                Next extension
            Next i
            store.Close()
        Catch
            Console.WriteLine("Information could not be written out for this certificate.")
        End Try

    End Sub
End Module

.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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